ANNOUNCEMENTS
Every year print media report the incapability of the water treatment plants of Delhi in treating surface water due to a high level of ammonia coming from Haryana. Presence of ammonia causes high chlorine demand during treatment affecting the disinfection efficiency and leads to the production of tri-halo-methanes and organo-chlorines which are suspected to be carcinogenic. Partial nitrification of ammonia in distribution pipelines can lead to the formation of nitrite which can cause serious health hazard such as methemoglobinemia (Blue Baby Syndrome). There is a need for a separate ammonia removal treatment scheme which can be modified in conventional treatment plants of Delhi. This study presents a biological treatment of ammonia in surface water using the principle of nitrification. The lab setup consists of two 3 liters glass reactors in series filled with gravel as growth media for bacteria. The setup was fed with water containing ammonia concentration (5-7 mg/l). Orthophosphate was fed to the system as it is one of the primary nutrients of nitrifying bacteria. Initially, 0.4 mg/l of orthophosphate was maintained in the system which was then increased to 0.6 mg/l to study its effect on ammonia oxidation. The rate of nitrification under different ammonia concentration was studied by analyzing ammonia, nitrite and nitrate concentration with respect to time. In the early stage of the experiment the rate of nitrification was slow; however, after the complete acclimation of the bacterial population up to 7 mg/l of ammonia was oxidized within a day.
Keywords: ammonia, biological treatment, nitrification, surface water.
