‌Removal of biochemical oxygen demand from domestic wastewater with trickling filter in the scale of pilot plant

Background : Biochemical oxygen Demand (BOD) is one of the most important indicator for wastewater pollution & applying biological methods for wastewater treatment, its value can be decreased to standard. Objective : To survey BOD removal from domestic wastewater using trickling filrer pilot plant. Methods : Pilot growth media was divided into three separate layers and natural ventilation was used. Pilot tests were performed in two separately phases. BOD tests were done according to winkler iodometry according to standard methods. Findings: In the first phase of this study, according to 2.25 L/min hydraulic loading, 4.5 min detention time and influent BOD concentration of 278 mg/l the average BOD removal rate was 80 percent, while in the second phase with increasing hydraulic loading to 3.75 L/min according to 3.5 min detention time and 242 mg/l influent BOD, the rate of BOD removal was 68 percent. Conclusion : In this research the filter was used during slow & intermediate rates. Increasing SOR to 60 percent and using the filter as intermediate rate, caused a decrease in average BOD removal to 12 percent. The quality of effluent in both methods was according to Iran EPA standards for land irrigation.