Dewatering Automation and Optimization at the Morris Forman Water Quality Treatment Center

The Morris Forman Water Quality Treatment Center (MFWQTC) in Louisville, Kentucky dewaters and dries approximately 70 dry tons per day of biosolids. To process those solids MFWQTC utilizes five Alfa Laval DS706 high solids centrifuges with an emulsion polymer for solids conditioning. Polymer consumption and the associated cost constitute a significant portion of the annual chemical budget at MFWQTC. Operations and management identified polymer consumption as an area of operation that could benefit from an improvement in the control of delivery and utilization, with the expected ancillary benefits of more stable operations in dewatering and drying.To achieve that goal MFWQTC partnered with Alpine Technology of Austin, Texas and implemented a polymer control and solids measurement system on one of MFWQTCs five centrifuges.The basis of the system entails Total Suspended Solids (TSS) measurement of the sludge feed to the centrifuge, TSS measurement of the resulting centrate, and control of the polymer feed to achieve an optimized polymer dose rate, identified as pounds of polymer per dry ton of solids processed. Criteria were established to provide operational boundaries regarding centrate quality, percent capture of solids to the centrifuge, pounds of polymer per ton of dry solids.The existing centrate system was modified to collect centrate in a vessel and using Hach infrared/scattered light technology accurately measure TSS content. Similarly, the sludge feed line to the centrifuge was modified to allow the insertion of a Hach sensor for the same purpose. Based on measurements by the sensors, the established boundary criteria and program algorithms, a Programmable Logic Computer (PLC)/SCADA based system communicates with the dewatering PLC to adjust polymer delivery.In addition to the expected benefits, MFWQTC realized ancillary benefits identified by better operator control, reduced system upsets, better operator understanding of dewatering. This paper will highlight the challenges, process, technology and improvements realized by MFWQTC.