Contaminants of Emerging Concern in Minnesota Subsurface Sewage Treatment Systems

Abstract

Highlights CEC are quantified in septic tank effluent, soil, and groundwater within septic systems. The success of septic system treatment of specific CEC is discussed. Treatment of CEC is compared between wastewater in septic systems and land-applied septage. Advanced treatment impact on CEC levels is analyzed. Abstract. Contaminants of Emerging Concern (CEC) are gaining attention as they continue to attract public awareness and more environmental and health consequences are recognized. This study showcases CEC concentrations within Minnesota’s Subsurface Sewage Treatment Systems (SSTS). The study identifies a broad range of CECs associated with subsurface sewage treatment at four sites. Three sites are Minnesota Department of Transportation rest area SSTS with high user inputs, and one site is a septage land application field that receives septage from residential and septic commercial tanks. The studied CEC include antibiotics, chronic disease prescriptions, veterinary medicine, stimulants, hormones, antihistamines, pain and fever relief prescriptions, and a plasticizer. CEC were quantified in the septage, septic tank effluent, advanced treatment effluent, soil, and shallow groundwater. The samples were analyzed via mass spectrometry coupled with light chromatography, revealing that CEC concentrations decrease as they move through the SSTS system. Septage had the highest concentrations of CEC, followed by septic tank effluent. Groundwater had the third highest concentrations, and soils had the lowest concentrations of CEC. CEC concentrations are being reduced through SSTS, but some persist in shallow groundwater. Keywords: Decentralized wastewater system, Groundwater, Pharmaceuticals, Septage, Septic system, Septic tank, Wastewater.