ASSESSMENT OF BIOLOGICAL-ACTIVITY DURING TEMPERATURE-CHANGES IN A BENCH-SCALE SEQUENCING BATCH REACTOR FED WITH SYNTHETIC MEDIUM CONTAININGLIGNIN

The influence of temperature on activated sludge in a bench-scale SBR fed with a synthetic medium simulating paper mill effluents was determ ined using biological methods based on the measurement of enzymatic ac tivities. Redox activity inside cells and in the extracellular polymer ic substances as well as the proportion of active cells in the sludge were measured by the reduction of the tetrazolium salts XTT and CTC, r espectively. A significant shift in the size distribution of lignin at 30 degrees C correlated with a maximum of extracellular redox activit y. The percentage of active cells in the biocoenosis was independent o f temperature. alpha-glucosidase and L-alanine-aminopeptidase activiti es were steady at 20, 30 and 40 degrees C. After shifting the temperat ure to 50 degrees C there was an enormous short-time increase of both enzyme activities because of the change from mesophilic to thermophili c conditions. Of the biological parameters tested, only extracellular redox activity correlated with degradative activity as detected by a c hange in molecular size distribution of lignin molecules. (C) 1998 IAW Q. Published by Elsevier Science Ltd.