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Environmental Science and Biology for Engineers

Unit 2 10 hr

Strategies and Technology-based solutions for Improvement of Environment Quality:

Environment quality objectives and ‗Waste challenge‘ in modern society - types of waste:

municipal, agricultural, medicinal, E-waste, industrial. Engineering ethics, 3 R‘s – Reduce,

Reuse & Recycle, and Sustainable waste management: Compacting, drying, dewatering, bio-

drying, composting, bioremediation, biodegradation (chemicals and oil spillage). Waste to

energy – energy recovery by incineration, bio-gasification, gasification and pyrolysis,

bioconversion to clean energy (biofuels). Some examples: Upflow anaerobic sludge blanket

(UASB) digestion for waste water treatment and biogas production. Technology to reduce

pollution: SO2/CO2 reduction by smoke-scrubber in coal thermal plants, chlorofluorocarbon

(CFC) and incandescent bulb replacement, Renewable energy sources – wind, solar, tidal waves

and biomass. Emerging technologies: Geo-engineering - ocean iron fertilization, green cement,

bioremediation by terminator insects and synthetic biology.

Unit 2

Strategies and Technology-based solutions for Improvement of Environment Quality: 10 hrs

1. Environment quality: Objectives and ‘Waste challenge’ in modern society.

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2. Types of waste: Municipal, Agricultural, Medicinal, E-waste, Industrial.

What is Solid Waste?

"Wastes are materials that are not prime products (that is products produced for the market) for which the initial

user has no further use in terms of his/her own purposes of production, transformation or consumption, and of

which he/she wants to dispose. Wastes may be generated during the extraction of raw materials, the processing of

raw materials into intermediate and final products, the consumption of final products, and other human activities.

Residuals recycled or reused at the place of generation are excluded." Solid wastes are any discarded (abandoned or

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considered waste-like) materials. Solid wastes can be solid, liquid, semi-solid or containerized gaseous material.

Types of solid waste

Solid waste can be classified into different types depending on their source:

1. Municipal,

2. Agricultural,

3. Medicinal,

4. E-waste,

5. Industrial.

Municipal Solid Waste,

Municipal solid waste (MSW), commonly known as trash or garbage (US), refuse or rubbish (UK) is a waste

type consisting of everyday items that are discarded by the public.

Municipal solid waste consists of household waste, construction and demolition debris, sanitation residue,

and waste from streets. This garbage is generated mainly from residential and commercial complexes. With rising

urbanization and change in lifestyle and food habits, the amount of municipal solid waste has been increasing rapidly

and its composition changing. In 1947 cities and towns in India generated an estimated 6 million tonnes of solid

waste, in 1997 it was about 48 million tonnes. More than 25% of the municipal solid waste is not collected at all; 70%

of the Indian cities lack adequate capacity to transport it and there are no sanitary landfills to dispose of the waste.

The existing landfills are neither well equipped or well managed and are not lined properly to protect against

contamination of soil and groundwater.

Over the last few years, the consumer market has grown rapidly leading to products being packed in cans,

aluminium foils, plastics, and other such nonbiodegradable items that cause incalculable harm to the environment.

In India, some municipal areas have banned the use of plastics and they seem to have achieved success. For

example, today one will not see a single piece of plastic in the entire district of Ladakh where the local authorities

imposed a ban on plastics in 1998. Other states should follow the example of this region and ban the use of items

that cause harm to the environment. One positive note is that in many large cities, shops have begun packing items

in reusable or biodegradable bags. Certain biodegradable items can also be composted and reused. In fact proper

handling of the biodegradable waste will considerably lessen the burden of solid waste that each city has to tackle.

There are different categories of waste generated, each take their own time to degenerate (as illustrated in

the table below).

The type of litter we generate and the approximate time it takes to

degenerate

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Type of litter Approximate time it takes to

degenerate the litter

Organic waste such as vegetable and

fruit peels, leftover foodstuff, etc.

a week or two.

Paper 10–30 days

Cotton cloth 2–5 months

Wood 10–15 years

Woolen items 1 year

Tin, aluminium, and other metal items

such as cans

100–500 years

Plastic bags one million years?

Glass bottles undetermined

Hazardous waste/Industrial Waste

A waste or combination of wastes of a solid, liquid, contained gaseous, or semisolid form which may cause,

or contribute to, an increase in mortality or an increase in serious irreversible, or incapacitating reversible illness,

taking into account the toxicity of such waste, its persistence and degradability in nature, its potential for

accumulation or concentration in tissue, and other factors that may otherwise cause or contribute to adverse acute

or chronic effects on the health of persons or other organisms.

Waste exhibiting one or more of the following four characteristics is considered hazardous:

Toxicity.

Corrosivity.

Ignitability.

Reactivity.

Toxicity: Waste that exhibits the Toxicity Characteristic (TC) poses a substantial threat to human health and the

environment. Waste toxicity is measured by using the Toxicity Characteristic Leaching Procedure (TCLP) (40 CFR

261.24). The TCLP extract is analyzed for lead (or other constituents) to determine if it is above or below the

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allowable TC regulatory threshold, which for lead is 5 ppm (milligrams/ liter).

“Leachable” lead analysis differs from “total” lead analysis, which is typically performed on paint chips during

a risk assessment or inspection, in that leachable lead is dependent on the type of lead compound present and the

size of the particle (that is, its solubility). Because total lead analysis does not determine the specific lead compound

present, it is difficult, if not impossible, to predict how much of the lead will be leachable. Therefore, XRF or paint-

chip analysis (by the usual hot nitric acid digestion/ atomic absorption spectroscopy methods) are unlikely to help

determine leachability. The total lead levels determined by a paint-chip analysis are usable in two circumstances:

total lead level that is very low (e.g., less than 100 ppm), indicates that waste should not exceed the TC regulatory threshold; and

total lead levels can be used in combination with total waste volume estimates to determine whether recycling for lead recovery is feasible.

Corrosivity: Corrosive waste has a pH that is either less than or equal to 2 (highly acidic) or greater than or equal to

12.5 (highly basic), or which can corrode steel at a certain rate (40 CFR 261.22). Unneutralized caustic paint strippers

and acidic paint strippers (including the resulting sludge) may be corrosive.

Ignitability: Ignitable waste generally includes liquids with flash points below 140°F (60°C), flammable solids and

compressed gases, and oxidizers (40 CFR 261.21). Certain solvents from paint strippers (e.g., xylene) and the

resulting sludge or slurry waste may be ignitable.

Reactivity: Lead-based paint hazard control projects are unlikely to produce reactive waste. Reactive waste includes

substances that are capable of easily generating explosive or toxic gases, especially when mixed with water (40 CFR

261.23). These also include waste that is unstable and undergoes violent change without detonating.

Agricultural Expanding agricultural production has naturally resulted in increased quantities of livestock waste, agricultural crop

residues and agro-industrial by-products. Following Table provides an estimate of annual production of agricultural waste

and residues in some selected countries in the region (ESCAP 1997). Among the countries in the Asian and Pacific Region,

People‘s Republic of China produces the largest quantities of agriculture waste and crop residues followed by India. In

People‘s Republic of China, some 587 million tonnes of residues are generated annually from the production of rice, corn

and wheat alone (see Figure 8.5). Figure 8.6 illustrates the proportions of waste that Malaysia generates from the production

of rice, palm oil, rubber, coconut and forest products (ESCAP 1997). In Myanmar, crop waste and residues amount to some

4 million tonnes per year (of which more than half constitutes rice husk), whilst annual animal waste production is about 28

million tonnes with more than 80 per cent of this coming from cattle husbandry.

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In Pakistan, about 56.22 million tonnes of different crop residues are generated of which 12.46 million tonnes originate

from cotton, 2.90 million tonnes from maize, 12.87 million tonnes from sugarcane, 8.16 million tonnes from rice and 19.83

million tonnes from wheat. In addition, Pakistan produces other wastes amounting to some 28 million tonnes of which 58

per cent is animal waste, 40 per cent is sugarcane bagasse and the remaining two per cent comprises a mix of jute sticks,

mustard stalks, sesame sticks, castor seed stalks, sunflower stalks and tobacco stalks (ESCAP 1997).

In Sri Lanka, agricultural waste comprises animal waste, paddy husk, straw, coir fibre and coir dust, bagasse, as well as

the waste from the timber industry, which comprises sawdust, off-cuts and charcoal. Commercial rice milling generates

around 2 million tonnes of paddy husk per annum, whilst coir (the fibres from coconut husks) processing generates an

annual 700 000 tonnes of coir dust (ESCAP 1997). Each year, Thailand produces about 4.6 million tonnes of paddy husk, 35

million tonnes of rice straw, 7 million tonnes of bagasse and more than 25 million tonnes of animal waste (ESCAP 1997).

Other countries such as Australia, Cambodia, Japan, Lao People‘s Democratic Republic, Nepal, New Zealand, Republic of

Korea, Viet Nam and Small Island States in the South Pacific also generate huge quantities of agricultural waste and

residues (ESCAP 1997, UNEP/SREP 1997). Medicinal,

What are Biomedical wastes?

Biomedical wastes are defined as waste that is generated during the diagnosis, treatment or immunization of human

beings or animals, or in research activities pertaining thereto, or in the production of biological.

What are biodegradable and non biodegradable wastes?

Biodegradable waste means any waste that is capable of undergoing anaerobic or aerobic decomposition, such as

food and garden waste, and paper and paperboard. It also includes waste from households, which because of its

nature and composition is similar to biodegradable waste from households.

Non biodegradable wastes are the wastes that cannot be decomposed by bacteria e.g plastics, bottles and tins.

What is the quantum of waste that is generated by a hospital?

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The quantum of waste that is generated in India is estimated to be 1-2 kg per bed per day in a hospital and 600 gm

per day per bed in a general practioner’s clinic. e.g. a 100 bedded hospital will generate 100 – 200 kgs of hospital

waste/day. It is estimated that only 5 – 10% of this comprises of hazardous/infectious waste (5 – 10kgs/day)

What are the hazards associated with poor health care waste management?

Proper disposal of biomedical waste is of paramount importance because of its infectious and hazardous

characteristics. Improper disposal can result in the following:

· Organic portion ferments and attracts fly breeding

· Injuries from sharps to all categories of health care personnel and waste handlers

· Increase risk of infections to medical, nursing and other hospital staff

· Injuries from sharps to health workers and waste handlers

· Poor infection control can lead to nosocomial infections in patients particularly HIV, Hepatitis B & C

· Increase in risk associated with hazardous chemicals and drugs being handled by persons handling wastes

· Poor waste management encourages unscrupulous persons to recycle disposables and disposed drugs for

repacking and reselling

· Development of resistant strains of microorganisms

What are the rules and regulations governing the disposal of these wastes?

The Government of India has promulgated the Biomedical Waste (Management and Handling) Rules 1998. They are

applicable to all persons who generate, collect, receive, store, transport, treat, dispose or handle biomedical wastes.

This includes hospitals, nursing homes, clinics, dispensaries, veterinary institutions, animal houses, pathological

laboratories and blood banks.

What are the responsibilities of health care institutions regarding biomedical waste management?

It is mandatory for such institutions to:

Set up biomedical waste treatment facilities like incinerators, autoclave and microwave systems for

treatment of the wastes

Make an application to the concerned authorities for grant of authorization

Submit a report regarding information about the categories and quantities of biomedical wastes handled

during the preceding year by 31 Jan every year

Maintain records about the generation, collection, reception, storage, transportation, treatment, disposal

and/or any form of handling bio medical waste

Report immediately any accident to the prescribed authority

What are the different hospital waste categories?

Category Type of Waste Treatment and Disposal Options

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Category 1 Human Anatomical Waste (Human tissues,

organs, body parts) Incineration/Deep Burial

Category 2

Animal waste (Animal tissues, organs,

body parts, carcasses, bleeding

parts,blood and experimental animals

used in research)

Incineration/Deep Burial

Category 3

Microbiology and biotechnology

waste(waste from lab culture, specimens

from microorganisms, vaccines, cell

cultures, toxins, dishes, devices used to

transfer cultures)

Local Autoclaving/ Microwaving/ Incineration

Category 4 Waste Sharps (Needles, Syringes, scalpels,

blades, glass)

Chemical Disinfection Autoclaving/

Microwaving, Mutilation and Shredding

Category 5

Discarded medicines and cytotoxic drugs

(outdated, contaminated, discarded

drugs)

Incineration/Destruction and disposal in land

fills

Category 6

Soiled waste (contaminated with blood

and body fluids including cotton,

dressings, soiled plasters, linen)

Autoclaving/ Microwaving/ Incineration

Category 7 Solid waste (tubes, catheters, IV sets) Chemical Disinfecion/Autoclaving/

Microwaving, Mutilation and Shredding

Category 8

Liquid waste (Waste generated from

laboratory and washing, cleaning,

disinfection)

Disinfection by chemical treatment and

discharge into the drains

Category 9 Incineration ash Land fills

Category 10 Chemical waste Chemical disinfection and discharge into the

drains

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E-waste,

"Electronic waste" may be defined as discarded computers, office electronic equipment, entertainment device electronics, mobile

phones, television sets, and refrigerators. The EU defines this new waste stream as ‗Waste Electrical and Electronic

Equipment‘ (WEEE). Since there is no definition of the WEEE in the environmental regulations in India, it is simply

called ‗e-waste‘. E-waste or electronic waste, therefore, broadly describes loosely discarded, surplus, obsolete, broken,

electrical or electronic devices4. This definition includes used electronics which are destined for reuse, resale, salvage, recycling, or disposal.

Composition of E-waste

E-waste consists of all waste from electronic and electrical appliances which have reached their end- of- life period or

are no longer fit for their original intended use and are destined for recovery, recycling or disposal. It includes

computer and its accessoriesmonitors, printers, keyboards, central processing units; typewriters, mobile phones and

chargers, remotes, compact discs, headphones, batteries, LCD/Plasma TVs, air conditioners, refrigerators and other

household appliances.5 The composition of e-waste is diverse and falls under ‗hazardous‘ and ‗non-hazardous‘

categories. Broadly, it consists of ferrous and non-ferrous metals, plastics, glass, wood and plywood, printed circuit

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boards, concrete, ceramics, rubber and other items. Iron and steel constitute about 50% of the waste, followed by

plastics (21%), non-ferrous metals (13%) and other constituents. Non-ferrous metals consist of metals like copper,

aluminium and precious metals like silver, gold, platinum, palladium and so on.6 The presence of elements like lead,

mercury, arsenic, cadmium, selenium, hexavalent chromium, and flame retardants beyond threshold quantities make e-

waste hazardous in nature. It contains over 1000 different substances, many of which are toxic, and creates serious

pollution upon disposal.7 Obsolete computers pose the most significant environmental and health hazard among the e-

wastes.

E-waste generation in India

All over the world, the quantity of electrical and electronic waste generated each year, especially computers and

televisions, has assumed alarming proportions. In 2006, the International Association of Electronics Recyclers

(IAER)8 projected that 3 billion electronic and electrical appliances would become WEEE or e-waste by 2010. That

would tantamount to an average e-waste generation rate of 400 million units a year till 2010. Globally, about 20-50

MT (million tonnes) of e-wastes are disposed off each year, which accounts for 5% of all municipal solid waste.

Although no definite official data exist on how much waste is generated in India or how much is disposed of, there are

estimations based on independent studies conducted by the NGOs or government agencies. According to the

Comptroller and Auditor- General‘s (CAG) report, over 7.2 MT of industrial hazardous waste, 4 lakh tonnes of

electronic waste, 1.5 MT of plastic waste, 1.7 MT of medical waste, 48 MT of municipal waste are generated in the

country annually.10 In 2005, the Central Pollution Control Board (CPCB) estimated India‘s e-waste at 1.47 lakh tonnes

or 0.573 MT per day.

The main sources of electronic waste in India are the government, public and private (industrial) sectors, which

account for almost 70 per cent of total waste generation. The contribution of individual households is relatively small

at about 15 per cent; the rest being contributed by manufacturers. Though individual households are not large

contributors to waste generated by computers, they consume large quantities of consumer durables and are, therefore,

potential creators of waste. An Indian market Research Bureau (IMRB) survey of ‗E-waste generation at Source‘ in

2009 found that out of the total e-waste volume in India, televisions and desktops including servers comprised 68 per

cent and 27 per cent respectively. Imports and mobile phones comprised of 2 per cent and 1 per cent respectively.

Environment concerns and Health hazards

E-waste is highly complex to handle due to its composition. It is made up of multiple components some of which

contain toxic substances that have an adverse impact on human health and environment if not handled properly. Often,

these problems arise out of improper recycling and disposal methods. This underlines the need for appropriate

technology for handling and disposal of these chemicals.

Pollutants or toxins in e-waste are typically concentrated in circuit boards, batteries, plastics, and LCDs (liquid crystal

displays). Given below is a table showing the major pollutants occurring in waste electrical and electronic equipments:

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Listed in the table below are the harmful elements in the compositions of electrical and electronic appliances that can

be hazardous to health and environment

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Potential Environmental Impacts from Solid Waste Management Activities

The typical municipal solid waste stream will contain general wastes (organics and recyclables), special

wastes (household hazardous, medical, and industrial waste), and construction and demolition debris. Most

adverse environmental impacts from solid waste management are rooted in inadequate or incomplete

collection and recovery of recyclable or reusable wastes, as well as codisposal of hazardous wastes. These

impacts are also due to inappropriate siting, design, operation, or maintenance of dumps and landfills.

Improper waste management activities can:

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• Increase disease transmission or otherwise threaten public health. Rotting organic materials pose great

public health risks, including, as mentioned above, serving as breeding grounds for disease vectors.

Waste handlers and waste pickers are especially vulnerable and may also become vectors,

contracting and transmitting diseases when human or animal excreta or medical wastes are in the

waste stream. (See the discussion on medical wastes below and the separate section on ―Healthcare

Waste: Generation, Handling, Treatment, and Disposal‖ in this volume.) Risks of poisoning, cancer,

birth defects, and other ailments are also high.

• Contaminate ground and surface water. Municipal solid waste streams can bleed toxic materials and

pathogenic organisms into the leachate of dumps and landfills. (Leachate is the liquid discharge of

dumps and landfills; it is composed of rotted organic waste, liquid wastes, infiltrated rainwater and

extracts of soluble material.) If the landfill is unlined, this runoff can contaminate ground or surface

water, depending on the drainage system and the composition of the underlying soils.

Many toxic materials, once placed in the general solid waste stream, can be treated or

removed only with expensive advanced technologies. Currently, these are generally not feasible in

Africa. Even after organic and biological elements are treated, the final product remains harmful.

• Create greenhouse gas emissions and other air pollutants. When organic wastes are disposed of in deep

dumps or landfills, they undergo anaerobic degradation and become significant sources of methane, a

gas with 21 times the effect of carbon dioxide in trapping heat in the atmosphere.

Garbage is often burned in residential areas and in landfills to reduce volume and uncover

metals. Burning creates thick smoke that contains carbon monoxide, soot and nitrogen oxide, all of

which are hazardous to human health and degrade urban air quality. Combustion of polyvinyl

chlorides (PVCs) generates highly carcinogenic dioxins.

• Damage ecosystems. When solid waste is dumped into rivers or streams it can alter aquatic habitats and

harm native plants and animals. The high nutrient content in organic wastes can deplete dissolved

oxygen in water bodies, denying oxygen to fish and other aquatic life form. Solids can cause

sedimentation and change stream flow and bottom habitat. Siting dumps or landfills in sensitive

ecosystems may destroy or significantly damage these valuable natural resources and the services

they provide.

• Injure people and property. In locations where shantytowns or slums exist near open dumps or near

badly designed or operated landfills, landslides or fires can destroy homes and injure or kill residents.

The accumulation of waste along streets may present physical hazards, clog drains and cause

localized flooding.

• Discourages tourism and other business. The unpleasant odor and unattractive appearance of piles of

uncollected solid waste along streets and in fields, forests and other natural areas, can discourage

tourism and the establishment and/or maintenance of businesses.

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2. Solid waste management (SWM)

Waste management is the collection, transport, processing, recycling or disposal of waste materials, usually

ones produced by human activity, in an effort to reduce their effect on human health or local aesthetics or

amenity. A focus in recent decades has been to reduce waste materials' effect on the natural world and the

environment and to recover resources from them.

Waste management practices differ for developed and developing nations, for urban and rural areas, and for

residential, industrial, and commercial producers. Waste management for non-hazardous residential and

institutional waste in metropolitan areas is usually the responsibility of local government authorities, while

management for non-hazardous commercial and industrial waste is usually the responsibility of the

generator.

2.2 Functional Elements of SWM:

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The activities associated with the management of Solid Waste can be grouped into six functional

groups;

2.2.1- Waste Generation. This step is simply identification/scoping step to locate the sites where the waste is being generated.

2.2.2- Waste handling and separation, storage, and processing at the source. Handling and separation activities until placed in storage containers. From the stand point of materials specifications

and revenues from the sale of recovered materials, best place to separate for reuse and recycling.

2.2.3- Collection Gathering of the solid waste and recyclables.

Waste collection is the component of waste management which results in the passage of a waste material from the

source of production to either the point of treatment or final disposal. Waste collection also includes the kerbside

collection of recyclable materials that technically are not waste, as part of a municipal landfill diversion program.

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2.2.4- Separation and processing and transformation of solid wastes.

Separation and processing usually occurs at materials recovery center (MRF), transfer station, combustion facilities,

disposal sites. Waste transformation is supplied by altering the waste physically, chemically, and biologically

(decreases the amount to be landfilled)

2.2.4.1 Pulverization

1. To reduce to powder or dust, usually by crushing, pounding or grinding. To break up into tiny particles: bray, crush, granulate, grind, mill, powder, triturate. See help/harm/harmless.

2.2.4.2 Hammer mill

A type of impact mill or crusher in which materials are reduced in size by hammers revolving rapidly in a

vertical plane within a steel casing. Also known as beater mill. A grinding machine which pulverizes feed

and other products by several rows of thin hammers revolving at high speed.

2.2.4.3 Baling

A technique used to convert loose refuse into heavy blocks by compaction; the blocks are then burned and

are buried in sanitary landfill.

2.2.5- Transfer and transport. Proper transport means to be used with trem cards with detailed disclosure.

2.2.6- Disposal

Waste Disposal Methods

Disposal methods for waste products vary widely, depending on the area and type of waste material. For

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example, in Australia, the most common method of disposal of solid household waste is in landfill sites, as it

is a large country with a low-density population. By contrast, in Japan it is more common for waste to be

incinerated, because the country is smaller and land is scarce. Other waste types (such as liquid sewage) will

be disposed of in different ways in both countries.

2.2.6.1 Landfill

Disposing of waste in a landfill is one of the most traditional method of waste disposal, and it remains a

common practice in most countries. Historically, landfills were often established in disused quarries, mining

voids or borrow pits. A properly-designed and well-managed landfill can be a hygienic and relatively

inexpensive method of disposing of waste materials in a way that minimises their impact on the local

environment. Older, poorly-designed or poorly-managed landfills can create a number of adverse

environmental impacts such as wind-blown litter, attraction of vermin, and generation of leachate where

result of rain percolating through the waste and reacting with the products of decomposition, chemicals and

other materials in the waste to produce the leachate which can pollute groundwater and surface water.

Another byproduct of landfills is landfill gas (mostly composed of methane and carbon dioxide), which is

produced as organic waste breaks down anaerobically. This gas can create odor problems, kill surface

vegetation, and is a greenhouse gas.

Design characteristics of a modern landfill include methods to contain leachate, such as clay or plastic lining

material. Disposed waste is normally compacted to increase its density and stablise the new landform, and

covered to prevent attracting vermin (such as mice or rats) and reduce the amount of wind-blown litter.

Many landfills also have a landfill gas extraction system installed after closure to extract the landfill gas

generated by the decomposing waste materials. Gas is pumped out of the landfill using perforated pipes and

flared off or burnt in a gas engine to generate electricity. Even flaring the gas is a better environmental

outcome than allowing it to escape to the atmosphere, as this consumes the methane, which is a far more

potent greenhouse gas than carbon dioxide.

Many local authorities, especially in urban areas, have found it difficult to establish new landfills due to

opposition from owners of adjacent land. Few people want a landfill in their local neighborhood. As a result,

solid waste disposal in these areas has become more expensive as material must be transported further away

for disposal (or managed by other methods).

This fact, as well as growing concern about the impacts of excessive materials consumption, has given rise

to efforts to minimise the amount of waste sent to landfill in many areas. These efforts include taxing or

levying waste sent to landfill, recycling the materials, converting material to energy, designing products that

use less material, and legislation mandating that manufacturers become responsible for disposal costs of

products or packaging. A related subject is that of industrial ecology, where the material flows between

industries is studied. The by-products of one industry may be a useful commodity to another, leading to a

reduced materials waste stream.

Some futurists have speculated that landfills may one day be mined: as some resources become more scarce,

they will become valuable enough that it would be economical to 'mine' them from landfills where these

materials were previously discarded as valueless. A related idea is the establishment of a 'monofill' landfill

containing only one waste type (e.g. waste vehicle tyres), as a method of long-term storage.

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2.2.6.2 Incineration

Incineration is a waste disposal method that involves the combustion of waste at high temperatures.

Incineration and other high temperature waste treatment systems are described as "thermal treatment". In

effect, incineration of waste materials converts the waste into heat, gaseous emissions, and residual solid

ash. Other types of thermal treatment include pyrolysis and gasification.

A waste-to-energy plant (WtE) is a modern term for an incinerator that burns wastes in high-efficiency

furnace/boilers to produce steam and/or electricity and incorporates modern air pollution control systems

and continuous emissions monitors. This type of incinerator is sometimes called an energy-from-waste

(EfW) facility.

Incineration is popular in countries such as Japan where land is a scarce resource, as they do not consume as

much area as a landfill. Sweden has been a leader in using the energy generated from incineration over the

past 20 years. Denmark also extensively uses waste-to-energy incineration in localised combined heat and

power facilities supporting district heating schemes.

Incineration is carried out both on a small scale by individuals, and on a large scale by industry. It is

recognised as a practical method of disposing of certain hazardous waste materials (such as biological

medical waste), though it remains a controversial method of waste disposal in many places due to issues

such as emission of gaseous pollutants.

Breaking down complex chemical chains such as dioxin through the application of heat usually cannot be

done by simply burning the material at the temperatures seen in an open-air fire. It is often necessary to

supplement the combustion process with gas or oil burners and air blowers to raise the temperature high

enough to result in molecular breakdown. Alternately, the exhaust gases from a natural air fire may pass

through tubes heated to sufficiently high temperatures to trigger thermal breakdown.

Thermal breakdown of pollutant molecules can indirectly create other pollution problems. Dioxin

breakdown begins at 1000°C, but at the same time poisonous nitrogen oxides and ozone begin to form when

atmospheric nitrogen and oxygen break down at 1600°C. This undesired oxide formation may require

further catalytic treatment of the exhaust gases.

2.2.6.3 Resource recovery

A relatively recent idea in waste management has been to treat the waste material as a resource to be

exploited, instead of simply a challenge to be managed and disposed of. There are a number of different

methods by which resources may be extracted from waste: the materials may be extracted and recycled, or

the calorific content of the waste may be converted to electricity.

The process of extracting resources or value from waste is variously referred to as secondary resource

recovery, recycling, and other terms. The practice of treating waste materials as a resource is becoming more

common, especially in metropolitan areas where space for new landfills is becoming scarcer. There is also a

growing acknowledgement that simply disposing of waste materials is unsustainable in the long term, as

there is a finite supply of most raw materials.

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There are a number of methods of recovering resources from waste materials, with new technologies and

methods being developed continuously.

In some developing nations some resource recovery already takes place by way of manual labourers who sift

through un-segregated waste to salvage material that can be sold in the recycling market. These

unrecognised workers called waste pickers or rag pickers, are part of the informal sector, but play a

significant role in reducing the load on the Municipalities' Solid Waste Management departments. There is

an increasing trend in recognising their contribution to the environment and there are efforts to try and

integrate them into the formal waste management systems, which is proven to be both cost effective and also

appears to help in urban poverty alleviation. However, the very high human cost of these activities including

disease, injury and reduced life expectancy through contact with toxic or infectious materials would not be

tolerated in a developed country.

2.2.6.4. Recycling

Recycling means to recover for other use a material that would otherwise be considered waste. The popular

meaning of ‗recycling‘ in most developed countries has come to refer to the widespread collection and reuse

of various everyday waste materials. They are collected and sorted into common groups, so that the raw

materials from these items can be used again (recycled).

In developed countries, the most common consumer items recycled include aluminium beverage cans, steel,

food and aerosol cans, HDPE and PET plastic bottles, glass bottles and jars, paperboard cartons,

newspapers, magazines, and cardboard. Other types of plastic (PVC, LDPE, PP, and PS) are also recyclable,

although not as commonly collected. These items are usually composed of a single type of material, making

them relatively easy to recycle into new products.

The recycling of obsolete computers and electronic equipment is important, but more costly due to the

separation and extraction problems. Much electronic waste is sent to Asia, where recovery of the gold and

copper can cause environmental problems (monitors contain lead and various "heavy metals", such as

selenium and cadmium; both are commonly found in electronic items).

Recycled or used materials have to compete in the marketplace with new materials. The cost of collecting

and sorting the materials often means that they are equally or more expensive than virgin materials. This is

most often the case in developed countries where industries producing the raw materials are well-

established. Practices such as trash picking can reduce this value further, as choice items are removed (such

as aluminium cans). In some countries, recycling programs are subsidised by deposits paid on beverage

containers.

However, most economic systems do not account for the benefits to the environment of recycling these

materials, compared with extracting virgin materials. It usually requires significantly less energy, water and

other resources to recycle materials than to produce new materials. For example, recycling 1000 kg of

aluminum cans saves approximately 5000 kg of bauxite ore being mined (source: ALCOA Australia) and

prevents the generation of 15.17 tonnes CO2 greenhouse gases; recycling steel saves about 95% of the

energy used to refine virgin ore.

