ENZYME ACTIVITIES AND SHIFTS IN MICROBIAL POPULATIONS ASSOCIATED WITH ACTIVATED SLUDGE TREATMENT OF TEXTILE EFFLUENTS

The enzyme studies on an activated sludge (AS) were aimed at providing information about adaptive response of microbial community during four significant alterations in textile wastewater treatment plant behavior associated with: shock loading with azo compounds: recovery after the xenobiotic shock; building up additional aerobic reactor; breakdown of facility exploitation for 5 months. The activity of several enzymes associated with target biodegradation processes was assessed. Induction of catechol 1,2-dioxygenase (C12DO), catechol 2,3-dioxygenase (C23DO), protocatechate 3,4-dioxygenase (P34DO) occurred under aerobic and notably under anoxic/microaerobic conditions, depending on the control point. Key microbial groups in the AS consortium were determined by cultivation-based-methods. The densities of bacteria from g. Pseudomonas (Ps) and Acinetobacter (Acin) were increased during the toxic shock. Aerobic heterotrophs (AH) and g. Acinetobacter decreased after pause of facility exploitation. The numbers of denitrifying bacteria (Dn) in denitrifying reactor were significantly decreased after each of the critical events.