using of powdered activated carbon as coagulant aid in total organic carbon removal in koot amir water treatment plant

the removal of organic precursors of disinfection by-products (dbps), i.e. natural organic matter (nom), prior to disinfection is considered as the most effective approach to minimise the formation of dbps. trihalomethanes (thms) as the main group of dbps are categorized and considered to have the potentiality of increasing the rate of liver, kidney and cns adverse effects. this study which presents experimental results, aimed at the reduction of organic matters using the powdered activated carbon (pac) in the process of coagulation in koot amir water treatment plant in ahwaz city. the affect of two coagulant such as ferric chloride and poly aluminum chloride (pacl) with pac in removing total organic carbon (toc) considering different parameters such as concentration and the kind of coagulants, concentration of pac, ph changes and contact time has been surveyed. the results of this study clearly indicated that maximum removal in optimum ph of ferric chloride was 40% while 44% toc removal was achieved at ph 6.5 for poly aluminum chloride coagulant. in use of powdered activated carbon with optimum ph and concentration of ferric chloride, toc reduction will increase with increasing pac concentration and up to 90%. also by addition of powdered activated carbon at similar conditions together with poly aluminum chloride 87% reduction of toc was occurred. poly aluminum chloride was more effective in toc removal than ferric chloride and pac adsorption as coagulant aid improved toc removal efficiency.