KINETIC MODELLING FOR BIO-METHANE GENERATION DURING ANAEROBIC DIGESTION OF MUNICIPAL SEWAGE SLUDGE UTILIZING ACTI-ZYME (BIO-CATALYST) AS A RESOURCE RECOVERY STRATEGY
MUSAIDA M. MANYUCHI *
Department of Chemical and Process Systems Engineering, Harare Institute of Technology, P.O.Box BE 277, Belvedere, Harare, Zimbabwe and Department of Chemical Engineering, Cape Peninsula University of Technology, Bellville, Western Cape, Cape Town 7530, South Africa
DANIEL I. O. IKHU-OMOREGBE
Department of Chemical Engineering, Cape Peninsula University of Technology, Bellville, Western Cape, Cape Town 7530, South Africa
OLUWASEUN O. OYEKOLA
Department of Chemical Engineering, Cape Peninsula University of Technology, Bellville, Western Cape, Cape Town 7530, South Africa
WILLARD ZVAREVASHE
Department of Mathematical Sciences, Harare Institute of Technology, P.O.Box BE 277, Belvedere, Harare, Zimbabwe
TREVOR N. MUTUSVA
Department of Mathematical Sciences, Harare Institute of Technology, P.O.Box BE 277, Belvedere, Harare, Zimbabwe
*Author to whom correspondence should be addressed.
Abstract
This paper focuses on the kinetic modelling for simulation of bio-methane generation from sewage sludge digestion utilizing Acti-zyme as a bio-catalyst. Sewage sludge was digested at 37°C and 55°C for Acti-zyme loadings of 50 g/m3, sewage sludge loadings of 5-7.5 g/L.day and retention time of up to 40 days. Optimal bio-methanation was achieved at 37°C with 78% composition. The bio-methane production experimental data was fitted to the linear, exponential, logistics kinetic, exponential rise to a maximum and the modified Gompertz kinetic models and the coefficients of determination (R2) obtained. A lag phase of 10 days was observed during the bio-methanation process. The exponential rise to a maximum kinetic model fully simulated the bio-methane generation with a R2 value of 0.999 and a rate constant of 0.073 day-1. The logistics kinetic model can therefore be accurately applied for modelling the experimental data for bio-methane production.
Keywords: Acti-zyme, bio-methane, exponential rise to a maxima model, kinetic modeling