Characterization and modeling of activated sludge for tannery wastewater

A comprehensive experimental evaluation of tannery wastewater was performed as a basis for the modeling of the activated-sludge process. Characterizat ion studies involved, aside from conventional parameters, a detailed chemic al oxygen demand (COD) fractionation for the identification of biodegradabl e and inert COD components. Respirometric analysis was carried out to asses s significant rate constants associated with the stoichiometry and kinetics of activated sludge. Specific emphasis was placed on the evaluation of the hydrolysis mechanism for slowly biodegradable GOD, apparently the rate-lim iting step for organic carbon removal. Parallel experiments were run both o n plain and chemically settled samples to investigate the effect of chemica l settling on biological treatability. The fate and variation of primary pr ocess components affecting effluent quality with the sludge age were evalua ted by means of model simulations using recent multicomponent modeling tool s and generated experimental data.