Wastewater Situation, Applied Strategies & Wastewater management -

Bangladesh

Presented By, Prantor Kumar Mondal

Introduction

People’s Republic of Bangladesh领域 (area) ： 1 ， 47 ， 570 sq-km人口 (population) ： 160 Millions文 ：孟加拉语城池： 7 个首都 (capital) ：达卡 (DHAKA)金钱 (currency) ： Taka

孟加拉国的地图

Water pollution

• Bangladesh has about 230 small and large rivers and a large chunk of the country’s 140million people depend on them for a living and for transportation. But experts say many of them are drying up or are choked because of pollution and encroachment.

Standards of Water & Waste water In Bangladesh

Household Drinking Water Quality

Ground Water Situation

The Dhaka Water Supply and Sewerage Authority relies on the treatment of surface water sources to complement groundwater supplies. However, during the dry season, river water can become so polluted that it cannot be effectively treated to drinking water standards. If the situation worsens, the Dhaka Water Supply and Sewerage Authority may have to obtain water from the Padma and Meghna Rivers, with estimated investment costs of $430million and $285 million, respectively(IWM 2007);

The groundwater situation in Dhaka is particularlycritical .Although reliabledata is hard to obtain (as most groundwater abstraction is carried out through unmeteredself-supply), initial calculations suggest that the textile mills in and around Dhaka may consume as much groundwater as is supplied to the entire megacity of over 12 million inhabitants

Water Pollution

Water Pollution

Point source

Industrial effluent

Textile

Tannery

Dyeing

Thermal

Municipal waste

Non-point source

Agricultural runoff

Atmospheric

Situation of Waste water in Bangladesh

Bangladesh’s economy has benefited from the growth ofits garment sector, but the country faces considerablechallenges managing industrial standards

Impact of Water Pollution

Major urban and industrial areas over the past few years have shown increased evidence of the degradation of both groundwater and surface water quality.

A pollution assessment carried out by IWM (2007) found that industrial sources, notably the textile industry, tanneries, and the pharmaceutical industry, were the largest contributors to pollution in the Dhaka watershed.

Over 1.3 million cubic meters of heavily polluted industrial wastewater entered the drainage and river system without treatment on a daily basis in Dhaka alone. There is also evidence of heavy metals and dissolved solids in shallow aquifers, while surface water bodies (such as rivers, canals, and ponds) have low oxygen levels due to domestic sewage and chemical residues from industry. Most surface water is unfit for human use and is likely to be dangerous for livestock. The environmental, health, and economic costs associated with pollution from untreated industrial effluent are significant.

Major Types

Municipal Wastewater

Ground Water Contamination

Oil Spills or Leakage

Salinity Intrusion

Agricultural Pesticides Wastewater

Industrial Wastewater

Results:

Surface Water Source: Pond, Lake, Wetland, Stream, Channel, River and Sea.

Ground Water Source: Water Table, Deep Tube-well, Dug well, and Shallow

Pump.

Industrial Effluent Discharge

• Numerous textile and tannery industries in Bangladesh

• Required to have ETP• Expensive to treat effluent• Owners reluctant to spend money on non-

productive issues such as ETP• Engineers tend to compromise with the owners• Technology to treat textile dye may not always be

economically viable• Buyers and consumers expect good governance

& implementation of rules • Enforcement of regulations inadequate in the

past; at present more strictly enforced

Water pollution sources and their Ranking

Standards for Textile Industry

Waste materials dumping in Turag RiverSewage discharge in Bonshi River

Sewage discharge in Balu riverIndustrial wastewater discharge in Turag river

Polluted waste water

Hatirjheel

Sewage outfall

Thermal Plume Discharge in Sitalakhhya River

Haripur Barge-Mounted Power Plant CDC Globeleque Power Plant

Shiddhirgonj Power Plant Outfall

Sludge Cake

Dysfunctional ETP

Arsenic pollution in Bangladesh

• For the past two decades the water from over a million tubes has been slowly poisoning Bangladeshi villagers with naturally occurring arsenic. Over 18 millions people are drinking this poisoned water daily

Arsenic affected people

Sewerage system• Mixed provision: noted by Hawkins et al. (2013) many towns and cities, especially in

developing countries, have a mix- ture of on- and off-site sanitation facilities and ser- vices. These may be provided by householders, by developers or by the municipality or utility. The poor sanitary conditions experienced in many towns and cities around the world and the problems relating to badly managed and inadequate on-site and off-site sanitation systems can be illustrated using a faecal waste flow diagram (developed by Peal et al., in press a/b), which illustrates the different pathways that faecal waste takes along the sanitation ser- vice chain. Figure 3, illustrates the problems seen in Dhaka in Bangladesh, where 20% of faecal waste is sewered and 79% goes to on-site containment.

