ANAEROBIC-ANOXIC-AEROBIC PROCESS WITH RECYCLING AND SEPARATED BIOMASS FOR ORGANIC-CARBON AND NITROGEN REMOVAL FROM WASTE-WATER

A study was made of an anaerobic-anoxic-aerobic process with recycling and different biomasses to maximize the.removal of organic material and nitrogen from domestic wastewater by varying the recycling ratio between the aerobic and anoxic reactors. The anaerobic and anoxic reactors were UASB type and the aerobic was submerged filter packed with PVC tubes. With a 3:1 recycling ratio, 80% of the TOCs, 62% of N and 90% of TSS were removed. The concentration of TSS in the treated water was lower than 20 mg L-1 (12 mg TSS L-1) making unnecessary the use of final settlers. The concentration of TOCs and N-NH4 in the system effluent operating with a 3:1 ratio was 7 and 4.6 mg L-1, respectively. The proposed system may be used in treatment schemes designed to provide water for reuse or discharge at low operational cost.