To reduce disinfection by-product (DBP) formation in drinking water treatment, the presence of natural organic matter in surface waters must be minimised. This paper describes pilot plant studies carried out on two surface waters to assess the effectiveness of coagulation in organic matter removal, the Turia and Jucar rivers, which supply the city of Valencia (1m inhabitants). The experiments were conducted with different coagulants (iron sulphate, polyaluminium chloride (PACl)) and treatment schemes. Process effectiveness was evaluated in terms of effluent turbidity, presence of residual metal in final water, and organic matter removal. Four parameters were used to quantify organic matter concentration: total organic carbon (TOC), trihalomethane precursors, ultraviolet absorbance at 254 nm, and oxidability to permanganate. Iron sulphate yielded better results than PACl. Finally, some mathematical relationships were established between coagulant dosages and organic matter removal.
This paper involves a preliminary study on controlling DBP formation in conventional treatment. Future work will set out the results obtained using GAC filtration and ozonation.