Width of the bars represents the proportion of faecal waste at each step in the chain; orange shading represents

unsafe management; green shading represents effective management

De-centralised domestic wastewater and faecal sludge management in Bangladesh

• Inspired by the success of a technology called Vacutug developed in Kenya , Water Aid imported a Vacutug system to pilot in Dhaka. Based at Sanitation Programme in Mirpur, started the pilot phase in December 2000 to test the use of Vacutug in the Bauniaband slum.

The Vacutug being used to desludge a cesspool

Comparative picture of the Vacutug and traditional services Vacutug service Traditional sweeper’s service

Bangladesh Export Processing Zone

Central or Common: Effluent Treatment plant at Savar

Individual: ETP, Hossain Dyeing, Tongi

Pagla Sewage Treatment Plant in Dhaka

Waste water treatment plant Dhaka Video

Water Treatment Technologies in Bangladesh

Applied Water Treatment Technologies in Bangladesh:

Arsenic Removal

Safi Filter (laterite soil),

Tin Kolsi Method (Sand, gravel, pebble),

Oxidation,

Coagulation, precipitation and filtration,

Adsorption (sorptive filtration),

Ion exchange, and

Membrane techniques.

Iron Removal Tin Kolsi Method, and

Well Water Iron Filters

Industrial Effluent and Municipal Wastewater

Physical Process,

Chemical Process, and

Biological Process

Oil Removal

Drinking Water

Powdered chemicals spray from a vessel to

subside the oil to protect oxygen reduction

Fishing nets to sweep away oil

Traditional methods of neutralising oil and

New technology based on local ones

Adsorption,

Co-precipitation, and

Reverse Osmosis (RO) Method.

Desalinisation

Reverse Osmosis (RO) Method , Solar Desalinisation, Multi-Stage-Flash (MSF), Multieffect-Distillation (ME) with Thermal Vapour Compression (ME-TVC) and

There are also some technologies for rural area and new modern technologies

Wastewater Treatment Using Duckweed

Wastewater Treatment Using Duckweed

• Technical Description This is a relatively new technology in which small-

scale wastewater treatment can be achieved using duckweed (Lemna spp. or Spirodela sp.). Duckweed is a self growing plant abundant in the tropical countries. It is commonly used as a fertilizer in paddy fields, but has recently been used in the treatment of wastewater in Bangladesh. In Mirzapur, Bangladesh.

Duckweed Ponds

Low-cost pour-flush latrine. Excreta is collected and digested in the submerged bamboo case placed directly in

the duckweed pond releasing nutrients through diffusion

Family/village level pour-flush pit latrine. Settle able solids sink to thebottom of the water-sealed pit where they undergo anaerobic decomposition. The liquid effluent overflows from the pit into the adjacent duckweed pond, while sludge remains at the bottom of the pit from where it has to be removed periodically (Edwards et al. 1987

Wastewater Treatment Using Duckweed

• Operation and Maintenance Use of this technology is simple, being based upon a modification of conventional

maturation lagoon technology.• Level of Involvement This technology can be implemented at either the individual farm or community

levels.• Costs costs are estimated to be low.• Effectiveness of the Technology Since 1989, PRISM, Bangladesh, has developed farming systems using

duckweed-based technology and tested their potential for wastewater treatment and fish food.

• Suitability This technology is suitable in tropical climates

Different duckweed treatment systems depending on type and amount

of wastewater.

Pond Design

• Two basic principles for pond design andoperation are Used for duckweed treatment. Namely

1. plug-flow2. batch systems.Plug-flow design is suitable for treatment of large and

regular wastewater flows originating from communities and peri-urban areas.

Duckweed-covered serpentine plug-flow lagoon in the USAfor tertiary treatment of effluent from three facultative lagoons followed by a

wetland buffer. Design flow is reported at 19,000 m3/d, with peak flowsreaching 38,000 m3/d. (Photograph: Lemna Corp. 1994).

Duckweed can be used for combined wastewater treatment and production of high protein biomass up to the point where nutrient limitation diverges the two so far parallel running processes.

