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Student Advising M. Shah Alam Khan |
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Name of the student: Md. Rokunuzzaman Program: M.Sc. in Water Resources Development (WRD)
Title: Investigation into Suitability of Duckweed-Treated Wastewater for Multipurpose Use in Bangladesh
Background and present state of the problem:
Rapidly growing shortage of usable water has promoted attempts to re-use effluent from wastewater treatment plants in many parts of the world. After proper processing, the effluent is used for various urban, industrial, agricultural, aquacultural or recreational purposes. Duckweed covered stabilization ponds may significantly lower the pollutant concentrations in the effluent at relatively low costs (Hillman and Culley, 1978; Oron, 1994).
In Bangladesh, three relatively small duckweed-based treatment systems have been used to treat domestic wastewater. In these systems, duckweed ponds improve the treatment capability by natural bioaccumulation process. However, suitability of the treated water for agricultural, aquacultural or recreational uses is unknown. If found suitable, duckweed-treated water may provide an additional resource in both rural and urban areas. Duckweed also holds great potential in wastewater and sanitation projects if combined with duckweed feed applications in aquaculture (Gijzen and Kondker, 1997; FAO, 1999; Nhapi et al., 2001).
Objectives with specific aims and possible outcome:
The overall goal of the study is to assess the suitability of wastewater treated in a duckweed-based system for agricultural, aquacultural or recreational uses. The specific objectives of the study are:
(i) to test selected water quality parameters in a duckweed-based wastewater treatment facility, and (ii) to assess the suitability of the treated effluent for various applications as per the water quality standard and guideline in Bangladesh.
This study is expected to provide a better understanding of the potential of duckweed-based systems in Bangladesh for re-use of wastewater by low-cost natural purification process.
Outline of methodology:
For this study, field investigations will be conducted in a duckweed-based domestic wastewater treatment facility in Mirzapur, Tangail. Grab samples will be collected from several inflow and outflow locations of the facility. Sample collection accessories (sampling bottles, field test equipment, etc.) will be supplied by PRISM (Projects in Agriculture, Rural industry, Science and Medicine), Bangladesh. Water quality parameters including pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), ammonia (NH3), phosphate (PO4), manganese (Mn), iron (Fe), lead (Pb), arsenic (As), total dissolved solids (TDS) and bacteria (fecal coliform) will be analyzed using standard and spectrophotometric methods. Tests will be conducted in the laboratory of PRISM Bangladesh. Detention time in the pond will be varied several times to determine the corresponding changes in the effluent water quality. Water quality standards and guidelines will be consulted to determine the suitability of re-use of the effluent in various water resources applications including agricultural, aquacultural and recreational uses.
References:
Hillman, W.S. and Culley, D.D. (1978). The uses of duckweed. Am. Sci. 66: pp.442-451.
Oron, D. (1994). Duckweed culture for wastewater renovation and biomass production. Agric. Wat. Man. 26: pp.27-40.
Gijzen, H.J. and Kondker, K.M. (1997). An Overview of the Ecology, Physiology, Cultivation and Application of Duckweed, Inception Report, ANNEX 1: Literature Review, Duckweed Research Project (DWRP), Dhaka, Bangladesh, pp.53.
FAO (1999). Duckweed - A Tiny Aquatic Plant with Enormous Potential for Agriculture and Environment, FAO Publications, Rome, Italy.
Nhapi, I., Dalu J., Ndamba, J. and Gijzen, H.J. (2001). Sustainable decentralized sanitation using duckweed-based ponds, Proc. 27th WEDC Conf., Lusaka, Zambia, pp.228-231.
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