Wastewater Reuse For Irrigation Research Articles

Applying Quantitative Microbial Risk Assessment Model in Developing Appropriate Standards for Irrigation Water.

This study aimed to apply a quantitative microbial risk assessment (QMRA) model to estimate the annual risk probability of Salmonella infection associated with the consumption of crops, which were irrigated with raw wastewater abstracted by farmers without official permission. Data generated from the model were used to propose realistic standards for Salmonella in irrigation water needed for safe crop production. Results demonstrated the presence of total coliforms, fecal coliforms, fecal streptococci, and Salmonella in wastewater samples. Salmonella was recorded on lettuce and spinach in 3 different harvesting events, although it was not found in data obtained for parsley plant. The QMRA scenario included surface irrigation, consumption of raw crops, and 1-day withholding period before harvest. The annual risk probability of Salmonella infection for consumers exceeded the target tolerable risk (7.7 × 10-4 ) for investigated crops. The Pearson's correlation coefficient between different annual risk probabilities showed significant correlation (p < 0.05). The levels of risk posed from spinach and lettuce were roughly similar, although they tended to be higher for lettuce. The optimum concentrations of Salmonella in irrigation water needed to satisfy the World Health Organization guidelines of disease burden (disability-adjusted life years 10-6 ) per person per year ranged from 34 to 119 via multiple-tube fermentation technique/100 mL, for spinach and lettuce plants, respectively. The study concluded that unofficial reuse of wastewater in irrigation is a principle route for crop contamination. Water quality monitoring programs should be integrated with QMRA investigations for better estimation of risk level. The fit parameters used could be tailored to cover a wide array of local situations in different countries. Models applied for viruses, helminths, and bacteria other than Salmonella are encouraged in future studies. Integr Environ Assess Manag 2020;16:353-361. © 2019 SETAC.

Assessment of suspended growth biological process for treatment and reuse of mixed wastewater for irrigation of edible crops under hydroponic conditions

Due to the increasing freshwater deterioration and demand for irrigation, there is pressing need to reclaim and reuse wastewater for agricultural operations. While this practice is gaining significant traction in developed world, it is quite rare in most developing countries with inadequate or no functional sewerage facilities and treatment systems at both municipal and industrial levels occasioned by high investment and operational costs. Consequently, wastewaters generated are in complex heterogenous mix of industrial, domestic, municipal and agricultural runoff wastewater. Biological technologies which utilize the expertise of microorganisms are considered robust, efficient and economically attractive for treatment of wide range of wastewaters and they have high suitability in developing countries. This work therefore assessed the potential of suspended growth biological process (SGBP) for reclamation and reuse of mixed wastewater composed a mixture of domestic effluent, pharmaceutical, textile, petroleum discharges and agricultural runoff for irrigation of edible crops (lettuce and beets) with plants phenological parameters as measuring indicators. The germination and phenological characteristics of crops were studied in a hydroponic unit under four irrigation regimes: tap water as control, mixed wastewater, SGBP treated wastewater, and tap water mixed with nutrient solution as upper control, for a duration of 45-d. The results proved that the SGBP treated wastewater had no negative impact on germination responses of the seed crops. However, residual recalcitrant compounds caused early stunted growth in plant root systems with resultant limited access to nutrients. Consequently, plant vegetative growth and phenological development as well as chlorophyll production were reduced. In comparison to nutrients supplemented solution, nutrients deficiency and imbalance in treated wastewater contributed to the poor development in irrigated plants. The outcomes of seed germination and plant growth experiments show a positive indication for reuse of mixed wastewater in agriculture. However, there is need for further research to explore the long-term benefits and limitations of reusing such treated wastewater.

Occurrence and human health risk assessment of pharmaceuticals and personal care products in real agricultural systems with long-term reclaimed wastewater irrigation in Beijing, China.

