Global Water Reuse, Food and Health Workshop Presentation Abstracts (as of 10/2/18):
MONDAY, OCTOBER 8, 2018
Opening Keynote: Perspectives on Integrative Urbanization, Water and Food Security
Bryan W. Brooks (Distinguished Professor, Environmental Science and Biomedical Studies, Baylor University; Director, Environmental Health Science Program; Editor-in-Chief, Environmental Management)
By 2050, 70% of human populations will reside in urban areas with a majority living along or upstream from coastlines. Such high population densities result in elevated demand for food, energy, and water and other resources, including chemicals, which are then concentrated in these urban areas. Environment and health implications of global megatrends, including environmental quality intersections with the food – energy – water nexus, present challenges and unique opportunities to achieving the United Nations Sustainable Development Goals. For example, global food production must increase by 50% over the next few decades to meet the increasing population demands - aquaculture will play an important role to meet these needs. However, 80% of the global sewage production is not treated, but returned to the environment and then subjected to reuse. Judicious water reuse will become increasingly critical because 50% of the world population will live in water stressed regions by 2025, and 22 megacities will exist in Asia-Pacific alone by 2030. Unfortunately, environmental quality implications of water security and food safety are not routinely examined, particularly within the context of global climate change and urban stressors. Clearly, urban water-food security challenges represent an emerging frontier in integrative global environment and health studies, which require transdisciplinary engagement to advance mechanistic understanding and management strategies to promote more integrative water and food security while reducing adverse health outcomes
Session 1: Recycled Irrigation Water Availability, Quality and Treatment Systems(Moderator: Amy R. Sapkota, University of Maryland, College Park)
Hotspots of Water Reuse for Food Crop Irrigation, Xin-Zhong Liang (University of Maryland, College Park)
Increasing scarcity of water resources for food production is an urgent threat to posterity, given that agriculture today consumes more than 70% of global freshwater withdrawals. This threat occurs in the face of the expanding water deficit under climate change and population growth. Global warming is projected with hotter and drier conditions in major agricultural production regions, while a larger world population demands a greater food and water supply. Therefore, water reuse for agricultural irrigation will grow, especially in arid and semiarid regions. Effective water reuse for food crop irrigation depends on the balance among multiple factors, including availability and quality, accessibility and reliability, demand and cost of treated water, as well as consequences on ecosystems and public health. Water reuse will not prevail in areas where the natural water supply is abundant or crop production is low. Nor will it succeed where treated water does not meet regulations or is inconvenient for irrigation access or unreliable for steady acquisition. These areas are generally characterized by low demand, high cost, or compromising public health, and thus not of key interest to water reuse. This presentation will outline a framework for identifying hotspots of water reuse for food crop irrigation, where treated water is highly demanded, accessible, economic, and beneficial. It will involve an interdisciplinary analysis for availability and accessibility of treated water (reclaimed from municipal wastewater or sewage) relative to natural (rain, surface and ground) water, crop production and irrigation demand, evaporation and runoff, urban water use and treatment, climate variability and uncertainty, economic cost and health risk, among others. The outcome will be a comprehensive ensemble of the geographic maps of these variables that enables the identification of water reuse hotspots and thus facilitates the development of a decision support system to safely navigate toward the cost-effective use of reclaimed irrigation water.
Microbial Degradation of Pharmaceuticals, Endocrine-Disrupting Compounds and Acrylamide in Wastewater Effluent and Agricultural Irrigation Systems,Duane Moser (Desert Research Institute)
Background: The role of microbial communities in the degradation of contaminants in wastewater effluent is little understood. To better constrain the relationships between microorganisms and environmental variables, we characterized the biotransformation potential of 27 pharmaceuticals and endocrine-disrupting compounds in parallel with microbial communities from four sites variously impacted by wastewater in Lake Mead, Nevada, USA. We also examined the role of microorganisms in the degradation of acrylamide (AMD, a contaminant from polyacrylamide canal sealants) in agricultural irrigation systems in Colorado, USA.
Methods: Organic compounds were added to microcosms and incubated for up to 120 days. Organic compounds were measured at intervals by LC-MS/MS or HPLC and microbial communities tracked using 16S rRNA gene libraries. The metabolic potential of microbial communities were assessed using Biolog Ecoplates.
Results: Compounds were more rapidly and completely degraded in the most wastewater-impacted sites (e.g. Las Vegas Wash and Las Vegas Bay), with the majority exhibiting shorter half-lives than at the pristine sites. Some compounds (e.g. atrazine, carbamazepine, and primidone) were not degradated; whereas, antibiotics (sulfamethoxazone and trimethoprim) were only degraded in the Las Vegas Wash. Microorganisms of Las Vegas Wash were the most metabolically active and genetically distinct from less urban-impacted locations. Microorganisms used AMD as sole N and C source both aerobically and anaerobically with nitrate, sulfate, or iron as terminal electron acceptors.
