Treatment of phthalic waste by anaerobic hybrid reactor

The anaerobic treatment performance of phthalic acid at 4,000 mg/L (dry weight) by a hybrid reactor consisting of an upflow anaerobic sludge blanket (UASB) and a biofilter was examined. Using anaerobic sewage sludge as the seed and glucose as a carbon supplement, it took 3 months to initiate phthalate degradation. After that, the glucose supplement could be discontinued. At 35 degrees C and a phthalic loading of 20 g-COD/L-d, the chemical oxygen demand (COD) removal efficiency was nearly 95\%. About 89.5\% of the removed phthalic COD was converted to methane. When the phthalic loadings were increased to 26.7, 33.0, 39.7, and 46.3 g-COD/L-d, the COD removal efficiencies were progressively reduced to 78, 65, 58, and 47.7\%, respectively. More than 95\% of the residual effluent COD was composed of nondecomposed phthalic acid. In the hybrid reactor, 86\% of the biomass was found in the UASB section while the remaining 14\% was found in the biofilter section. The anaerobic sludge could lead to granulation. At 35 degrees C and a phthalic loading of 26 g-COD/L-d, the overall specific removal rate was 0.81-0.85 g-COD/g VSS-d, and the corresponding methane production rate was 0.24-0.26 L CH4/g VSS-d