Reclaimed wastewater (RW) is increasingly used to irrigate agricultural land and to alleviate agricultural water shortages worldwide. This usage has resulted in concerns about soil contamination by pharmaceuticals and personal care products (PPCPs) and the human health risks associated with dietary crop intake. In this study, we systematically analysed the occurrence and accumulation of 11 PPCPs and one active metabolite in soils and various crops (cucumber, eggplant, long bean and wheat) from realistic RW irrigation fields with different irrigation histories (20, 30 and 40 years) in Beijing and evaluated the human health risks associated with the consumption of these crops. The 11 PPCPs and one active metabolite were detected at concentrations ranging from 0.67 to 22.92ngL-1 in RW, 0.029-28.13μgkg-1 in irrigated soil, and <0.01-28.01μgkg-1 in crops. The concentrations of N4-acetyl-sulfamethoxazole and triclosan were higher than those of other PPCPs, with respective concentrations of 14.39-31.44ngL-1 and 15.93-26.23ngL-1 in RW, 10.92-23.29μgkg-1 and 20.22-28.13μgkg-1 in irrigated soil and 17.92-28.01μgkg-1 and 8.92-14.91μgkg-1 in crops. However, the estimated threshold of toxicological concern (TTC) and hazard quotient (HQ) values revealed that the concentrations of N4-acetyl-sulfamethoxazole and triclosan in crops irrigated with RW should be considered a de minimis risk to human health. The concentrations of 11 PPCPs and one active metabolite in soils and crops and the calculated fruit bioconcentration factors (BCFs) did not display obvious increases associated with the duration of RW irrigation in real agricultural systems (P>0.05). The concentrations of the studied PPCPs in the RW used for irrigation followed different patterns from the concentrations detected in the irrigated soils and crops. Although the concentrations of sulfamethoxazole, sulfisoxazole, sulfamethazine and trimethoprim in RW were higher than those of many other studied PPCPs, their respective values in the irrigated soils and crops did not display a similar tendency. The uptake and accumulation of PPCPs varied among the crop species (P<0.05). Although PPCPs were detected in eggplant, long bean and wheat (BCFs: not applicable-1.67, 0.03-1.35 and 0.01-5.01, respectively), PPCPs accumulated at increased levels in cucumber (BCFs 0.03-18.98). The estimated TTC and HQ values showed that the consumption of crops irrigated long-term with RW presents a de minimis risk to human health. However, further studies with more PPCPs and additional crop species need to be conducted, the synergistic effects of chemical mixtures of multiple PPCPs and the toxic effects of PPCP metabolites should be elucidated to obtain more reliable information on the safety of wastewater reuse for irrigation.

Wastewater reuse in Jordan and its potential as an adaptation measure to climate change

Reclaiming wastewater for reuse in agriculture is increasingly adopted by many countries around the globe. This is particularly true for Jordan, which is characterised as a water-scarce country where the per-capita share from renewable water resources is less than 100 (m3/capita)/year. The Third National Jordanian Communication report on climate change has estimated a significant decrease in precipitation of 1·2 mm/year and an increase in the mean air temperature by 0·02°C/year, which will be adversely reflected on the water resources potential. To bridge the gap between water resources, supply potential and the demand, Jordan utilises non-conventional water resources, such as wastewater reuse in irrigation, where agriculture accounted for 52% of the water use in the country in 2017. The main objective of the present paper is to update the Jordanian experience in wastewater reuse and to explore its potential as an adaptive measure to climate change. The analysis revealed that 92% of the treated wastewater has been reused either directly or indirectly, mainly for irrigation. Treated wastewater can be considered as an adaptation measure to climate change that is capable of reducing the deficit between demand and water resource potential up to 48% by the year 2025.

Investigation of chlorine tolerance profile of dominant gram negative bacteria recovered from secondary treated wastewater in Jaipur, India

Management of bacterial survival post chlorine disinfection is vital for safe wastewater reuse for irrigation, as the presence of microorganisms in large numbers may lead to subsequent contamination of the surface and ground water reservoirs. Even after satisfying the current norms of coliform counts after disinfection (less than 1000 MPN per 100 mL), chlorine tolerant bacteria surviving in inadequately treated wastewater may pose a public health threat as many of these bacteria are able to re-grow upon storage. The current study is aimed to assess the magnitude of the problem posed by chlorine tolerant bacteria during chlorine disinfection and attempts to derive a strategy for safe disinfection. The chlorine tolerance was examined in the dominant gram negative bacteria (GNB) recovered from secondary treated sewage from a treatment plant located at Jaipur, India. Bacterial survival and re-growth (after 24 h) studies on test species (n = 11) with reference to E.coli ATCC 25922 reveal that, while the lethal doses of isolates ranged from 0.5 to 1.25 mgL−1,the chlorine doses for complete inhibition of re-growth were much higher (0.75–1.75 mgL−1).The isolates showing highest lethal dose and re-growth inhibition dose, identified as Citrobacter freundii, Klebsiella sp. and Stenotrophomonas maltophilia also exhibited very low log effective reduction (0.72–1.90) values and were selected as chlorine tolerant bacteria. Results of inactivation kinetics experiments on chlorine tolerant bacteria reveal a strong correlation (R2 > 0.89–0.99) between log reduction values and contact time. In re-growth kinetics experiments, maximum re-growth was observed after 6 h exposure following which, only marginal increase was registered up to 24 h. The study indicates that the existing approach of bacterial elimination post chlorine treatment may be grossly inadequate to assess the performance of the disinfection process adopted for drinking water treatment. It further brings out a novel approach to arrive at meaningful chlorine doses that take bacterial re-growth into account for achieving safe disinfection.

