comparison of coagulants performance with enhanced coagulation in turbidity and organic matter removal in karaj river

enhanced coagulation (ec) is defined as the addition of excess coagulation to improve the removal of disinfection by-product (dbps) precursors through the use of conventional water treatment processes. in this research, most of coagulants of ferric chloride (fecl3), poly aluminum chloride(pacl) in removal of most parameters of total organic carbon (toc), dissolved organic carbon (doc), organic adsorption in wavelength of 254 nm (uv-254), alkalinity, aluminum and ferric remain, total trihalomethans (tthms), studied and compared in karaj river in tehran for water treatment plant no.2 efficient ph for removal of natural organic matter(nom) at enhanced coagulation condition for ferric chloride and poly aluminum chloride are 6 and 6.5, respectively. this results show that poly aluminum chloride application instead of fecl3 as an enhanced coagulation in annual average turbidity (6ntu), high turbidity, toc, doc and toc removal, decrease of ph and lower alkalinity. the lower coagulant consumption, the high floc size, the lower floc detention time, the lower sludge production, no need to ph adjustment in turbidity of 25 ntu and the lower alum consumption were the advantages of pacl application instead of fecl3 as a coagulant. also, pacl application was efficient in average turbidity (6 ntu) in toc, turbidity, uv-254 and doc removal.