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In 2017, Zoeller Pump offered design assistance and components for a new mound system to treat waste from numerous structures at Huber’s Orchard and Winery, located in Starlight, IN, including an ice cream shop and a catering operation. After one year of careful monitoring by the local county health department and the State Department of Health, it was determined that the waste strength loading was too high for the new mound system and an additional pretreatment system was needed to lower the waste strength prior to discharge to the mounds.

Zoeller Pump assisted with recommendations for a new pretreatment system and ultimately recommended a recirculating media filter (RMF) treatment system to be installed between the existing septic tanks and the mound system. RMF treatment systems are similar to recirculating sand filters with the main difference being the size of the treatment media, which is typically 3/8-inch average diameter pea gravel instead of sand media. Having done many installations over the years, the experts at Zoeller have learned that 3/8-inch pea gravel is an excellent media for bacterial colonization, additionally, it doesn’t have the clogging issues that are inherent of sand, therefore, a RMF with pea gravel demonstrates a significantly increased lifespan. This translates to a very economical, low maintenance, high performance, and sustainable treatment system for the owner.

A local engineer designed the new RMF at 4,000 gallons per day using a waste strength of approximately 700 mg/L BOD5, which required a 30 ft x 30 ft RMF. Zoning of the RMF distribution laterals was utilized so the effective treatment area could be reduced as needed by turning off zones during slower times of the year when flows were lower. Two new 3,000-gallon dose tanks were installed and plumbed together for a combined total of 6,000 gallons. These tanks were used as recirculating dose tanks and contained two Zoeller Model 295 pumps that were controlled by a duplex time dose panel. A Zoeller Pump cat’s-eye weir recirculating device was used to recirculate effluent from the RMF and could be adjusted using various weirs to obtain optimum recirculation rates in order to maximize the treatment performance.

Commissioning of the RMF was done in October 2019. Within approximately one month, the new RMF was treating wastewater very efficiently, meeting the objective of effective pretreatment to the mound system. The last four samples collected average 10.5 mg/L BOD5 and 2.3 mg/L TSS.