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By Bob Dabkowski, Hach Company

Since the early 1970s, water and wastewater plants have been automating processes in order to achieve a more stable effluent and to decrease costs. Many of these pioneers automated their processes based upon daily averages, changes in flow, or computer-based models. These initial successes have bred the next generation of automation: controlling the process based upon real-time water quality criteria.

For example, many wastewater plants now automatically control their aeration process by measuring the real-time dissolved oxygen residual. Today's thought leaders are going one step further by controlling aeration based upon real-time ammonia concentrations, which reduces aeration expenses by an additional 30%. Similarly, many wastewater plants that perform chemical phosphorus removal do so through a flow proportional dose of chemical precipitant. The next generation of operators is using phosphate analyzers along with influent flowmeters to respond to changes in influent loading in real time — using just enough chemical to get the job done.