Removal of ammonia in raw water taken from Surabaya river using biofiltration process

Research on the removal of ammonia in raw water taken from the Surabaya river has been carried out. The study was conducted by operating a biofilter pilot plant consisting of lamella type-sedimentation tanks and biofilter reactors filled with honeycomb type-plastic media. The results of the study showed that the biofilter process which consists of sedimentation tanks and biofilter reactors can reduce turbidity, ammonia, and nitrite inside raw water. Generally, the longer the retention time in the biofilter pilot plant is, the greater the efficiency is in eliminating turbidity, ammonia, and nitrite in the raw water. With the total retention time of 81 minutes in the biofilter test model, the efficiency of turbidity, ammonia, nitrate, and nitrite was 33.83%, 57.84%, 16.40%, and 59.41%, respectively. Based on the results of the research above, it was found that with the ammonia load of 1 until 5 gr/m 3 . Hours (24 until 120 gr/m 3 .day), it efficiently reduced the ammonia compounds by 30%-50%. In the chlorination process, chlorine compounds can react with ammonia compounds in the raw water, so by decreasing the concentration of ammonia, the consumption of chlorine will be reduced, resulting in lower production costs. With the reduced use of chlorine compounds, the potential formation of micropollutant compounds due to the chlorination process will also be reduced.