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2.2.6.5 Composting and anaerobic digestion

Waste materials that are organic in nature, such as plant material, food scraps, and paper products, are

increasingly being recycled. These materials are put through a composting and/or digestion system to control

the biological process to decompose the organic matter and kill pathogens. The resulting stabilized organic

material is then recycled as mulch or compost for agricultural or landscaping purposes.

There are a large variety of composting and digestion methods and technologies, varying in complexity from

simple windrow composting of shredded plant material, to automated enclosed-vessel digestion of mixed

domestic waste. These methods of biological decomposition are differentiated as being aerobic in

composting methods or anaerobic in digestion methods, although hybrids of the two methods also exist.

Examples

The Green Bin Program, a form of organic recycling used in Toronto and surrounding municipalities, makes

use of anaerobic digestion to reduce the amount of garbage shipped to landfills in the United States. This is

the newest facet of a three-stream waste management system has been implemented in the city and is a step

towards the goal of diverting 70% of current waste. Green Bins allow organic waste to be composted and

turned into nutrient rich soil. Examples of accepted waste products for the Green Bin are food products and

scraps, soiled papers and sanitary napkins.

Edmonton has adopted large-scale composting to deal with its urban waste. Its composting facility is one of

the largest in the world, representing 35 per cent of Canada's industrial composting capacity. The $100

million co-composter and various recycling programs enable Edmonton to recycle 60% of its residential

waste. The co-composter itself is 38,690 square metres in size, equivalent to 8 football fields. It's designed to

process 200,000 tonnes of residential solid waste per year and 22,500 dry tonnes of biosolids, turning them

into 80,000 tonnes of compost annually.

The BIOBIN is an on-site in-vessel organic waste management solution for small industrial and retail

organic waste (primarily food waste and small green waste). The BiobiN is used to collect food waste at

shopping centers, schools, hospitality sites, etc, and the bin has a built in aeration and biofiltration system,

that blows air through the waste, initiating the composting process and effectively managing any odor. The

end product is then transported to a larger organics recycling facility for final processing into soil

conditioner. The BiobiN reduces the need for frequent pickups and reduces waste going to landfill.

Uses of biodegradable waste

Biodegradable waste is a little recognised resource. Through correct waste management, often using the two

key processes of anaerobic digestion and composting, it can be converted into valuable products.

Anaerobic digestion converts biodegradable waste into several products, including biogas, which can be

used to generate renewable energy or heat for local heating, and soil amendment (digestate). Composting

converts biodegradable waste into compost.

2.2.6.6 Source Reduction (Waste Prevention)

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Source reduction can be a successful method of reducing waste generation. Practices such as grasscycling,

backyard composting, two-sided copying of paper, and transport packaging reduction by industry have

yielded substantial benefits through source reduction.

Source reduction has many environmental benefits. It prevents emissions of many greenhouse gases, reduces

pollutants, saves energy, conserves resources, and reduces the need for new landfills and combustors.

2.2.6.7 Recycling

Recycling, including composting, diverted 79 million tons of material away from disposal in 2005, up from

15 million tons in 1980, when the recycle rate was just 10% and 90% of MSW was being combusted with

energy recovery or disposed of by landfilling.

Typical materials that are recycled include batteries, recycled at a rate of 99%, paper and paperboard at 50%,

and yard trimmings at 62%. These materials and others may be recycled through curbside programs, drop-

off centers, buy-back programs, and deposit systems.

Recycling prevents the emission of many greenhouse gases and water pollutants, saves energy, supplies

valuable raw materials to industry, creates jobs, stimulates the development of greener technologies,

conserves resources for our children's future, and reduces the need for new landfills and combustors.

Recycling also helps reduce greenhouse gas emissions that affect global climate. In 1996, recycling of solid

waste in the United States prevented the release of 33 million tons of carbon into the air-roughly the amount

emitted annually by 25 million cars.

3. Engineering ethics.

ENVIRONMENTAL ETHICS

Ethics

- seeks to define fundamentally what is right or wrong, regardless of cultural differences.

Morals

- differ from ethics in that they reflect the predominant feelings of a culture about ethical

issues.

Environmental Principles

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- everything must go somewhere, or we can never really throw anything away.

- you can‘t get something for nothing, or there is no such thing as a free lunch.

- you can‘t even break even, or if you think things are mixed up now, just wait

- everything is connected to everything else, but how?

- natural systems can take a lot of stress or abuse, but there are limits.

- in nature you can never do just one thing, so always expect the unexpected.

Environmental Attitudes

- Development ethic

- based on action

- resources exist for the benefit of humans.

- ―progress‖

- Preservation ethic

- reasons: religious, asthetic, recreational, scientific

- nature is special in itself and must be preserved at all cost.

- Conservation ethic

- related to scientific preservationism

- considers the earth for all time

- balances resource use and availability, total development, and absolute

preservation.

Societal Ethics

- ―The Common Good‖

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- balances economics with environmental costs

- must consider:

- economic growth

- resource exploitation

- conservation

Corporate Ethics

- considers profitability – balance of environmental costs vs. profit

- controlling waste affects profit margin

- costs are:

- administration, advertising, public relations, lobbying

- stock dividends, salaries, interest on loans

- waste disposal / clean-up

- raw materials, manufacturing

- research & development

- court costs

- ―Ceres‖ Principles (Coalition for Environmentally Responsible Economics) – also

known as the ―Valdez Principles‖

- a set of voluntary codes for businesses

- ten (10) principles covering a wide range of goals

- a guide for corporate environmentalism

- Industrial Ecology

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- accounts for waste (actually residues)

Individual Ethics

- broad, fundamental decisions and actions

Global Ethics

- Earth Summits

- Rio Declarations – 1992

- Global Change

- Tokyo - 1997

3 R’s: Reduce, Reuse & Recycle

The three R's - reduce, reuse and recycle - all help to cut down on the amount of waste we throw away.

They conserve natural resources, landfill space and energy. Plus, the three R's save land and money

communities must use to dispose of waste in landfills. Sitting a new landfill has become difficult and

more expensive due to environmental regulations and public opposition. Missouri has a goal of reducing

the amount of waste going into landfills by 40 percent. Everyone can help meet this goal and save

natural resources, energy, and money by following the three R's.

REDUCE

The best way to manage waste is to not produce it. This can be done by shopping carefully and being

aware of a few guidelines:

Buy products in bulk, economy-size products or ones in concentrated form use less packaging and

usually cost less per ounce.

Avoid over-packaged goods, especially ones packed with several materials such as foil, paper, and

plastic. They are difficult to recycle, plus you pay more for the package.

Avoid disposable goods, such as paper plates, cups, napkins, razors, and lighters. Throwaways

contribute to the problem, and cost more because they must be replaced again and again.

Buy durable goods - ones that are well-built or that carry good warranties. They will last longer, save

money in the long run and save landfill space.

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At work, make two-sided copies when ever possible. Maintain central files rather than using several

files for individuals. Use electronic mail or main bulletin board. Use cloth napkins instead of paper

napkins. Use a dish cloth instead of paper towels.

REUSE

It makes economic and environmental sense to reuse products. Sometimes it takes creativity:

Reuse products for the same purpose. Save paper and plastic bags, and repair broken appliances,

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furniture and toys.

Reuse products in different ways. Use a coffee can to pack a lunch; use plastic microwave dinner

trays as picnic dishes.

Sell old clothes, appliances, toys, and furniture in garage sales or ads, or donate them to charities.

Reseals the containers rather than plastic wrap. Use a ceramic coffee mug instead of paper cups.

Reuse grocery bags or bring your own cloth bags to the store. Do not take a bag from the store unless

you need one.

RECYCLE

Recycling is a series of steps that takes a used material and processes, remanufactures and sells it as a

new product. Begin recycling at home and at work:

Buy products made from recycled material look for the recycling symbol or ask store managers or

salesmen.

The recycling symbol means one of two things - either the product is made of recycled material, or

the item can be recycled. For instance, many plastic containers have a recycling symbol with a

numbered code the identifies what type of plastic resin it is made from. However, just because the

container has this code does not mean it can be easily recycled locally.

Check collection centers and curbside pickup services to see what they accept, and begin collecting

those materials. These can include metal cans, newspapers, paper products, glass, plastics and oil.

Consider purchasing recycled materials at work when purchasing material for office supply, office

equipment or manufacturing.

Speak to store managers and ask for products and packaging that help cut down on waste, such as

recycled products and products that are not over packaged. Buy products made from material that is

collected for recycling in your community. Use recycled paper for letterhead, copier paper and

newsletters.

4. Sustainable waste management: Compacting, drying, dewatering, bio-drying, composting,

bioremediation, biodegradation (chemicals and oil spillage).

Compacting: Waste compaction is the process of compacting waste, reducing it in size. Garbage compactors

and waste collection vehicles compress waste so that more of it can be stored in the same space. Waste is

compacted again, more thoroughly, at the landfill to conserve valuable airspace and to extend the landfills

life span. A side effect of this is that important items, like evidence in a crime, may be difficult to recover

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from the garbage due to reduced oxygenation, biodegradation of organic waste. Pre-landfill waste

compaction is often beneficial, both for people disposing of waste and the company collecting it. This is

because waste collection companies frequently charge by volume. A landfill compaction vehicle has two

main functions: To spread the waste evenly in layers over the landfill and to compact waste to reduce its

volume and help stabilize the landfill. The higher the compaction rate, the more trash the landfill can receive

and store. This will also reduce landslides, cave-ins and minimize the risk of fire. Main compaction is

produced by the landfill compactors steel tooth on the wheel drums. Special teeth can penetrate the waste

and deliver a focused compression point, providing compaction and increased density. Ground pressure of

the tooth can exceed over 4000 PSI. The design of the machine and more importantly the wheels and the

teeth is very critical in compaction. The steel wheels should be as wide as possible and have as many teeth

as possible.

Drying: Rolling bed dryers are used for efficiently processing large bulks of material that need their

respective moisture levels reduced. Rolling bed Dryers are most often used for drying wood chips and

organic residues and are most often utilized in the biomass, waste/recycling, wood particle board, pellet, and

biofuels industries. This provides for efficiency and conservation in energy which results in lower

production costs. Biomass is being increasingly used throughout the world as an alternative fuel source as

heat, light, mobility, etc. Applications are wood chips, cropped biomass, alternative fuels, sugar beets pulp

and green waste management industries. The process of large bulks of biomass is permanently circulated

and mixed by highly effective paddles. This basic idea combines the flow of large bulks of product good

heat transfer with continuous movement of the product for even drying results. The drying air is supplied

through a perforated plate under the moving bulk of product. Depending on the amount of ventilation, it is

possible to separate fine materials such as dust, fibers, and sand from the bulk material collecting this

separately alongside the ongoing drying process. This simultaneous cleaning occurs through the use of the

material against itself to remove, separate and collect fine materials such as fibers, sand and dust from the

drying bulk material. Having this occur at the same time as the drying process saves not only time and

energy, but also maintains better the caloric value of the residual biomass and reduces ash content. After the

drying process is completed the dried output is suitable for direct firing and pelletizing/briquetting as well as

for more demanding processes such as gasification or torrefaction of biomass. The rotary dryer is a type of

industrial dryer employed to reduce or minimize the liquid moisture content of the material it is handling by

bringing it into direct contact with a heated gas. Rotary dryer is suitable to dry metallic and nonmetallic

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mineral, clay in cement industrial and coal slime in coal mine etc. Rotary dryer can be widely used to dry

various materials, and it is simple to be operated. Rotary Dryers have many applications but are most

commonly seen in the mineral industry for drying sands, limestone, stones and soil, ores, fertilizers, wood

chips, coal, iron sulphate, filter cakes, sewage sludge, etc.

Dewatering: Dewatering is the removal of water from solid material or soil by wet

classification, centrifugation, filtration or similar solid-liquid separation processes, such as removal of

residual liquid from a filter cake by a filter press as part of various industrial processes. Construction

dewatering, unwatering, or water control are common terms used to describe removal or draining

groundwater or surface water from a riverbed, construction site, caisson by pumping or evaporation. On a

construction site, this dewatering may be implemented before subsurface excavation for foundations,

shoring, or cellar space to lower the water table. This frequently involves the use of submersible

"dewatering" pumps, centrifugal ("trash") pumps, eductors, or application of vacuum to well points. A deep

well typically consists of a borehole fitted with a slotted liner and an electric submersible pump. As water is

pumped from a deep well, a hydraulic gradient is formed and water flows into the well forming a cone of

depression around the well in which there is little or no water remaining in the pore spaces of the

surrounding soil. The installation of horizontal dewatering systems is relatively easy. A trencher installs an

unperforated pipe followed by a synthetic or organic wrapped perforated pipe.

Bio-drying: Biodrying is the process by which biodegradable waste is rapidly heated through initial stages

of composting to remove moisture from a waste stream and hence reduce its overall weight. In biodrying

processes, the drying rates are augmented by biological heat in addition to forced aeration. The major

portion of biological heat, naturally available through the aerobic degradation of organic matter, is utilized to

evaporate surface and bound water associated with the mixed sludge. This heat generation assists in

reducing the moisture content of the biomass without the need for supplementary fossil fuels, and with

minimal electricity consumption. It can take as little as 8 days to dry waste in this manner. This enables

reduced costs of disposal if landfill is charged on a cost per tonne basis. Biodrying may be used as part of

the production process for refuse-derived fuels. Biodrying does not however greatly affect the

biodegradability of the waste and hence is not stabilised. Biodried waste will still break down in a landfill to

produce landfill gas and hence potentially contribute to climate change.

Composting: Compost is organic matter that has been decomposed and recycled as a fertilizer and soil

amendment. Compost is a key ingredient in organic farming. At the simplest level, the process of

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composting simply requires making a heap of wetted organic matter (leaves, "green" food waste) and

waiting for the materials to break down into humus after a period of weeks or months. Modern, methodical

composting is a multi-step, closely monitored process with measured inputs of water, air, and carbon and

nitrogen rich materials. The decomposition process is aided by shredding the plant matter, adding water and

ensuring proper aeration by regularly turning the mixture. Worms and fungi further break up the material.

Aerobic bacteria manage the chemical process by converting the inputs into heat, carbon dioxide and

ammonium. The ammonium is further converted by bacteria into plant-nourishing nitrites and nitrates

through the process of nitrification. Compost can be rich in nutrients. It is used in gardens, landscaping,

horticulture, and agriculture. The compost itself is beneficial for the land in many ways, including as a soil

conditioner, a fertilizer, addition of vital humus or humic acids, and as a natural pesticide for soil. In

ecosystems, compost is useful for erosion control, land and stream reclamation, wetland construction, and as

landfill cover. Organic ingredients intended for composting can alternatively be used to generate biogas

through anaerobic digestion. Anaerobic digestion is fast overtaking composting in some parts of the world as

a primary means of down cycling waste organic matter. Composting organisms require four equally

important things to work effectively:

Carbon — for energy; the microbial oxidation of carbon produces the heat, if included at suggested

levels. High carbon materials tend to be brown and dry.

Nitrogen — to grow and reproduce more organisms to oxidize the carbon. High nitrogen materials

tend to be green (or colorful, such as fruits and vegetables) and wet.

