recycle and reuse of wastewater

Reuse of Treated wastewater

PULKIT SHUKLA

SIDDHARTH KATIYAR

ROBIN AJMERA

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What is Wastewater Reuse

The U.S. Environmental Protection Agency (EPA) defines wastewater reuse as, “using wastewater or reclaimed water from one application for another application. A common type of recycled water is water that has been reclaimed from municipal wastewater (sewage).”

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Reasons for Wastewater Reuse

The most common reasons for establishing a wastewater reuse program is to identify new water sources for increased water demand and to find economical ways to meet increasingly more stringent discharge standards

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Types of Reuse

• Urban reuse-the irrigation of public parks, school yards , highway medians, and residential landscapes, as well as for fire protection and toilet flushing in commercial and industrial buildings.

• Agricultural reuse-irrigation of non food crops, such as fodder and fiber , commercial nurseries, and pasture lands. High-quality reclaimed water is used to irrigate food crops.

• Recreational impoundments-such as pond sand lakes.

• Environmental reuse-creating artificial wetlands, enhancing natural wetlands, and sustaining stream flows.

• Industrial reuse-process or makeup water and cooling tower water.

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Technical Description

One of the most critical steps in any reuse program is to protect the public health, especially that of workers and consumers. To this end, it is most important to neutralize or eliminate any infectious agents or pathogenic organisms that may be present in the wastewater. For some reuse applications, such as irrigation of non-food crop plants, secondary treatment may be acceptable. For other applications, further disinfection, by such methods as chlorination or ozonation, may be necessary. Table 18 presents a range of typical survival times for potential pathogens in water and other media

Table 18

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Application of Treated Wastewater

Agricultural Irrigation

Crop irrigation

Commercial nurseries

Landscape Irrigation

Parks

School yards

Highway medians

Golf courses

Cemeteries

Residential

Industrial Recycling and Reuse

Cooling water

Boiler feed

Process water

Heavy construction

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Groundwater Recharge

Groundwater replenishment

Saltwater intrusion control

Subsidence control

Recreational / Environmental Uses

Lakes & ponds

Marsh enhancement

Stream-flow augmentation

Fisheries

Non-Potable Urban Uses

Fire protection

Air conditioning

Toilet flushing

Potable Reuse

Blending in water supply reservoirs

Pipe-to-pipe water supply

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Historical Examples 3000 BC – Crete (Minoan culture)

Collection of rainwater and sand “filtration” for reuse

1890 – Mexico

Agricultural irrigation

1912 – Europe & US

Landscape irrigation

1926 – US & Europe

Industrial uses: cooling processes & boilers

1960 – US; Europe; Africa; Australia

Landscape Irrigation (including golf-courses)

Groundwater Recharge

Advanced WW reclamation for potable water supply augmentation

1980 – US; Europe; Japan

Water recycling for toilet flushing in urban areas

Agricultural irrigation of food crops eaten uncooked

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Constituents to be checked in Reclaimed Water

Conventional (measured in mg/L; used in designing conventional WWTPs)

TSS

BOD; COD

TOC

Nitrogen (Ammonia; Nitrate; Nitrite)

Phosphorus

Microorganisms: Bacteria; Viruses ; Protozoan cysts & oocysts

Non-conventional (to be removed or reduced by advanced treatment processes)

Refractory organics

VOC

Surfactants

Metals

TDS

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Problems associated with Wastewater Reuse

Heavy Elements

Public Health – nervous system disorders, mutagenesis, teratogenesis, carcinogenesis

Bioaccumulation (food chain on crops and animals)

Surface water pollution

Environmental Impact – acute and chronic toxicity for plant and animal life, chronic degradation effect on soil

Nutrients (N & P)

Public Health – blue-baby syndrome (from NO3-)

infiltration into potable water supplies

Environmental Health – Eutrophication, crop yield effects (+ive & -ive)

Surface water pollution

Irrigation practices

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Dissolved Solids (salinity)

Environmental Health

Induce problems for the crops’ yield selection and quantity

Accumulation in soil

Effect on soil permeability

Clogging drip-irrigation systems

Emerging Pollutants

Public Health

Acute and chronic health effects – effect on growth, reproduction problems

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Groundwater contamination Nitrate contamination on private drinking wells

Antibiotics lower effectiveness of antibiotics if irrigation of fodder is involved