To achieve optimum treatment efficiency and protein production, an ideal plug-flow design should include multiple wastewater inlet points and allow recirculation of the final effluent.

Ideal plug-flow system for combined duckweed-based wastewater

treatment and protein production

Batch-operated ponds are a feasible option for introduction of duckweed aquaculture in villages where already existing ponds can often be used and, thus, save capital costs for extra earth work. In comparison with a continuous flow through system, duckweed growth may be enhanced near the nutrient inlet points as a result of reduced nutrient mixing and distribution.

A narrow pond design allowing duckweed harvesting from the embankment is also favored here.

Batch-operated pond for duckweed cultivation at villagelevel showing dense duckweed cover and pour-flush latrine influent for nutrient supply in the background (Bangladesh).

Water Depth

The critical factor with respect to water depth is to ensure vertical mixing in the pond to allow the wastewater to be treated to come into contact with the duckweed fronds for nutrient uptake and BOD degradation through attached microbial populations. An outlet structure is recommended in order to vary the operating depth (Metcalf and Eddy 1991).

Reported pond depths range from 0.3 to 2.7 m up to even 5 m (Lemna Corp. 1994). The majority of authors report an optimal depth ranging from 0.4 to 0.9 m, implying that a maximum depth of one meter is sufficient for acceptable temperature buffering. Higher depths are also a feasible option for systems with relatively low BOD loads, a low recirculation rate and high land costs. Shallow system depths are, however, better suited for high organic loads, a high recirculation rate and for regions with inexpensive land prices .Both shallow and deeper pond d epths are currently being applied, depending on organic load and land availability.

Organic Loading Rate

Average organic loading rates expressed in terms of BOD5 for plant systems without artificial aeration should not exceed 100 to 160

kg/ha·d in order to obtain an effluent quality of 30 mg BOD/l or less (Metcalf and Eddy 1991, Gijzen and Khondker1997). Odors can develop at lower loading rates, especially where the sulphate concentration in the wastewater is greater than 50 mg/l. It seems that duckweed is less suitable for the treatment of wastewaters containing high BOD loads.

Duckweed systems alone appear to be less suitable for treating wastewaters containing high BOD loads.

Operating Considerations

It includes –• Labour Requirements• Initial Work• Maintenance and Operational Work• Work Related to Animal Cultivation

Transport of fresh duckweed in a wickerwork basketto the weighing station and adjacent fish pond, using a wooden board, abamboo pole and strings for suspension of the basket (Bangladesh

Freshly harvested duckweed grown on diluted sewageis filled into a wickerwork basket, where it remains for some time to allowsome water drainage and pathogen removal by sunlight irradiation (Bangladesh).

Determination of duckweed wet weightusing a spring scale and record keeping (Bangladesh).

Distribution of fresh sewage-grownduckweed into floating bamboo feeding zone of fish pond.The feeding zone prevents the floating duckweed frombeing undiscovered by fish through dispersal in the fishpond (Bangladesh).

Harvesting of Duckweed

The quantity and frequency of duckweed harvesting plays a major role in the treatment efficiency and nutritional value of the plants. Regular harvesting ensures that the accumulated nutrients or toxins are permanently removed from the system.

Optimum standing crop density to achieve highest productivity is site specific.

Alaerts et al. (1996) reported a standing crop density of 1600 g(wet wt)/m2 for a duckweed-covered sewage lagoon in Bangladesh.

Harvesting Frequencies And Amount

Removal Efficiencies

Reliable data on removal efficiency in full-scale duckweed treatmentsystems is practically inexistent.

The most relevant study on removal efficiencies in a full-scaleduckweed treatment system in a low-income country was publishedby Alaerts et al. (1996). The study focused on a 0.6 haplug-flow sewage lagoon covered with Spirodela for 2000-3000inhabitants in Bangladesh. The lagoon received the effluent of ananaerobic sedimentation pond with a HRT of 1-3 days. The plugflow’sdepth increased from 0.4 to 0.9 m with a HRT of about 20days.

Comparisons with other Methods

Wastewater Treatment Using Duckweed

• Advantages This technology is inexpensive to construct and operate, and easy to implement.

Duckweed is a prolific plant, especially in nitrogen-rich environments, and can be easily used as mulch or a natural soil organic enrichment.

• Disadvantages If the flows through the oxidation pond are not properly controlled, there is a

possibility that the duckweed will flow out with the effluent. Treatment capacity may also be lost during high floods, if the area is not protected.