Oxygen — for oxidizing the carbon, the decomposition process.

Water — in the right amounts to maintain activity without causing anaerobic conditions.

Micro-organisms - to break down organic matter into compost. There are many types of

microorganisms found in active compost of which the most common are:

Bacteria- The most numerous of all the micro organisms found in compost.

Actinomycetes- Necessary for breaking down paper products such as newspaper, bark, etc.

Fungi- Molds and yeast help break down materials that bacteria cannot, especially lignin in

woody material.

Protozoa- Help consumes bacteria, fungi and micro organic particulates.

Rotifers- Rotifers help control populations of bacteria and small protozoans.

Vermicompost is the product of composting utilizing various species of worms, usually red wigglers, white

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worms, and earthworms to create a heterogeneous mixture of decomposing vegetable or food waste, bedding

materials and vermicast. Vermicast, also known as worm castings, worm humus or worm manure, is the

end-product of the breakdown of organic matter by species of earthworm.

Bioremediation: Bioremediation is the use of any organism metabolism to remove pollutants. Technologies

can be generally classified as in-situ or ex-situ. In situ bioremediation involves treating the contaminated

material at the site, while ex-situ involves the removal of the contaminated material to be treated elsewhere.

Some examples of bioremediation related technologies are phytoremediation, bioventing, bioleaching,

landfarming, bioreactor, composting, bioaugmentation, rhizofiltration, and biostimulation. Bioremediation

can occur on its own (natural attenuation or intrinsic bioremediation) or can be spurred on via the addition of

fertilizers to increase the bioavailability within the medium (biostimulation). Recent advancements have also

proven successful via the addition of matched microbe strains to the medium to enhance the resident

microbe population's ability to break down contaminants. Microorganisms used to perform the function of

bioremediation are known as bioremediators. Recent experiment suggests that fish bones have some success

absorbing lead from contaminated soil. Bone char has been shown to bioremediate small amounts of

Cadmium Copper and Zinc. The assimilation of metals such as mercury into the food chain materials.

Phytoremediation is useful in these circumstances because natural plants or transgenic plants are able to

bioaccumulate these toxins in their above-ground parts, which are then harvested for removal. The heavy

metals in the harvested biomass may be further concentrated by incineration or even recycled for industrial

use. Mycoremediation is a form of bioremediation in which fungi are used to decontaminate the area. The

term mycoremediation refers specifically to the use of fungal mycelia in bioremediation.

Biodegradation: Biodegradation is the chemical dissolution of materials by bacteria or other biological

means. Although often conflated, biodegradable is distinct in meaning from compostable. While

biodegradable simply means to be consumed by microorganisms and return to compounds found in nature,

"compostable" makes the specific demand that the object break down in a compost pile. The term is often

used in relation to ecology, waste management, biomedicine, and the natural environment (bioremediation)

and is now commonly associated with environmentally friendly products that are capable of decomposing

back into natural elements. Organic material can be degraded aerobically with oxygen, or anaerobically,

without oxygen. Biosurfactant, an extracellular surfactant secreted by microorganisms, enhances the

biodegradation process. Biodegradable matter is generally organic material such as plant and animal matter

and other substances originating from living organisms, or artificial materials that are similar enough to

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plant and animal matter to be put to use by microorganisms. Some microorganisms have a naturally

occurring, microbial catabolic diversity to degrade, transform or accumulate a huge range of compounds

including hydrocarbons (e.g. oil), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs),

pharmaceutical substances, radionuclides, pesticides and metals. Decomposition of biodegradable

substances may include both biological and abiotic steps and the overall rate of biodegradation may be

controlled by competing abiotic processes, such as adsorption or volatilization. Major methodological break

throughs in microbial biodegradation have detailed mechanism of genomic, metagenomic, proteomic,

bioinformatic and other high-throughput analyses of environmentally relevant microorganisms providing

insights into key biodegradative pathways and the ability of microorganisms to adapt to changing

environmental conditions.

5. Waste to energy: Energy recovery by incineration, gasification, pyrolysis and bio-gasification

Waste-to-energy or energy-from-waste is the process of generating energy in the form of electricity and/or heat directly

through combustion, or produce a combustible fuel commodity, such as methane, methanol, ethanol, synthetic fuels. Etc.

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The following sections discuss the main available thermochemical conversion technologies for calorific waste (RDF) treatment: 1. Incineration: full oxidative combustion; 2. Gasification: partial oxidation; 3. Pyrolysis: thermal degradation of organic material in the absence of oxygen;

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6. Bioconversion: To clean energy (biofuels).

Clean energy may also be called renewable energy or green energy, and it specifically refers to energy

produced from renewable resources without creating environmental debt. There are several other ways that

this term can be defined, however. It may refer to energy processes that pollute less or, alternately, to energy

that doesn‘t pollute at all and doesn‘t use resources that can‘t be easily renewed.

A biofuel is a fuel that contains energy from geologically recent carbon fixation. These fuels are produced

from living organisms. Examples of this carbon fixation occur in plants and microalgae. These fuels are

made by a biomass conversion (biomass refers to recently living organisms, most often referring to plants or

plant-derived materials). This biomass can be converted to convenient energy containing substances in three

different ways: thermal conversion, chemical conversion, and biochemical conversion. This biomass

conversion can result in fuel in solid, liquid, or gas form. This new biomass can be used for biofuels.

Biofuels have increased in popularity because of rising oil prices and the need for energy security.

Bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced

in sugar or starch crops such as corn, sugarcane, or sweet sorghum. Cellulosic biomass, derived

from non-food sources, such as trees and grasses, is also being developed as a feedstock for

ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually

used as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol is

widely used in the USA and in Brazil. Current plant design does not provide for converting

the lignin portion of plant raw materials to fuel components by fermentation.

Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as

a diesel additive to reduce levels of particulates, carbon monoxide, andhydrocarbons from

diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is

the most common biofuel in Europe.

In 2010, worldwide biofuel production reached 105 billion liters (28 billion gallons US), up 17%

from 2009, and biofuels provided 2.7% of the world's fuels for road transport, a contribution

largely made up of ethanol and biodiesel. Global ethanol fuel production reached 86 billion liters

(23 billion gallons US) in 2010, with the United States and Brazil as the world's top producers,

accounting together for 90% of global production. The world's largest biodiesel producer is

the European Union, accounting for 53% of all biodiesel production in 2010. As of 2011,

mandates for blending biofuels exist in 31 countries at the national level and in 29 states or

provinces. The International Energy Agency has a goal for biofuels to meet more than a quarter

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of world demand for transportation fuels by 2050 to reduce dependence on petroleum and coal.

First-generation biofuels

'First-generation' or conventional biofuels are made from sugar, starch, or vegetable oil.

Ethanol

Biologically produced alcohols, most commonly ethanol, and less commonly propanol and butanol, are

produced by the action of microorganisms and enzymes through the fermentation of sugars or starches

(easiest), or cellulose (which is more difficult). Biobutanol (also called biogasoline) is often claimed to

provide a direct replacement for gasoline, because it can be used directly in a gasoline engine (in a similar

way to biodiesel in diesel engines).

Ethanol fuel is the most common biofuel worldwide, particularly in Brazil. Alcohol fuels are

produced by fermentation of sugars derived from wheat, corn, sugar beets, sugarcane, molasses and any

sugar or starch from which alcoholic beverages such as whiskey, can be made (such

as potato and fruit waste, etc.). The ethanol production methods used are enzyme digestion (to release sugars

from stored starches), fermentation of the sugars, distillation and drying. The distillation process requires

significant energy input for heat (often unsustainable natural gas fossil fuel, but cellulosic biomass such

as bagasse, the waste left after sugar cane is pressed to extract its juice, can also be used more sustainably).

Ethanol can be used in petrol engines as a replacement for gasoline; it can be mixed with gasoline to

any percentage. Most existing car petrol engines can run on blends of up to 15% bioethanol with

petroleum/gasoline. Ethanol has a smaller energy density than that of gasoline; this means it takes more fuel

(volume and mass) to produce the same amount of work. An advantage of ethanol (CH3CH2OH) is that it

has a higher octane rating than ethanol-free gasoline available at roadside gas stations, which allows an

increase of an engine's compression ratio for increased thermal efficiency. In high-altitude (thin air)

locations, some states mandate a mix of gasoline and ethanol as a winter oxidizer to reduce atmospheric

pollution emissions.

Ethanol is also used to fuel bioethanol fireplaces. As they do not require a chimney and are

"flueless", bioethanol fires are extremely useful for newly built homes and apartments without a flue. The

downsides to these fireplaces is that their heat output is slightly less than electric heat or gas fires, and

precautions must be taken to avoid carbon monoxide poisoning.

In the current corn-to-ethanol production model in the United States, considering the total energy

consumed by farm equipment, cultivation, planting, fertilizers, pesticides, herbicides, and fungicides made

from petroleum, irrigation systems, harvesting, transport of feedstock to processing plants, fermentation,

distillation, drying, transport to fuel terminals and retail pumps, and lower ethanol fuel energy content, the

net energy content value added and delivered to consumers is very small. And, the net benefit (all things

considered) does little to reduce imported oil and fossil fuels required to produce the ethanol.

Although corn-to-ethanol and other food stocks have implications both in terms of world food prices

and limited, yet positive, energy yield (in terms of energy delivered to customer/fossil fuels used), the

technology has led to the development of cellulosic ethanol. According to a joint research agenda conducted

through the US Department of Energy, the fossil energy ratios (FER) for cellulosic ethanol, corn ethanol,

and gasoline are 10.3, 1.36, and 0.81, respectively.

Even dry ethanol has roughly one-third lower energy content per unit of volume compared to

gasoline, so larger (therefore heavier) fuel tanks are required to travel the same distance, or more fuel stops

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are required. With large current unsustainable, unscalable subsidies, ethanol fuel still costs more per distance traveled than current high gasoline prices in the United States.

Biodiesel

Biodiesel is the most common biofuel in Europe. It is produced from oils or fats

using transesterification and is a liquid similar in composition to fossil/mineral diesel.

Chemically, it consists mostly of fatty acid methyl (or ethyl) esters (FAMEs). Feedstocks for

biodiesel include animal fats, vegetable oils, soy, rapeseed, jatropha and algae, Pure biodiesel

(B100) is the lowest-emission diesel fuel. Although liquefied petroleum gas and hydrogen have

cleaner combustion, they are used to fuel much less efficient petrol engines and are not as

widely available.

Biodiesel can be used in any diesel engine when mixed with mineral diesel. In some countries,

manufacturers cover their diesel engines under warranty for B100 use,

although Volkswagen of Germany, for example, asks drivers to check by telephone with the VW

environmental services department before switching to B100. B100 may become

more viscous at lower temperatures, depending on the feedstock used. In most cases, biodiesel is

compatible with diesel engines from 1994 onwards, which use 'Viton' (by DuPont) synthetic

rubber in their mechanical fuel injection systems.

Electronically controlled 'common rail' and 'unit injector' type systems from the late 1990s

onwards may only use biodiesel blended with conventional diesel fuel. These engines have

finely metered and atomized multiple-stage injection systems that are very sensitive to the

viscosity of the fuel. Many current-generation diesel engines are made so that they can run on

B100 without altering the engine itself, although this depends on the fuel rail design. Since

biodiesel is an effective solvent and cleans residues deposited by mineral diesel, engine

filters may need to be replaced more often, as the biofuel dissolves old deposits in the fuel tank

and pipes. It also effectively cleans the engine combustion chamber of carbon deposits, helping

to maintain efficiency. In many European countries, a 5% biodiesel blend is widely used and is

available at thousands of gas stations. Biodiesel is also an oxygenated fuel, meaning it contains a

reduced amount of carbon and higher hydrogen and oxygen content than fossil diesel. This

improves the combustion of biodiesel and reduces the particulate emissions from unburnt

carbon.

Biodiesel is also safe to handle and transport because it is as biodegradable as sugar, one-tenth

as toxic as table salt, and has a high flash point of about 300°F (148°C) compared to petroleum

diesel fuel, which has a flash point of 125°F (52°C).

In the USA, more than 80% of commercial trucks and city buses run on diesel. The emerging

US biodiesel market is estimated to have grown 200% from 2004 to 2005. "By the end of 2006

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biodiesel production was estimated to increase fourfold [from 2004] to more than" 1 billion US

gallons (3,800,000 m3).

Other bioalcohols

Methanol is currently produced from natural gas, a nonrenewable fossil fuel. It can also be

produced from biomass as biomethanol. The methanol economy is an alternative to

the hydrogen economy, compared to today's hydrogen production from natural gas.

Butanol (C4H9OH) is formed by ABE fermentation (acetone, butanol, ethanol) and experimental

modifications of the process show potentially high net energy gains with butanol as the only

liquid product. Butanol will produce more energy and allegedly can be burned "straight" in

existing gasoline engines (without modification to the engine or car), and is less corrosive and

less water-soluble than ethanol, and could be distributed via existing

infrastructures. DuPont and BP are working together to help develop butanol. E. coli strains

have also been successfully engineered to produce butanol by modifying their amino aci

metabolism.

Green diesel

Green diesel is produced through hydrocracking biological oil feedstocks, such as vegetable oils

and animal fats. Hydrocracking is a refinery method that uses elevated temperatures and

pressure in the presence of a catalyst to break down larger molecules, such as those found

in vegetable oils, into shorter hydrocarbon chains used in diesel engines. It may also be called

renewable diesel, hydrotreated vegetable oil or hydrogen-derived renewable diesel. Green diesel

has the same chemical properties as petroleum-based diesel. It does not require new engines,

pipelines or infrastructure to distribute and use, but has not been produced at a cost that is

competitive with petroleum. Gasoline versions are also being developed. Green diesel is being

developed in Louisiana and Singapore byConocoPhillips, Neste Oil, Valero, Dynamic Fuels,

and Honeywell UOP.

Biofuel gasoline

In 2013 UK researchers developed a genetically modified strain of Escherichia coli which could

transform glucose into biofuel gasoline that does not need to be blended. Later in

2013 UCLA researchers engineered a new metabolic pathway to bypass glycolysis and increase

the rate of conversion of sugars into biofuel, while KAIST researchers developed a strain

capable of producing short-chain alkanes, free fatty acids, fatty esters and fatty alcohols through

the fatty acyl (acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA pathway in vivo. It is

believed that in the future it will be possible to "tweak" the genes to make gasoline from straw

49

or animal manure.

Vegetable oil

Straight unmodified edible vegetable oil is generally not used as fuel, but lower-quality oil can

and has been used for this purpose. Used vegetable oil is increasingly being processed into

biodiesel, or (more rarely) cleaned of water and particulates and used as a fuel.

Also here, as with 100% biodiesel (B100), to ensure the fuel injectors atomize the vegetable oil

in the correct pattern for efficient combustion, vegetable oil fuel must be heated to reduce

its viscosity to that of diesel, either by electric coils or heat exchangers. This is easier in warm or

temperate climates. Big corporations like MAN B&W Diesel, Wärtsilä, and Deutz AG, as well

as a number of smaller companies, such as Elsbett, offer engines that are compatible with

straight vegetable oil, without the need for after-market modifications.

