Slaughterhouse wastewater treatment: evaluation of a new three-phase separation system in a UASB reactor

The anaerobic treatment of the wastewater from the meat processing industry was studied using a 7.2 1 UASB reactor. The reactor was equipped with an unconventional configuration of the three-phase separation system. The effluent was characterized in terms of pH (6.3-6.6), chemical oxygen demand (COD) (2000-6000 mg l(-1)), biochemical oxygen demand BOD5 (1300-2300 mg l(-1)), fats (40-600 mg l(-1)) and total suspended solids (TSS) (850-6300 mg l(-1)). The reactor operated continuously throughout 80 days with hydraulic retention time of 14, 18 and 22 h. The wastewater from Rezende Industrial was collected after it had gone through pretreatment (screening, flotation and equalization). COD, BOD and TSS reductions and the biogas production rate were the parameters considered in analyzing the efficiency of the process. The average production of biogas was 111 day(-1) (STP) for the three experimental runs. COD removal varied from 77% to 91% while BOD removal was 95%. The removal of total suspended solids varied from 81% to 86%. This fact supports optimal efficiency of the proposed three-phase separation system as well as, the possibility of applying it to the treatment of industrial effluents. (C) 2001 Elsevier Science Ltd. All rights reserved.