Background and purpose: Waste stabilization pond is one of the conventional wastewater treatment processes especially in warm climate regions. This study investigated the effect of baffle and attached growth on improvement of coliform removal efficiency.
Materials and methods: This research was carried out in pilot scale adjacent to wastewater treatment plant in Ahvaz, Iran. The pilot composed of a control system and three other systems. In control system two ponds were serially connected. Dimension and configuration of other three systems were similar to those of the control system. However, the ponds in these systems were equipped with various baffles and fixed bed media. Within four months, the capability of each system in coliform removal was evaluated in various detention times and coliform die-off coefficient (K_b) of each pond was determined.
Results: During sampling with average detention time of 8.7 day, the average of coliform removal was 69% in control system, while it in two, three and four baffles system these values were 80, 84 and 86%, respectively. Also, K_b20 average in the first pond of control system was 0.11 d^-1 and in other systems with increasing of baffles and media packages number to two, three and four it increased to 0.16, 0.17 and 0.18 d^-1, respectively. Furthermore, K_b20 in second pond was higher than first pond of each system.
Conclusion: Use of baffles and fixed bed media improved coliform removal efficiency. The efficiency of two and three baffles system was more than that of the control system and was found to be better than four baffles system technically and economically