Design of a bioaugmented multistage biofilter for accelerated municipal wastewater treatment and deactivation of pathogenic microorganisms

Biological treatment of municipal wastewater for reuse in irrigation is highly required, especially with the current global financial and water shortage crises. Bioaugmentation is a simple and cost-effective technology which could be a useful tool in alleviating this challenge. Thus, this study aimed to enhance the biological treatment of municipal wastewater using a bioaugmented substance supplemented in a three-stages bio-filter consisting of a sedimentation step followed by gravel biofiltration and then sand biofiltration at a laboratory scale. Also, a toxicity assay, the antimicrobial effect of the bioaugmented substance against pathogenic microorganisms, and identification of the synergistic effect of the bacterial consortium involved in the bioaugmented substance were studied. The bioaugmented substance was nontoxic and had an antimicrobial effect against the tested potentially pathogenic microorganisms (Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, and Candida albicans). The minimum effective concentration of the bioaugmented substance for organic, inorganic and microbial pollutants removal from high strength wastewater was 2.5 ppm with a contact time of 6–8 h. The removal efficiencies of H2S, COD, BOD5, total solids (TS), total dissolved solids, total suspended solids, ammonia, nitrate, phosphorus, and oil and grease reached 85, 93.4, 83.5, 37, 49.2, 93.4, 100, 55.7, 76.6 and 76.6%, respectively in the treated effluent after sand biofiltration. The physicochemical parameters of the treated wastewater effluent were below the Egyptian recommended limits (Law 84/1984) for use in irrigation. However, COD and BOD values were 90.33 and 38.46 mgO2/L, respectively, and were still above the regulations (COD ≤60 and BOD ≤20). The high fecal coliforms count in the wastewater influent (8.4 × 108 MPN-index/100 mL) were 95.1% removed after the sedimentation stage, and 99.99% removal was achieved after gravel and sand biofiltration. Thus, this study successfully designed a bioaugmented multistage biofiltration system for the effective removal of pollutants from wastewater, especially in resource-limited areas.

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).

A Review on the Current Knowledge and Prospects for the Development of Improved Detection Methods for Soil-Transmitted Helminth Ova for the Safe Reuse of Wastewater and Mitigation of Public Health Risks

Climate change, increase in population and scarcity of freshwater have led to a global demand for wastewater reuse in irrigation. However, wastewater has to be treated in order to minimize the presence of pathogens, in particular, the ova of soil-transmitted helminthes (STHs). Limiting the transmission via removal of STH ova, accurate assessment of risks and minimizing the exposure to the public have been recommended by health regulators. The World Health Organization (WHO) guideline specifies a limit of ≤1 ova/L for safe wastewater reuse. Additionally, the Australian Guidelines for Water recycling (AGWR) recommend a hydraulic retention time of over 25 days in a lagoon or stabilization pond to ensure a 4 log reduction value of helminth ova and to mitigate soil-transmitted helminths associated risks to humans. However, the lack of fast and sensitive methods for assessing the concentration of STH ova in wastewater poses a considerable challenge for an accurate risk assessment. Consequently, it has been difficult to control soil-transmitted helminthiasis despite effective mass drug administration. This limitation can be overcome with the advent of novel techniques for the detection of helminth ova. Therefore, this review presents an assessment of the current methods to detect the viable ova of soil-transmitted helminths in wastewater. Furthermore, the review focuses on the perspectives for the emerging state-of-the-art research and developments that have the potential to replace currently available conventional and polymerase chain reaction based methods and achieve the guidelines of the WHO in order to allow the safe reuse of wastewater for non-potable applications, thereby minimizing public health risks.

Interpreting Farmers’ Perceptions of Risks and Benefits Concerning Wastewater Reuse for Irrigation: A Case Study in Emilia-Romagna (Italy)

Water recycling is becoming progressively more important as the need for Integrated Urban Water Management (IUWM) is increasing to ensure a transition towards a more sustainable use for water. Perceptions and public acceptance of water reuse are recognised as paramount factors for the successful introduction of wastewater reuse projects, regardless of the strength of scientific evidence in their favour. This article analyses perceptions of risks and benefits of using treated wastewater for irrigation purposes in agriculture when dealing with different crops. Data from an original farmer survey are analysed through descriptive statistics and a classification tree approach. The study reveals limited knowledge of wastewater treatment, yet a good level of openness towards the reuse of wastewater for irrigation. A lower risk perception and a higher acceptance level are mainly explained by positive expectations with regard to the environmental characteristics of effluent water, higher education, and specific cropping choices. Enhancing information availability is also found to positively affect social acceptance. The ease of converting current water-management practices to the new water source explains the perceived benefits of reusing water.