Vegetable oil can also be used in many older diesel engines that do not use common rail or unit

injection electronic diesel injection systems. Due to the design of the combustion chambers

in indirect injectionengines, these are the best engines for use with vegetable oil. This system

allows the relatively larger oil molecules more time to burn. Some older engines, especially

Mercedes, are driven experimentally by enthusiasts without any conversion, a handful of drivers

have experienced limited success with earlier pre-"Pumpe Duse" VW TDI engines and other

similar engines with direct injection. Several companies, such as Elsbett or Wolf, have

developed professional conversion kits and successfully installed hundreds of them over the last

decades.

Oils and fats can be hydrogenated to give a diesel substitute. The resulting product is a straight-

chain hydrocarbon with a high cetane number, low in aromatics and sulfur and does not contain

oxygen.Hydrogenated oils can be blended with diesel in all proportions. They have several

advantages over biodiesel, including good performance at low temperatures, no storage stability

problems and no susceptibility to microbial attack.

Bioethers

Bioethers (also referred to as fuel ethers or oxygenated fuels) are cost-effective compounds that

act as octane rating enhancers."Bioethers are produced by the reaction of reactive iso-olefins,

such as iso-butylene, with bioethanol." They also enhance engine performance, whilst

significantly reducing engine wear and toxic exhaust emissions. Greatly reducing the amount of

ground-level ozone emissions, they contribute to air quality.

When it comes to transportation fuel there are six ether additives- 1. Dimethyl Ehters (DME) 2.

Diethyl Ether (DEE) 3. Methyl Teritiary-Butyl Ether (MTBE) 4. Ethyl ter-butyl ether (ETBE) 5.

50

Ter-amyl methyl ether (TAME) 6. Ter-amyl ethyl Ether (TAEE)

The European Fuel Oxygenates Association (aka EFOA) credits Methyl Tertiary-Butyl Ether

(MTBE) and Ethyl ter-butyl ether (ETBE) as the most commonly used ethers in fuel to replace

lead. Ethers were brought into fuels in Europe in the 1970s to replace the highly toxic

compound. Although Europeans still use Bio-ether additives, the US no longer has an oxygenate

requirement therefore bio-ethers are no longer used as the main fuel additive.

Biogas

Biogas is methane produced by the process of anaerobic digestion of organic material by anaerobes. It can be

produced either from biodegradable waste materials or by the use of energy crops fed intoanaerobic

digesters to supplement gas yields. The solid byproduct, digestate, can be used as a biofuel or a fertilizer.

Biogas can be recovered from mechanical biological treatment waste processing systems.

Note: Landfill gas, a less clean form of biogas, is produced in landfills through naturally

occurring anaerobic digestion. If it escapes into the atmosphere, it is a

potential greenhouse gas.

Farmers can produce biogas from manure from their cattle by using anaerobic digesters.

Syngas

Syngas, a mixture of carbon monoxide, hydrogen and other hydrocarbons, is produced by partial

combustion of biomass, that is, combustion with an amount of oxygen that is not sufficient to

convert the biomass completely to carbon dioxide and water. Before partial combustion, the

biomass is dried, and sometimes pyrolysed. The resulting gas mixture, syngas, is more efficient

than direct combustion of the original biofuel; more of the energy contained in the fuel is

extracted.

Syngas may be burned directly in internal combustion engines, turbines or high-temperature fuel cells. The wood gas generator, a wood-fueled gasification reactor, can be connected to an internal combustion engine.

Syngas can be used to produce methanol, DME and hydrogen, or converted via the Fischer-Tropsch process to produce a diesel substitute, or a mixture of alcohols that can be blended into gasoline. Gasification normally relies on temperatures greater than 700°C.

Lower-temperature gasification is desirable when co-producing biochar, but results in

51

syngas polluted with tar.

Solid biofuels

Examples include wood, sawdust, grass trimmings, domestic refuse, charcoal, agricultural

waste, nonfood energy crops, and dried manure.

When raw biomass is already in a suitable form (such as firewood), it can burn directly in a

stove or furnace to provide heat or raise steam. When raw biomass is in an inconvenient form

(such as sawdust, wood chips, grass, urban waste wood, agricultural residues), the typical

process is to densify the biomass. This process includes grinding the raw biomass to an

appropriate particulate size (known as hogfuel), which, depending on the densification type, can

be from 1 to 3 cm (0 to 1 in), which is then concentrated into a fuel product. The current

processes produce wood pellets, cubes, or pucks. The pellet process is most common in Europe,

and is typically a pure wood product. The other types of densification are larger in size

compared to a pellet, and are compatible with a broad range of input feedstocks. The resulting

densified fuel is easier to transport and feed into thermal generation systems, such as boilers.

Industry has used sawdust, bark and chips for fuel for decades, primary in the pulp and paper

industry, and also bagasse (spent sugar cane) fueled boilers in the sugar cane industry. Boilers in

the range of 500,000 lb/hr of steam, and larger, are in routine operation, using grate, spreader

stoker, suspension burning and fluid bed combustion. Utilities generate power, typically in the

range of 5 to 50 MW, using locally available fuel. Other industries have also installed wood

waste fueled boilers and dryers in areas with low cost fuel.

One of the advantages of biomass fuel is that it is often a byproduct, residue or waste-product of

other processes, such as farming, animal husbandry and forestry. In theory, this means fuel and

food production do not compete for resources, although this is not always the case.

A problem with the combustion of raw biomass is that it emits considerable amounts

of pollutants, such as particulates and polycyclic aromatic hydrocarbons. Even modern pellet

boilers generate much more pollutants than oil or natural gas boilers. Pellets made from

agricultural residues are usually worse than wood pellets, producing much larger emissions

of dioxins and chlorophenols.

In spite of the above noted study, numerous studies have shown biomass fuels have significantly

less impact on the environment than fossil based fuels. Of note is the US Department of Energy

Laboratory, operated by Midwest Research Institute Biomass Power and Conventional Fossil

Systems with and without CO2 Sequestration – Comparing the Energy Balance, Greenhouse

Gas Emissions and Economics Study. Power generation emits significant amounts of

greenhouse gases (GHGs), mainly carbon dioxide (CO2). Sequestering CO2 from the power

52

plant flue gas can significantly reduce the GHGs from the power plant itself, but this is not the

total picture. CO2 capture and sequestration consumes additional energy, thus lowering the

plant's fuel-to-electricity efficiency. To compensate for this, more fossil fuel must be procured

and consumed to make up for lost capacity.

Taking this into consideration, the global warming potential (GWP), which is a combination of

CO2, methane (CH4), and nitrous oxide (N2O) emissions, and energy balance of the system need

to be examined using a life cycle assessment. This takes into account the upstream processes

which remain constant after CO2 sequestration, as well as the steps required for additional power

generation. Firing biomass instead of coal led to a 148% reduction in GWP.

A derivative of solid biofuel is biochar, which is produced by biomass pyrolysis. Biochar made

from agricultural waste can substitute for wood charcoal. As wood stock becomes scarce, this

alternative is gaining ground. In eastern Democratic Republic of Congo, for example,

biomass briquettes are being marketed as an alternative to charcoal to protect Virunga National

Park from deforestation associated withcharcoal production.

Second-generation (advanced) biofuels

Second generation biofuels, also known as advanced biofuels, are fuels that can be manufactured

from various types of biomass. Biomass is a wide-ranging term meaning any source of organic

carbon that is renewed rapidly as part of the carbon cycle. Biomass is derived from plant

materials but can also include animal materials.

First generation biofuels are made from the sugars and vegetable oils found in arable crops,

which can be easily extracted using conventional technology. In comparison, second generation

biofuels are made from lignocellulosic biomass or woody crops, agricultural residues or waste,

which makes it harder to extract the required fuel.

7. Some examples: Upflow anaerobic sludge blanket (UASB) digestion for waste water treatment and

biogas production.

Upflow Anaerobic Sludge Blanket (UASB) reactors are anaerobic centralised or decentralised industrial

wastewater or blackwater treatment systems achieving high removal of organic pollutants. The wastewater flows

upwards in a vertical reactor through a blanket of granulated sludge.Bacteria living in the sludge break down organic

matter by anaerobic digestion, transforming it into biogas. Solids are also retained by a filtration effect of the

blanket. The upflow regime and the motion of the gas bubbles allow mixing without mechanical assistance. Baffles at

the top of thereactor allow gases to escape and prevent an outflow of the sludge blanket. As

all aerobic treatments, UASB require a post-treatment to removepathogens, but due to a low removal of nutrients,

53

the effluent water as well as the stabilised sludge can be used in agriculture.

In countries with a warm climate throughout the whole year, high wastewater temperatures – which are a

requirement for anaerobic degradation – allow and favour an anaerobic treatment of the entire sewage flow, not

only the sludge portion (TBW 2001b). Anaerobic treatment systems (e.g. UASB, anaerobic biogas reactors/digesters)

do not require an energy consuming aeration system and can be constructed much simpler than aerobic treatments.

They convert the organic matter into biogas, which can be recovered. The nutrient-rich effluent can be used for

agricultural irrigation (ROSE 1997) and produced sludge, even though only minimal, isstabilised (mineralised) and can

be used as an organic soil fertiliser or directly proceeded for dewatering.

Upflow Anaerobic Sludge Blanket (UASB) reactors are such anaerobic treatment systems based on break-

down of organic pollutants by anaerobic digestion. They can treat high-strengthindustrial wastewater. They can also

be used in decentralised and centralised treatment systems for domestic wastewaters; yet this use is still relatively

new and not always successful as their performance is highest for high-load influents (www.training.gpa.unep.org).

UASB can retain a high concentration of active suspended biomass, leading to a good removal performance

of organics (biological oxygen demand, BOD, and chemical oxygen demand, COD) and total suspended

solids (TSS). Pathogens and nutrients however, are not removed.

Treatment Process and Basic Design Principles of UASB reactors

Figure 1: Cross-section of an Upflow Anaerobic Sludge Blanket (UASB) reactor. Source: TILLEY et al. (2008)

UASB Reactors are constructed out of concrete or another watertight material and can be designed in a

circular or rectangular way. Wastewater is pumped from the bottom into thereactor where influentsuspended solids

and bacterial activity and growthlead to the formation ofsludge. The upflow regimeallows for an intense contact of

the influent sewage with the sludge blanket or sludgebed. Anaerobicmicroorganisms living in thesludge blanket

digest theorganic pollutants in the incoming sewage. Anaerobic digestion produces biogas (a mixture of methane,

CH4, carbon dioxide, CO2, and trace gases). The upflow stream and the gas bubbles keep the sludge in suspension

and mix the reactor without mechanical assistance. Upstream velocity and settlingspeed of the sludge is in

54

equilibrium and forms a locally rather stable, but suspended sludgeblanket (SASSE 1998). After some weeks of

maturation, granular sludge forms (SASSE 1998). The formation of granules is very important because bacteria in

granules are more efficient for biogas production than flocculated biomass (WENDLAND 2008). Additionally,

granules enhance the filter capacity of the sludge. Sludge granules are also heavier than single sludgeparticles and a

granular sludge bed remains more stable (SASSE 1998). Baffles in the upper part of the reactor act as deflectors and

prevent the sludge to wash out and a gas-liquid-solids separator (GLSS) separates the gas from the

treated wastewater and the sludge (ROSE 1997, SANIMAS 2005). Because of the upflow regime, granule-forming

organisms are preferentially accumulated as the others are washed out (TILLEY et al. 2008).

Figure 2: UASB reactors are separated in three phases: granules, liquid and gas (left). They can be constructed circular or rectangular (right).

Source: TBW (2001b)

Produced biogas can be collected and used as anenergy source for cooking, heating or other, but scrubbing

before use is required (UNEP 2004). If thebiogas is converted to electricity, the heat produced as a by-product can be

reused to heat the reactor, favouring anaerobic digestion. Sludge production is relatively low (WSP 2008) and de-

sludging of the UASBreactor is required only ever few years and can even be counterproductive, as the

granular sludge mass guarantees proper performance (SANIMAS 2005). The residual sludge can be reused as

an organic solid fertiliser in agriculture (TBW 2001b). The effluent is rich innutrients and is therefore adapted to be

reused in agriculture for irrigation.

To maintain the reactor well-mixed and allowing the formation of granules and a good contact of the

active sludge blanket and the influent sewage, it is critical that the influent is equally distributed in the bottom

before moving upwards (see Figure 1). Besides these design requirements, the main influencing parameters

are pH, temperature, chemical oxygen demand(COD), volumetric COD loads, HRT and flow, upflow velocity,

concentration of ammonia and start-up phase (TBW 2001b).

The pH-value needs to be between 6.3 and 7.85 (TBW 2001b) to allow bacteria responsible foranaerobic

digestion to grow. The pH-value is also important because at high pH-values, ammoniac (NH4+) dissociates

to NH3 which inhibits the growth of the methane producingbacteria. For an optimal growth of these bacteria and

thus a optimal anaerobic digestion, thetemperature should lie between 35 to 38°C. Below this range, the digestion

rate decreases by about 11% for each 1°C temperature decrease and below 15°C the process is not sufficient

55

efficient anymore (ALAERTS et al. 1990 in TBW 2001b), although bacterial activity can still be noticed

at temperatures less than 10°C (TBW 2001b). Influents should have concentrations of above 250 mg COD/Lm, as for

lower rates, anaerobic digestion is not beneficial. Optimuminfluent concentrations are above 400 mg COD/L and an

upper limit is not known (TBW 2001b). The hydraulic retention time (HRT) should not be less than 2

hours. Anaerobicmicroorganisms, especially methane producing bacteria, have a slow growth rate. At lower HRTs,

the possibility of washout of biomass is more prominent (BAL & DHAGAT 2001). The optimal HRT generally lies

within 2 to 20 hours (TBW 2001b). The upflow velocity in UASB is an important design parameter as the process

plays with the balance of sedimentation and upflow (SASSE 1998). On one hand, sludge should not be washed out

the reactor, and on the other hand, a minimum speed needs to be maintained to keep the blanket in suspension,

and also for mixing (TBW 2001b). Typically, upflow velocity should be in the range of 0.2 to 1 m/h (TBW

2001b). BOD removal is generally high in UASBs, and lies between 60 to 90 % depending on

the influent (SCHELLINKHOUT et al. 1999; ROSE 1997; UNEP 2004).

