MICROSCOPIC STUDIES OF ACTIVATED SLUDGES IN BIOLOGICAL WASTE-WATER TREATMENT PLANTS OF THE PAPER-INDUSTRY

Paper mill effluents that have been subjected to aerobic biological tr eatment frequently tend to form activated sludge with a high share of filiform microorganisms and a high sludge volume index. However, chang es occurring in the microbiota are identified inadequately or too late by the chemical analytics that are typically being applied to monitor waste water treatment plants today. Regular microscopy of the activat ed sludge by comparison allows timely detection of such changes so tha t appropriate countermeasures can be initiated. Microscopic studies an d measurements of operating conditions which were conducted in 13 wast e water treatment plants of the paper industry have successfully ident ified relevant microorganisms in aerobic-biological treatment plants, The investigations included variation in the microbiota depending on l oads and process engineering techniques. 021N, beggiatoa and thiothrix (sulfur bacteria) as well as H. hydrossis and nosticoida limicola wer e identified to be the dominant filiform bacteria. A database-assisted assessment and information system has been developed to monitor aerob ic-biological effluent treatment plants. The system evaluates and comp ares the results obtained from microscopy and analytics and proposes s uitable remedial action in case of operating failures.