Putting the Operator in Charge; Improved Human Machine Interface Leads to Significant Centrifuge Operation Savings

All plants have an obligation to ratepayers to deliver the best wastewater treatment service at the lowest cost. As polymer prices started to soar even faster than energy costs, plants have needed to find new ways to reduce its dewatering polymer use. Some improvements are capital intensive, such as installing newer equipment. Others cost very little; they are simply improving the way we do things, such as putting the operators in charge.Most plants change operating goals passed down to operators intermittently as specific directives: “Try not to use more than 15 GPM of polymer, and keep the cake at least 27%.” This sort of instruction is OK, but usually not done often enough to account for changes in the dewatering processes. In the Minneapolis-St Paul Metro Plant the control system displays, operators are empowered to make changes independently, hour by hour, so the dewatering costs can be constantly minimized.