Figure 3: Large-scale UASBreactor followed by a post-treatment in trickling filters. Source: http://www.entec-

biogas.com/de/leistungen/technik-system-uasb.php

However, the treatment process is mostly adapted forinfluents with a high BOD and COD content and the

removal is much lower for low-strength effluent, as the UASB reactorsare able to bring the BOD content only down

to 70 to 100 mg/L (TARE & NEMA n.y.; WSP 2008). Total suspended solid(TSS) removal is also high due to a straining

effect of the formed granules, and lies between 60 to 85 % (TBW 2001b; UNEP 2004). The degradation

of nutrients such as nitrogen(N) and phosphorus (P) is almost negligible. Because nitrogenand phosphorous are not

effectively reduced in anaerobictechnologies, this primary treatment approach is particularly apt when used in

parallel with agriculture or aquaculture(ROSE 1997). As in all anaerobic treatment processes, sludgeis stabilised and

if not used in agriculture, has good dewatering characteristics and can be treated in thickening ponds and drying

beds or by composting before safe disposal (ROSE 1997; WSP 2008). As the destruction of pathogens is not

considered high, restricted reuse of the effluent according toWHO (WHO 2006) must be considered for agricultural

application. To meet higher effluentstandards, the effluent may be post-treated in pond systems

(e.g. wastewater stabilisation ponds), constructed wetlands or anaerobic treatment units (e.g. trickling filter). The

most common post-treatment alternatives for effluents are maturation ponds where nutrients are further reduced,

their primary function however being pathogen removal (TBW 2001b). Pre-treatment (e.g. screening or grit

chamber) prior to UASB is advisable for municipal wastewater in order to reduce the coarse and inorganic fractions

(sand).

56

Applicability

UASB are suited for centralised or decentralised treatment systems at community level if skilled labour and electricity are

available. They are particularly adapted for densely populated urban areas as they have low land requirements.

UASB can treat industrial wastewater (brewery, distillery, food processing and pulp and paper waste) (TARE & NEMA n.y.)

and blackwater, even though its application to domestic sewage is still relatively new and they are not resistant to shock loading

and are not adapted for low strength influent. As anaerobic digestion strongly depends on temperatures, UASB are not adapted

for colder climates. UASB reach high treatment levels regarding organics and the produced biogas can be used

for energy conversion. Pathogens, however, as well as nutrientsare not removed. Due to the low nutrient removal,

the effluent is adapted for reuse in agriculture.

Advantages

High treatment efficiency for high-strength wastewater

Biogas can be used for energy (but usually requires scrubbing first)

No aeration system required (thus little energy consumption)

Low sludge production, treated sludge is stabilised (can be used for soil fertilisation)

Effluent is rich in nutrients and can be used for agricultural irrigation

Low land demand, can be constructed underground and with locally available material

Reduction of CH4 and CO2 emissions

Low odour emissions in case of optimum operation

Disadvantages

Requires skilled staff for construction, operation and maintenance (control of feeding pump and influent organic load)

Treatment may be unstable with variable hydraulic and organic loads

Insufficient pathogen removal without appropriate post-treatment

Long start-up phase

Not resistant to shock loading

Constant source of electricity and water flow is required

Not adapted for cold regions

8. Technology to reduce pollution: Reduction of SO2/CO2 by smoke-scrubber in coal thermal plants,

chlorofluorocarbon (CFC) and incandescent bulb replacement.

Scrubber is a device used to entrap a targeted object using a scrubbing medium. The scrubbing medium can

be selected based on the properties of the pollutant and the carrier gas in the exhaust.

In a scrubber, the polluted gas stream is brought into contact with the suitable scrubbing medium, by

spraying, by forcing through, by sucking out or by some other contact method. The scrubbing media entraps

the targeted pollutant by physical phenomenon like simple capture, adsorption, etc. or by chemical

phenomenon like absorption, dissolution, ion exchange, etc.

Based on the type of scrubbing media used, the scrubbers are of two types, dry scrubbers and wet scrubbers.

In dry scrubbers solid scrubbing media like activated granular charcoal, activated alumina, zeolt, etc. been

used

57

Scrubbers can be designed to collect particulate matter and/or gaseous pollutants. Wet scrubbers remove

dust particles by capturing them in liquid droplets. Wet scrubbers remove pollutant gases by dissolving or

absorbing them into the liquid. Wet scrubbers are widely used in cleaning contaminated gas streams because

of their ability to remove effectively both particulate and gaseous pollutants. They are designed to

incorporate small dust particles into larger water droplets, which can then be removed by simple

mechanisms such as gravity, impaction on baffles, or by centrifugal collectors. The droplets are produced,

for example, by spray nozzles, by the shearing a liquid film with the gas stream, or by the motion of a

mechanically driven rotor, and principles used to incorporate the dust into droplets include inertial

impaction, direct interception, diffusion,

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59

Flue gas desulfurization

Flue gas desulfurization is commonly known as FGD and is the technology used for removing sulfur dioxide (SO2) from the

exhaust flue gases of power plants that burn coal or oil to produce steam for the turbines that drive their

electricity generators. The most common types of FGD contact the flue gases with an alkaline sorbent such

as limeor limestone. [1][2][3] As sulfur dioxide is responsible for acid rain formation, stringent environmental protection

regulations have been enacted in many countries to limit the amount of sulfur dioxide emissions from power plants and other

industrial facilities.

Prior to the advent of strict environmental protection regulations, tall flue gas stacks (i.e., chimneys) were built to disperse

rather than remove the sulfur dioxide emissions. However, that only led to the transport of the emissions to other regions.

For that reason, a number of countries also have regulations limiting the height of flue gas stacks.

60

For a typical conventional coal-fired power plant, FGD technology will remove up to 99 percent of the SO2 in the flue gases.

FGD chemistry SO2 is an acid gas. Therefore, the most common large-scale FGD systems use an alkaline sorbent such

as lime or limestone to neutralize and remove the SO2 from the flue gas. Since lime and limestone are not soluble in

water, they are used either in the form of an aqueous slurry or in a dry, powdered form.

When using an aqueous slurry of sorbent, the FGD system is referred to as a wet scrubber. When using a dry,

powdered sorbent, the system is referred to as a drysystem. An intermediate or semi-dry system is referred to as

a spray-dry system.

The reaction taking place in wet scrubbing using a CaCO3 (limestone) slurry produces CaSO3 (calcium sulfite) and can

be expressed as:

CaCO3 (solid) + SO2 (gas) ⇒ CaSO3 (solid) + CO2 (gas)

When wet scrubbing with a Ca(OH)2 (lime) slurry, the reaction also produces CaSO3 (calcium sulfite) and can be expressed

as:

Ca(OH)2 (solid) + SO2 (gas) ⇒ CaSO3 (solid) + H2O (liquid)

When wet scrubbing with a Mg(OH)2 (magnesium hydroxide) slurry, the reaction produces MgSO3 (magnesium sulfite) and

can be expressed as:

Mg(OH)2 (solid) + SO2 (gas) ⇒ MgSO3 (solid) + H2O (liquid)

Some FGD systems go a step further and oxidize the CaSO3 (calcium sulfite) to produce marketable CaSO4 · 2H2O

(gypsum):

CaSO3 (solid) + ½O2 (gas) + 2H2O (liquid) ⇒ CaSO4 · 2H2O (solid)

Aqueous solutions of sodium hydroxide (known as caustic soda or simply caustic) may also be used to neutralize and

remove SO2 from flue gases. However, caustic soda is limited to small-scale FGD systems, mostly in industrial facilities

other than power plants because it is more expensive than lime. It has the advantage that it forms a solution rather than a

slurry and that makes it easier to operate. It produces a solution of sodium sulfite or sodium bisulfite (depending on the pH),

or sodium sulfate that must be disposed of. This is not a problem in a paper mill for example, where the solution can be

recycled and reused within the paper mill.

Types of FGD systems The major types of large-scale, power plant FGD systems include spray towers, spray dryers and dry sorbent injection

systems.

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Spray tower

(PD) Image: Milton Beychok

Location of the various FGD options

There are various types of wet scrubbers. For example, spray towers, venturi scrubbers, packed towers and trayed towers.

Slurries would cause serious erosion problems in a venturi scrubber because of the high speeds at the throat of the venturi

section. Packed towers or trayed towers would plug up if handling slurries. For handling slurries, the spray tower is a good

choice and it is in fact a commonly used choice in large-scale FGD systems.[3][9][10]

Spray towers are used downstream of the particulate equipment (electrostatic precipitator or baghouse) where the flue gas

contains very little, if any, combustion fly ash. In a spray tower system, the sorbent slurry is simply injected via spray nozzles

into a vertical tower where the slurry droplets are contacted with the upflowing flue gas.

Part of the water in the slurry is evaporated by the hot flue gas and the flue gas becomes saturated with water vapor.

The SO2 dissolves into the slurry droplets and reacts with the alkaline sorbent particles. The slurry falls to the bottom of the

spray tower and is sent to a reaction tank where the reaction is completed and a neutral salt is formed. In a regenerable

system, the residual slurry is recycled back for reuse in the spray tower. In a once-through system, the residual slurry is

dewatered and either disposed of or oxidized to CaSO4 · 2H2O and sold as a by-product gypsum.

Spray-dryer

Spray-dryers are used upstream of the particulate removal equipment (electrical precipitator or baghouse) where the flue

gas contains the combustion fly ash. In a spray-dryer system, the alkaline sorbent is usually lime slurry. The slurry is

atomized and sprayed into a vessel as a cloud of fine bubbles where it contacts the hot flue gas. The water is completely

evaporated by the hot gas and the residence time in the vessel (about 10 seconds) allows the SO2 and any other acid

62

gases, such as SO3 and HCl, to react with the lime to form a dry powder of calcium sulfite, calcium sulfate and unreacted

lime.[3][11][12]

The dry powder is removed from the flue gas along with the combustion fly ash in the particulate removal equipment. Some

of the solids from the particulate removal equipment (i.e., fly ash, calcium sulfite, calcium sulfate and unreacted lime) may be

recycled and reused as part of the sorbent slurry.[12]

Dry sorbent injection

The dry FGD system simply injects powdered lime or limestone sorbent directly into the flue gas. As shown in the adjacent

location diagram, the dry sorbent may be injected into any one of three locations: (1) the upper section of the steam

generator, (2) the economizer section of the steam generator or the ducting between the air preheater and the electrostatic

precipitator.[2][3][11][13]

The powdered sorbent is pneumatically injected through lances designed to distribute the sorbent evenly across the flow

path of the flue gas.

When injected into the upper section of the steam generator, it should enter at a point where the temperature range is about

900 to 1200 °C. Injection into the economizer should be at a point where the temperature range is about 400 to 600 °C.

Injection into the ducting between the preheater and the precipitator should be at point where the flue gas temperature is

about 150 to 180 °C.[3][11]

The SO2 reacts directly with the powdered sorbent and the spent sorbent is removed from the flue gas along with the

combustion fly ash in the particulate removal equipment

Sulfur dioxide emission removal performance

levels Partial flue gas desulfurization (FGD) can achieve about 50-70 % removal of sulfur dioxide by the injection of

dry limestone just downstream of the air preheater. The resultant solids are recovered in the electrostatic precipitators along

with the fly ash.

In power plants burning pulverized coal, wet flue gas desulfurization (FGD) that contacts the flue gases with lime slurries (in

what are called wet lime scrubbers) can achieve 95% sulfur dioxide removal without additives and 99+% removal with

additives. Wet FGD has the greatest share of the FGD usage in the United States and it is commercially proven, well

established technology.[14]

The typical older FGD units in power plants burning pulverized coal within the United States achieve average sulfur dioxide

emission levels of about 0.340 kg/MWh (0.22 lb SO2 /106 Btu), which meets the level to which those units were permitted.

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The lowest demonstrated sulfur dioxide emission level (in 2005) for power plants burning pulverized high-sulfur coal within

the United States was 1.08 kg/MWh (0.07 lb SO2 /106 Btu) and 0.046 kg/MWh (0.03 lb SO2 /10

6 Btu) for plants burning low-

sulfur pulverized coal.[14]

chlorofluorocarbon (CFC) replacement.

A. The first generation replacement of CFCs as refrigerants (HCFC)

HCFCs are compounds containing carbon, hydrogen, chlorine and fluorine. The HCFCs

have shorter atmospheric lifetimes than CFCs and deliver less reactive chlorine to the

stratosphere where the "ozone layer" is found. Consequently, it is expected that these chemicals

will contribute much less to stratospheric ozone depletion than CFCs. Because they still contain

chlorine and have the potential to destroy stratospheric ozone, they are viewed only as

temporary replacements for the CFCs.

HCFCs are less stable than CFCs because HCFC molecules contain carbon-hydrogen

bonds. Hydrogen is attacked by the hydroxyl radical in the lower part of the atmosphere known

as the troposphere. When HCFCs are oxidized in the troposphere, the chlorine released typically

combines with other chemicals to form compounds that dissolve in water and ice and are

removed from the atmosphere by precipitation. When HCFCs become destroyed in this way

their chlorine does not reach the stratosphere and contribute to ozone destruction.

A certain portion of HCFC molecules released to the atmosphere will reach the

stratosphere and be destroyed there by photolysis (light-initiated decomposition). The chlorine

released in the stratosphere can then participate in ozone depleting reactions as does chlorine

liberated from the photolysis of CFCs. Because HCFCs are degraded significantly by two

mechanisms in the atmosphere (as opposed to the CFCs which are destroyed almost exclusively

by photolysis in the stratosphere), and because photolysis rates of HCFCs are generally slower

than those for CFCs, proportionately less chlorine is released from HCFCs in the lower

stratosphere when compared to CFCs. These properties explain why HCFCs are expected to

deplete much less stratospheric ozone than equivalent amounts of CFCs. HCFCs phase-out dates

are shown in Figure 3.

64

Figure 3: HCFC refrigerant phase-out dates (13)

B. The second generation replacement of CFCs as refrigerants (HFCs)

Table 3: HFCs as alternative for CFCs

HFC-23 (CHF3) HFC-143a (CF3CH3 )

HFC-32(CH2F2 ) HFC-152a (CH3CHF2)

HFC-43-10mee (CF3CHF2CHFCH2FCF3) HFC-227ea (CF3CHFCF3)

HFC-125(CHF2CF3 ) HFC-236fa (CF3CH2CF3 )

HFC-134a (CH2FCF3 ) HFC-245fa (CF3CH2CHF2)

Hydrofluorocarbons (HFCs) are compounds containing carbon, hydrogen, and fluorine.

Certain chemicals within this class of compounds are viewed by industry and the scientific

community as acceptable alternatives to CFCs and HCFCs on a long-term basis. Because the

HFCs contain no chlorine they do not directly affect stratospheric ozone. Furthermore,

mechanisms for ozone destruction involving fragments produced as HFCs are decomposed

within the atmosphere (CF3 radicals) have been shown to be insignificant.All HFCs have an

ozone depletion potential of 0.

Like HCFCs, the HFCs contain hydrogen that is susceptible to attack by the hydroxyl

radical. Oxidation of HFCs by the hydroxyl radical is believed to be the major destruction

65

pathway for HFCs in the atmosphere. Atmospheric lifetimes of the most commonly used HFCs

(HFC-134a and HFC-152a) are limited to <12 years because of this reaction.

Although it is believed HFCs will not deplete ozone within the stratosphere, this class of

compounds has other adverse environmental effects. It has been postulated that extensive use of

these chemicals in the future could contribute significantly to enhanced radiative atmospheric

heating. Also, a number of the HFCs, for example HFC-134a, are expected to decompose in the

atmosphere and produce a long-lived chemical called trifluoroacetic acid (or TFA) that is known

to have adverse effects on certain biota. Concern over these effects may make it necessary to

regulate production and use of these compounds at some point in the future.

