Year Established: 2013 Start Date: 2013-03-01 End Date: 2016-02-28
Total Federal Funds: $39,000 Total Non-Federal Funds: $78,497
Principal Investigators: John Buchanan, Jennifer DeBruyn
Abstract: This project will create new information as to the ability of recirculating packed-bed media biofilters to remove seven trace organic contaminants from domestic wastewater. Each day hundreds of chemicals, including hormones, antibiotics, surfactants, and other pharmaceuticals and personal care products (PPCPs) are used and subsequently released to the environment through domestic/municipal wastewater discharge. These organic wastewater contaminants (OWCs) have been widely detected in surface and groundwater resources, and in soils under the land application of municipal biosolids and septage. The ecological and environmental risks resulting from the release of OWCs are not fully understood. Recirculating packed-bed media biofilters (RPBMB) are a low-cost and low-maintenance wastewater treatment process that is well suited for individual onsite and very small community applications. Approximately 25% of the domestic wastewater generated in the U.S. is processed by individual onsite or very small wastewater treatment systems. This represents approximately 26 million septic systems that release in excess of four billion gallons of wastewater each day. Unlike municipal sewage treatment plants, these small systems generally depend on the soil for treatment and effluent dispersal. RPBMB are commonly employed when the soil resource is not sufficient to ensure wastewater renovation. RPBMB are a slow-rate, fixed-film treatment process. The media is typically a well-graded coarse sand or fine gravel and serves as the substrate for biofilm growth. Under non-saturated conditions (aerobic), primary-treated wastewater trickles through the media and comes into contact with the biofilm for biochemical oxygen demand removal and nitrification. Effluent from the media unit is split between a recirculation tank (80%) and a final dispersal system (20%). Effluent in the recirculation tank is anaerobic and allows for denitrification. These devices operate in endogenous respiration mode, which minimizes the accumulation of biosolids. The specific objective of this project is to determine whether the combination of endogenous respiration and nitrate-reducing conditions found in a RPBMB can maximize the biodegradation of OWCs found in domestic wastewater. Using a series of laboratory-scale RPBMB, the removal of seven commonly found OWCs will be monitored. The OWCs will include triclosan, bisphenol-A, ibuprofen, diclofenac, naproxen, sulfamethoxazole, and 17thinylestradiol. Previous organic contaminant research has focused on the disappearance of these compounds as wastewater passes through various treatment technologies and subsequent environmental monitoring in surface water. This project will answer specific questions regarding effective remediation techniques within a specific decentralized wastewater unit process. This knowledge will allow scientists and engineers to optimize these processes for organic compound remediation and to minimize or eliminate their release to natural environments mitigating potential ecological disturbance.