ABSTRACT
The Chemical Analysis Laboratory under study weekly generates 46.5 L effluent with low pH (0.7), high COD concentration (6535 mg O2/L), sulphate (10390 mg/L) and heavy metals (213 mg Hg/L, 55 mg Cr/L, 28 mg Al/L, 22 mg Fe/L, 10mg Cu/L, 4 mg Ag/L). A treatment sequence has been proposed using a physical chemical step (coagulation/flocculation or chemical precipitation) followed by a biological step (anaerobic treatment). Removals of COD (18%), turbidity (76%) and heavy metals (64-99%) were attained only after adjusting pH to 6.5, without requiring the addition of Al2(SO4)3 and FeCl3. Due to the low COD:sulphate ratio (0.9-1.3), it was possible to efficiently operate the UASB reactor (at the biological step) only upon mixing the effluent with household wastewater. COD, sulphate and heavy metals removals of 60%, 23% and 78% to 100%, respectively, were attained for 30% effluent in the reactor feed. The results pointed to the need of a pretreatment step and mixing the effluent in household wastewater prior to the biological step. This alternative is feasible as this can be achieved using sanitary wastewater generated in the university campus.
Subject(s)
Bioreactors , Chemistry, Analytic , Laboratories , Universities , Waste Disposal, Fluid/methods , Water Pollutants, Chemical/analysis , Bacteria, Anaerobic/metabolism , Brazil , Chemistry, Physical/methods , Metals, Heavy/analysis , Metals, Heavy/metabolism , Oxygen/metabolism , Waste Disposal, Fluid/instrumentationABSTRACT
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) (2,000-6,000 mg l(-1)), biochemical oxygen demand BOD5 (1,300-2,300 mg 1(-1)), fats (40-600 mg l(-1)) and total suspended solids (TSS) (850-6,300 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.
