Development of a polymer coagulant injection control system used in the sewage sludge dehydration process

摘要

Conventionally, the injection rate of polymer coagulant used in the sludge dehydration process is changed as needed by the operator while observing the moisture content of dehydrated sludge. Optimizing the polymer injection rate requires experience. Furthermore, when the properties of the sludge vary greatly, it is hard to quickly follow the variation and inject the optimum amount, causing instability of the moisture content. Therefore, we aimed to develop a system that automatically optimizes the injection rate by following variations in sludge properties using instruments to measure the input sludge density, dehydrated sludge moisture content and colloid charge amount of the water separated by dehydration. We also built a system within on-site equipment and evaluated its controllability.