Location: Water Management and Conservation Research
2024 Annual Report
Objectives
The long-term objective of this project is to provide science-based data to ensure that treated municipal wastewater used for irrigation poses minimal threat to people and the environment. Specifically, during the next five years the project will focus on the following objectives.
Objective 1: Determine the processes that govern the environmental fate and transport of emerging contaminants and other constituents found in treated wastewater used for irrigation to provide a research basis for potential regulation of these constituents.
Sub-objective 1.A: Determine the effect of temperature on the sorption, fate, and transport of pharmaceuticals in soil.
Sub-objective 1.B: Determine the effects of long-term wastewater irrigation on soil contaminant concentration and the soil microbiome.
Sub-objective 1.C: Optimize removal of pharmaceuticals from water.
Objective 2: Develop and optimize low input treatment systems to reduce emerging contaminants and nutrients found in degraded waters to increase water resources used for food production.
Approach
Objective 1 will seek to Increase water supplies available for irrigation and managed aquifer recharge through safely reusing treated wastewater. The effect of temperature and season on the environmental fate and transport of contaminants of emerging concern (CEC) found in reclaimed wastewater will be characterized and quantified. Ten different pharmaceuticals that have a range of pKa’s from (4.0 – 16.0) will be evaluated in the lab by batch sorption and column flow through experiments using soils from the Southwest US. Experiments will be conducted at 10° C, 25° C, and 40° C. Pharmaceutical mobility will be evaluated and compared to seasonal soil temperatures to determine seasonal variability in soil transport. A set of paired stormwater recharge basins, one that receives wastewater inputs and one that does not, will be sampled for pharmaceutical analysis. Results from lab experiments and the paired basins will be used to model the potential for stormwater retention basins to contaminate groundwater with pharmaceuticals found in the wastewater used for irrigation. These results will be used to provide management guidance for stormwater retention basins. Finally, biochar pyrolyzed from walnut shells and cotton gin waste will be evaluated as a treatment method for removing pharmaceuticals from wastewater. Biochar pretreatments will include untreated, acid treated, and base treated prior to pyrolysis. Lab scale columns will be constructed and water containing pharmaceuticals will be passed through biochar filter columns. Removal efficiency and capacity will be calculated, and sorption mechanisms elucidated.
Objective 2 Will be a modeling exercise to determine the potential for using reclaimed wastewater as a supplemental irrigation source in rainfed agricultural systems. The volume of produced wastewater in regions of the Midwest will be spatially matched to potential crop needs. Crop irrigation needs will be modeled using historical weather data and then spatially matched to wastewater availability. Results will be used to determine potential yield loss related to reduced rainfall due to short term spatial and temporal drought. Yield recovery will be related to available water and distance water needs to be transported.
Progress Report
This report documents progress for project 2020-13000-005-000D, “Increased Water Security through Safe Reuse of Reclaimed Water,” which began in January 2022.
In support of Sub-objective 1A, ARS researchers in Albany, California, have completed column flow through experiments at 10°, 25°, and 30°C. Overall, mobility of the pharmaceuticals has been evaluated at temperatures representative of Winter and Spring/Fall. Experiments for Summer temperatures are currently being conducted. The temperatures investigated are indicative of the low desert regions of the Southwestern United States. Generally, as temperatures increase, sorption decreases, resulting in increased transport. Results indicate that the optimal use of treated wastewater is dependent on season. When temperatures are high, wastewater is better suited for irrigation. However, when temperatures are low, mobility is reduced and the use of treated municipal wastewater for groundwater recharge is acceptable.
For Sub-objective 1B, ARS researchers have collected soil samples from non-wastewater and wastewater irrigated infiltration basins. Samples are being extracted for pharmaceutical quantification and are in the process of being extracted for pharmaceutical analysis. Quantification is currently underway using LCMS. Samples have also been collected and extracted for whole genome analysis.
Under Sub-objective 1C, biochars produced from cotton gin waste and walnut shells have been evaluated for removal of pharmaceuticals from water. ARS researchers conducted a series of experiments to determine the effect of treatment prior to pyrolysis and after pyrolysis on sorption potential. It was found that the pretreatment of feedstock with acid and base prior to pyrolysis resulted in a five-fold increase of surface area. In addition, it was found that a 24-hour water rinse of biochar’s after pyrolysis resulted in a ten-fold increase in surface area. Results are being used to optimize removal of pharmaceuticals from water in low input flow through systems.
In support of Objective 2, a crop growth model is being used to evaluate critical growth stages in Maize when water deficits can lead to significant reduction in overall yield. The model uses simulated weather data with micro droughts lasting 7-21 days. Results indicate that there are several critical growth stages where temporary water stress significantly reduced yield. Historical weather data has been identified for several counties in Iowa that will be used for input into the crop growth model to evaluate potential yield loss due to short term water stress. Currently wastewater treatment flows are being acquired via collaborators at Arizona State University. Wastewater flows will be matched to supplemental irrigation needs to determine the potential for yield recovery.
