ACTIVATED CARBON ADDITION TO ACTIVATED SLUDGE IN THE TREATMENT OF KRAFT PULP BLEACHING WASTES

This study examines the effect of powdered activated carbon (PAC) addition to activated sludge in the treatment of pulp bleaching effluents which contain a large amount of nonbiodegradable matter. The effect of PAC addition has been studied in both batch and continuous-flow reactors. Isotherms were developed for PAC and biomass adsorption. It was shown that substrate removal by air stripping and biosorption was negligible. The change in substrate concentration occurred mainly by biodegradation. The biological removal data obtained in batch and continuous-flow reactors were fitted to kinetic models. Both batch and continuous-flow experiments revealed that there remained a high amount of nonbiodegradable substrate as expressed by residual COD and Color436. Carbon addition to activated sludge resulted in a high decrease in substrate concentration, particularly for color. However, the results indicated that there was no noticable biological enhancement with PAC addition. The combined PAC and activated sludge process seemed to be a combination of adsorption and biodegradation.