Improved Jar Testing Optimization with Organics Monitoring

Jar testing is used extensively in the drinking water purification industry to simulate performance of various chemical coagulants and process conditions without altering full-scale treatment process. This testing has become even more critical in recent years due to climate changes and security threats. For many plants, optimization of treatment processes to increase removal of total organic carbon (TOC) can help reduce formation of undesirable and highly regulated disinfection by-products (trihalomethanes and haloacetic acids). TOC removal can often be improved by selecting the optimum dose and type of aluminum or ferric-based coagulant. Other treatment parameters including the addition of permanganate, powdered activated carbon, or pH adjustment can also be easily modeled in jar testing. Traditionally, turbidity and often UV254 have been used as a primary indicator of good floc formation and a measure of optical clarity in jar tests. More recent laboratory and field testing has shown that TOC may be a better indicator of fully optimized treatment processes for many waters. This is particularly true if TOC measurements can be made immediately as various process changes are made to a jar testing plan. Real-world advantages of fully optimized jar tests may include reduced chemical usage or cost, improved removal of organics, and a reduction in regulated disinfection by-products. This study includes jar testing results with both turbidity and TOC data for water samples from multiple locations in the US. In addition, a Size Exclusion Chromatography TOC (M9SEC) instrument is used to evaluate organic size distributions before and after jar testing.