DO PHARMACEUTICALS, PATHOGENS, AND OTHER ORGANIC WASTEWATER COMPOUNDS PERSIST WHEN WASTEWATER IS USED FOR RECHARGE?

Authors: CORDY, GAIL - USGS, TUCSON, AZ; Duran, Norma; BOUWER, HERMAN - CONSULTANT, PHX, AZ; RICE, ROBERT - CONSULTANT, PHX, AZ; FURLONG, EDWARD - USGS, LAKEWOOD, CO; ZAUGG, STEVE - USGS, LAKEWOOD, CO; MEYER, MICHAEL - USGS, OCALA, FL; BARBER, LARRY - USGS, BOULDER, CO; KOLPIN, DANA - USGS, IOWA CITY, IA

Submitted to: Ground Water Monitoring and Remediation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2003
Publication Date: 2/15/2004
Citation: Cordy, G., Duran, N.L., Bouwer, H., Rice, R., Furlong, E., Zaugg, S., Meyer, M., Barber, L., Kolpin, D. Do pharmaceuticals, pathogens, and other organic wastewater compounds persist when wastewater is used for recharge?. Ground Water Monitoring and Remediation. 24(2):58-69.

Interpretive Summary: Municipal wastewater effluent is increasingly being used for irrigation needed to sustain agriculture and to replenish groundwater resources in areas with limited water resources such as the arid West. Although municipal wastewater is regarded as a valuable water resource, little is known about the fate and transport of wastewater contaminants or its potential effects on crops and groundwater quality. A soil column experiment simulating a groundwater recharge system was conducted to determine which contaminants (including pathogens and organic chemicals) were present in the wastewater used for recharge and remained in the water after infiltration through the soil column. This project demonstrated under a set of likely recharge conditions, the potential for pharmaceuticals (carbamazapine and sulfonamide antibiotics), pathogens (Legionella) and other organic wastewater contaminants (OWCs) to persist and be transported into the groundwater. This experiment identified Legionella and eight of the 141 OWCs tested as most persistent under typical recharge conditions. Additional research and monitoring are needed to determine the magnitude of transport under field conditions. This information will greatly reduce the cost of field experiments by helping concentrate efforts on contaminants that have the greatest potential to reach the groundwater and thus help assess the vulnerability of aquifers under recharge. This information is important to prevent future problems of groundwater contamination and will help ensure that the subsequent use of groundwater will not contaminate crops or pose a risk to public health.

Technical Abstract: A proof-of-concept experiment was devised to determine if pharmaceuticals, hormones, and other organic wastewater compounds (OWCs) and pathogens in treated effluent could be transported through a 2.4-m soil column and thus, potentially reach ground water under recharge conditions likely to occur in semiarid or arid climates. Treated effluent was applied at the top of the 2.4-m long, 32.5-cm diameter soil column over 22 days. Samples of the column inflow were collected from the storage tank effluent at the beginning (Tbegin) and end of the experiment (Tend), and a sample of the soil-column drainage at the base of the column (Bend) was collected at the end of the experiment. Samples were analyzed for 141 pharmaceuticals, hormones, and other OWCs as well as the pathogens Salmonella and Legionella. The number of compounds detected in the column inflow decreased from 34 in Tbegin to 27 in Tend. Column drainage, Bend, contained 14 compounds. Decreases in the number of compounds in the column inflow may be the result of adsorption to the storage tank containing the effluent or to organic particulates that settled to the bottom of the tank or loss of compounds by biodegradation, biotransformation, or volatilization. During infiltration through the soil column, OWCs may have been further adsorbed/desorbed, biodegraded, biotransformed, or volatilized. In addition, OWC concentrations greater than the reporting limit decreased in the column drainage compared to the inflow with the exception of N-N-diethyltoluamide. Results from real-time polymerase chain reactions demonstrated the presence of Legionella in all three samples. Salmonella was detected only in Tbegin, suggesting that the bacteria died off in the inflow storage tank over the period of the experiment. This preliminary study demonstrates that, under a set of likely recharge conditions, the potential for some pharmaceuticals, pathogens, and other OWCs to be transported into the ground water exists and merits additional research and monitoring.