AWWA WQTC58844

Small drinking water systems using surface water sources will soon have to comply with the Stage I Disinfectants/Disinfection Byproducts (D/DBP1) Rule (January 1st, 2004). Small systems have the most difficulty meeting federal compliance standards for drinking water, because the treatment technology that may be affordable to large-scale operations may not be affordable for small-scale operations. Therefore, small system compliance problems are the most difficult problems to solve in the water industry. The overall objective of this research was to study the treatment of a variety of Missouri surface waters using techniques applicable to small systems such as powdered activated carbon (PAC), aluminum sulfate (alum), polyaluminum chloride (PACl), and anion exchange resin (MIEX) for removal of NOM and minimization of DBPs by single and sequential treatments. This study demonstrated that PAC treatment is unlikely to be a sole remedy to DBP problems because it cannot remove a sufficient amount of NOM at reasonable doses (30 mg/L). MIEX treated water had the highest ultraviolet absorbance (UVA) and Total trihalomethanes (TTHM) removal at 88 % and 86 %, respectively. For alum treatment, a minimum dose of 20 mg/L was required to destabilize the particles, causing a decline in UVA254. Lower pH improved alum and PACl performance. Sequential treatment clearly showed better UVA removal than single PAC or alum treatments. Sequential treatment for alum/PAC is at least 42 % to 47 % higher than PAC treatment alone and 6 % to 26 % higher than alum treatment alone, whereas sequential treatment for PACl/MIEX is at least 10 % to 26 % higher than PACl alone and 5 % to 33 % higher than MIEX alone. TTHM versus UVA and UFC chlorine dose (C24) correlation analysis showed that the UVA was better than C24 and dissolved organic carbon (DOC) for predicting TTHM for most waters. Includes 13 references, tables, figures.