Journal Article

Concentrations of pharmaceuticals and other micropollutants in groundwater downgradient from large on-site wastewater discharges

Elliott, Sarah M., Krall, Aliesha L., Adams, Byron A., Erickson, Melinda L.

2018

Overview

Large subsurface treatment systems (LSTS) and rapid infiltration basins (RIB) are preferred onsite wastewater treatments compared to direct discharge of treated wastewater to streams and adjacent facilities. Discharge of these wastewater treatments may result in contaminant loading to aquifers that also serve as drinking water sources downgradient from the discharge site. Until recently, few studies have characterized the contribution of micropollutants (e.g. pharmaceuticals, fragrances, flame retardants, etc.) to receiving aquifers. We conducted a pilot project to characterize the occurrence of micropollutants in groundwater downgradient from 7 on-site treatment systems in Minnesota, USA: 5 community LSTS and 2 municipal RIB. One downgradient monitoring well was sampled three times at each facility over one year. Of 223 micropollutants analyzed, 35 were detected. Total sample concentrations ranged from 90 to 4,039 ng/L. Sulfamethoxazole (antibiotic) was detected in all samples at concentrations from 7 to 965 ng/L. Other pharmaceuticals (0.12-1,000 ng/L), organophosphorus flame retardants (10-500 ng/L), and other anthropogenic chemicals (4-775 ng/L) were also detected. The numbers and concentrations of micropollutants detected were inversely related to dissolved oxygen and depth to water. Ratios of pharmaceutical concentrations to human-health screening values were <0.10 for most samples. However, concentrations of carbamazepine and sulfamethoxazole exceeded screening values at two sites. Study results illustrate that large on-site wastewater systems designed to discharge to permeable soil or shallow groundwater effectively deliver pharmaceuticals and other micropollutants to groundwater aquifers and could contribute micropollutants to drinking water via water supply wells.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Analysis / Anthropogenic factors / Antibiotics / Aquifers / Basins / Carbamazepine / Chemical properties / Chromatography / Contaminants / Discharge / Dissolved oxygen / Drinking water / Drugs / Earth Sciences / Ecology and Environmental Sciences / Effluents / Engineering and Technology / Fire retardant chemicals / Flame retardants / Fragrances / Geology / Groundwater / Groundwater treatment / Infiltration / Mass spectrometry / Medical screening / Medicine and Health Sciences / Micropollutants / Onsite / Organic chemistry / Oxygen / Personal grooming / Pharmaceuticals / Physical Sciences / Pilot projects / Pollution monitoring / Pollution sources / Purification / Recharge basins / Research and Analysis Methods / Retardants / Scientific imaging / Screening / Sewage / Sewage disposal / Sewage treatment plants / Soil contamination / Soil permeability / Sulfamethoxazole / System effectiveness / Wastewater discharges / Wastewater pollution / Wastewater treatment / Water depth / Water pollution / Water quality / Water sources / Water supply / Water treatment / Water wells / Water, Underground