Elizabeth Heise, E.I.T. and Scott Trotter, P.E., BCEE, received the 2019 Radebaugh Award at the CSWEA 92nd Annual Meeting Awards presentation on May 15, 2019.  The Radebaugh Award is awarded for the best paper presented at the Annual Meeting in that year by a Central States member.

The paper “The Effects of Side Streams On Phosphorus Removal” reviews the nationwide push to reduce nutrient levels in United States waterways that has been implemented by the USEPA. Noting that, effort has affected NPDES permits for treatment systems through implementation of a total phosphorus effluent limit. In some states, this limit is as low as 0.075 mg/L. These new regulations have necessitated advanced treatment methods at plants that were not originally designed with the intention of removing phosphorus. There are many phosphorus removal methods that can be implemented including chemical removal, biological removal, or a combination of the two.

The best method is plant specific, based on parameters including size, existing processes, available land, and public opinion. This study was conducted to determine the impact on the existing infrastructure, specifically the sludge stabilization and dewatering processes, of phosphorus removal at various wastewater treatment facilities throughout Northeastern Illinois.

It was concluded that without thorough evaluation of the impact of the side streams, both Chemical Phosphorus Removal and Biological Nutrient Removal (BNR) are likely not going to perform as effectively as possible. The impact of compounding phosphorus due to the side stream was found to be so significant in some situations that BNR proved to be completely ineffective. A detailed analysis of the side stream is recommended for any WWTFs that are implementing phosphorus removal processes. This was also found to be a primary contributing factor in plants under-performing as compared to the designed phosphorus removal efficiencies.