مقايسه كارآيي حذف TOC و نيترات با كاربرد منعقدكننده هاي آلوم و كلرورفريك در دو تصفيه خانه آب

The Comparison of the Efficiency of Eliminating TOC and Nitrate by Using Alum and Ferric chloride in Two Water Treatment Plant

Nowadays, water treatment is an important point in human life, as a result of water contamination. Conventional water treatment methods are effective enough for removing suspended and colloidal matter of water , but organic matter which are a carbon sources for microorganisms and a main factor for THMs formation , requires improved methods for their removal. Coagulation is a conventional method for removing suspended and colloidal matter from water, through adding chemicals. In this process less amount of coagulants, iron and aluminum, may remain in water and some compounds may be removed from water like total organic carbon and nitrate. In this study, a comparison has been addressed between two municipal water treatment plant which use two different types of coagulants. Ferric chloride and Alum, in order to measure residual Iron and Aluminum, and also the removal rate of nitrate and total organic carbon. Two treatment plant with common raw water resources were selected. Their raw water quality was the same, but use different coagulants. Alum and Ferric chloride. Samples was collected according to recommended methods during three seasons-Autumn, Winter and Spring- from common input and output of each plant and analyzed. Total organic carbon, nitrate. Iron and Aluminum, were measured with high temperature combustion, UV Spectrophotometer , atomic absorption and Spectrophotometer methods, respectively. The results showed that there was no significant statistical differences between the amounts of total organic carbon and nitrate in raw and treated water of both plants. The amount of mean and removal rate showed that ferric chloride had more efficiency for reducing total organic carbon. The maximum amount of total organic carbon and nitrate, were measured in autumn and spring, respectively. The measured iron and aluminum showed a significant increase in output of the plant, respectively, using ferric chloride and alum as coagulant. The amount of all measured parameters, in both plant, are according to standards values.