Organic and nutrient removal for domestic wastewater treatment using bench-scale sequencing batch reactor

Most domestic wastewater produced that are untreated before discharge, is a major threat to the ecosystem, environment, and human health. As the sewerage generation increases with the population and economic growth in developing countries, the existing plants are undersized to cater and treat the sewerage discharges while outpacing the investments. Altogether, this study is focused on determining the feasibility of utilising the aerobic sequencing batch reactor (SBR) to remove the organic (COD, TSS) and nutrient (nitrate NO3−N, ammonia NH3−N, phosphorus PO43−) of synthetic domestic wastewater. The SBR was designed and fabricated with an active volume of 1.5 L, consisting of 66 % wastewater and 33 % sludge inoculum. It was operated in a fixed 48.0 h cycle time to assess the organic and nutrient removal. The operational parameters of the SBR reaction system per cycle were set at: fill 0.17 h, react 46.5 h, settle 1.0 h, decant 0.17 h and idle 0.17 h. The removal efficiencies of COD, TSS, NO3-N, NH3−N and PO43− were found to be 62 - 93%, 93 – 97%, 55 – 78%, 62 – 83%, and 76 – 100%, respectively. The bench-scale SBR meets the effluent discharge limit of COD, TSS, and NH3−N. Regardless, the discharge limits of NO3−N and PO43− were not met due to the destabilisation of denitrifiers and lack of anaerobic environment in the SBR. The denitrifiers were able to function better than nitrifiers under the aerobic environment as no anoxic condition was adequately provided. The obtained results will be useful for future expansion of this study, which the feasibility of textile wastewater treatment is focused.