C. The third generation replacement of CFCs as refrigerants

The third generation substitutes for CFCs are listed in Table 4.

refrigerant

or cooling

technology

Technological

feasibility (at

present time)

Cost of

plant

relative to

HFCs

Efficiency

relative

to HFCs

Availability

of

commerciale

quipment

Comments

Ammonia

invapor

compression

systems

Yes, well tried

and proven

technology

Higher Better Yes (chiller

only)

Strict compliance with

safety standards & codes

necessary to minimize

toxicity hazards.

Hydrocarbons

in Vapour

compression

systems

Yes, uses

conventional

vapour

compression

technology

Similar Slightly

better Yes

Strict compliance with

safety standards & codes

necessary to minimize fire

and explosion hazard. BS

EN378 currently limit its

use to chillers (indirect

systems).

Carbon

dioxide in

vapour

compression

systems

Yes (in

principle)

Porbably

higher

Currently

lower No

More development needed

to overcome poor

efficiency. Might be best

suited as a secondary

refrigerant.

Air in gas

cycle (Air

cycle)

Yes (in

principle)

Currently

higher

Much

lower No

Must provide simultaneous

heating and cooling to be

energy efficient in

buildings. Commercial

systems available for

aircraft cabin and train air

conditioning but not yet for

buildings.

66

Water in

vapour

compression

chillers

Yes (in

principle)

Substantially

higher at

present

Slightly

higher No

Chillers currently need to be

specially made and would

require more plant room

space.

Absorption

cycle Yes Higher

Much

lower Yes

Only viable where waste

heat exists or where chp can

be justified. Larger heat

rejection surface area

needed than for vapor

compression.

Evaporative

cooling Yes Higher Higher Yes

Cooling performance

limited in the UK climate

unless combined with

desiccant technology.

Ground water Yes Similar Higher Yes

Can be used with chilled

ceilings or for water-cooled

chillers. Not available at all

sites.

River water Yes Higher Higher Yes

Cannot be used alone

because river water is too

warm in summer. Can be

used for heat rejection from

water-cooled chillers, but

not as effective as cooling

towers.

D. The future replacement of CFCs as refrigerants

Looking further down the road, carbon dioxide may someday replace today‘s refrigerants.

Though carbon dioxide is a "greenhouse gas" that may contribute to global warming, it is non-

toxic, non-flammable, cheap and abundant. But to work as a refrigerant, carbon dioxide must be

run at extremely high pressures - up to several thousand psi! As long as the gas is safely

contained at high pressure, it works pretty well as a refrigerant. But such high pressures pose a

potential danger to technicians who must ultimately work on such systems.

Someday a perfect air conditioner may use no refrigerant whatsoever. Some time back,

the Rovac Corporation in Rockledge, FL, announced it had developed a revolutionary A/C

system that required no refrigerant at all, and used air itself as the working medium. The Rovac

system used a "circulator" that was essentially an expander rather than a compressor. By

expanding the volume of air, the drop in pressure produced a corresponding drop in temperature.

The system supposedly required 35 to 40% less power than a refrigerant-based A/C system and

provided equivalent cooling. Mitsubishi has licensed rights to the technology and was

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investigating it further. That was 20 years ago. We‘re still waiting.

Ten years ago, the Naval Postgraduate School in Monterey, CA, claimed it had developed

a refrigeration process using an acoustic generator. Sound waves were used to create pressure

changes that had a chilling effect. No word as to what ever happened to this technology.

Although there are a lot of substitutes for CFCs as refrigerants, scientists continue to

research new substitutes, which are less expensive, less destructive for ozone layer and more

practical for industry.

incandescent bulb replacement

The idea of phasing out incandescent light bulbs in order to save energy has been widely welcomed across the world and for many

the question is not “if” we should do it, but “how fast” we can do it.

The benefits are clear: The potential energy savings are 10 billion Euros per year in Europe alone, along with 25 million tonnes of

CO2. Globally, these savings are roughly four to five times. Politically too it seems an easy win at a time when strict carbon

reduction targets are being set and the absolute need to reduce carbon emissions have been widely accepted by governments,

scientists and NGOs.

However, a number of people remain uncomfortable with the idea. Resistance is generally based on the notion that the only

alternative to the incandescent light bulb is the CFL energy saving bulb and a number of supposed (negative) issues associated

with this light source are then listed and multiplied. This picture however is misleading.

In fact, the Lighting Industry is fast developing several alternatives to the incandescent light bulb in addition to the new ranges of

CFL lamps. A new generation of energy saving Halogen lamps is now becoming available in Europe and the US. These offer

energy savings from 30 to up to 50 %, will last three times longer, and provide a quality of light, which is equal to that of an

incandescent bulb. These new lamps are dimmable, allowing for even greater energy savings, and are the same size and shape as

the ordinary incandescent bulbs. Most importantly, they can directly replace incandescent bulbs. Within a few years these new

halogen alternatives will be available in the huge quantities needed.

The second alternative being developed is light emitting diodes (LEDs). These will truly take lighting into the 21st Century with

lifetimes that are fifty times longer than incandescent bulbs and anticipated energy savings of 95 %. The first high quality light

generation to provide enough light to replace low wattage incandescent bulbs will be available within 1–2 years and major

developments are expected within the next 3–5 years. LEDs will also offer energy saving alternatives for those specialist areas

such as fridge and oven lamps, which CFL lamps are unsuited for.

The existing CFL lamp also offers an important alternative. The days when they were heavy, ugly and pricey have long gone.

Today‟s CFL lamps offer energy savings of up to 80 %, are small, bulb or candle-shaped, and much cheaper. Colour variations are

also available and increasing numbers can also be dimmed. Well known brands offer the best all round quality. They are ideal for

areas where lighting is left on for longer periods such as halls, landings and porches.

However a number of concerns still exist regarding CFLs. These lamps contain minute amounts of mercury, which is needed to

create light in an efficient way. Despite the fact that the mercury used would fit on the tip of a ballpoint pen, there is a justified worry

about this mercury being disposed of in the ground. CFL‟s fall under the EU WEEE recycling laws and it is expected that in the

future the great majority will be recycled.

However, mercury is also omitted in the atmosphere from the power system, and the mercury contained in lamps need to be

weighed against that emitted from power plants.

Studies show that indirectly the additional energy usage of incandescent bulbs is responsible for more mercury entering the

environment than that is contained in a CFL. It should also be remembered that each CFL lamp means that 6–10 incandescent

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bulbs don‟t need making, transporting and disposing off. Life cycle studies have clearly shown that about 90 % of the environmental

impact of a light bulb is in its usage phase, in other words when it consumes electricity. Both these factors favour the CFL.

It is often assumed that the discussion about phasing out incandescent bulbs is about lighting in the home, but figures show that

about 25 % of all such bulbs still sold in Europe today end up in commercial applications such as hotels, restaurants and even

offices.

There is also a striking unbalance between the amount of electricity used by incandescent bulbs, their sales volumes and the work

they actually perform: Incandescent bulbs consume 25 % of all electricity used for lighting in the world, but they only produce 4 % of

all electric light. This is despite the fact that they represent 2/3 of all global lamp sales!

Huge savings can thus be made in the way we are lighting our offices, roads, shops and factories. It would be a real shame, if we

let our nostalgia for a century-old, inefficient bulb, obscure the need to switch to more energy efficient technologies.

9. Renewable energy sources: Wind, Solar, Tidal waves and Biomass energy.

alternative energy sources Alternative energy refers to energy sources that have no undesired consequences such for example

fossil fuels or nuclear energy. Alternative energy sources are renewable and are thought to be "free" energy

sources. They all have lower carbon emissions, compared to conventional energy sources. These include

Biomass Energy, Wind Energy, Solar Energy, Geothermal Energy, Hydroelectric Energy sources. Combined

with the use of recycling, the use of clean alternative energies such as the home use of solar power systems

will help ensure man's survival into the 21st century and beyond. 1. Bio Energy

Biomass is yet another important source of energy with potential to generate power to the extent of

more than 50% of the country‟s requirements. India is predominantly an agricultural economy, with huge

quantity of biomass available in the form of husk, straw, shells of coconuts wild bushes etc. With an

estimated production of 350 million tons of agricultural waste every year, biomass is capable of

supplementing coal to the tune of about 200 million tonnes producing 17,000 MW of power and resulting in

a saving of about Rs.20,000 crores every year. Biomass available in India comprises of rice husk, rice

straw, bagasse, coconut shell, jute, cotton, husk etc. Biomass can be obtained by raising energy farms or

may be obtained from organic waste.

The biomass resources including large quantities of cattle dung can be used in bio-energy

technologies viz., biogas, gasifier, biomass combustion, cogeneration etc., to produce energy-thermal or

electricity. Biomass can be used in three ways – one in the form of gas through gasifiers for thermal

applications, second in the form of methane gas to run gas engines and produce power and the third

through combustion to produce steam and thereby power.

2. Wind Energy

The evolution of windmills into wind turbines did not happen overnight and attempts to produce

electricity with windmills date back to the beginning of the century. It was Denmark which erected the first

batch of steel windmills specially built for generation of electricity. After World War II, the development of

wind turbines was totally hampered due to the installation of massive conventional power stations using

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fossil fuels available at low cost. But the oil crisis of 1973 heralded a definite break through in harnessing

wind energy.

Many European countries started pursuing the development of wind turbine technology seriously

and their development efforts are continuing even today. The technology involves generation of electricity

using turbines, which converts mechanical energy created by the rotation of blades into electrical energy,

some times the mechanical energy from the mills is directly used for pumping water from well also. The

wind power programme in India was started during 1983-84 with the efforts of the Ministry of Non-

Conventional Energy Sources. In India the total installed capacity from wind mills is 1612 MW.

3. Solar Energy

Solar Power was once considered, like nuclear power, „too cheap to meter‟ but this proved illusory

because of the high cost of photovoltaic cells and due to limited demand. Experts however believe that with

mass production and improvement in technology, the unit price would drop and this would make it attractive

for the consumers in relation to thermal or hydel power. The Solar Photo Voltaic (SPV) technology which

enables the direct conversion of sun light into electricity can be used to run pumps, lights, refrigerators, TV

sets, etc., and it has several distinct advantages, since it does not have moving parts, produces no noise or

pollution, requires very little maintenance and can be installed anywhere. These advantages make them an

ideal power source for use especially in remote and isolated areas which are not served by conventional

electricity making use of ample sunshine

available in India, for nearly 300 days in a year.

A Solar Thermal Device, on the other hand captures and transfers the heat energy available in solar

radiation. The energy generated can be used for thermal applications in different temperature ranges. The

heat can be used directly or further converted into mechanical or electrical energy.

4. Other Sources

The other sources of renewable energy are geothermal, ocean, hydrogen and fuel cells. These have

immense energy potential, though tapping this potential for power generation and other applications calls

for development of suitable technologies.

(i) Geo-Thermal Energy

Geo-Thermal energy is a renewable heat energy from underneath the earth. Heat is brought to near

surface by thermal conduction and by intrusion into the earth‟s crust. It can be utilised for power generation

and direct heat applications. Potential sites for geo-thermal power generation have been

identified mainly in central and northern regions of the country. Suitable technologies are under

development to make its exploitation viable.

(ii) Ocean thermal and Tidal energy (Ocean Thermal Energy Conversion – OTEC)

The vast potential of energy of the seas and oceans which cover about three fourth of our planet,

can make a significant contribution to meet the energy needs. Ocean contains energy in the form of

70

temperature gradients, waves and tides and ocean current, which can be used to generate electricity in an

environment-friendly manner. Technologies to harness tidal power, wave power and ocean thermal energy

are being developed, to make it commercially viable.

(iii) Hydrogen and Fuel Cells

In both Hydrogen and Fuel Cells electricity is produced through an electro-chemical reaction

between hydrogen and oxygen gases. The fuel cells are efficient, compact and reliable for automotive

applications. Hydrogen gas is the primary fuel for fuel cells also. Hydrogen can be produced from the

electrolysis of water using solar energy. It can also be extracted from sewage gas, natural gas, naptha or

biogas. Fuel cells can be very widely used once they become commercially viable.

(iv) Bio fuels

In view of worldwide demand for energy and concern for environmental safety there is need to

search for alternatives to petrol and diesel for use in automobiles. The Government of India has now

permitted the use of 5% ethanol blended petrol. Ethanol produced from molasses/ cane juice, when used

as fuel will reduce the dependence on crude oil and help contain pollution. Further, technology is also being

developed to convert different vegetable oils especially non-edible oils as bio-diesel for use in the transport

sector. They are however, in R & D stage only.

10. Emerging technologies: Geo-engineering - ocean iron fertilization, green cement, bioremediation by

terminator insects and synthetic biology.

ocean iron fertilization

Iron fertilization is the intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom. This is intended

to enhance biological productivity, which can benefit the marine food chain and is under investigation with regards to being a

successful means of facilitating increased carbon dioxide removal from the atmosphere. Iron is a trace element necessary

for photosynthesis in all plants. It is highly insoluble in sea water and is often the limiting nutrient for phytoplankton growth.

Large phytoplankton blooms can be created by supplying iron to iron-deficient ocean waters. A number of ocean labs,

scientists and businesses are exploring fertilization as a means to sequester atmospheric carbon dioxide in the deep ocean,

and to increase marine biological productivity which is likely in decline as a result of climate change. Since 1993, thirteen

international research teams have completed ocean trials demonstrating that phytoplankton blooms can be stimulated by iron

addition.[1]

However, controversy remains over the effectiveness of atmospheric CO

2sequestration and ecological effects.[2]

The most recent open ocean trials of ocean iron fertilization were in 2009 (January to

March) in the South Atlantic by project LOHAFEX, and in July 2012 in the North Pacific off the coast of British Columbia,

Canada, by the HaidaSalmon Restoration Corporation (HSRC)

The maximum possible result from iron fertilization, assuming the most favourable conditions and disregarding practical

considerations, is 0.29W/m2 of globally averaged negative forcing, which is almost sufficient to reverse the warming effect of about

1/6 of current levels of anthropogenic CO

2 emissions. It is notable, however, that the addition of silicic acid or choosing the proper location could, at least theoretically,

71

eliminate and exceed all man-made CO2.

Role of iron

About 70% of the world's surface is covered in oceans, and the upper part of these (where light can penetrate) is inhabited

by algae. In some oceans, the growth and reproduction of these algae is limited by the amount of iron in the seawater. Iron is a vital

micronutrient for phytoplankton growth and photosynthesis that has historically been delivered to thepelagic sea by dust

storms from arid lands. This Aeolian dust contains 3–5% iron and its deposition has fallen nearly 25% in recent decades.

The Redfield ratio describes the relative atomic concentrations of critical nutrients in plankton biomass and is conventionally written

"106 C: 16 N: 1 P." This expresses the fact that one atom of phosphorus and 16 of nitrogen are required to "fix" 106 carbon atoms

(or 106 molecules of CO2). Recent research has expanded this constant to "106 C: 16 N: 1 P: .001 Fe" signifying that in iron

deficient conditions each atom of iron can fix 106,000 atoms of carbon, or on a mass basis, each kilogram of iron can fix 83,000 kg

of carbon dioxide. The 2004 EIFEX experiment reported a carbon dioxide to iron export ratio of nearly 3000 to 1. The atomic ratio

would be approximately: "3000 C: 58,000 N: 3,600 P: 1 Fe".