• Cultural Aspects No problems relating to the use of this technology are known to occur.• Further Development of the Technology More research through pilot projects is needed in order to refine the sizing of

the ponds used and to determine the correct inoculums of plant material to achieve a predetermined effluent quality

New Approach For Greener & Cleaner city Model Development

• Water Quality Map provides a good visual picture of pollution status of river

• It can be presented to managers and decision makers as a good visualization aid

Water Quality Mapping using Biological and Chemical Indicators

Effect of Untreated Wastewater Discharge

Water Quality Map around Dhaka Industrial effluent discharge

Shared Responsibility

• The responsibilities do not rest with the Engineers only.

• Government, Policy Makers, General Populace, Entrepreneurs should share the responsibilities

• Good governance in every sector is essential to ensure ethical management of the environment

1)Self-purification of

water body

2)Building WWTP

1)Increasing treating

fees for wastewater.

2)Using the wastewater

as resources

3)Recycling

1)Improving legislation

2) monitoring

Media and Environmental Awareness

Erin Brockovich• The movie portrays the environmental disaster due to contamination of drinking

water at Hinkley, California.

• Chromium (VI), a carcinogen, caused by a Pacific Gas & Energy Ltd.

• The pipeline was constructed in 1952. The company knew that Hinkley GW was being contaminated through their pipeline but tried to cover up.

• The case was settled in 1996 for $333 million in a direct action law suit.

• Another lawsuit, against this company alleges contamination near PG&E Kettleman Hills compressor station in Kings County, California

In Conclusion• Professional ethics is essential for ensuring a safe and sound

environment• The responsibilities rest upon not only on the Engineers but

also on the policy makers, govt. and non-govt. organizations, donor agencies as well as the general public

• Good governance in every sector is essential to ensure ethical management of the environment

• Communication between the professionals and policy makers-end users provides the key to success

References• Alaerts, G. J., Md. M. Rahman, and P.

Kelderman. 1996.Performance analysis of a full-scale duckweed-covered sewage lagoon. Wat. Res. Vol. 30, No. 4: 843-852.

• Angerilli, N. P. D., and B. P. Beirne. 1980. Influence of aquatic plants on colonization of artificial ponds by mosquitoes and their insect predators. Can. Entomol. 112: 793-796.

• Arthur, J. P. 1983. Notes on the design and operation ofline an agricultural system that utilizes aquatic plants. J. Aquat. Plant Manage. 17: 74-75.

• Lueoend, A. 1983. Das Wachstum von Wasserlinsen (Lemnaceae) in Abhaengigkeit des Naehrstoffangebots,insbesondere Phosphor und Stickstoff. Veroeff.

Geobot. Inst. ETH, Stiftung Ruebel, Zuerich 80: pp.116.

• Mandi, L. 1994. Marrakesh wastewater purification experiment using vascular aquatic plants Eichhornia crassipes and Lemna gibba. Water Sci. Technol. 29: 283-287.

• Mara, D. D. 1976. Sewage treatment in hot climates. Chichester. John Wiley.

• Mara, D. D., P. Edwards, D. Clark, and S. W. Mills. 1993. A rational approach to the design of wastewater fed fishponds. Wat. Res. 27: 1797-1799.

References• Reed, S.C., E. J. Middlebrooks, and R.

W. Crites. 1988. Natural Systems for Waste Management and Treatment. McGraw-Hill, New York.

• Rejmankova, E. 1982. Proc. 1st Intern. Wetlands Conf. New Delhi. pp. 397-403.

• Robson, E. 1996. Lemnaceae cleanes waste and creates protein. Weekend Independent. pp. 20-21.

• Rodriguez, L. and T. R. Preston. 1996. Comparative parameters of digestion and N metabolism in MongCai and Mong Cai large white cross piglets having free access to sugar cane juice and duckweed. Livestock

• Research for Rural Development, Vol. 8.

• cattle. J. Dairy Sci. 60: 161.• Russoff, L. L., S. P. Zeringue, A. S.

Achacoso, abd D. D.• Culley. 1978. Feeding value of

duckweed (an aquatic plant. Family Lemnaceae) for ruminants. J. Dairy Sci. 61: 186.

• Schulz, B. 1962. Wasserlinsen. Die neue Brehm- Buecherei, Ziemsen, Wittenberg. pp. 95.

• Shahjahan, M., A. H. Khan, N. Akhtar, A. S. M. A.

Thank You