ABSTRACT
Ammonia and fecal coliform removal from wastewater is of high necessity because of its inappropriate impact on environment where wastewater accumulates. Aerated lagoons as well as polishing ponds would not be able to decrease ammonia and fecal coliforms in an efficient way. Different procedures are usually applied for the removal of ammonia and fecal coliform in wastewater treatment plants. In this study, effluent of polishing pond in wastewater treatment plant of Khoy in North-West Azerbaijan with three different loading flow rates [0.3, 0.6, 0.9 m[3]/m[3].d] was entered into the rock filter with volcanic rock bed, rock diameter size of which was 50 mm. To determine the efficiency of rock filter in any loading flow rates, 10 samples of influent and effluent were taken. The results showed that mean of effluent ammonia level changed from 16.8 to 4.8 mg/1 and effluent fecal coliform from 1.9xl0[4] MPN/l00ml to SJxl0[3] MPN/lOOml. Rock filter efficiency for Ammonia and fecal coliform removal of pond effluent were 71.4% and 70% respectively. Ammonia and fecal coliform decreased in all loading flow rates but in the first rate changes were more remarkable than the two other rates. As loading flow rate increased, removal efficiency decreased. This is probably due to low hydraulic retention time that resulted in decreasing nitrification. Thus it is concluded that rock filter here presented has better efficiency than what were used in similar studies