Performance Evaluation of Fecal Sludge Treatment Plant at Khulna City and Proposal for Sustainable Development

Abstract

Bangladesh strides successfully towards full sanitation coverage which contributing to healthier life for every citizen. However, there is typically no management system in place for the accumulated fecal sludge in various containments connected to toilets. FSM (fecal sludge management) is a relatively new field, however, it is currently rapidly developing and gaining acknowledgement. Containment, emptying, transport, treatment and reuse are the basic elements of FSM. The present study is related to treatment part of FSM. Khulna the third largest city in Bangladesh having more than 1.5 million populations where people predominantly depend onsite sanitation technologies. There was no designated disposal site for collected fecal sludge and emptier had been habituated to discharge in nearby lowlands, water bodies or in drains which ultimately pollutes the environment and poses serious threat to human health. So, to fix up the situation, with the financial assistance of SNV Netherlands, Khulna city corporation (KCC) decided to establish a fecal sludge treatment plant (FSTP) at Rajbandh within the municipal landfill site boundary. The FSTP was built on a passive landfill site adopting the constructed wetlands (CW) treatment technology. This study aims at evaluating the treatment efficiency of Khulna FSTP and identifying the difficulties in operation and maintenance (O&M) at the field level and giving proposals for sustainable development.

In FSTP treated effluent, the BOD values were found to be varied from 16 mg/L to 25 mg/L while the allowable disposal limit is 40 mg/L for inland surface water bodies (ECR’97, Bangladesh). Total suspended solids (TSS) concentrations were observed in the range of 30~80 mg/L which is within the allowable limit of 100 mg/L. The nitrate and phosphate concentrations in treated effluent were always found to be far less than the acceptable limit. Escherichia coli (E.coli) in final effluent never exceeded 100N/100ml while the acceptable limit is 1000N/100ml. This study also focuses on operation and maintenance (O&M) issues. Field monitoring focused on various critical intervention issues such as: adjustment of water levels, maintenance of flow uniformity, vegetation management, odor control and maintenance of berms. Finally, some constitutive recommendations have been made for the FSTP which would ensure its long-term sustainability.