Development of a Pilot-Scale Treatment Plant for Market Wastewater of Khulna City

Abstract

developing countries like Bangladesh, urbanization mostly takes place in unplanned and informal way. With high population density and inappropriate construction approach of commercial areas, market wastewater has become a severe problem and threat to environmental sustainability. Market wastewater is mainly produced at butcher houses, during chicken slaughtering and processing, at fish markets, etc. Market wastewater contaminated with animal body fluid, blood, worms, bacteria and viruses are causing environmental pollution and posing a threat to public health. Therefore, market wastewater should be treated prior to disposal into the environment. In this context, this study aims at: (a) determining the physical, chemical/biochemical and microbial characteristics of market wastewater, (b) developing a pilot-scale treatment unit for the market wastewater and finally (c) monitoring its performance and address any modification if necessary. A comprehensive field survey had been conducted in three markets situated near Moyur River. The market wastewater was collected in jerry can and brought to laboratory for various wastewater quality analyses such as Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Iron (Fe), Nitrate (NO3), Phosphate (PO4), Total Solids, Total Suspended Solids (TSS), Total Volatile Solids (TVS), Volatile Suspended Solids (VSS), Electrical Conductivity (EC), Temperature, pH, Alkalinity, Total Coliform (TC) and Escherichia coli (E. coli). In market wastewater: TSS, BOD5 and TC were found to be 1,840-3,300 mg/L, 62-619 mg/L and 3,400-6,00,000 N/100 mL, respectively. In order to minimize the pollutants in market wastewater, a pilot-scale treatment unit, adopting the activated sludge process, has been developed in the laboratory. In treated water: TSS, BOD5 and TC were found to be in the range of 760-2,800 mg/L, 17-124 mg/L and 2,740-7,00,000 N/100 mL, respectively. These laboratory test results suggest that the performance of the treatment unit was not adequate to meet the acceptable limit for disposal into inland watercourses (ECR’97). Installing a duel-media granular filtration system as an additional treatment unit to developed activated sludge process treatment system improved the effluent quality within the acceptable limit. The TSS, BOD5 and TC in treated effluent was found to be 95 mg/L, 4 mg/L and 750 N/100 mL, respectively. This study finally recommended an implementation plan of installing treatment plants in various markets of Khulna city.