Feasibility of the AF/Aerobic contact Reactor/Sand Filter System for Reuse Treatment of Domestic Sewage

This paper is concerned with the alternative proposed here in order to treat domestic sewage from residential district for reuse in a combined system composed of an anaerobic filter (AF) - aerobic contact reactor following by sand filter. The AF reactor, investigated in present study, represented an efficient pre-treatment process for domestic sewage at -4-25degC. Average COD removal efficiency accounted to 60%, 61%, 57%, 69%, 61%, and 47% at an HRT of 6.7 h, 4.4 h, 3.5 h, 2.9 h, 2.1 h, and 1.3 h, respectively. Average SS removal efficiency amount to 77%, 85%, 82%, 87%, 83%, and 56% at an HRT of 6.7 h, 4.4 h, 3.5 h, 2.9 h, 2.1 h, and 1.3 h, respectively. For the pre-treatment of domestic sewage at low temperatures, the application of an AF reactor at an HRT of 3 h was recommended. The COD loading rate of the AF reactor should be 1.0~6.0 kgCOD/ (m³-d). In the aerobic contact reactor, average COD and SS removal efficiency amount were 62% and 30% respectively. The average COD and SS of the effluentles58 mg/L and 50 mg/L respectively. For the post-treatment of domestic sewage at low temperatures, the application of an aerobic contact reactor at an HRT of 3 h was recommended. The refinery treatment by filtration with double layer media filter was very effective in SS removal. The value of the effluent for reuse in non-potable was constantly satisfied, that is, effluent COD and SSles50 mg/L and 10 mg/L respectively. The results also indicate that such combined anaerobic - aerobic - filtration competes favorable with conventional aerobic system in two essential cost features: energy consumption and excess sludge production.