Maximum removal is necessary both to make the water aesthetically pleasing to customers and to assist in the elimination of pathogenic organisms. The conventional treatment process is complicated by tradeoffs and uncertainties. Unlike ground water, the quality of surface water has temporal changes due to weather and seasonal events. Seasonal water quality changes occur gradually over weeks, while weather can change water quality drastically in hours. As a consequence, maintaining optimum coagulant treatment is impossible during subtle and severe water quality changes.
Optimization is important here because coagulating agents are costly.
Jar tests are bench scale coagulation tests that are set up as single variable experiments, even though there are usually two or three coagulant chemicals. Usually, the best information on coagulation dosage comes from an operator who has experienced years of seasonal changes, mild as well as severe weather events, and knows how the plant water moves through the plant, with all its site-specific idiosyncrasies. The primary water quality parameter used is turbidity. Less frequently monitored is daily algae content. The problem of finding a relationship between turbidity and a set of other variables is a classic regression problem.