Odor Public health of neighboring communities

Aesthetic concern - Reduced land values

Concerns with industrial processesScaling

Corrosion

Biological growth & fouling

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Reclaimed wastewater can be safe for agricultural irrigation

Reduce the pathogen levels

Avoid direct contact of crops with reclaimed wastewater

Restrict the type of crops irrigated

Different treatment for safe irrigation of different crops: For tree nurseries, pastures, industrial crops

Secondary treatment & detention in surface reservoirs

For fruits to be canned, vegetables for cooking and fruits with non-edible peels

Tertiary treatment (i.e. AS & Sand Filtration)

For edible crops (uncooked)

Tertiary treatment followed by soil aquifer treatment (or advanced)

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Guidelines and RegulationsTYPE OF REUSE TREATMENT RECLAIMED WATER

QUALITYRECLAIMED WATER MONITORING

SETBACK DISTANCES

Urban Reuse

Landscape irrigation,

vehicle washing, toilet

flushing, fire protection,

commercial air

conditioners, and other

uses with similar access

or exposure to the water.

SecondaryFiltrationDisinfection

pH = 6–9<10 mg/L biochemicaloxygen demand (BOD)< 2 turbidity units (NTU)5No detectable faecalcoliform/100 mL41 mg/L chlorine (Cl2)residual (min.)

pH – weeklyBOD – weeklyTurbidity – continuousColiform – dailyCl2 residual –continuous

50 ft (15 m) topotable watersupply wells

Agricultural Reuse

For Non-Food Crops

Pasture for milking

animals; fodder, fiber and

seed crops.

SecondaryDisinfection

pH = 6–9< 30 mg/L BOD< 30 mg/L totalsuspended solids (TSS)< 200 faecal coliform/100 mL51 mg/L Cl2 residual(min.)

pH – weeklyBOD – weeklyTSS – dailyColiform – dailyCl2 residual –continuous

300 feet (90 m)to potable watersupply wells

Indirect Potable Reuse

Groundwater recharge by

spreading into potable

aquifers.

Site Specific Secondary and Disinfection. May also need Filtration and/or advanced waste water treatment

Site specificMeet drinking waterstandards afterpercolation throughvadose zone.

pH – dailyTurbidity – continuousColiform – dailyCl2 residual – continuousDrinking water standards– quarterlyOther – depends onconstituent

100 ft (30 m) toareas accessibleto the public (ifspray irrigation)site specific

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Some Wastewater Reuse Advantages and Disadvantages

• This technology reduces the demands o potable sources of freshwater.

• It may reduce the need for large wastewater treatment systems, if significant portions of the waste stream are reused or recycled.

• The technology may diminish the volume of wastewater discharged, resulting in a beneficial impact on the aquatic environment.

• Capital costs are low to medium for most systems and are recoverable in a very short time; this excludes systems designed for direct reuse of sewage water.

• Operation and maintenance are relatively simple except in direct reuse systems where more extensive technology and quality control are required.

• Provision of nutrient-rich wastewaters can increase agricultural production in water-poor areas.

• Pollution of rivers and groundwater may be reduced.

• Lawn maintenance and golf course irrigation is facilitated in resort areas.

• In most cases, the quality of the wastewater, as an irrigation water supply, is superior to that of well water.

Advantages

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If implemented on a large scale, revenues to water supply and wastewater utilities may fall as the demand for potable water for non-potable uses and the discharge of wastewaters is reduced.

• Reuse of wastewater may be seasonal in nature, resulting in the overloading of treatment and disposal facilities during the rainy season; if the wet season is of long duration and/or high intensity, the seasonal discharge of raw wastewaters may occur.

• Health problems, such as water-borne diseases and skin irritations, may occur in people coming into direct contact with reused wastewater.

• Gases, such as sulphuric acid, produced during the treatment process can result in chronic health problems.

• In some cases, reuse of wastewater is not economically feasible because of the requirement for an additional distribution system.

• Application of untreated wastewater as irrigation water or as injected recharge water may result in ground

Disadvantages

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New Technologies and Approaches Used In Wastewater Reuse

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Membrane Filtration Systems

Nanotechnology

Microbial Fuel cells

Natural Treatment Systems

Urine Separating Toilets


For wastewater treatment applications, membranes are currently being used as a tertiary advanced treatment for the removal of dissolved species; organic compounds; phosphorus; nitrogen species; colloidal and suspended solids; and human pathogens, including bacteria, protozoan cysts, and viruses.

