Use of an ecological treatment system (ETS) for removal of nutrients from dairy wastewater

The Waterman Ecological Treatment System (WETS) had four replicate treatment lines. Together, the four lines treated 1310 L/day of diluted wastewater from a dairy facility with over 99% removal of ammonium-nitrogen (NH4-N) and carbonaceous biochemical oxygen demand (CBOD), and 79% removal of orthophosphate (PO4-P). The average influent/effluent concentrations of NH4-N, CBOD, and PO4-P were 52.1/0.07 mg/L, 517/5.2 mg O2/L, and 21.0/4.4 mg/L, respectively. Nitrate + nitrite (NOx-N) was produced and removed within the system, and had an average effluent concentration of 0.53 mg/L. The multiple anaerobic-aerobic interfaces in the WETS design enhanced biological removal of nitrogen and phosphorus. NH4-N, CBOD, and NOx-N were consistently removed throughout the 20-week study, but PO4-P removal efficiency decreased over time in one of the four treatment lines.