Is your sewer utility looking for ways to save on energy costs? A great place to start is the often-overlooked workhorse of the sanitary sewer system – the lift station! Many people don’t realize that even after a lift station is designed and installed there are still significant cost savings available to those who are willing to regularly maintain and/or upgrade their facilities.
Optimization of the pumping process is the key to potential cost savings available at your lift station. Variable frequency drives (or “VFDs”) are a great way to increase pump performance while minimizing power consumption. These drives allow the pumps to operate at maximum efficiency under a range of influent flows, effectively matching the pump speed to the current flow conditions. Many existing pumps can be retrofitted with VFDs, but it’s worth doing your research to make sure the decision is cost-effective for your application. VFDs are best suited for applications where there are significant friction losses in the force main.
Regularly checking the impeller clearance to the pump housing will also optimize your pump. This clearance grows larger over time due to general wear, which can result in clogging and inefficient operation. Check with the pump manufacturer to make sure your impeller clearances are within acceptable tolerances. If you’re experiencing issues with regular clogging, try using a “semi-open” or “back-swept” type of pump impeller. These specialty impellers are specifically designed to reduce clogging and improve performance. While you’re checking your pump clearances, be sure to keep an eye on other critical pump parts including the seals, bearings, and motor to ensure efficient operation.
Another way to achieve energy savings at your lift station is to make sure that you’re getting the best information available from your SCADA (supervisory control and data acquisition) system. SCADA systems can provide you with real-time monitoring of pumps and other equipment at your facility, allowing for easy station management and timely response to failures. SCADA systems are also a critical source of historical data, including flow rates and pump run times, which can better inform operational decisions that will save money.
If you have questions about ways that you can ensure efficient operation of your lift stations and achieve energy savings, don’t hesitate to contact Mark Van Weelden at Ruekert & Mielke, Inc.
About the Author
Mark B. Van Weelden, P.E.
Mark joined Ruekert & Mielke, Inc. (R/M) as a full-time employee in 2014. His broad area of focus includes experience in both point and non-point source characterization and treatment. He has worked with both agricultural partners and small communities to investigate waste management solutions, evaluate treatment alternatives, and implement field-scale best management practices.