Over 700 communities in the United States rely on their local combined sewer system to remove wastewater from homes and businesses. These systems are space-efficient and cost-effective, and they can often mitigate flooding into residential structures or even roads. Preventing downtime, especially in combined sewer systems, is essential for public health. It also ensures the efficient operation of wastewater treatment plants, particularly when managing double or triple the usual wastewater volume. This month’s blog will explore the various types of sewer systems. We will identify potential points of failure in treatment plants. Additionally, we will provide tips for minimizing downtime and reducing the amount of flush water used.
What is a Combined Sewer System?
Sewer systems are classified as ‘separate sanitary sewer systems’ or ‘combined sewer systems’. Separate sanitary systems use two sets of pipes: one for stormwater runoff leading to local bodies of water and another for wastewater directed to treatment plants. Combined sewer systems merge stormwater and wastewater into a single system, using flow regulators to direct water to treatment plants while excess stormwater flows to local bodies of water.
What Can Cause System Downtime in Wastewater Treatment Plants?
Pumps are simultaneously the key to treating wastewater and one of the most vulnerable points in a treatment plant. The submersible pumps that bring the wastewater into the plant are susceptible to clogging when encountering foreign objects that unintentionally enter sewer systems. End-suction pumps that deal with return-activated sludge (RAS) or waste-activated sludge (WAS) often break prematurely from mechanical seal failure. Many cartridge seal designs incorporate springs to support appropriate seal designs. Older designs submerge the springs in the process fluid to reduce heat. As a result, the springs often become clogged with suspended solids, leading to seal failure, premature shaft ware, and wastewater leakage. The latest best practice regarding spring placement is to have them outside of the process fluid for the best fit on the seal.
Broken seals and pumps can reduce output and increase safety hazards within the treatment plant. Slips and falls reduce the availability of on-site staff while also adding significant, preventable housekeeping costs to the facility’s budget.
How SpiralTrac Can Help:
SpiralTrac™ Environmental Controller by Enviroseal combined with AW Chesterton mechanical seal or packing on pumps protects against premature seal and pump failures. Adding SpiralTrac with a new seal or packing installation removes three potential problems associated with lengthy system downtime:
1. SpiralTrac prevents suspended solids from encountering the seal.
Suspended solids found in RAS and WAS greatly contribute to seal failure in wastewater treatment plants. Placing SpiralTrac between the impeller and the mechanical seal or packing prevents access for the suspended solids to clog the springs or packing. This, along with its unique, patented throat-brushing design, protects the seal and the pump shaft from abrasive solids.
2. SpiralTrac dissipates heat within the stuffing box.
Overheating seals or packing can warp the shape of the seal around the shaft. This warping can contribute to seal damage and eventually lead to pump failure. By adding a buffer to the mechanical seal or packing, SpiralTrac allows air to circulate within the mechanical seal, rather than using the fluid itself to allow for cooling.
3. SpiralTrac reduces or outright eliminates flush requirements for seals and packing.
Mechanical seals require maintenance staff to wash or ‘flush’ the seal face with water to remove debris at routine intervals. When it comes to packing, maintaining a delicate balance is essential: keeping as much fluid as possible inside the pump while ensuring the packing remains moist. Insufficient fluid can damage the packing, while excessive fluid may pose a safety risk and reduce the pump’s output. SpiralTrac helps reduce the flush rate for mechanical seals and minimizes leakage when used alongside packing.
Chesterton & Enviroseal engineer SpiralTrac & paired seal to the application at hand for maximum performance. They configure the designs based on operating parameters, stuffing box arrangement, and the materials of construction to ensure a long-lasting seal solution for your pumps. SpiralTrac can reduce the flush water use by 60% for packing and potentially eliminate it for mechanical seals. Utilizing SpiralTrac can save thousands of dollars annually in utility costs and increase the efficiency of maintenance staff.
Next Steps
Ready to drastically reduce your system downtime? Use the Contact Us button below to reach our team and discuss your new SpiralTrac Environmental Controller. If you need service for your current pumps or seals, use the Request Service button to schedule an appointment with our Chesterton-trained service technicians.