Conclusions: Microbial communities can acclimatize to effluent-derived contaminants. Wastewater- and agricultural systems possess an innate potential for the attenuation of manmade contaminants.
Wastewater treatment from minimum to maximum, Yael Mishael (Hebrew University)
Background: Wastewater treatments (WWT) range from very basic to super advanced. Plants were built to clean wastewater for discharge into streams or lakes. In Israel most of the treated water is directed towards irrigation. Years ago, sewage was dumped into water and natural processes of purification began. The sheer volume of clean water in the stream diluted wastes. Organisms in the water consumed the sewage and other organic matter, turning it into new bacterial cells; carbon dioxide and other products. Today the function of WWT is to speed up the natural processes. In the primary stage, solids settle and are removed from wastewater. The secondary stage uses biological processes. Additional treatment stages include traditional and advanced technologies. Our studies focus on tailoring composite sorbents for the filtration of treated wastewater. The real challenge of treating pharmaceuticals from treated wastewater, is the variety of pharmaceuticals and the background water solution. More specifically, the pharmaceuticals are present at low concentrations while higher concentrations of effluent organic matter (EfOM) and salts are present.
Methods: In the current study, we tested the efficacy of novel polymer-clay composite sorbents to remove pollutants. The physicochemical compatibility between the pollutant and the composite determine the affinity of the pollutant towards a specific sorbent.
Results: The removal of most of the pharmaceuticals by the composites was higher than by GAC within 10 min. The removal by a composite, of the non-ionic molecules was twice its removal by GAC. The removal of anionic molecules was 6-7 fold and cationic pharmaceuticals, were completely removed. The removal of EfOM by the composites was efficient.
Conclusions: These results suggest that polymer-clay composites can be designed to efficiently remove an array of pollutants.
Non-conventional water treatment processes, Erick Bandala (Desert Research Institute)
The reuse of wastewater effluents in agriculture is a common practice since the Bronze Age (3200-1100 BC) which has evolved with the history of mankind. Wastewater reuse in agricultural fields has been continuously adopted in major European cities and the United States until the early 20th century mainly as a response to agriculture sector high water demand. For the last several decades, the risk of epidemiologic outbreaks and other food safety-related concerns have remained related to the reuse of even treated wastewater for agricultural purposes and the concern have increased significantly with the consistent higher frequency of reports related with the presence of emerging contaminants (e.g., pharmaceuticals, personal care products, flame retardants) and highly resistant pathogens in treated wastewater effluents resulting from the lack of capability of the conventional wastewater treatment processes for removing this type of contaminants. Non-conventional water treatment processes have emerged as an alternative for the removal of recalcitrant organic contaminants and highly resistant pathogens in water treatment processes. Among the different processes, advanced oxidation processes (AOPs) shows great promise due to: (i) its non-selective nature: it attacks organic, and pathogenic contaminants, therefore it can be used effectively to remove these contaminants from water (ii) its ability to degrade even the most recalcitrant molecules into biodegradable compounds or mineralize it completely, (iii) its green nature, and (iv) ability of some AOPs to take advantage of renewable solar energy. Although the strong potential of AOPs is widely recognized. This presentation will review the advantages and challenges of use of AOPs for water treatment for agricultural reuse.
Development of Treatment Media for Stormwater Quality Improvement, Allen Davis (University of Maryland, College Park)
Background: Bioretention and other nature-based practices have been promoted as “low impact” stormwater management technologies to mitigate impacts of impervious surfaces. Understanding the unit treatment processes in bioretention allow characterization of water quality performance. Various adsorption processes play a large role in bioretention performance. Heavy metals and hydrocarbons are adsorbed strongly on organic and inorganic fractions of the media. Phosphorus and nitrogen species are problematic.
Methods: Novel modifications to bioretention can enhance the efficacy of bioretention facilities for P and N removal. N removal may be enhanced via the use of adsorbing media amendments, with a submerged anoxic zone to promote denitrification in the bioretention media depths. For P, increasing the level of amorphous aluminum and iron in the media will enhance adsorption.
Results: Materials such as aluminum hydroxide-based water treatment residual (WTR), alum, or partially hydrolyzed aluminum chloride may be used to modify treatment media and provide enhanced P removal performance. Capacity and rate studies show effective P removal under stormwater conditions.
Conclusions: Material synthesis complexity will depend on the material selected. Field studies confirm the improved performance of the modified media.
Session 2: Impacts of Recycled Irrigation Water on Soil Health, Plant Health and Crop Yields (Moderator: Yael Mishael, Hebrew University)
Irrigation with reclaimed wastewater: Pharmacokinetics and pharmacodynamics of pharmaceuticals in plants, Benny Chefetz (HUJI)
Background: A wide range of pharmaceuticals detected in treated wastewater are introduced into the agricultural environment. Thus, their uptake and metabolism by plants are of increasing concern. The research aimed to examine the uptake of compounds exposed individually or as mixtures.
Methods: Tomato and cucumber plants were grown in hydroponic solutions. Following 3 weeks of growth plants were exposed to individual and mixtures of benzodiazepines along with carbamazepine and other antiepileptic drugs. Following 2-8 hours of exposure, plants were decapitated and connected to a pressurized suction based xylem sap collecting system. The xylem sap was analyzed along with the nutrient solution to normalize results along the Transpiration Steam Concentration Factor (TSCF).
Results: There was no significant effect on the TSCF for the benzodiazepam when exposed individual or as a mixture. However, the exposure of the compounds as a mixture with carbamazepine resulted in a significant change. The TSCF of Clobazam and Temazepam were reduced from 0.79±0.06 to 0.51±0.02 and from 0.75±0.02 to 0.43±0.03. There was also a significant increase in the TSCF for Aplrozolam and Diazepam. Nordiazepam was not significantly affected. Similar experiments have examined the effect of Oxcarbamazepine, 10,11-epoxycarbamazepine and 10,11-dihydroxycarbamazepine. Additional experiments examining diazepam and carbamazepine individual versus mixed exposure demonstrate that the presence of carbamazepine increases the xylem sap concentration of diazepam.
Conclusions: The results clearly indicate that plant uptake of pharmaceutical compounds is influenced by other compounds within the solution. These results are relevant to both modeling and understanding the fate of pharmaceutical compounds in plants as well as to past studies of xylem uptake whereas differences in results may be due to mixture effects.
Using Sensor Networks for Precision Irrigation, to Increase Water Security and Reduce Nutrient Runoff from Farming Operations, John Lea-Cox (University of Maryland, College Park)
Background: This presentation will review the current state of the technology and summarize the various impacts of the technology on reduction in irrigation water applications and nutrient leaching, increased crop quality and other economic benefits that we have observed in various studies on commercial farming operations across the United States.
Methods: We have developed sensor technologies that provide advanced irrigation monitoring and control capabilities for farmers, for use on a large scale. These commercially-available sensor networks take advantage of either ground-based or cloud-based telemetry, and include a “toolbox” of various sensors for adapting these installations to the specific needs of individual farmers.
Results: Our research over the past ten years has found that sensors provide farmers with real-time intelligence that can now be delivered directly to their smart-phones, for better decision making.
Conclusions: Our research has repeatedly demonstrated that sensors can reduce water use and runoff by 40-70% depending on species, season and type of irrigation systems, compared to experienced growers scheduling irrigation events.
Session 3: Impacts of Recycled Irrigation Water on Food Safety and Quality (Moderator: Erick Bandala, Desert Research Institute)
Shifts in lettuce phyllosphere microbiota in response to overhead application of agricultural water, Shirley Micallef (University of Maryland, College Park)
Background: Adopting use of surface and recycled water sources for agriculture would greatly alleviate pressures on groundwater resources. The use of these alternative water sources for irrigation of fresh produce crops may lead to crop contamination and increased food safety risk if water quality is inadequate. However, data on the relationship between the microbial quality of irrigation water and the microbial safety of crops is limited.
Methods: Microbially characterized water was applied to lettuce grown in the field on mulched or bare ground raised beds, over two growing seasons; spring and fall. Water application was overhead to simulate spray irrigation. Levels of bacterial indicators Escherichiacoli, fecal coliforms and Enterococcusspp. were monitored in the lettuce phyllosphere and in soil over a two week period.
Results: Counts of indicator bacteria on lettuce decreased over time, with more rapid E. coli declines in the fall than in spring. In spring, E. coli decline rates were faster for the bare ground treatment compared to mulches. This difference was not observed in the fall. Enterococci persisted throughout the duration of sampling. Bacteria fluctuated more, and persisted longer, in soil compared to lettuce phyllosphere, and mulch type was a factor for fecal coliform levels, with higher counts retrieved under plastic mulches.
Conclusions:Bacteria in water were transferred to the lettuce phyllosphere. E. colideclined over time, though bacterial die-off varied by season. Enterococci became established in the phyllosphere and persisted. This study shows the complexity of microbial agricultural systems; providing evidence that several factors, in addition to microbial water quality, contribute to microbial diversity of the lettuce phyllosphere.
Risk assessment approaches for understanding the impact of recycled irrigation water on food safety,Abani K. Pradhan (University of Maryland, College Park)
Background: Recently, the importance of recycled water for potential use as irrigation water during crop production is gaining much attention. At the same time there is also concern about food safety related to irrigation water quality and the extent to which pathogen may present and persist. Quantitative microbial risk assessments (QMRAs) are gaining more attention as an effective tool to assess potential risks associated with foodborne pathogens.
Methods: A QMRA framework for E. coliO157:H7 was developed in which the fresh-cut lettuce production and supply chain was modeled from field production, with both irrigation water and soil as initial contamination sources, to consumption at home. Using the risk model the effects of different potential intervention strategies on the reduction of public health risks were evaluated. Furthermore, an innovative system model was developed to understand the pathway of E. coliO157:H7 in leafy greens production.
Results: All intervention strategies evaluated (chlorine, ultrasound and organic acid, irradiation, bacteriophage, and consumer washing) using risk model significantly reduced the estimated mean number of illness cases (from 11 to 18 fold reduction). Results of the system model indicate that the seasonality of E. coliO157:H7 associated leafy greens outbreaks was in good agreement with the prevalence of this pathogen in cattle and wild pig feces.
Conclusions: The developed models have their significance in predicting the public health risk and providing a better understanding of the seasonality of disease outbreaks associated with leafy greens. Further, these modeling frameworks could be used to evaluate public health risk arising from recycled irrigation use in crop production.
Novel technology for water treatment, Zvi Hayouka (HUJI)
Antimicrobial peptides (AMPs) have strong antimicrobial activity against a wide range of microorganisms. Despite the broad molecular diversity among them, they are mostly characterized by positive charge and high prevalence of hydrophobic amino acids. The broad diversity of AMPs in terms of sequences and structures has inspired the development of random peptide mixtures (RPMs), which are composed of hydrophobic and cationic amino acids in binary ratio, with random sequences but controlled chain length and stereo chemistry. Previously we have shown that the RPMs are highly effective towards many bacterial species and are able to destroy biofilm. We were also able to demonstrate their ability to form pore-like structure in synthetic lipid bilayers. In the current study, we aimed to develop antimicrobial bioactive beads, which are composed of RPMs immobilized on polystyrene beads. We demonstrated the antimicrobial activity of the beads and explored their mechanism of action against bacteria. Our results are the first steps for future development of useful antimicrobial bioactive beads for with varied possible applications in the fields of water safety, food safety, agriculture and medicine.
TUESDAY, OCTOBER 9, 2018
Ethiopian Perspectives on Water and Food Security, Tomer Malchi (HUJI) and Mulunesh Abebe Alebachew (Bahir Dar University)
Ethiopia, a source of human origin, ancient civilization and an agrarian country has a complex topography, diverse climate conditions, huge potential of ground and surface water resources, and huge potential of irrigable land. Ethiopian is considered to be the water tower of Africa. However, these huge potential of water and natural resources are not translated into sustainable development practices due to various interconnected factors and driving forces. These factors include climate change, high population growth, rapid urbanization, rain-feed and traditional agricultural practices, poor natural resource management, uncontrolled inorganic fertilizer and pesticide application, open field waste disposal, environmental pollution and weed infestations. Consequently, food security, poor clean water supply, poor sanitation and associated health problems are among the major challenges of the country. Water reuse practices and recycling technologies are untouched areas in the country. They are critical gaps that call for international partnership and collaborative initiatives between academia and other development partners interested to engage and support the ambitious development plans and vision of the country to be one of the middle income countries by 2025.
Session 4: Impacts of Recycled Irrigation Water on Public Health(Moderator: Clive Lipchin, Arava Institute for Environmental Studies)
Recycled irrigation water microbiomes, human exposure pathways and potential public health impacts, Amy R. Sapkota (University of Maryland, College Park)
Background: Increasing water insecurity in key food production regions calls for the urgent need to explore and adopt water treatment and reuse strategies that can sustain food production and protect public health.
Methods: To address this need, our group has conducted a two-year water quality assessment of recycled water sources that--given appropriate treatment—could supplement existing irrigation sources for food crops. Specifically, we have been evaluating recycled water microbiomes using novel DNA-labeling and sequencing approaches. We also completed a related field study, tracking bacterial communities and pathogens from an irrigation water source to field grown crops. Similarly, we have been assessing potential human exposure pathways for the transfer of antibiotic-resistant bacteria from recycled irrigation water sources to human populations.
Results: Our findings show that 1) the dominant bacterial genera, viruses and resistance genes present in recycled water vary between water types and sampling dates; and 2) a significant proportion of bacterial communities persisting in recycled water sources are metabolically active. Nevertheless, although irrigation water microbiomes are viable and can influence crop-associated microbiota, our data show that bacterial pathogens are not likely to be transferred to crops. However, our human exposure assessment studies have demonstrated that spray irrigators utilizing recycled water are more likely to be exposed to antibiotic-resistant bacterial pathogens than control groups.
Conclusions: As agricultural water reuse continues to emerge as a viable solution to address water and food insecurity, appropriate treatment approaches must be employed to reduce the risk of exposure to pathogens among consumers and other exposed groups.
Study of viruses in recycled waters for reuse in irrigation and groundwater recharge, Walter Betancourt (University of Arizona)
Background: Safe and sustainable wastewater reuse requires the implementation of reliable water reclamation processes to minimize environmental and health risks, particularly those associated with acute contaminants such as pathogenic viruses where a single exposure can produce an effect. In Arizona, the Arizona Department of Environmental Quality (ADEQ) establishes that Class A+ reclaimed water produced by secondary treatment followed by filtration and disinfection, can be used for landscape irrigation and groundwater recharge operations.
Methods: In this study, Class A+ effluents produced by two major water reclamation facilities were analyzed for multiple viruses using a filter adsorption-elution method followed by quantitative PCR (qPCR) and integrated cell culture qPCR (ICC-qPCR).
Results: The results of these investigations demonstrated infrequent occurrence of human viruses such as genogroup II Norovirus, Adenovirus, Reovirus, and Aichi virus in treated wastewater at concentrations of 10E+02, 10E+06 genome copies per liter (GC/L). ICC-qPCR allowed the detection of infectious Adenovirus and Reovirus in wastewater effluents. These investigations also demonstrated the frequent occurrence of Pepper Mild Mottle virus (PMMoV), a plant virus, and a bacteriophage (crAssphage) at concentrations of 10E+05-10E+06 GC/L.
Conclusions:Despite variations in virus recovery efficiency associated with the complexity of wastewater matrices, the results of this research demonstrate the importance of applying multiple viruses and detection approaches for adequate evaluation of human virus occurrence in treated wastewater. These human viruses and surrogates may be applied as potential predictors of wastewater treatment performance at eliminating viruses for water reuse applications that involve significant human contact.
Herbicides, Antibiotics, Stimulants, and Disinfectants in Agricultural Water Sources, Amir Sapkota (University of Maryland, College Park)
Background: Frequency, intensity, and duration of extreme events including draught are on the rise and this trend is projected to continue in the foreseeable future in response to changing climate. Such increases in frequency, intensity, and duration of draught combined with increasing municipal water demand will exacerbate agricultural water shortage. Therefore, alternative solutions to agricultural water crises are urgently needed, including the use of nontraditional water sources such as advanced treated wastewater or reclaimed water, brackish water, return flows, and effluent from produce processing facilities. However, it is critical to ensure that such usage is protective of public health.
Methods: We analyzed five different nontraditional water types (n= 300 samples) for herbicides, antibiotics, stimulants, and disinfectants using ultra-high-pressure liquid chromatography tandem mass spectrometry based method (UPLC-MS/MS). We then evaluated whether levels of these contaminants were influenced by season and extreme weather events.
Results and Conclusion: Untreated surface water sources had the highest concentrations of atrazine, oxacillin and penicillin G at 106.9, 188.8 and 214.5 ng/L, respectively. Reclaimed water had the highest levels of antibiotics. Produce processing plant water also tended to have higher levels of atrazine (635.7 ng/L), ciprofloxacin (38 ng/L) and tetracycline (72 ng/L). In addition, we observed seasonal variability, with the highest azithromycin concentrations observed over the winter months, while maximum atrazine levels were observed during the summer months. Further studies are needed to evaluate the effectiveness of economically feasible on-farm water treatment technologies that can effectively remove emerging chemical contaminants.
Impact of urbanization on quality of recycled water sources: Public Health Implications, Kumud Acharya, Desert Research Institute)
Background: Rapid urbanization has put severe pressure on quality of water sources in many parts of the world, both because of increasing point source and non-point source discharges to surface and groundwater, but also because of increasing per capita consumption of water in the growing urban centers causing concerns for public health.
Methods: Lake Taihu, the third largest fresh water lake in China with a surface area of 2,400 km2, supplies water for irrigation, drinking and industry in the Taihu Basin and plays a key role in regional water management. My group has been studying Lake Taihu water quality for the past few years trying to assess pollution types and identify source areas, so that appropriate best management practices can be recommended.
Results: Our long-term data sets suggest that the point loads coming from large urban centers contribute three times more pollution than non-point sources. Similarly, pollution loads are higher during dry periods compared to wet periods. Among pollutants of concerns are various pathogens, toxic organic compounds, elevated COD among others. There are concerns about potential adverse health effects associated with chronic exposure to these pollutants via irrigation water use and fisheries in the Taihu Basin.
Conclusions: There is an urgent need to develop best management practices for treating the source water before recycling for irrigation and other purposes in the Taihu Basin.
Session 5: Cultural, Behavioral, Regulatory and Economic Factors Influencing Recycled Irrigation Water Use (Moderator: Debra L. Weinstein, (University of Maryland, College Park)
Recycled water reuse in Israel, the Palestinian Authority and Jordan, Clive Lipchin (Arava Institute for Environmental Studies)
In this presentation, I will discuss the challenges of transboundary water management among Israel, the Palestinian Authority and Jordan. One of the most pressing transboundary water challenges is the cross border flow of untreated sewage from the West Bank to Israel. A huge gap exists between Israel and the West Bank in wastewater treatment and reuse, exacerbating the risk to shared groundwater resources. Where Israel is a world leader in wastewater treatment, the Palestinians lag far behind. This presentation will discuss the socio-political reasons behind this large gap and the opportunities available (technical, economic and political) to resolving this problem so that maximum use may be made for recycled water in agricultural use in an arid region. In particular, the presentation will present the opportunities for off grid and decentralized greywater treatment and reuse for Palestinian, Jordanian and Bedouin communities that lack access to centralized wastewater infrastructure. Under the CONSERVE program, water quality monitoring of elements of emergent concern (pharmaceuticals, etc.) have been measured for such systems for the first time. Preliminary results indicate the importance of comprehensive water quality assessments for off grid, small-scale wastewater treatment and reuse systems. Also under the CONSERVE program, preliminary data will be presented on the Israeli and Palestinian public's’ level of awareness and acceptance to consuming food irrigated with recycled water. This research is an essential step for developing sustainable and robust planning for recycled water management at local leve
Recycled Irrigation Water and the Law, Robert Percival (University of Maryland Cary School of Law)
Throughout the world water law is governed by a complex mixture of judicial doctrines and statutes that reflect historic practices not always suited to promoting efficient use of water. Thus, it can vary considerably from one jurisdiction to another. As more efficient use of water increasingly becomes an urgent priority, water law is rapidly evolving to encourage more efficient allocation, use and reuse of water supplies, including the use of recycled water for irrigation and to discourage practices that degrade water resources.
The Economic Value of Irrigation-Water Salinity: An Economy-wide Long-Run Analysis, Iddo Kan (Hebrew University)
Background:The growing demand for domestic freshwater uses increases the reliance of agricultural irrigation on treated wastewater and other high-salinity water sources that reduce vegetative farming outputs and indirectly raise food prices.
Methods:We developed a hydro-economic mathematical programming model for analyzing the impact of irrigation-water salinity on the optimal long-term development of water infrastructures. The model integrates physical constraints and costs of a water-supply system with water demand functions at urban and agriculture regions; the latter comprise optimal decisions of farmers on crop acreage given the salinity of the water delivered to the region and yield prices which are determined in equilibrium in the country-wide vegetative-food markets.
Results:We calibrated the model to the case of Israel in 2015, wherein seawater and brackish water desalination have supplied, respectively, 30% and 1% of total consumption, and treated wastewater has comprised 45% of irrigation water. We simulate optimal management throughout 30 years with 1.8% annual population growth. For first year (2015), the model suggests extending the desalination of seawater and brackish water by 60% and 350%, respectively, as well as desalinating 70% of the treated wastewater prior to irrigation. Consequently, irrigation-water salinity reduces from 1.06 to 0.39 dS/m, which in turn increases yields by 10% and reduces agricultural output prices by 15%. To evaluate the overall economic value of salinity we run the model while assuming zero salinity at all Israel’s water sources, obtaining welfare increase of $1.4 billion per average year.
Conclusions:The overall welfare in the economy increases $600 million a year (6%), of which about 1/3 is farming profits and nearly 2/3 is surpluses of vegetative-product consumers.
Spatial and policy aspects of wastewater recycling, Eran Feitelson (Hebrew University)
The ability to reuse wastewater is a function of three main variables: 1) spatial relations between sources (cities) and potential users (mainly agriculture), as well as administrative and political boundaries. These vary between humid and semi-arid areas. 2) Policies, which determine the level of treatment, the funds available for treatment and constraints on re-use, as well as the institutional structures that facilitate or impede re-use. 3) Technology - which determines the cost of different levels of treatment. The first two facets will be discussed on the basis of the Israeli experience. In addition the implications of desalination will also be touched upon.
Session 6: Extension/Outreach and Education Regarding Recycled Irrigation Water Use(Moderator: Zvi Hayouka (Hebrew University)
U.S. farmers’ needs and concerns regarding water reuse for agricultural irrigation, Rachel Rosenberg Goldstein (University of Maryland, College Park)
Background: Water reuse will become increasingly necessary as climate change impacts water resources, including those used for agriculture.
Methods: A needs assessment survey was distributed to farmers in the Mid-Atlantic and Southwest regions of the United States about water availability and nontraditional irrigation water perceptions.
Results: Eighty percent of farmers surveyed considered the use of nontraditional water sources to be at least moderately important and 61% would use nontraditional water if given the option. Farmers were more likely to consider nontraditional water very important for agriculture if they lived in the arid Southwest compared to the Mid-Atlantic, were concerned about water availability, primarily used groundwater, had a graduate or professional degree, had access to nontraditional water, or had some knowledge of nontraditional water. Farmers in both regions were more willing to use nontraditional water if they thought it was very or moderately important for agriculture. Concern about water availability and knowledge of nontraditional water sources were significantly associated with willingness to use these water sources (p<0.001 for both). Water quality and health risks were the main concerns regarding nontraditional water use in both regions. Willingness to use nontraditional water increased significantly if the water quality was proven to be as good or better than farmers’ current water sources.
Conclusions:Water reuse projects should be regionally tailored and education on climate change impacts and adaptive strategies will be crucial for adoption of these water sources.
Consumer response to recycled irrigation water use, Kent Messer (University of Delaware)
This talk will highlight recent research on the consumer response to different agricultural products produced with treated, non-traditional waters in the United States and Israel.
These results, mostly drawn through testing using experimental economics techniques, show that consumers have different levels of concern and willingness to pay for these products, especially when the level of processing differs. This presentation will also explore how consumer responses vary by various social demographic factors and what opportunities exist for future research and collaboration.
How to Communicate Clearly about Health Risks with Expert and Non-expert Audiences, Cynthia Baur (University of Maryland, College Park)
Background: Expert and non-expert audiences bring different types of knowledge, experience, perspectives, and expectations to situations that involve scientific and technical questions and concerns when evaluating health benefits and risks. These differences affect what they want to know and why, as well as how information will be used to evaluate benefits and risks. Clear communication techniques based on multi-disciplinary science about how people attend to, comprehend, and use risk information can help reduce the communication gap between experts and non-experts.
Methods: Examples of clear and unclear information about health benefits and risks related to recycled water for agricultural purposes will be analyzed.
Results: Revised examples will illustrate how to communicate clearly with different audiences about health risks and benefits of recycled water for agricultural purposes.
Conclusions: Scientific and technical information is an essential component of informed decisions about health benefits and risks, and clear communication techniques can make the information more relevant and useful for a wider range of audiences and purposes.
TRAINEE PRESENTATION AND POSTER ABSTRACTS (as of 10/2/18, updates at globalwaterreusefoodhealth.org):
Soil Moisture Effects on Growth, Yield and Fruit Quality of Strawberry (Fragaria X ananassa), Bruk Belayneh (UMD)
The United States is the second major supplier of strawberries in the world, producing one-third of the global supply and the industry valued upward of $2.5 billion. Water resource limitations and environmental regulations are among the main challenges to achieving sustainable production. There is need for innovative ways to reduce water losses and increase water-use efficiency, which requires understanding how soil matric potential (SMP) affects moisture availability and the responses of strawberry plants. We are conducting field and greenhouse experiments to study the effect of soil/substrate moisture on the growth, yield and fruit quality of strawberry (Fragaria X ananassa). Wireless sensor networks coupled with control data loggers are being used to precisely control irrigation based on real-time measurements of soil matric potential and moisture content sensors. Our objective is to implement irrigation treatments with incremental drought stress and study associated plant response.
Environmental and temporal heterogeneity influence microbial community structure and phage-host relationships in surface and reclaimed waters, Jessica Chopyk (UMD)
Background: Nontraditional waters are an important potential resource for agricultural irrigation. However, little is known about their microbiome. To fill this knowledge gap we utilized shotgun sequencing to characterize nine nontraditional water sites.
Methods: Samples (n=24) were collected within the Mid-Atlantic, U.S. (Oct-Nov 2016), filtered, and subjected to DNA extraction and shotgun sequencing.
Results: The assembled metagenomic profiles varied among sites (e.g. river, pond, etc.), geographic location, and sampling date. However, there was a core set of bacterial genera that occurred at a high relative abundance in all samples. We also identified over 600 CRISPR arrays, with over 2,600 unique spacers, suggesting a diverse and specific phage community. Prophage regions were also predicted and found to be abundant at various sites.
Conclusions:These results provide insights into the microbial communities and phage-host interaction dynamics in nontraditional waters.
Assessing the Safety and Efficacy of Agricultural Irrigation Water Produced by Small-Scale Greywater Treatment Systems in the West Bank, Palestine, Hillary Craddock (UMD)
Background: The reuse of wastewater for agricultural irrigation is emerging in water scarce regions around the world, including the West Bank, Palestine. However, to our knowledge, no long-term testing of this water has been done.
Methods: Water samples (n= 64) were collected over nine months from off-grid greywater systems. Bacteria levels were tested using membrane filtration. Samples were tested for antibiotic and pesticide residues with HPLC/MS-MS. Hach probes and a Lutron meter were used to test pH, Electrical Conductivity, and turbidity.
Results: These systems are generally within quality standards for pH and salinity. Turbidity values were highly variable. Regarding bacteria, the systems are not effective at reducing bacteria to acceptable levels. Systems showed evidence of pesticide and antibiotic residues in influent and effluent.
Conclusions: The presence of high levels of bacteria coupled with the presence of antibiotic residues is a point of concern regarding these systems.
Drought stress limits the growth of the human pathogen Salmonella enterica on leafy greens, Xingchen Liu (UMD)
Introduction: Salmonella can survive on leafy greens surfaces utilizing leached and exuded nutrients. Previous work reported specialized compounds on tomato plant surfaces correlated negatively with Salmonella survival. When plants are under drought, they tend to accumulate more polyphenols.
Purpose: Evaluate drought effect on Salmonella surface colonization of leafy greens
Methods: Four-week-old lettuce ‘Mascara’ and kale ‘Improved Dwarf Siberian’ plants (2-8 weeks post germination) were subjected to drought. Leaves were inoculated with ~10E6 Salmonella and bacterial populations enumerated 24 hours later to assess the effect of drought and plant age on Salmonella colonization. Phenylalanine-Ammonia-Lyase (PAL) activity and anthocyanin contents of lettuce were measured.
Results: Salmonella counts retrieved from drought-stressed lettuce and kale surfaces were significantly lower than those retrieved from regularly-watered plants (p<0.05). Moreover, the levels of Salmonella populations on the surface of 20-day-old regularly watered kale leaves were significantly higher than on 59-day-old regularly watered kale leaves (p<0.05). The PAL activity and anthocyanin content of drought-treated lettuce plants were significantly higher than control lettuce plants (p<0.05). Conclusion: Lettuce and kale plants respond to drought stress metabolically. Leaf surfaces under drought stress may be less favorable for Salmonella colonization. Salmonella susceptibility in kale is age-dependent, with juvenile control plants supporting larger Salmonella populations.
Conclusions: The physiological effects, exometabolomic and metabolomic profiles of leafy green plants under the applied mild drought stresses need further studies.
Simultaneous Removal of Pharmaceuticals from Treated Wastewater by Tailored Clay Sorbents, Amir Perez (HUJI)
The removal of emerging micro-pollutants, including pharmaceuticals, by different composites sorbents is widely studies in recent years. Most of the studies examine the removal of a single pollutant by a single composite. The real challenge in treating pharmaceuticals from surface waters and all the more so from treated wastewater, is the variety of pharmaceuticals and the background water solution. More specifically, the pharmaceuticals are characterized by different chemical properties and present at low concentrations while higher concentrations of dissolve organic matter (DOM) and salts are present. In the current study we developed a novel polycation-clay sorbent based on poly-4-vinylpyridine (PVP) modified with an ethanol (on the pyridine) (OHPVP) adsorbed to montmorillonite (MMT). The OHPVP composite reach a positive zeta potential of at 40mV. In the first stage we focused on the removal of three pollutants, metoprolol (MET), diclofenac (DCF) and lamotrigine (LTG).
Random Peptide Mixtures as New Crop Protection Agents, Shiri Topman (HUJI)
Chemical control of bacterial plant diseases in agriculture mostly relies on copper-based bactericides, which possess limited efficacy. In addition, copper-resistant strains often emerge after continuous application of these compounds. Host defense peptides have been suggested as potential candidates to tackle the antibiotic resistance crisis. However, these types of peptides present two major disadvantages: the ability of bacteria to develop resistance towards them and their high cost. Recently, the concept of Random Peptide Mixtures (RPMs) has been introduced. In the current study, we explored the potential of RPMs as crop protection agents in vitro and in planta, and investigated their mode of action. Our findings suggest that the RPMs possess strong antimicrobial activity without significant toxic effect on the environment and have the potential to serve as novel crop protection agents.