Removal of phosphorus from domestic wastewater using discontinuous aerobic anoxic reactor

Abstract

The discharge of excessive amounts of phosphorus (P) from domestic wastewater treatment plant is of interest in this study because the abnormally high levels of P as one of the nutrient elements can lead to eutrophication for the receiving waters. Although many methods have been proposed for the removal of P matter from industrial and municipal wastewater, such as Phoredox, A2OTM and UCT-type, the use of alternating aerobic-anoxic (AAA) system must be verified. This study proposes the use of Discontinuous Aerobic-Anoxic Reactor (DAAR) to remove P from domestic wastewater at Taman Impian Emas, Skudai, Johor using the nitrification and denitrification type of activated sludge. The objectives of this study are: (1) to evaluate the efficiency of P removal from domestic wastewater by a single reactor under aerobic digestion (AD) condition, and (2) to assess the performance of AAA process of using the different cycles of nitrification-denitrification to remove P from domestic wastewater. The average efficiency of AD to remove P from domestic wastewater was 48%. The efficiencies of AAA system to remove P from domestic wastewater, on the other hand, were verified as follows: (1) at 6-h AD and 6-h anoxic time (AT), the efficiency was 0%, indicating that there was no removal of P during the AAA process, (2) at 5-h AD and 5-h AT, the average efficiency was 48%, (3) at 4-h AD and 4-h AT, the average efficiency was 82%, (4) at 3-h AD and 3-h AT, the average efficiency was 91%, and (5) at 2-h AD and 2-h AT, the average efficiency was 88%. Therefore, the AAA system has exhibited a better performance compared to AD. The results of the study also show that the best condition of AAA system had a period of 3-h AD and 3-h AT and reached 91% efficiency with an average treated effluent concentration of less than 1.0 mg P/L. High performance of the AAA process has been proven by using domestic wastewater from Taman Impian Emas, Skudai, Johor, giving new insights into environmental engineering practices.