Impact of source-separation of urine on effluent quality, energy consumption and greenhouse gas emissions of a decentralized wastewater treatment plant

Abstract The impact of urine diversion on the biological treatment processes at a decentralized wastewater treatment plant (WWTP) was investigated. BioWin software was used for the simulations, and the model was firstly validated with data from a real WWTP. The simulations showed that upto 82% N, 30% P, 6% chemical oxygen demand (COD) load to the WWTP can be reduced by complete urine diversion but effluent N reduction was notable up to 75% urine diversion. Under the current WWTP operating conditions, the simulations suggest that 33% of aeration energy can be saved by 90% urine diversion. Direct N2O and CO2 emissions in the treatment processes can also be reduced by 98% and 25% respectively. Indirect green house gas emissions can also be reduced by 20%. Overall, the reduction in the discharge of nutrients and in the operation of blowers was found to contribute to a 22% reduction in the operating costs (on energy consumption and nutrient discharge).