Accomplishments
1. Identify research gaps and priorities for quantitative microbial risk assessment (QMRA). Quantitative microbial risk assessment (QMRA) is a framework that uses data to inform mathematical models to better understand the potential danger posed by microbial agents via environmental exposures and to predict adverse outcomes. An ARS researcher from Maricopa, Arizona, provided chemical expertise for the international workshop Advances in Research for quantitative microbial risk assessment (QMRA). Key research priorities and needs were identified and provided to US and global policy organizations. Research priorities identified were: (1) Use of molecular tools in QMRA; (2) Advancing dose-response methodology; (3) Addressing needed exposure assessments; (4) Harmonizing environmental monitoring for QMRA: (5) Validating models; (6) Modeling co-exposures and mixtures; and (7) Standardizing practices for incorporating variability and uncertainty throughout a source-to outcome continuum. Cross-cutting needs identified were to: (1) Develop a community of research and practice, (2) Integrate QMRA with other scientific approaches, (3) Increase QMRA translation, and (4) Encourage sustainable funding mechanisms.
2. Use of graphene-coated sand to enhance water reuse by improving water quality and reducing chemicals of emerging concern found in municipal treated wastewater. Graphene-coated sand is an advanced filtration media that can improve water quality. An ARS researcher from Maricopa, Arizona, evaluated three types of sand (Ottawa, masonry, and concrete) coated with graphene as a treatment for removing turbidity, nutrients, chemical oxygen demand, bacteria, and 10 chemicals of emerging concern (Aciclovir, Diatrizoic acid, Levodopa, Miconazole, Carbamazepine, Diphenhydramine, Irbesartan, Lidocaine, Losartan, and Sulfamethoxazole). Graphene-coated sand was found to be effective at increasing water quality by reducing turbidity 14.1%, chemical oxygen demand 69.1%, and bacterial contaminants 99.91 %. In addition, Contaminants of Emerging Concern (CECs) were also reduced between 45-90%. Graphene-coated sands were found to be an effective water treatment for reuse of wastewater.
3. Low-cost and sustainable materials that enhance the removal of contaminants from treated municipal wastewater. Chemicals of emerging concern, including pharmaceuticals, are found in municipal wastewater at low concentrations. Current wastewater treatment systems are not optimized for removal of these compounds. An ARS researcher from Maricopa, Arizona, was part of a team that developed and evaluated 3D-printed bricks made of clay and crawfish shell waste to remove turbidity, Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), total coliforms and E. coli. Additionally, their ability to remove chemicals of emerging concern (CECs) was measured. All three systems, including the control, effectively removed turbidity (up to 96%), total coliforms (up to 99%) and E. coli (up to 99%). The sand filter with clay bricks showed the highest removal rates for turbidity (87.1%), COD (55%) and TOC (47%). Overall, the reactor with crawfish bricks performed slightly better in removing total coliforms (97.3%) compared to the reactor with clay bricks. A similar trend was also observed in terms of E. coli. Among the different CECs analyzed, the highest removal rates were recorded for fluoxetine (100% removal), diphenhydramine (>90% removal) and erythromycin (60% -100% removal) regardless of the reactor used. However, the reactor with crawfish bricks outperformed the other two in removing CECs exhibiting a 40% - 80% removal such as trimethoprim, tramadol, irbesartan, guaifenesin, gabapentin and losartan, as well as CECs exhibiting a relatively low removal (10 – 40 %) including lidocaine and sucralose. Overall, the 3-D printed bricks provided effective removal of the contaminants of interest from wastewater.
Review Publications
Franklin, A.M., Weller, D.L., Durso, L.M., Bagley, M., Davis, B.C., Frye, J.G., Grim, C., Ibekwe, A.M., Jahne, M., Keely, S.P., Kraft, A.L., McConn, B.R., Mitchell, R., Ottesen, A., Sharma, M., Strain, E., Tadesse, D., Tate, H., Wells, J., Williams, C.F., Cook, K.L., Kabera, C., McDermott, P., Garland, J. 2024. A one health approach for monitoring antimicrobial resistance: Developing a national freshwater pilot effort. Frontiers in Water. 6. Article 1359109. https://doi.org/10.3389/frwa.2024.1359109.
Mcconn, B.R., Kraft, A.L., Durso, L.M., Ibekwe, A.M., Frye, J.G., Wells, J., Tobey, E.M., Ritchie, S.M., Williams, C.F., Cook, K.L., Sharma, M. 2024. An analysis of culture-based methods used for the detection and isolation of Salmonella spp., Escherichia coli, and Enterococcus spp. from surface water: a systematic review. Science of the Total Environment. 927. Article 172190. https://doi.org/10.1016/j.scitotenv.2024.172190.