Energy efficient digestion

Energy efficient digestion

Vorelodos from Xylem

Aerobic digestion is often the second largest consumer of energy — after biological treatment aeration — at a wastewater treatment plant. With energy efficiency now at the top of the priority list for most municipalities, Xylem has launched a Sanitaire aerobic digester that claims to decrease energy consumption by up to 90 percent, promoting more sustainable wastewater treatment operation. The Vorelodos aerobic digester combines equipment, controls, and services to future-proof wastewater treatment plants by ensuring they meet current and future EPA effluent and biosolids regulations while simultaneously reducing operational costs.

“Xylem’s Sanitaire Vorelodos’ efficient operation supports the sustainability and efficacy of the entire wastewater treatment facility,” says Sarah Elger, Sanitaire global product manager, Xylem. “The solution also promotes sustainable wastewater treatment by enabling biosolids to be reused for agricultural purposes.”

The system combines Xylem’s biological treatment process with Sanitaire aeration, decanting, and process controls; Flygt mixing and pumping; and YSI and WTW instrumentation. Each digester solution is engineered to meet specific project needs, as biological process experts work closely with consulting engineers and customers to ensure that the digester is designed to precisely meet individual applications.

“The aerobic digester is very effective, ensuring that up to 90 percent less phosphorus and nitrogen is returned to the main plant compared to a fully aerated digester,” Elger says. “This, in turn, stabilizes the wastewater treatment process by ensuring that the supernatant that is recycled back to the main treatment plant does not introduce a ‘spike’ of nutrients. It also means that chemical quantity in secondary and tertiary processes is reduced due to stabilized pH and alkalinity recovery. It involves lower capital cost and is easier to operate than alternatives, as the technology does not rely on membranes or other thickening equipment.”

The digester is suitable for newly constructed conventional activated sludge plants or upgrades to existing plants over 0.5 mgd, as well as oxidation ditch upgrades and aerobic digester aeration retrofits. The significant energy reduction means that in larger plants, according to Xylem’s calculations, the system can effectively pay for itself within one year. The solution also helps lower chemical use as a result of alkalinity recovery and a reduction in the amount of phosphorus being returned to the main plant. An automated decanting feature and aeration control means that staff time can be invested in other activities. 855-995-4261;


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