1a. Objectives (from AD-416):
Objective 1: Develop new and novel water quality indicators (biological and chemical) for assessment of reclaimed water quality. Objective 2: Determine the processes that govern the fate and transport of emerging contaminants, pathogens, and nutrients found in treated wastewater used for irrigation to provide a research basis for potential regulation of these constituents. Objective 3: Develop and optimize small on-site treatment systems to reduce emerging contaminants and pathogens found in domestic waste water used for irrigation.
1b. Approach (from AD-416):
Field data from sites where treated effluent has been used will be gathered and used to determine the presence and suitability of selected emerging contaminants and pathogens found in treated municipal wastewater as indicators. Qualitative and quantitative enzyme-linked immunosorbent assays (ELISA) will be developed for the identified wastewater indicators. Environmental samples will be taken and analyzed for nutrients, pathogens, and emerging contaminants. Distribution of nutrients, pathogens, and emerging contaminants will be used to determine which constituents may be accumulating in the environment for further investigations. Using a combination of lab studies fate and transport parameters will be determined for the identified constituents. Concurrently, a series of laboratory and field experiments will be conducted to determine the development of antibiotic resistance in native soil microbial populations. Finally, a small scale, low input treatment systems will be developed and validated to provide improvement in water quality and increased water supply by treating household wastewater.
3. Progress Report:
Significant progress has been achieved in all three objectives related to emerging contaminants. However, work related to pathogens and indicator organisms has not progressed due to a scientist vacancy and subsequent abolishment due to reductions in appropriations. Currently, there is no microbiological expertise devoted to the project. Commercially available antibodies for several emerging contaminants have been identified and are being evaluated for Enzyme-Linked Immunosorbert Assay (ELISA) development. Initially, non-specific interactions between primary and secondary antibodies were observed. A series of cross reactivity experiments were conducted to isolate and eliminate these cross reactions. Currently a system of two primary antibodies and one secondary antibody have been determined for three compounds (carbamazepine, ciprofloxacin and caffeine) for development of a 'sandwich' ELISA. Annual loading rates of emerging contaminants at a ground water recharge facility were determined. Deep percolation (> 1m) of these compounds were also quantified by collecting solution samples from the soil profile. The concentration of emerging contaminant found in solution samples were related to the mass sorbed to soil. The reduction of redox sensitive emerging contaminants was also measured at depths <1 meter below the surface of the recharge basin. Sorption of the antibiotic lincomycin was found to be effected by pH and the non-equilibrium sorption of the drug carbamazepine was quantified. Additionally, soil profile analyses of nutrients to 1 m have been completed. Nutrient analysis shows that extractable nitrate and boron are at very low levels throughout the profile. Phosphorus concentrations, on the other hand are high, especially in the surface layers. A Material Transfer Research Agreement (58-5347-3017) has been entered into with Forret Plasma Labs to investigate the use of a plasma arc system for treatment of household wastewater and the potential for removal of emerging contaminants from municipal wastewater. The plasma arc system has been setup at the Arid Land Agricultural Research Center and initial testing is ongoing.