Anaerobic/aerobic integration via UASB/enhanced aeration for greywater treatment and unrestricted reuse

Abstract

Abstract The aim of the present study is to achieve an efficient treatment of greywater for reuse in food crops' irrigation. For this purpose, anaerobic followed by enhanced aerobic treatment system was examined via both bench scale and pilot plant. The greywater was separated and collected from the source. The examined systems consisted of Up flow Anaerobic Sludge Blanket (UASB) followed by anaerobic aeration enhanced by Effective Microorganism (EM). The characteristics of the raw greywater were within a high strength level due to the presence of detergents, phosphates, oil and grease. The BOD5/COD was 0.75, showing that biological treatment to this greywater could be achieved. Treatment with UASB showed high elimination of oil & grease, BOD5, COD, total phosphates, and TKN in the range of 60 to 84%. However, TSS and ammonia were poorly removed. UASB effluent was further aerobically treated in a continuous aerated system where the predetermined optimum EM dose was added. Both aeration time and EM dose were previously examined to reach the optimum. Anaerobic/aerobic pilot plant in the continuing treatment was evaluated, where the final treated effluent successfully reached the permissible limits for unrestricted reuse according to the international regulation, namely FAO, WHO, US EPA and Egypt.