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Nutrient Removal Upgrades

Client: Village of New Lenox

Location: New Lenox, Illinois

The Village of New Lenox owns and operates three water reclamation facilities.  Water reclamation facility number 1 (known as STP No. 1) is a 2.5 mgd, single stage nitrification facility, which was tasked with meeting new effluent phosphorus limits by November 2013. Donohue & Associates was retained to complete the planning, design, and construction-related services for the facility.

The existing facilities at STP No. 1 did not include biological or chemical phosphorus removal facilities. One limitation of biological phosphorus removal was the existing 30-year-old centrifugal blowers, which were oversized and inefficient. The layout resulted in elevated oxygen concentrations in the aeration basins, limiting anaerobic contact time.

Using process modeling, field testing, and historical data, Donohue developed capital and annual cost estimates for biological and chemical alternatives.  The biological phosphorus removal alternative had a significantly higher capital cost due to the required blower modifications; however, annual operating costs were approximately ¼ of the chemical phosphorus removal alternative. Therefore, Donohue recommended installing new, high efficiency blowers for improved DO control and selector zones for biological nutrient removal.

Donohue completed the design of the nutrient removal improvements over an expedited three-month period in order to meet IEPA’s implementation deadline.