Occurrence of Pharmaceuticals and Consumer Product Chemicals in Raw Wastewater and Septic Tank Effluent from Single-Family Homes

Methods were modified and tested to monitor the occurrence of 20 pharmaceuticals and consumer product chemicals in raw wastewater and septic tank effluent (STE) from six single-family homes (two each located in Florida, Colorado, and Minnesota) each utilizing an onsite wastewater treatment system. Ten compounds were detected, including the stimulant caffeine, the metal-chelating agent ethylenediaminetetraacetic acid, the surfactant metabolite 4-nonylphenolmonoethoxylate, and the antimicrobial triclosan, which were present in all wastewater samples. Pharmaceutical occurrence and levels were more variable than consumer product chemicals; nonprescription anti-inflammatory drugs were the most frequently detected pharmaceuticals. Concentrations ranged from <1 mu g/L to > 1,000 mu g/L and varied by compound, site, and sampling event. No clear relationship between raw wastewater and STE composition existed. Raw wastewater composition, which previously has not been reported, reflected the per-capita water consumption and chemical-consuming activities at the source during the 24 h of sample collection. STE composition was likely affected by all consumptive activities during the tank hydraulic residence time (similar to 1 to 2 weeks) as well as differences in conditions between sites and at a single site over time (e. g., residence time, temperature, and load of organic compounds). Knowledge of source activities regarding the types, frequencies, and levels of pharmaceuticals and consumer product chemicals present in onsite wastewaters can aid in efforts to minimize potential risk to ecological and human health.