EVALUATING THE PERFORMACE OF WASTE STABILIZATION PONDS FOR WASTEWATER TREATMENT

Wastewater treatment is done to reduce the transmission of excreta related diseases and to reduce water pollution to avoid damage to aquatic biota. In developing countries, waste stabilization ponds are widely used for wastewater treatment as they are simple to construct, operate and maintain. The objective of this study was to evaluate the performance of a stabilization pond system for wastewater treatment. In this study, data was collected using the composite sampling method. The physiochemical and biological were analyzed on-site and others were analyzed in the laboratory. The hydraulic retention time and volumetric loading rates were calculated to assess the hydraulic performance of the stabilization pond. The following were the results of the physico-chemical and biological water quality parameters; temperature was 26.7, pH 10.13, EC 772 us/cm, TSS 89.75 mg/L, TDS 392.67 mg/L, phosphate 38.77 mg/L, nitrate 15 mg/l, sulfate 25.33 mg/L, chloride 12.16 mg/L, alkalinity 125.67 mg/L, COD 89.57 mg/L, BOD 67.67 mg/L and fecal coliform 14333 counts/100ml. It was found that most of the physico-chemical and microbiological parameters were above the effluent discharge limits of the Malawi bureau of standards except TDS, nitrate and alkalinity complied with the limits. The hydraulic characteristics such as HRT, VLR, and sludge depth of the three ponds were calculated. A second maturation pond can be added to achieve a greater removal efficiency of fecal coliforms, addition of water baffles and regular clearance of the pre-treatment units such as the screen can be done to ensure that wastewater treatment is done efficiently.

Wastewater treatment is done to reduce the transmission of excreta related diseases and to reduce water pollution to avoid damage to aquatic biota. The following were the results of the physico-chemical and biological water quality parameters; temperature was 26.7, pH 10.13, EC 772 us/cm, TSS 89.75 mg/L, TDS 392.67 mg/L, phosphate 38.77 mg/L, nitrate 15 mg/l, sulfate 25.33 mg/L, chloride 12.16 mg/L, alkalinity 125.67 mg/L, COD 89.57 mg/L, BOD 67.67 mg/L and fecal coliform 14333 counts/100ml. It was found that most of the physico-chemical and microbiological parameters were above the effluent discharge limits of the Malawi bureau of standards except TDS, nitrate and alkalinity complied with the limits. A second maturation pond can be added to achieve a greater removal efficiency of fecal coliforms, addition of water baffles and regular clearance of the pre-treatment units such as the screen can be done to ensure that wastewater treatment is done efficiently.

The study will be carried out in Phalombe district, Malawi. Phalombe district is approximately 97km from Blantyre city. The district experiences a warm and cloudy weather in the months of November to April and it is cool between May and October. The general temperature of the region is usually between 150C and 300C, making it ideal for the use of WSPs for the treatment of wastewater. The WSPs at Phalombe TTC started working in 2017 and now more than 600 people use the facility. The wastewater comes from the staff houses and Phalombe TTC campus and is directed to the WSPs. The plant has a series of four ponds that are in parallel. The pond system effluent from the treatment plant is discharged into a stream located in Ganeti village, the stream then discharges into a river called Migowi River. The map below shows Phalombe TTC waste stabilization pond and its surrounding areas.

District: Phalombe

Coordinates: -15.6822, 35.6724