Mathematical Modeling of Distillery Wastewater Biomethanation in Fluidized-bed Bioreactor

Abstract

An anaerobic fluidized- bed reactor was designed to treat distillery wastewaters for biogas generation using actively digested aerobic sludge of a sewage plant. The optimum digestion time was 8 h and optimum initial pH of feed was observed as 7.5 respectively. The optimum temperature of feed was 40°C and optimum feed flow is 14 L/ min with maximum OLR was 39.513 kg COD m -3 h -1 respectively. The OLR was calculated on the basis of COD inlet in the bioreactor at dierent flow rates. Maximum CH 4 gas concentration was 63.56 % (v/v) of the total (0.835 m 3 /kg COD m -3 h -1 ) biogas generation, corresponding to 0.530 m 3 /kg COD m -3 h -1 at optimum digestion parameters. Maximum COD and BOD reduction of the distillery wastewaters were 76.82% (w/w) and 81.65% (w/w) with maximum OLR of 39.513 kg COD m -3 h -1 at optimum conditions respectively. The rate constant ( k ) was measured as 0.31 h -1 in fluidized-bed bioreactor and followed a first order rate equation. The specific growth rate ( μ ) was 0.99 h -1 and maximum sp. growth rate ( μ max ) was 1.98 h -1 respectively. The bacterial yield coefficient ( Y ) was determined as 0.319 /kg COD m -3 h -1 at optimum parameters. The studies also dealt with the mathematical modeling of the experimental data on biomethanation and suggested modeling equations relating to kinetic parameter (rate constant, k ), maximum specific growth rate ( μ max ) with respect to COD (substrate) removal. The mathematical model was also analyzed for hydrodynamic pressure ( Δp ) vs feed flow ( u ) and hydrodynamic pressure ( Δp ) with respect to CH 4 gas yields. The linear and non-linear equations which fitted the models were obtained. Keywords: Biomethanation, anaerobic, optimum condition, modeling DOI = 10.3329/cerb.v14i1.4224 Chemical Engineering Research Bulletin 14 (2010) 37-43