ACHIEVING AND VERIFYING ULTRA-LOW PHOSPHORUS FOR WASTEWATER DISCHARGE OR REUSE

According to the USEPA’s Nutrient Pollution website, “nutrient pollution is one of America's most widespread, costly and challenging environmental problems, and is caused by excess nitrogen and phosphorus in the air and water” [USEPA (2013)]. Phosphorus (P) in the water increases algae growth, which can kill off the waterway’s plant and animal life, produce harmful dioxins when disinfected for drinking water, and create a decline in the tourism, fishing, and real estate industries. To combat this problem, several areas in the U.S. now, or will soon, require low levels of phosphorus in the effluent of wastewater plants discharging to state waterways. One such example of this is the Cahaba River basin in Alabama; wastewater plants discharging more than 1 MGD (3,788 m 3 /day) into this river - or tributaries feeding it - will be required to meet an average monthly total phosphorus limit of 0.043 mg/l by 2022. To determine how to consistently meet these low phosphorus limits, a pilot study was conducted in December of 2012 at the Buxahatchee Wastewater Treatment Plant (WWTP) in Calera, AL. The main plant processes are a sequencing batch reactor (SBR) secondary system and a cloth media filtration (CMF) tertiary system. To achieve the required ultra-low phosphorus level, a sidestream of the filter effluent was passed through an ultrafiltration (UF) pilot unit. This paper describes the system parameters required to obtain ultra-low effluent phosphorus levels. In addition, some of the challenges encountered in the study are discussed, along with how these challenges were overcome.