Effectiveness of chlorination and ozonation methods on pure cultures of fl oc-forming micro-organisms and activated sludge: A comparative study

Abstract

Chlorination is a very useful control method of filamentous bulking in activated sludge systems; however, it favours formation of undesirable compounds such as trihalomethanes. Other oxidants, such as ozone, could be used for bulking control. In view of the fact that chlorine and ozone are both non-selective chemical agents affecting filamentous and floc-forming micro-organisms, the determination of optimum dosage conditions becomes essential to minimise the impact produced on the activated sludge process. In this work, the effects of chlorine and ozone on the biomass concentration of activated sludge and on different parameters that characterise the microbial metabolic activity were compared. The following techniques were applied: Respirometry (oxygen uptake rate); and INT-dehydrogenase activity test carried out both by spectrophotometry (DHAa) and image analysis (DHA i).

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