Membrane bioreactors—usually microfiltration (MF) or ultrafiltration (UF) membranes immersed in aeration tanks (vacuum system), or implemented in external pressure-driven membrane units..

Low-pressure membranes—usually MF or UF membranes, either as a pressure system or an immersed system, providing a higher degree of suspended . UF membranes are effective for virus removal.

High-pressure membranes—nanofiltration or reverse osmosis pressure systems for treatment and production of high-quality product water suitable for indirect potable reuse and high-purity industrial process water. Also, recent research has shown that microconstituents, such as pharmaceuticals and personal care products, can be removed by high-pressure membranes.

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Nanotechnology

Further dramatic improvements are feasible in the near future (Shannon et al., 2008). Nanotechnology concepts are being investigated for higher performing membranes with fewer fouling characteristics, improved hydraulic conductivity, and more selective rejection/transport characteristics. Advances in RO technology include improved membranes and configurations, more efficient pumping and energy-recovery systems, and the development of process technology, such as membrane distillation (Kim et al., 2008).

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Microbial Fuel Cells

With microbial fuel cells, a potential breakthrough technology, electrical energy could be extracted directly from organic matter present in the waste stream by using electron transfer to capture the energy produced by microorganisms for metabolic processes (Logan et al., 2006). First, microorganisms are grown as a biofilm on an electrode; the electron donor is separated from the electron acceptor by a proton exchange membrane, which establishes an electrical current. Electrical energy is then generated through the oxidation of organic matter (BOD5).

Although this technology is still in the early stages of development and significant advances in process efficiency and economics will be necessary, it has the potential to produce electrical energy directly from organic matter in the waste stream.

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Our fundamental understanding and characterization of processes in natural treatment systems (NTSs) is also improving, enabling us to take advantage of natural processes to improve water quality (Kadlec and Knight, 1996). In NTSs, a variety of physical, chemical, and biological processes function simultaneously to remove a broad range of contaminants.

For example, NTSs are increasingly being used to capture, retain, and treat storm water, thereby converting this “nuisance” into a valuable source of water. These natural systems have the advantage of being able to remove a wide variety of contaminants, including nutrients, pathogens, and micro-constituents (e.g., pharmaceuticals and endocrine-disrupting chemicals). Long proven effective for treatment of potable water, NTSs are increasingly being used for water reclamation.

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The development of urine-separating toilets and technologies for treating urine to produce hygienic fertilizer products is a key to managing nutrients with minimal requirements for outside resources, such as additional energy (Larsen et al., 2001; Maurer et al., 2006). Urine-separating toilets have already been developed and continue to be refined, and research on using them for waste management is ongoing. Struvite precipitation and other processes are already available for producing usable fertilizer products from separated urine, and efforts are ongoing to improve the established approaches.

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Case Studies-1Wastewater Reuse in Europe

In Europe the last two decades has witnessed growing water stress, both in terms of water scarcity and quality deterioration, which has prompted many municipalities to look for a more efficient use of water resources, including a more widespread acceptance of water reuse practices.

The study identified more than 200 water reuse projects as well as many others in an advanced planning phase.

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Identifable Water reuse projects in Europe,including their size and intended use

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Conclusion

Almost all medium- and large-scale schemes have been designed as add-on technology to conventional secondary treatment processes.

Despite the fact that water reuse is already becoming an essential and reliable water supply option for many municipalities, there is still significant potential for an increased utilisation of reclaimed wastewater.

The water sector in Europe is in a transitional phase with unique opportunities for water reuse to be implemented on a larger scale as a sustainable practice within a framework of integrated water management.

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Case Study-2Waste water quality and reuse in irrigation in Kuwaitusing microfiltration technology in treatment

Micro filtration (MF) unit has been tested in Kuwait Institute for Scientific Research to treat the secondary wastewater effeulant from Riqqawastewater treatment plant.

There was a consistent reduction in biological oxygen demand (BOD), Chemical oxygen demand (COD), Total bacterial count (TBC) and total suspended solid (TSS).

