Ghasem Najafpour - Biochemical Engineering and Biotechnology, Faculty of Chemical Eng., Noshirvani University of Technology, Babol, Iran
Bahar Hosseini - Environmental Engineering, Faculty of Civil Eng., Noshirvani University of Technology, Babol, Iran
Maedeh Sadeghpoor - Environmental Engineering, Faculty of Civil Eng., Noshirvani University of Technology, Babol, Iran
Mohammad Norouzi - University of Peyame-Nour, Sari, Iran

Amol's industrial wastewater treatment plant was evaluated over a period of eight months (July 2005 and February 2006). The operating conditions were optimized for a period of one month, to obtain a suitable efficiency. The major problems associated with the treatment plant were chemical shock (high acidic influent), bulking and rising of sludge, low F/M and MLSS/ MLVSS ratios, inadequate mixing in equalization tank, inappropriate C/N/P ratio in the anaerobic and aerobic tanks. Based on diagnostic condition, fresh manure was added to the anaerobic digestion tank for the revival of anaerobic microbial consortium and then a 15% increase in removal efficiency was obtained in the anaerobic tank. Addition of urea and phosphate into the aerobic tank improved total removal efficiency of only 5%. The effluent COD concentration was decreased by 50%. Activated sludge and the sludge volume indices were improved by 15 and 27%, respectively.

Wastewater treatment, industrial effluent, MLVSS/MLSS, pH, Dissolved oxygen