A steady state model for anaerobic digestion of sewage sludges

摘要: A steady state model for anaerobic digestion of sewage sludge is developed that comprises three sequential parts – a kinetic part from which the % COD removal and methane production are determined given retention time; stoichiometry gas composition (or partial pressure CO,sub>2 ), ammonia released alkalinity generated calculated %COD removal; carbonate system weak acid/base chemistry digester pH CO 2 generated. From acid base model, removal, composition, released, com¬pletely defined by influent i.e. X, Y, Z in CXHYOZNA hydrolysable organics; volatile fatty (VFA) concentration; pH. For four hydrolysis equations were calibrated against 7 to 60 d time digesters treating two different types, viz. first order; order specific; Monod; saturation. Once type data sets taking into account experimental error effluent concentration (i.e. mass balance error), each equa¬tions predicted versus equally well, compared well with measured data. primary humus mixture trickling filter plant, “pure” sludge, rate constants obtained indicating hydrolysed faster had lower unbiodegradable particulate fraction (f PS'up = 0.33) than (0.36). With known again C N balances free saline (FSA) concentration, 3.5 H O 0.196 . independent measurement CHON this estimated within 96%, 100%, 95% 99% average 3.65 1.97 0.190 lending strong support model. Keywords : Anaerobic digestion, kinetics, biodegradability Water SA Vol. 31(4) 2005: 511-528