The comparison is based on calculation sodium absorption ratio (SAR), residual sodium carbonate (RSC), adjusted SAR, sodium hazards (SSP), and measured parameters such as the electrical conductivity (EC), chloride, calcium and potassium concentration, total suspended solids, trace metal analysis and other parameters of health significance.

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Conclusion

Mf filtrate water will not cause any clogging problem related to its EC, SAR, and ESP.

Only chloride potential might causes a moderate potential problem

The MF product water satisfied all the microbiological and organic matter restrictions and standards

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Case Study-3The risks associated with wastewater reuse and xenobiotics in the agroecological environment

The technological progress in respect to analytical chromatographic methods has enabled the identification and quantitation of a number of organic xenobiotic compounds in treated wastewater.

It is also widely accepted that the currently applied treatment processes for urban wastewater abatement fail to completely remove such contaminants and this lead to their subsequent release in the terrestrial and aquatic environment through disposal and reuse applications.

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Conclusion

Since the traditional wastewater treatment methods are not capable of fully removing recalcitrant xenobiotic compounds, advanced technologies must be applied such as Advanced Oxidation Processes (AOPs) and membrane-separation technologies, which are effective in simultaneously removing, both pathogens and xenobiotics, and perhaps their combined application may constitute today, the best option for wastewater treatment and reuse schemes.

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Case Study-4Ultrafiltration for the reuse of spent filter backwash waterfrom drinking water treatment

During most water treatment processes, spent filter backwash water (SFBW) is generated.Innovations in membrane technology, especially in micro- and ultrafiltration processes, offer a suitable treatment for SFBW in order to guarantee a water quality necessary for reuse.

Experiments were performed with SFBW from a full-scale water treatment plant. The plant was operated with high fluxes of more than 40 L/(m2·h) using clarified and non-clarified SFBW. Best membrane performance was obtained using non-clarified SFBW.

As a result, no space- and time consuming sedimentation processes are necessary.Results confirmed that the filtrate can be used as an additional and safe water source. When a continuous maintenance disinfection was provided, filtrate was free of microbial contamination and could be reused without any safety concerns.

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Listing of References

1. U.S. Environmental Protection Agency, Process Design Manual: Guidelines/or Water Reuse.Cincinnati, Ohio, 1992 (Report No. EPA-625/R-92-004).

2. US Environment Protection Agency ,1992. Guidelines for Water Reuse

3. http://cdmsmith.com/en/Insights/Viewpoints/Membrane-Technology-Advances-Wastewater-Treatment-and-Water-Reuse.aspx

4. D Bixtio, C. Thoeye, J. De Koning, D Joksimovic, D. Savic, T Wintgens, T. Melin:Wastewater Reuse in Europe;Desalination 187(2006) 89-101

5. M. Al-Shammiri*, A. Al-Saffar, S. Bohamad, M. Ahmed; Waste water quality and reuse in irrigation in Kuwait using microfiltration technology in treatment; Desalination 185 (2005) 213–225

6. D. Fatta-Kassinosa, , , , I.K. Kalavrouziotisb, P.H. Koukoulakisc, M.I. Vasqueza The risks associated with wastewater reuse and xenobiotics in the agroecologicalenvironment Volume 409, Issue 19, 1 September 2011, Pages 3555–3563

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http://www.sciencedirect.com/science/article/pii/S0048969710003074

http://www.sciencedirect.com/science/article/pii/S0048969710003074#af0005







http://www.sciencedirect.com/science/journal/00489697/409/19

7. Florian G. Reissmanna*, Wolfgang Uhlb; Ultrafiltration for the reuse of spent filter backwash water from drinking water treatment;Desalination 198 (2006) 225–235

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TITLE SLIDE Reuse of Treated wastewater

What is Wastewater Reuse

Reasons for Wastewater Reuse

Types of Reuse

Technical Description

Application of Treated Wastewater

Historical Examples

Constituents to be checked in Reclaimed Water


Reclaimed wastewater can be safe for agricultural irrigation

Guidelines and Regulations

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Some Wastewater Reuse Advantages and Disadvantages

New Technologies and Approaches Used In Wastewater Reuse


Nanotechnology

Microbial Fuel Cells



Case Studies-1 Wastewater Reuse in Europe

Case Study-2 Waste water quality and reuse in irrigation ...

Case Study-3 The risks associated with wastewater reuse a...

Listing of References

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recycle and reuse of wastewater

Engineering