Therefore small amounts of iron (measured by mass parts per trillion) in "desolate" HNLC zones can trigger large phytoplankton

blooms. Recent marine trials suggest that one kilogram of fine iron particles may generate well over 100,000 kilograms of plankton

biomass. The size of the iron particles is critical, however, and particles of 0.5–1 micrometer or less seem to be ideal both in terms

of sink rate and bioavailability. Particles this small are not only easier for cyanobacteria and other phytoplankton to incorporate, the

churning of surface waters keeps them in the euphotic or sunlit biologically active depths without sinking for long periods of time.

Volcanic ash as a source of iron

Large amounts of eolian (wind deposited) sediment are deposited annually in the world‟s oceans. These deposits have long been

thought to be the main source of iron to the surface ocean, and therefore the main source of iron for biological productivity. Recent

studies suggest that volcanic ash has a significant role in supplying the world‟s oceans with iron as well. Volcanic ash is composed

of glass shards, pyrogenic minerals, lithic particles, and other forms of ash which release nutrients at different rates depending on

structure and the type of reaction caused by contact with water.

Murray et al. recently assessed the relationship between increases of biogenic opal in the sediment record with increased iron

accumulation over the last million years. In August 2008, an eruption in the Aleutian Islands, Alaska deposited ash in the nutrient-

limited Northeast Pacific. There is strong evidence that this ash and iron deposition resulted in one of the largest phytoplankton

blooms observed in the subarctic.

Carbon sequestration

Previous instances of biological carbon sequestration have triggered major climatic changes in which the temperature of the planet

was lowered, such as the Azolla event. Plankton that generate calcium orsilicon carbonate skeletons, such

as diatoms, coccolithophores and foraminifera, account for most directcarbon sequestration. When these organisms die their

carbonate skeletons sink relatively quickly and form a major component of the carbon-rich deep sea precipitation known as marine

snow. Marine snow also includes fish fecal pellets and other organic detritus, and can be seen steadily falling thousands of meters

below active plankton blooms.

Of the carbon-rich biomass generated by plankton blooms, half (or more) is generally consumed by grazing organisms

(zooplankton, krill, small fish, etc.) but 20 to 30% sinks below 200 meters (660 ft) into the colder water strata below

the thermocline. Much of this fixed carbon continues falling into the abyss, but a substantial percentage is redissolved and

remineralized. At this depth, however, this carbon is now suspended in deep currents and effectively isolated from the atmosphere

for centuries. (The surface to benthic cycling time for the ocean is approximately 4,000 years.)

Green cement

72

Green cement is a cementitious material that meets or exceeds the functional performance capabilities of

Ordinary Portland Cement (OPC) by incorporating and optimizing recycled materials, thereby reducing

consumption of natural raw materials, water, and energy, resulting in a more sustainable construction

material. OPC is mixture of compounds produced by burning limestone and clay together in a rotary kiln at

about 1450 C. The manufacturing process for green cement succeeds in reducing, and even eliminating, the

production and release of damaging pollutants and greenhouse gases, particularly CO2. Growing

environmental and increasing cost of fuels of fossil origin has resulted in many countries in sharp reduction

of the resources needed to produce cement and effluents (dust and exhaust gases).

Commonly used supplementary cementous materials (SCM) instead of Portland cement:

1) Ground limestone cement: it is a low cost material & easier to grind than clinker and leads to

improved particle packing and hydration. They contain about 20% limestone and can reduce carbon

emission by 10% compared to Portland cement

2) Fly ash and pulverized fuel ash (PFA): Both are essential the same, it is ash produced from coal and

some other solid fuel combustion systems.fly ash is a mixture of silicon oxides (SiO2), aluminum

oxides (Al2O3) and iron oxides (Fe2O3 & Fe3O4). Fly ash replaces 30% of Portland cement in a

concrete mix to lower permeability & reduce initial heat evolution.

3) Ground granulated blast furnace slag (GGBS): this is a byproduct of iron and steel industry while pig

iron is extracted from melted raw iron ore, the left over material that floats on top is called slag. It

consists of calcium, magnesium aluminosilicates and also has pozzolanic properties. Granulated slag

is formed by by quenching molten slag with water that results in glassy sand like that when ground to

fine powder & contacted with lime or Portland cement. GGBS reduce CO2 emission significantly.

4) Silica fume: silicafume or microsilica is a byproduct of production of silicon and silicon alloys in

electric arc furnaces. It is added to cement to produce high performance concretes that are much

stronger & durable than other concretes made using blend cements. Helps in reduced CO2 emissions.

Drawback is that greatly increases water demand.

Limestone based novel cements

1) Calcium sulfoaluminate cement (4CaO.3Al2O3.SO3 , Ca2SiO4 , C2 (A,F)):

Less CO2 emissions, less heat requirement (energy savings by about 25% as compared to Portland

cement)

2) Calcium aluminate (CaAl2O4) and calcium alumina silicate cements:

Made in rotary kiln by using bauxite instead of calcium silicates found in clays. The limestone &

bauxite mix is fused in a cement clinker in same way as Portland cement to result in high strength. It

is more expensive & less readily available in comparison to Portland cement and generally are

blended with GGBS except in refractory applications.

3) Magnesium oxide based cement as ―carbon negative cement‖: The precursor material is carbonated

in an autoclave process at 180°C and 150 bars. The process produces MgCO3 which is further heated

I air at 700°C to produce MgO. The final product is a blend of MgO and hydrated magnesium

carbonates. It is referred to as carbon negative not just because the fuel it uses but also because the

CO2 produced is recycled back into the process.

4) Alkali activated cements/geopolymers(AAC): It consists of sand, water natural or synthetic

pozzolans and alkali activator as composition. The activator is mixed with water before mixing. The

alkaline solution decomposes the precursors into silicates and aluminium units which then recombine

73

to produce geopolymers. These Aluminium and Silicate polymers grow into high molecular weights

creating strong binder.

5) Sequestrated carbon cement: Calcium and magnesium in seawater and captured CO2 from effluent

gases are used to form carbonates of Mg & Ca(cement). It is stronger than Portland cement.

bioremediation by terminator insects and synthetic biology

Insects are essential to global ecology and show remarkably varied adaptations to their environment. They

are also responsible for economic and social harm worldwide through the transmission of disease to humans

and animals, and damage to crops. Their genetic modification has been proposed as a new way of

controlling insect pests. However, regulatory guidelines governing the use of such technology have not yet

been fully developed.

Economic Impact of Insects Insect-borne diseases cause significant economic losses in countries where they are endemic through lost

productivity and healthcare expenditure. Malaria alone can decrease gross domestic product (GDP) by as

much as 1.3% in countries with high levels of transmission and is a serious barrier to economic

development. Insects also cause economic harm through direct damage and disease. transmission to crops.

Field vegetables, grasses and citrus fruit are all seriously affected by insects and insect-borne diseases.

Major Insect-borne Diseases

The World Health Organisation (WHO) publishes data on the incidence of insect-borne human diseases –

those where an infectious

agent such as a virus or parasite is transmitted by an insect. Exact figures are difficult to obtain due to the

difficulty of collecting complete

data in many countries.

Malaria is caused by parasites transmitted by several species of mosquito. In 2008, there were 247 million

cases of malaria worldwide and nearly one million deaths, most of these in Africa.

Dengue Fever is caused by viruses transmitted by mosquitoes. It infects 50-100 million people annually

with 2.5 billion worldwide at risk; it causes severe fever and may be fatal.

Chagas Disease is caused by a parasite spread by assassin bugs in the Americas. It can cause lifelong

debilitating medical problems. 16-18 million people are infected and 21,000 die annually.

Human African Trypanosomiasis, also known as sleeping sickness, is caused by a parasite spread by

certain species of tsetse fly in sub-Saharan Africa. Millions are at risk and 50-70,000 infections occur every

year; causing neurological symptoms and death if untreated.

Current Insect Control Strategies Insecticides

Chemical insecticides are the primary means of controlling insect pests for agriculture and public health. For

example, two important control strategies targeting mosquitoes are indoor spraying of residual insecticides,

such as DDT, and the use of insecticide-treated bed nets. However, some insecticides are linked to

environmental harms, such as the decline of beneficial insect pollinators (POSTnote 348). This has lead to

tighter regulation of their use globally, such as by the Stockholm Convention on Persistent Organic

Pollutants and the EU Directive on the Sustainable Use of Pesticides (POSTnote 336). This has resulted in

many products being taken off the market and some scientists fear that the current lack of alternative

insecticides may lead to an increase in insecticide resistance in insect pests, a problem that is already

74

occurring in mosquito control programmes around the world.

Alternative Control Strategies

An insecticide-free method to control insect pests is the Sterile Insect Technique in which laboratory-reared

male

insects, sterilised by radiation, are released over an area. These compete with fertile wild males to mate with

wild females in a form of area-wide birth-control that can be used for elimination of an insect population

from an area. This is a widely used method but can be employed only for a limited number of insect species.

Environmental management is also an important control method. For example, removal of breeding sites

around human habitations can be an effective way of controlling mosquito populations in urban areas.

Genetic Modification of Insects Genetically modified (GM) insects are produced by inserting new genes into their DNA. Many genes have

been identified that can alter the behaviour and biology of insects. When these genes are inserted into an

insect‘s genome they are called transgenes and the insect is described as transgenic or genetically modified.

Transgenes are usually inserted using short sequences of DNA that randomly integrate into the insect‘s

genome, carrying the transgenes with them. By injecting DNA containing the desired genes into the eggs of

insects, genetically modified strains can be created carrying complex arrangements of transgenes.

Researchers use a wide variety of transgenes, derived from a variety of organisms, to modify insects:

Marker genes are used to make the insects fluoresce. These allow researchers to distinguish them

from the unmodified variety, which is important for monitoring them in the environment.

Lethal genes cause the insect to die, or make it unable to reproduce.

Refractory genes confer resistance to a particular pathogen rendering the insect unable to transmit the

disease any longer.

Novel methods to manipulate genes over the last ten years have allowed many insects to be genetically

engineered including agricultural pests such as the Mediterranean fruit fly as well as disease vectors such as

mosquitoes. Researchers are preparing some GM insects for trial releases into the environment, with the

2006 release of a GM pink bollworm moth (a pest of cotton), containing a marker gene, in the United States

being the first use of GM insects in a plant pest control programme.

Potential Control Strategies Scientists have proposed two distinct strategies involving the release of GM insects: population suppression

and population replacement.

Population suppression strategies are potentially an improvement of the Sterile Insect Technique that

does not require radiation sterilisation. They are also applicable to a wide range of pest insects as the

design of the genes inserted may be readily adapted to new species. This strategy is the furthest

forward in development. A UK company, Oxitec ltd. has engineered GM mosquitoes for suppressing

the vector of dengue fever. Trial releases into the wild are imminent in several countries.

Population replacement technologies are more applicable to public health applications than

agricultural ones. Mosquitoes less able to transmit dengue fever have already been created and

scientists believe they are close to the more technically challenging goal of creating mosquitoes less

able to transmit malaria.

The Potential Benefits of GM Insect Strategies

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Proponents of GM insects consider them to be a tool to complement existing control methods. Several

unique benefits of GM insects have been proposed:

they would target only a single insect pest species, leaving beneficial insects unharmed

by using insects‟ natural propensity to find one another, pest populations inaccessible to traditional

control methods could be eliminated

GM insects could reduce the need for insecticides and any associated toxic residues in the

environment

when used in disease control programmes GM insects would protect everyone in the release area,

irrespective of socio-economic status.

disease control using GM insects would require less community involvement and so would be less

vulnerable to the failure of individuals to participate in a control programme.

Possible Risks of GM Insects Several organizations have raised concerns about the release of GM insects:

new insects or diseases may fill the ecological niche left by the insects suppressed or replaced,

possibly resulting in new public health or agricultural problems

the new genes engineered into the insects may ―jump‖ into other species, a process called horizontal

transfer, causing unintended consequences to the ecosystem.

releases would be impossible to monitor and irreversible, as would any damage done to the

environment.

insects would be deployed only if they were able to reduce successfully the targeted harm and that

any ecological impacts would be detected during trial releases.

horizontal transfer is a concern. However, no study has yet identified a mechanism through which it

could occur in insects and furthermore methods have been developed to inactivate transgenes to

prevent their ―jumping‖ into other species.

self-limiting strategies are designed to remove themselves from the environment after release,

preventing persistence of any GM individuals in the wild.

although self-propagating strategies are designed to maximise the transgenes spread in the

environment,

recall mechanisms are being designed that should allow their spread to be reversed if need be.

Efforts to Develop Guidance on the Release of GM Insects

The WHO Special Programme in Research and Training in Tropical Diseases, in collaboration with

the US Foundation for the

National Institutes of Health, is developing guidance on the ―safety, efficacy, regulation and ethical,

social and cultural issues‖

surrounding the release of GM mosquitoes.

The European Food Safety Authority (EFSA) is constructing guidelines for the environmental risk

assessment of GM insects for

commercial use in the EU.

The Cartagena Protocol on Biosafety has just released the conclusions of an ad hoc technical expert

group on risk

assessment and management of GMOs that includes provisions for GM insects.

MosqGuide is a project funded to develop ―guidance on the potential deployment of different types

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of GM mosquitoes to control vector borne disease, specifically malaria and dengue fever‖.

Unit 3

Design and Modeling for Development of Environment 6 hrs

1. Environmental Design: Principles, benefits and motivation.

2. Environmental design for manufactured products: Building and for developmental planning.

3. Systems Engineering: Analysis-Design-synthesis-applications to environmental Engineering Systems.

4. Environmental Modeling: Introduction, forecast modeling, growth modeling and sensitivity analysis.

5. Application of remote-sensing: Geographic information systems (GIS) in environmental modeling.

Unit 4

Introduction to cell and organ systems 6 hrs

1. Cell Types: Structure of plant, animal and microbial cell and specialized cells like stem cells and nerve

cells.

2. Biological macromolecules: Carbohydrates, proteins and nucleic acids.

3. Special biomolecules: Hormones, enzymes, vitamins and antibiotics.

4. Introduction to organ systems: Digestive, respiratory, excretory nervous and circulatory.

5. Nervous systems: Control and coordination.

6. Sensory organs: Auditory, vision, olfactory, touch and taste.

Unit 5

Bio-Inspired engineering (BIE) or Bionics 8 hrs

1. Biological phenomena and innovative engineering.

2. Introduction to Bioelectronics, Biocomputing, Biophotonics and Biomechatronics.

3. Locomotion and Bio-inspired Robotics, Prosthesis and biomedical implants, Aerodynamics and flight

muscle functioning (birds & Drosophila).

4. Signaling: Enzymes and recognition receptors in biosensors; Neurotransmission and neural networks

(artificial intelligence, signal processing and imaging);

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5. Bioelectric signals and cardiac generator.

6. Sound: Ultrasonics in biology (echolocation in bats, sonar in whales & dolphins) and instrumentation

(medical ultrasonography - ultrasound imaging).

7. Light: Photosynthesis and photovoltaic cells.