Anaerobic Treatment of Wastewater from Coffee Pulping in Upflow Anaerobic Sludge Blanket (UASB) in Two Stages

摘要

In this work, the efficiency of two-stage up/low anaerobic sludge blanket (UASB) reactors was evaluated in bench scale, for treating a liquid effluent from coffee pulping. Hydraulic detention times (HOT) were 4.0; 5.2 and 6.2 days, resulting in organic loadingrates (OLR) of 5.8; 3.6 and 3.0 g total COD per (L-d) in the first reactor (R1) and HOT of 2.0; 2.6 and 3.1 days with OLR of 5.8; 0.5 and 0.4 g total COD per (L-d) in the second reactor (R2). The medium values of total COD affluent varied from 15.440 to 23.040 mg O_2/L, and in the effluent to the reactors 1 and 2 were from 1.100 to 11.500 mg OJL and 420 to 9 000 mg O_2/L, respectively. The medium values of removal efficiencies of total COD and TSS varied from 66 to 98% and 93 to 97%, respectively, in the system of treatment with the UASB reactors, in two stages. The content of methane in the biogas varied from 69 to 89% in the Rl and from 52 to 73% in the R2. The maximum volumetric methane production of 0.483 m~3 CH_4 per (m~3 reactor d)was obtainedwith OLR of 3.6 g total COD per (L reactor d) and HDT of 6.2 days in the Rl. The volatile fatty acids concentration was kept below 100 mg/L with HDT of 5.2 and 6.2 days in theR1 and HDT of 2.6 and 3.1 days in the R2.