Most control systems use Proportional-Integral-Derivative (PID) algorithms for controlling DO, basin air flow distribution, and blower pressure or flow. These algorithms are prone to hunting - the cyclic fluctuation of the controlled variable. Fluctuations that oscillate the DO several mg/L above and below the target DO concentration are common.
This article aims to discuss the various technologies of equipment that could be presented to a wastewater operator faced with a temporary need for blower air and to help the operator understand the impact (both monetarily through a “Total Cost of Rental” approach and environmentally) of their decisions.
A small site located within a floodplain, prone to erosion, and currently occupied by an existing in-service wastewater treatment facility is not at the top of any engineer’s list for a desirable site to expand a wastewater treatment plant or reclamation facility. However, these challenges created opportunity for specialized solutions during the design of the facility expansion; in particular, in designing the aeration and digester blower system.
Ever since it was commissioned in 1974, the Echallens wastewater treatment plant in the Swiss canton of Vaud has been generating power from the recovery of biogas. In May 2020, two old oil-lubricated piston compressors used to mix the sludge in the digester were replaced by one MINK claw compressor from Busch Vacuum Solutions. This enabled the amount of power required for this process to be reduced by up to 40 percent. For the director of the treatment plant, this means he needs less energy to produce energy.
Aerobic digestion is a common treatment technology used at small-to medium-sized wastewater treatment plants for the treatment of waste activated sludge (WAS). The objective of aerobic digestion is to treat the sludge for disposal, and for those trying to meet Class B biosolids, further reduce volatile solids (VS) and pathogens to ensure the sludge is suitable for land application.
When the plant’s original aeration blowers became costly to operate and newer technology offered the promise of energy-savings, Fuqua took decisive action and replaced the older blowers with high-speed turbo blowers. As a result, the plant saves ratepayers approximately $30,000 per year in energy costs and bolsters the plant’s ability to maintain uptime and achieve extremely clean effluent.
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.
In this article, we discuss both vacuum pump inlet and exhaust filtration and explore how protecting your vacuum pump can increase productivity and help businesses reach their sustainability objectives.
One need look no further than the treatment plant’s digester project upgrade to see the value of the plant’s forward-thinking approach at work. The upgrade involved the replacement of five Positive Displacement (PD) blowers with four, high-speed Inovair integrally geared blowers for aerating the digesters. With fewer – and smaller – blowers the plant saves tens of thousands of dollars in energy costs per year. The blowers also offer flexibility to cost-effectively adapt to the need for increased water treatment in the future.
KC Water encompasses six wastewater plants and 43 flood and sanitary stations. There are 15 flood stations along the Missouri River that keep Kansas City dry. Then we have 1,350 acres of land for biosolids application. Industrial pre-treatment is the responsibility of the Regulatory Compliance Division. We all work closely together.
Julie Gass, P.E., is a Lead Mechanical Process Engineer at Black & Veatch and an industry veteran with extensive experience in mechanical equipment in wastewater treatment plants. She also served on the American Society of Mechanical Engineers (ASME) Committee responsible for ASME PTC 13, Wire-to-Air Performance Test Code for Blower Systems, which is the performance test code published in October 2019 for all blower technologies. Blower & Vacuum Best Practices Magazine interviewed Gass to gain her views on aeration blowers, PTC 13, and the firm’s rigorous specification process to ensure treatment plants get the blower best suited for their application.