7/27/2019 Bangladesh Water Action: Weed for Wastewater Treatment

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Weed for Wastewater Treatment

Mirzapur, Bangladesh—An NGO found an innovative, low-cost, and sustainable sanitation solution in the duckweed plantto help treat wastewater produced by Bangladesh’s largest hospital complex.

Hospital Wastewater Treatment

The Kumudini Welfare Trust Hospital in the town of Mirzapur in the central Bangladeshi district of Tangail isone of the largest hospitals in the country and providesfree services to Mirzapur’s estimated 20,000 residentpopulation.

The hospital complex, with colleges and schools locatedwithin, produces huge amounts of wastewater that has a

significant impact on sanitation and health conditions dueto the indiscriminate discharge of toxins that contaminateand pollute the environment. It also produces bad odorsand is a breeding site for mosquitoes. It generates anaccumulated wastewater volume equivalent to thatproduced by about 3,000 people daily.

The hospital’s existing wastewater treatment system hasreached its limit and could no longer meet the institution’swastewater treatment requirements. To address theproblem, the Kumudini Welfare Trust teamed up withthe Project in Agriculture, Rural Industry Science andMedicine (PRISM-Bangladesh�, to install and operate a�, to install and operate a, to install and operate adedicated Mirzapur Shobuj Shona (Green Gold� project inthe hospital complex. PRISM, a local NGO that promoteslocal and family enterprises particularly for the poorer sectors of the community, initiated the first hospital wastemanagement system in Bangladesh. Together, they builtthe world’s first comprehensive duckweed research anddevelopment center, which developed the Shobuj Shonawastewater treatment process.

T he � re en � ol r o e t�reen �ol roet

The Mirzapur Green Gold project, a field-testingpilot project of PRISM’s Duckweed Research Projectintroduced the use of duckweed to treat wastewaterof the hospital complex and expanded the wastewatertreatment facility. Co-funded by the governments ofBangladesh and Netherlands, the new system costsapproximately $100,000.

Today, the facility is able to improve its wastewatertreatment from a conventional system to that of a moreadvanced tertiary level, treating 125 to 270 cubic metersof sewage per day. Before, the wastewater flow has abiochemical oxygen demand (BOD� of 600 mg/l (at timesexceeding 1,000mg/l� and about 400 to 600 mg/l of totasuspended solids (TSS�. With the use of duckweed, thenew treatment facility is able to generate effluent of 8.2mg/l of BOD and 7.8 mg/l of TSS.

The system has also shown efficient resource recovery,as it generates biogas and composted sludge for energy

use and fertilizer. The system also produces high qualityduckweed crop as feed supplement for fish and livestockTreated effluent is reused for irrigation.

Sanitation and WastewaOctober 2013

Country Water Action Bangladesh

efficient wastewater treatment facility (left� makes good use of the duckweed plant to treat wastewater from the Kumudini Welfare Trust Hospital (right�, the lapital complex in Bangladesh. Inset: The duckweed, a small floating aquatic plant, is an effective agent in wastewater treatment. Photo Courtesy of PRISM Ba

7/27/2019 Bangladesh Water Action: Weed for Wastewater Treatment

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This Country Water Action was written by Masum Patwary (PRISM-Bangladesh� and

Robert Domingo (ADB Consultant�.

 ADB Water for All’s Country Water Action series showcases reforms and good practices

in the water sector undertaken in ADB’s member countries. It offers a mix of experience

and insights from projects funded by ADB and those undertaken directly by civil society,

local governments, the private sector, media, and the academe. The Country Water 

 Actions are regularly featured in ADB’s Water for All News enewsletter, which covers

water sector developments in the Asia and Pacific region.

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Dukwee Tehnology System

The hospital’s existing wastewater treatment systemconsists of four facultative lagoons—a series of ponds,each focused on a specific stage of the wastewater focused on a specific stage of the wastewater on a specific stage of the wastewater treatment process. The hospital’s wastewater flowsrange from 0.5 liters per second (lps� to 1.5 lps. whicheasily triples during the monsoon season.

The Green Gold Project introduced the duckweedfor advanced/tertiary treatment of wastewater as it iseffective in nutrient removal/recovery. Duckweed is asmall floating aquatic plant that thrives in nitrogen-richenvironments, usually abundant throughout the humidtropics. It is capable of producing protein-rich biomassthat is commonly used in paddy fields as fertilizer. TheTheuse of duckweed in wastewater treatment also lessensse of duckweed in wastewater treatment also lessens

the growth of mosquito, provides cost recovery measuresthrough aquaculture or other applications, and reduceswastewater odor.

The project expanded the existing 1-hectare wastewater treatment system by connecting it to a 0.6-hectare plugflow duckweed wastewater treatment system. Threeof the four existing lagoons were converted to fishproduction tanks, while the fourth became a primaryreceiving and settling tank.

Three tanks collect wastewater from toilets, kitchens,bathrooms and laboratories within the hospital complex.Lift pumps equipped with float switches transport thewastewater to the 0.25-hectare primary receiving pond.It then flows to an adjacent duckweed-covered lagoonfor treatment.

No Tari ffs, Just Inome

 Aside from offering a low-cost, energy efficientwastewater solution to address the sanitation needs ofthe hospital complex, Green Gold system has shownefficient resource recovery. These include reuse oftreated effluent for irrigation, production of high qualityduckweed feed supplement for fish and livestock,generation of biogas for energy use, and use ofcomposted sludge as fertilizer.

The system has also proven to be a model forsustainability, churning out more than enough profit tocover capital investment and O&M costs. The systemearns an average net profit before taxes of 83,777

Bangladeshi Taka (about $1,000� annually. In fact, the(about $1,000� annually. In fact, theannually. In fact, thesystem is self-reliant. It does not charge any form ofuser fees and does not avail any subsidies from thegovernment to sustain its operation.

References: 

 Agriquatics. 2012. Business Case: No-Fee/No-Tariff Treatment of Hospital Complex Wastewater to an Advanced Tertiary Condition.Jonathan Parkinson (GHK�. 2005. Decentralised Domestic Wastewater and Faecal Sludge Management in Bangladesh. United Kingdom-Departmentfor International Development (UK-DFID�. p. 13.

Masum A. Patwary. 2013. Duckweed-based wastewater treatment and aquaculture: The case of Mirzapur, Bangladesh. Paper submitted to theConference on Promoting Innovations in Wastewater Management in Asia and the Pacific. Asian Development Bank. Manila, Philippines, 29–31January 2013

The Kumudini Welfare Trust Hospital’s wastewater treatment facility is capable of treating

125 to 270 cubic meters of sewage per day. Photo courtesy of PRISM Bangladesh

The use of duckweed in wastewater treatment lessens the growth of mosquito, promotes

aquaculture, and reduces wastewater odor. Photo courtesy of PRISM Bangladesh