A KINETIC-MODEL OF A RECIRCULATED UPFLOW ANAEROBIC SLUDGE BLANKET TREATING PHENOLIC WASTE-WATER

Sludge taken from a recirculated upflow anaerobic sludge blanket (RUASB) treating phenolic wastewater at organic loadings of 6, 12, 16, and 20 kg COD/m(3) day was tested by the biochemical methane potential (BMP) method at intervals over a three-year period for an accurate determination of the specific gas production rate. A modified version of the Haldane equation was used in the selection of a statistically significant model describing this process. Statistical diagnosis was carried out with student t-test, Durbin-Watson test for two-tail distribution and Kalmogorov-Smirmov statistical approach. The estimated ranges of the maximum specific reaction rate, K; saturation constant, K-s; inhibitor constant, K-i; and the order of inhibition, n were as follows: 280-764 mt biogas/g VSS-day, 202-398 mg phenol/L, 516-880 mg phenol/L, and 1.47-2.51, respectively. The physical meaning of these parameters is explained. BMP tests with sludge taken from the recirculating upflow anaerobic sludge blanket (RUASB) bioreactor running at a loading of 14 kg COD/m(3) day validated the effectiveness of the selected model through comparisons of experimental data and predictions. The results indicate that model predictions accurately reflect experimental data within one standard deviation.