Energy efficiency and energy consumption are common terms in today’s wastewater treatment industry. Along with pumping, running blowers for aeration is the most energy consumptive part of the treatment process.
To reduce aeration energy costs, operators and engineers adopt better maintenance practices, consult with energy-use specialists, and quite commonly upgrade technologies and facilities. Among the most popular means of achieving better energy efficiencies is upgrading to modern or relatively new technologies like high-speed turbo blowers. However, many plants across the country find that upgrading aeration blowers isn’t always feasible. New blowers can have price tags in the hundreds-of-thousands, not including the cost of engineering and construction. Often overlooked, however, is a simple means of significantly reducing energy consumption: upgrading blower intake filters.
Optimized intake filters can save thousands of dollars annually in energy savings and may not require construction crews, engineering bids, or grant applications. The benefits can also be realized for treatment plants of all sizes. Described below are examples of three wastewater treatment plants that upgraded filters and came out ahead: a small rural operation with positive displacement (PD) blowers, a suburban plant using multi-stage blowers and a large urban plant that had already upgraded to airfoil bearing high-speed turbo blowers.
Small Plant Saves Thousands in Energy Annually
A wastewater treatment plant in the Midwest serves a population of just over 2,000. The plant uses PD blowers to aerate their activated sludge. While they meet their effluent requirements, they found their blowers were becoming expensive to run.
The installed PD blowers are not variable speed machines: they run at full power until dissolved oxygen (DO) requirements are met and are shut down pending demand. Using a throttle or control system to increase or decrease speed based on DO levels are not options. Near-constant machine operation leads to increased power consumption, and for small rural communities, expensive plant upgrades are not realistic options.
In 2017, the plant discussed blower filter options with Endustra Filter Manufacturers and installed Endustra Tri-Vent® Series intake filters and filter silencers on all nine of its PD blowers. The patented design of the Endustra filter reduces inlet restriction without compromising filter efficiency, allowing the plant’s PD blowers to produce the required DO with less runtime. And while all blower intake filters act as silencers to an extent, filter silencers have a reactive chamber designed into the filter for baffling sound. Endustra filters and filter silencers incorporate conical cartridge filter elements with proprietary self-supporting synthetic filter media to protect against particulate ingress without excessive restriction of airflow. The elements can be used interchangeably with intake filters or intake filter silencers which provide additional noise suppression.
According to plant operators, reaching required DO levels took less time, about 15-25 minutes less per machine. Additionally, less blower runtime led to an approximate power savings of nine dollars per day, adding up to over $3,000 dollars a year, a significant amount of savings for a rural wastewater treatment operation, and more than the total cost of their investment. In addition, the filter elements have only needed to be replaced once, saving on maintenance.
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