title: Occurrence and fate of organic contaminants during onsite wastewater treatment.
abstract: Onsite wastewater treatment systems serve approximately 25% of the U.S. population. However, little is known regarding the occurrence and fate of organic wastewater contaminants (OWCs), including endocrine disrupting compounds, during onsite treatment. A range of OWCs including surfactant metabolites, steroids, stimulants, metal-chelating agents, disinfectants, antimicrobial agents, and pharmaceutical compounds was quantified in wastewater from 30 onsite treatment systems in Summit and Jefferson Counties, CO. The onsite systems represent a range of residential and nonresidential sources. Eighty eight percent of the 24 target compounds were detected in one or more samples, and several compounds were detected in every wastewater sampled. The wastewater matrices were complex and showed unique differences between source types due to differences in water and consumer product use. Nonresidential sources generally had more OWCs at higher concentrations than residential sources. Additional aerobic biofilter-based treatment beyond the traditional anaerobic tank-based treatment enhanced removal for many OWCs. Removal mechanisms included volatilization, biotransformation, and sorption with efficiencies from <1% to >99% depending on treatment type and physicochemical properties of the compound. Even with high removal rates during confined unit onsite treatment, OWCs are discharged to soil dispersal units at loadings up to 20 mg/m2/d, emphasizing the importance of understanding removal mechanisms and efficiencies in onsite treatment systems that discharge to the soil and water environments.
authors.affiliation: Environmental Science and Engineering Division, Colorado School of Mines, 206 Coolbaugh Hall, Golden, Colorado 80401, USA.
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Conn
authors.forename: Larry B
authors.initials: LB
authors.lastname: Barber
authors.forename: Gregory K
authors.initials: GK
authors.lastname: Brown
authors.forename: Robert L
authors.initials: RL
authors.lastname: Siegrist
mesh_terms: D002614:Chelating Agents / Q000032:analysis; D003120:Colorado; D004202:Disinfectants / Q000032:analysis; D004350:Drug Residues / Q000032:analysis; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D008401:Gas Chromatography-Mass Spectrometry; D012987:Soil / Q000032:analysis*; D013501:Surface-Active Agents / Q000032:analysis; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002614:Chelating Agents; D004202:Disinfectants; D012987:Soil; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical