New standards at European Union level on water reuse for agricultural irrigation: Are the Spanish wastewater treatment plants ready to produce and distribute reclaimed water within the minimum quality requirements?

The new European regulation on minimum quality requirements (MQR) for water reuse (EU, 2020/741) was launched in May 2020 and describes the directives for the use of reclaimed water for agricultural irrigation. This Regulation will be directly applicable in all Member States from 26 June 2023. Since its publication in 2020, concerns have raised about potential non-compliance situations in water reuse systems. The present study represents a case study where three different water reuse systems have been monitored to establish their compliance with the MQR. Each water reuse system includes a wastewater treatment plant (WWTP), a distribution/storage system and an end-user point, where water is used for irrigation of leafy greens. The selected water reuse systems allowed us to compare the efficacy of water treatments implemented in two WWTPs as well as the impact of three different irrigation systems (drip, furrow and overhead irrigation). The presence and concentration of indicator microorganisms (Escherichia coli and C. perfringens spores) as well as pathogenic bacteria (Shiga toxin-producing, E. coli (STEC), E. coli O157:H7, and Salmonella spp.) were monitored in different sampling points (influent and effluent of the WWTPs, water reservoirs located at the distribution system and the end-user point at the irrigation system as well as in the leafy greens during their growing cycle. Average levels of E. coli (0.73 ± 1.20 log cfu E. coli/100 mL) obtained at the point where the WWTP operator delivers reclaimed water to the next actor in the chain, defined in the European regulation as the 'point of compliance', were within the established MQR (<1 log cfu/100 mL) (EU, 2020/741). On the other hand, average levels of E. coli at the end-user point (1.0 ± 1.2 log cfu/100 mL) were below the recommended threshold (2 log cfu E. coli/100 mL) for irrigation water based on the guidance document on microbiological risks in fresh fruits and vegetables at primary production (EC, 2017/C_163/01). However, several outlier points were observed among the samples taken at the irrigation point, which were linked to a specific cross-contamination event within the distribution/storage system. Regarding pathogenic bacteria, water samples from the influent of the WWTPs showed a 100% prevalence, while only 5% of the effluent samples were positive for any of the monitored pathogenic bacteria. Obtained results indicate that reclaimed water produced in the selected water reuse system is suitable to be used as irrigation water. However, efforts are necessary not only in the establishment of advance disinfection treatments but also in the maintenance of the distribution/storage systems.

Distribution and environmental risk assessment of trace metals in sludge from multiple sources in Taiwan.

This study evaluated the level of the contaminant of the heavy metals in sludge from different sources and the ecological risk criteria associated with it was also analyzed to establish its reuse in agriculture. The sludge samples were collected from the water plant (WTP), wastewater treatment plant (WWTP), and industrial water treatment plant (IPT) in Taiwan. The inductively coupled plasma mass spectrometry was used to measure the trace metals in sludge. The pollution level and ecological risk criteria for heavy metals in sludge were also used to evaluate its reuse in agriculture. The result shows the average concentrations of trace metals in sludge for three groups (WTP, WWTP, and ITP). Significant correlations were found between concentrations of Zn-Ag (p < 0.001). The higher values of Igeo showed in ITP, indicated Hg to be a major pollutant. In Taiwan, the regulations did not establish the reuse of sludge in agriculture. However, the concentration level of trace metals in sludge was particularly lower than the regular levels in most groups, like WTP and WWTP groups. The industrial sludge was not recommended for the use in agriculture. The results of this study can be used for regular monitoring to establish a reference for sludge management and application to agriculture.

Peak grain forecasts for the US High Plains amid withering waters.

Irrigated agriculture contributes 40% of total global food production. In the US High Plains, which produces more than 50 million tons per year of grain, as much as 90% of irrigation originates from groundwater resources, including the Ogallala aquifer. In parts of the High Plains, groundwater resources are being depleted so rapidly that they are considered nonrenewable, compromising food security. When groundwater becomes scarce, groundwater withdrawals peak, causing a subsequent peak in crop production. Previous descriptions of finite natural resource depletion have utilized the Hubbert curve. By coupling the dynamics of groundwater pumping, recharge, and crop production, Hubbert-like curves emerge, responding to the linked variations in groundwater pumping and grain production. On a state level, this approach predicted when groundwater withdrawal and grain production peaked and the lag between them. The lags increased with the adoption of efficient irrigation practices and higher recharge rates. Results indicate that, in Texas, withdrawals peaked in 1966, followed by a peak in grain production 9 y later. After better irrigation technologies were adopted, the lag increased to 15 y from 1997 to 2012. In Kansas, where these technologies were employed concurrently with the rise of irrigated grain production, this lag was predicted to be 24 y starting in 1994. In Nebraska, grain production is projected to continue rising through 2050 because of high recharge rates. While Texas and Nebraska had equal irrigated output in 1975, by 2050, it is projected that Nebraska will have almost 10 times the groundwater-based production of Texas.

Optimal fertigation for high yield and fruit quality of greenhouse strawberry.

Nitrogen (N), phosphorus (P), potassium (K), and water are four crucial factors that have significant effects on strawberry yield and fruit quality. We used a 11 that involved 36 treatments with five levels of each of the four variables (N, P, and K fertilizers and water) to optimize fertilization and water combination for high yield and quality. Moreover, we used the SSC/TA ratio (the ratio of soluble solid content to titratable acid) as index of quality. Results showed that N fertilizer was the most important factor, followed by water and P fertilizer, and the N fertilizer had significant effect on yield and SSC/TA ratio. By contrast, the K fertilizer had significant effect only on yield. N×K fertilizer interacted significantly on yield, whereas the other interactions among the four factors had no significant effects on yield or SSC/TA ratio. The effects of the four factors on yield and SSC/TA ratio were ranked as N fertilizer > water > K fertilizer > P fertilizer and N fertilizer > P fertilizer > water > K fertilizer, respectively. The yield and SSC/TA ratio increased when NPK fertilizer and water increased, but then decreased when excessive NPK fertilizer and water were applied. The optimal fertilizer and water combination were 22.28-24.61 g plant-1 Ca (NO3)2·4H2O, 1.75-2.03 g plant-1 NaH2PO4, 12.41-13.91 g plant-1 K2SO4, and 12.00-13.05 L water plant-1 for yields of more than 110 g plant-1 and optimal SSC/TA ratio of 8.5-14.

Risk assessment of contaminants of emerging concern in the context of wastewater reuse for irrigation: An integrated modelling approach.

Direct reuse of reclaimed wastewater (RWW) in agriculture has recently received increasing attention as a possible solution to water scarcity. The presence of contaminants of emerging concern (CECs) in RWW can be critical, as these chemicals can be uptaken in irrigated crops and eventually ingested during food consumption. In the present study, an integrated model was developed to predict the fate of CECs in water reuse systems where RWW is used for edible crops irrigation. The model was applied to a case study where RWW (originating from a municipal wastewater treatment plant) is discharged into a water channel, with subsequent irrigation of silage maize, rice, wheat and ryegrass. Environmental and human health risks were assessed for 13 CECs, selected based on their chemical and hazard characteristics. Predicted CEC concentrations in the channel showed good agreement with available measurements, indicating potential ecotoxicity of some CECs (estrogens and biocides) due to their limited attenuation. Plant uptake predictions were in good agreement with existing literature data, indicating higher uptake in leaves and roots than fruits. Notably, high uncertainties were shown for weakly acidic CECs, possibly due to degradation in soil and pH variations inside plants. The human health risk due to the ingestion of wheat and rice was assessed using the threshold of toxicological concern and the hazard quotient. Both approaches predicted negligible risk for most CECs, while sulfamethoxazole and 17α-ethinylestradiol exhibited the highest risk for consumers. Alternative scenarios were evaluated to identify possible risk minimization strategies (e.g., adoption of a more efficient irrigation system).

Recommendations to derive quality standards for chemical pollutants in reclaimed water intended for reuse in agricultural irrigation.

The reuse of treated municipal wastewater (herein referred to as reclaimed water) in agricultural irrigation (RWAI) as a means to alleviate water scarcity is gaining increasing policy attention, particularly in areas where water demand mitigation measures have proved insufficient. However, reclaimed water reuse in practice is lagging behind policy ambition, with <2.5% of it reused in a European context. A key barrier identified as limiting its full valorisation is concern over its impact on human and environmental health. To address this concern, and to meet further objectives including achieving parity between current reclaimed water reuse guidelines operational in various Member States, the European Commission has proposed a regulation which identifies minimum quality requirements (MQR) for a range of microbiological and physico-chemical parameters but the inclusion of compounds of emerging concern (CECs) in terms of the determination of quality standards (QS) is missing. This paper reviews the existing pertinent EU legislation in terms of identifying the need for CEC QS for RWAI, considering the scope and remit of on-going pan-European chemicals prioritisation schemes. It also evaluates opportunities to link in with the existing EQS derivation methodology under the EU WFD to address all protection targets in the environmental compartments exposed via potential pathways of RWAI. Finally, it identifies the main data gaps and research needs for terrestrial ecosystems, the removal efficiency of CECs by WWTPs and transformation products generated during the wastewater reuse cycle.

Microbiological Contamination of Strawberries from U-Pick Farms in Guangzhou, China.

This study quantified the association of rodent fruit damage and the microbiological quality of irrigation water on the risk of microbiological contamination of strawberries collected from 18 U-pick farms across five different districts in the Guangzhou metropolitan region of southern China. Fifty-four composite strawberries samples, with or without evidence of rodent or avian foraging damage (i.e., bitten), along with 16 irrigation water samples, were collected during the spring of 2014 and winter of 2015 from our cohort of 18 farms. Composite strawberry samples and irrigation water were analyzed for total coliforms, E. coli, Salmonella, E. coli O157, Giardia, and Cryptosporidium. Total coliforms and E. coli were detected in 100% and ~90% of irrigation water samples, respectively. In contrast, Cryptosporidium was detected in only two water samples, while Salmonella, E. coli O157, and Giardia were not detected in any water samples. Strawberries with signs of being bitten by wildlife had significantly higher concentrations of total coliforms and E. coli, compared to strawberries with no physical evidence of rodent damage (p < 0.001). Similarly, Cryptosporidium was detected in 7/18 (39%) of bitten, 4/18 (22%) of edge, and 5/18 (28%) of central strawberry samples, respectively. Concentration of E. coli on strawberries (p < 0.001), air temperature (p = 0.025), and presence of Cryptosporidium in irrigation water (p < 0.001) were all associated with the risk of Cryptosporidium contamination on strawberries. Salmonella and Giardia were detected in <4% strawberry samples and E. coli O157 was not detected in any samples. These results indicate the potential food safety and public health risks of consuming unwashed strawberries from U-pick farms, and the need for improved rodent biosecurity of U-pick strawberry fields and enhanced microbiological quality of irrigation water used at these facilities.

An assessment of irrigated rice production energy efficiency and environmental footprint with in-field and off-field rice straw management practices.

The research provided scientific evidences for improved rice straw management. Rice cultivation with in-field burning of rice straw is the worst option with the lowest energy efficiency and highest air pollution emission. This article comprises a comparative assessment of energy efficiency and the environmental footprint of rice production using four different rice straw management scenarios, namely, straw retained, straw burned, partial straw removal, and complete straw removal. Paddy yield, grain quality, and energy balance were assessed for two seasons while greenhouse gas emissions (GHGE) were measured weekly starting from land preparation through to the cropping and fallow period. Despite the added energy requirements in straw collection and transport, the use of collected rice straw for mushroom production can increase the net energy obtained from rice production systems by 10-15% compared to burning straw in the field. Partial and complete removal of rice straw reduces GHGE by 30% and 40% compared to complete straw retention, respectively.

Determination of optimum irrigation strategies and effect of drip irrigation system on growth and water use efficiency of pear jujube in Loess Hilly region of northern Shaanxi.

The aim of this study is to explore suitable drip irrigation system on the water saving and high yield of pear-jujube from 2009 to 2012 years in the mountain of northern Shaanxi. The treatments consisted of combinations of 5 drip irrigation systems (DP). The irrigation quota of DP-1, DP-2 and DP-3 treatment was 100 m3 hm-2, 135 m3 hm-2 and 180 m3 hm-2, respectively, irrigated 4 times. The irrigation quota of DP-4 and DP-5 treatment was 135 m3 hm-2 and irrigated 3 and 2times, respectively; and with no irrigation as the control (C). Results indicated that bearing branch length of jujube, fruit set and yield of different drip irrigation system are significantly better than C (P<0.05). Bearing branch length and yield of DP-3 treatment are reached maximum in 2012, which are 22.0 cm and 16772.8 m3 hm-2. And they are increased by 47.7% and 13.2% compared with C, respectively. In addition, the water consumption of different irrigation treatment increases along with the increasing of irrigation amount. And the DP-3 treatment is the highest in different years. The water use efficiency of pear-jujube of low irrigation quota is better than the high irrigation quota. Water use efficiency of 135 m3 hm-2 and irrigated 2 times treatment is the best, which is 1.92 m3 hm-2. Considering the lack of high annual precipitation, we conclude that DP-5 treatment was the best drip irrigation system in the mountain of northern Shaanxi.

Effect of sodium concentration on mobilization and fate of trace metals in standard OECD soil.

The effect of different Na concentrations on the fate of trace metals (Cd, Cu, Ni, Zn) in standard OECD soil was evaluated by performing soil leaching column experiments. Five Na concentrations added in synthetic irrigation water (0, 1, 5, 10, 50 mM) were studied in order to evaluate the fate of the metals contained in both the irrigation water leachate and the soil layer. In all experiments, metals mostly accumulated on the top soil layer (0-0.5 cm), at variable concentrations according to the Na content in the artificial irrigation water. Nevertheless, concentration peaks of metal contamination occurred at different sampling time in the soil leachates depending on the metal and on influent water sodicity. Peaks of metals in the leachate appeared simultaneously with the release of organic matter and/or release of Al, suggesting significant involvement of colloids in metals transport. Sodium concentration (10-50 mM) was demonstrated to highly reduce colloidal mobilization leading to the accumulation of more than 95% of the influent metal in the top soil layer. Conversely, low Na concentrations (1-5 mM) favored colloidal transport leading to the recovery of metals in the soil leachates.

Review of water quality criteria for water reuse and risk-based implications for irrigated produce under the FDA Food Safety Modernization Act, produce safety rule.

Questions related to the safety of alternative water sources, such as recycled water or reclaimed water (including grey water, produced water, return flows, and recycled wastewater), for produce production have been largely un-explored at the detail warranted for protection of public health. Additionally, recent outbreaks of Escherichia coli (E. coli) in fresh produce, in which agricultural water was suspected as the source, coupled with heightened media coverage, have elevated fruit and vegetable safety into the forefront of public attention. Exacerbating these concerns, new Federal regulations released by the U.S. Food and Drug Administration (FDA) as part of implementation of the FDA Food Safety Modernization Act (FSMA), require testing of agricultural water quality for generic E. coli. Here, we present a review of water quality criteria - including surface water, groundwater recreational water, and water reuse - in an attempt to better understand implications of new FDA regulations on irrigated produce. In addition, a Quantitative Microbial Risk Assessment (QMRA) was conducted to estimate risks from pathogen contamination of food crops eaten fresh under the context of FDA regulations to provide perspective on current water reuse regulations across the country. Results indicate that irrigation water containing 126 CFU/100 mL of E. coli correspond to a risk of GI illness (diarrhea) of 9 cases in 100,000,000 persons (a 0.000009% risk) for subsurface irrigation, 1.1 cases in 100,000 persons (a 0.0011% risk) for furrow irrigation, and 1.1 cases in 1000 persons (a 0.11% risk) for sprinkler irrigation of lettuce. In comparison to metrics in states that currently regulate the use of recycled water for irrigation of food crops eaten fresh, the FDA FSMA water quality metrics are less stringent and therefore the use of recycled water presents a reduced risk to consumers than the FDA regulations. These findings, while limited to a one-time exposure event of lettuce irrigated with water meeting FSMA water quality regulations, highlight the need for additional assessments to determine if the scientific-basis of the regulation is protective of public health.

Hydrochemical characteristics and quality assessment of groundwater from fractured Albian carbonaceous shale aquifers around Enyigba-Ameri, southeastern Nigeria.

Enyigba-Ameri area is known for its Pb-Zn mining activities and the mine water is usually discharged directly into nearby streams and surface runoff. In order to determine the impacts of mining activities on the quality of water in the area and the general hydrochemical characteristics, field measurements and laboratory tests were carried out on water samples collected from the area. Field measurements and laboratory analyses of physicochemical parameters were determined using standard methods. In addition to the multivariate analyses (principal component analysis and cluster analysis) and ANOVA analysis, ionic cross-plots were used to determine the groundwater physicochemical characteristics and geochemical evolution. From the results, it was observed that Pb4+, Zn2+, Fe2 + & 3+, Ca2+, Mg2+, and K+ had a concentration higher than the stipulated guideline values. Three principal components which explained 87.42% of the total dataset were extracted through the data reduction process. Cluster analysis of the hydrochemical data grouped the water samples into three distinct classes. It was observed that the water chemistry is mainly affected by silicate minerals weathering, carbonate weathering, and base ion exchange processes in descending order. ANOVA analysis showed that Zn2+, Fe2 + & 3+, and Mg2+ had mean values that significantly differed from each other based on the sources of the samples. The Wilcox diagram revealed 4 classes of irrigation water types and the irrigation water quality indices showed that the groundwater in the area is not generally suitable for irrigation purposes.

Predicting the uptake of emerging organic contaminants in vegetables irrigated with treated wastewater - Implications for food safety assessment.

Emerging organic contaminants (EOCs) undergoing incomplete removal during wastewater treatment may be found in treated wastewater (TWW) used for irrigation of agricultural products. Following uptake into edible plant parts, EOCs may eventually enter in the food chain, with associated human exposure. In the present study, we used a newly developed steady-state plant uptake model with added phloem transport to predict the uptake of four EOCs (carbamazepine, ibuprofen, ketoprofen and naproxen) into three varieties of lettuce. Input data were derived from an experimental study with vegetables grown in greenhouse and irrigated with TWW spiked with CBZ at 0, 30, 60, 120 and 210 µg/L in each variety of lettuce. Predicted carbamazepine concentrations in leaves were on average 82% higher than in roots, with good agreement between measured and calculated data. We subsequently predicted the uptake of anti-inflammatory compounds ibuprofen, ketoprofen and naproxen, for which the chemical analysis could not provide concentrations above detection limit. These three substances are weak acids and predicted concentrations in roots were higher than in the edible leaves, mainly due to phloem transport downwards. The daily dietary intake of all four EOCs was estimated for consumption of leafy vegetables, being far below usual therapeutic doses.

Long-term, low technicality sewage sludge amendment and irrigation with treated wastewater under Mediterranean climate: impact on agronomical soil quality.

We evaluated the agronomic quality of loam to clay-loam soils from a Mediterranean area, which have been submitted for more than 10 years to irregular and poorly controlled treated wastewater (TWW) irrigation and sewage sludge (SS) amendment, both TWW and SS issuing from a domestic effluent treatment plant. A soil was submitted to SS amendment only, another to TWW irrigation only, another to both treatments, and another was not submitted to any of these treatments. We found that the agronomic quality of the treated soils has not decreased. In treated soils, it was observed a slight increase of pH, an increase of the cation exchange capacity, and no change of either salinity or electrical conductivity. Sodium adsorption ratio and exchangeable sodium percentage remained satisfactory, below 13 and 15, respectively, and no infiltration problems were observed, indicating that rainwater percolation was sufficient to leach the salt brought by SS or TWW. The soil organic matter (SOM) increased in all SS-amended and/or TWW-irrigated soils, the increase being higher in SS-amended soils. The SOM kept a satisfactory C/N ratio, lower than 15; the SUVA (Specific UV Absorbance) and E2/E3 index showed normal characteristics of the water-extracted organic matter (WEOC). Both SS amendment and TWW irrigation brought high amounts of nutrients in the considered soils and increased the nutrients disponibility, especially regarding K and P, as shown by the nutrient concentrations in the soil water extracts. The pH increase does not seem to be a problem for the bioavailability of trace elements, at least regarding Cu, Zn, Co, and Fe. Complementary studies should be undertaken for Ni. These observations highlight the potential agronomical benefits of application of wastewater and sewage sludge, even without great technicality, the better results being obtained using both SS amendment and TWW irrigation.

Land Use Change Assessment and Water Quality of Ephemeral Ponds for Irrigation in the North West Province, South Africa.

In the semi-arid environments of the North West province of South Africa the amount, timing, and distribution of rainfall is irregular, while water accessibility is a key factor in production. In line with this, a study was conducted to assess the impact of land use change on water quality and water depth within the sub-catchment areas of ephemeral ponds. To determine land use dynamics, 2004 and 2013 Landsat images were classified using maximum likelihood algorithm. Pond water quality was analysed for physical, chemical, and microbiological parameters using standard the American Public Health Association (APHA) methods. Multiple linear regression models were computed to determine relationships between land use changes and water quality parameters. Results revealed a reduction in grass cover, whereas built-up areas increased at the expense of bare land. All the values for the physical characteristics were higher than the recommended Department of Water Affairs (DWAF) and Food and Agriculture Organisation (FAO) limits, but chemical parameters, except cadmium, were within limits. Regression showed that bare areas have a positive effect on Escherichia coli (E. coli) in ephemeral pond water. The study highlights the suitability of pond water for irrigation to increase crop production and the effects of land use changes on ecosystems as critical for proper catchment planning, water resource management, and food security.

Hydrochemical characteristics and quality assessment of groundwater for irrigation use in central and eastern Songnen Plain, Northeast China.

The hydrochemical characteristics of groundwater in Songnen Plain's agricultural area were analyzed based on aquifer types and topography classification to evaluate irrigation suitability and factors influencing groundwater quality. Samples of different groundwater types and topographical conditions within the research area were collected and chemical indices, such as sodium adsorption ratio, %Na+, residual sodium carbonate, and magnesium hazard values, were calculated to assess the groundwater suitability for irrigation. The results indicated that groundwater was generally neutral, with low total dissolved solids and slightly high hardness; the dominant anion in groundwater was HCO3-, while Ca2+ was the relatively stable primary cation found in water samples from the high plain and river valley plain. The nitrate in groundwater significantly exceeded WHO drinking water standards, especially in the unconfined water of the high plain, which was due to the large-scale agricultural production activities in the eastern regions. The main reactions in the groundwater system were weathering and dissolution of carbonates and sulfates and ion-exchange reactions. Horizontal zoning in water chemical characteristics was prominent; from the high plain to river valley plain and low plain, the hydrochemistry gradually transitioned from HCO3-Ca-Na to HCO3-Na-Ca and HCO3-Na. Based on the chemical indices, the majority of samples were suitable for agricultural irrigation except for some in the western area with high salinity and sodium hazards. Treatment measures to groundwater and soil should be taken to reduce the possibility of soil salinization and promote crop growth in these latter regions.

Analysis of the nexus between population, water resources and Global Food Security highlights significance of governance and research investments and policy priorities.

BACKGROUND: Analyses of sensitivity of Global Food Security (FS) score to a key set of supply or demand factors often suggest population and water supply as being the most critical and on which policies tend to focus. To explore other policy options, we characterized the nexus between GFS and a set of supply or demand factors including population, agricultural and industrial water uses, agricultural publications (as a surrogate for investment in agricultural research and development (R&D)) and corruption perception index (CPI), to reveal opportunities for attaining enduring GFS. RESULTS: We found that despite being the primary driver of demand for food, population showed no significant correlation with FS scores. Similarly, agricultural water use was poorly correlated with GFS scores, except in countries where evaporation exceeds precipitation and irrigation is significant. However, FS had a strong positive association with industrial water use as a surrogate for overall industrialization. Recent expansions in cultivated land area failed to yield concomitant improvements in FS score since such expansions have been mostly into marginal lands with low productivity and thus barely compensated for lands retired from cropping in several developed economies. However, FS was positively associated with agricultural R&D investments, as it was with the CPI scores. The apparent and relative strengths of these drivers on FS outcome amongst countries were in the order: industrial water-use ≈ publication rate ≈ corruption perception ≫ agricultural water use > population. CONCLUSIONS: We suggest that to enshrine enduring food security, policies should prioritize (1) increased R&D investments that address farmer needs and (2) governance mechanisms that promote accountability in both research and production value chains. © 2018 Society of Chemical Industry.

Assessment and modeling of groundwater quality using WQI and GIS in Upper Egypt area.

The continuous growth and development of population need more fresh water for drinking, irrigation, and domestic in arid countries like Egypt. Evaluation the quality of groundwater is an essential study to ensure its suitability for different purposes. In this study, 812 groundwater samples were taken within the middle area of Upper Egypt (Sohag Governorate) to assess the quality of groundwater for drinking and irrigation purposes. Eleven water parameters were analyzed at each groundwater sample (Na+, K+, Ca2+, Mg2+, HCO3 - SO4 2-, Fe2+, Mn2+, Cl-, electrical conductivity, and pH) to exploit them in water quality evaluation. A classical statistics were applied for the raw data to examine the distribution of physicochemical parameters in the investigated area. The relationship between groundwater parameters was tested using the correlation coefficient where a strong relationship was found between several water parameters such as Ca2+ and Cl-. Water quality index (WQI) is a mathematical model used to transform many water parameters into a single indicator value which represents the water quality level. Results of WQI showed that 20% of groundwater samples are excellent, 75% are good for drinking, and 7% are very poor water while only 1% of samples are unsuitable for drinking. To test the suitability of groundwater for irrigation, three indices are used; they are sodium adsorption ration (SAR), sodium percentage (Na%), and permeability index (PI). For irrigation suitability, the study proved that most sampling sites are suitable while less than 3% are unsuitable for irrigation. The spatial distribution of the estimated values of WQI, SAR, Na%, PI, and each groundwater parameter was spatially modeled using GIS.

Estimation of sodium adsorption ratio indicator using data mining methods: a case study in Urmia Lake basin, Iran.

Water quality is a major concern around the world, particularly in dry climates. Usually, assessment of surface water quality is costly and time-consuming. In this situation, a method which could estimate the water quality accurately with the minimum of hydro-chemical parameters would be appealing. In this study, three data mining methods, namely, M5 model tree, support vector machine (SVM), and Gaussian process (GP), were employed to estimate the sodium adsorption ratio (SAR) indicator in the Shahrchay River located in the west of the Urmia Lake basin, Iran. Results from these methods were compared with an artificial neural network (ANN). Different hydro-chemical parameters were assessed and the most effective parameters were selected. Five combinations of the selected parameters were developed as input parameters to the models. The results indicated that the M5 model tree has a superior performance among the data mining methods, where the combination of sodium and electrical conductivity (Na and EC) is used as input parameters, with a coefficient of determination (R2) = 0.987, root mean squared error (RMSE) = 0.017, mean absolute error (MAE) = 0.012, and mean relative error (MRE) = 5.584. Also, a sensitivity analysis was carried out which reported that the SAR is more sensitive to Na, Ca, and EC, respectively. This research highlights that the M5 model tree can be successfully employed for the estimation of SAR. It also indicates that the practical and simple linear equations and optimization performed with the M5 model tree reduce time and cost.

A risk-based approach for developing standards for irrigation with reclaimed water.

A generalised quantitative risk assessment (QRA) is developed to assess the potential harm to human health resulting from irrigation with reclaimed water. The QRA is conducted as a backward calculation starting from a pre-defined acceptable risk level at the receptor point (defined as an annual infection risk of 10-4 for pathogens and by reference doses (RfD) for chemical hazards) and results in an estimate of the corresponding acceptable concentration levels of the given hazards in the effluent. In this way the QRA is designed to inform the level of water treatment required to achieve an acceptable risk level and help establish reclaimed water quality standards. The QRA considers the exposure of human receptors to microbial and chemical hazards in the effluent through various exposure pathways and routes depending on the specific irrigation scenario. By considering multiple pathways and routes, a number of key aspects relevant to estimating human exposure to recycled water can be accounted for, including irrigation and crop handling practices (e.g., non-edible vs edible, spray vs. drip, withholding time) and volumes consumed (directly vs indirectly). The QRA relies on a large number of inputs, many of which were found to be highly uncertain. A possibilistic approach, based on fuzzy set theory, was used to propagate the uncertain input values through the QRA model to estimate the possible range of hazard concentrations that are deemed acceptable/safe for reclaimed water irrigation. Two scenarios were considered: amenity irrigation and irrigation of ready-to-eat food crops, and calculations were carried out for six example hazards (norovirus, Cryptosporidium, cadmium, lead, PCB118 and naphthalene) and using UK-specific input values. The human health risks associated with using reclaimed water for amenity irrigation were overall deemed low, i.e. the calculated acceptable concentration levels for most of the selected hazards were generally far greater than levels typically measured in effluent from wastewater treatment plants; however the predicted acceptable concentration levels for norovirus and Cryptosporidium suggested that disinfection by UV may be required before use. It was found that stricter concentration standards were required for hazards that are more strongly bound to soil and/or are more toxic/infectious. It was also found that measures that reduce the amount of effluent directly ingested by the receptor would significantly reduce the risks (by up to 2 orders of magnitude for the two pathogens). The results for the food crop irrigation scenario showed that stricter concentration standards are required to ensure the effluent is safe to use. For pathogens, the dominant exposure route was found to be ingestion of effluent captured on the surface of the crops indicating that risks could be significantly reduced by restricting irrigation to the non-edible parts of the crop. The results also showed that the exposure to some organic compounds and heavy metals through plant uptake and attached soil particles could be high and possibly pose unacceptable risk to human health. For both scenarios, we show that the predicted acceptable concentration levels are associated with large uncertainty and discuss the implications this has for defining quality standards and how the uncertainty can be reduced.