Potential transmission sources of Helicobacter pylori infection: detection of H. pylori in various environmental samples

Helicobacter pylori is one of the most common human infectious agents which may be transmitted via water. This study was designed to test H. pylori presence via molecular methods in various aquatic environments as well as sewage sludge (SS) to understand the role of these environments in the pathogen's transmission. specific primers for the 16S rRNA and ureA genes of H. pylori were used in a nested and semi-nested PCR, respectively. Detection sensitivity of H. pylori in environmental samples by semi-nested PCR was also compared with real-time PCR. Analysis of fecal coliforms (FC) as pollution indicator bacteria was also performed. H. pylori 16S rRNA gene was detected in 36% (14/39) of wastewater samples and 8% (2/25) of water samples, while amplification of ureA gene yielded only two positive results. None of the SS samples were positive for H. pylori and real-time PCR could not identify H. pylori in any of the samples. The results showed no correlation between the presence of H. pylori and FC. Our result revealed the widespread presence of H. pylori in wastewater samples which indicates wastewater may be a source for dissemination and transmission of H. pylori infection. Further research is needed to determine the risk of H. pylori in wastewater reuse for irrigation of crops.

Atacama Desert: water resources and reuse of municipal wastewater in irrigation of cut flower aeroponic cultivation system (first laboratory experiments)

Atacama Desert: water resources and reuse of municipal wastewater in irrigation of cut flower aeroponic cultivation system (first laboratory experiments)

Accumulation of trace elements by corn (Zea mays) under irrigation with treated wastewater using different irrigation methods

Treated wastewater reuse for irrigation has gained a greater significance as an alternative resource to meet the growing water demands for agriculture and reduce the pressure on limited existing fresh water. However, this reuse needs adapted management in order to avoid environmental and health risks. An experiment was conducted in a greenhouse to evaluate the effect of different irrigation methods on the Metallic Trace elements and metals concentrations of a Tunisian soil (pH = 8.6) and corn when using treated wastewater. Four irrigation methods: surface irrigation, sprinkler irrigation, drip irrigation and subsurface drip irrigation, and two water qualities were used: treated wastewater and fresh water. Samples of soil and corn were analyzed for several Metallic Trace elements. Results for soil showed that treated wastewater increased electrical conductivity, nutrients and metallic trace elements. The highest levels of salinity and Metallic Trace elements were recorded with using surface irrigation and the lowest were noticed by using subsurface drip irrigation. Whereas the highest levels of nutrients elements were recorded by using subsurface drip irrigation. Results for corn showed that irrigation with treated wastewater improved corn biomass, increased nutrient elements, nitrate reductase activity and chlorophyll content. The concentrations of Metallic Trace elements in different parts of corn were significantly higher under treated wastewater irrigation than fresh water irrigation and were reduced in case of subsurface drip irrigation. Among studied metals, Nickel concentration exceeded the permissible limits of 10 mg kg−1. Bio-concentration factor values were, in order, Iron > Zinc > Nickel > Copper > lead > Cadmium, whereas, translocation factor values were, in order, Copper > Zinc > Cadmium > iron > lead > Nickel. Because of translocation factor < 1 and bio-concentration factor ≥ 0.2, maize could be considered as both an excluder and an accumulator plant. Results of this study indicate that the use of subsurface drip irrigation decreased the amount of soil and corn contamination by Metallic Trace elements.

Effect of Irrigation Using Diluted Winery Wastewater on the Chemical Status of a Sandy Alluvial Soil, With Particular Reference to Potassium and Sodium

The re-use of winery wastewater for irrigation was investigated in a field trial with micro-sprinklerirrigated Cabernet Sauvignon/99 Richter in the Breede River Valley region of South Africa. Irrigation with winery wastewater diluted with river water to 100, 250, 500, 1 000, 1 500, 2 000, 2 500 and 3 000 mg/L chemical oxygen demand (COD) was compared to irrigation with river water. No trends were found in soil pH(KCl) and electrical conductivity of the saturated soil extract (ECe ) that were related to the different levels of dilution. However, ECe was considerably higher after the application of diluted winery wastewater irrigations compared to ECe at bud break. This suggests an accumulation of salts from the diluted winery wastewater. Under the prevailing conditions, soil K+ and Na+ increased with a decrease in the dilution of the winery wastewater. Increases in K+ could have a negative impact on wine colour stability should potassium be taken up by the grapevine in sufficient quantities, particularly if soil K+ accumulates to such an extent that it is luxuriously absorbed by grapevines. There were no consistent trends with regard to soil organic C, which indicates that there was too little organic material in the wastewater to have had a positive effect on soil fertility. Furthermore, organic material in the wastewater probably oxidised when the soil was aerated between irrigations. Although irrigation with diluted winery wastewater had almost no other effects, element accumulation, particularly with respect to K+ and Na+, might be more prominent in heavier soils or in regions with low winter rainfall.

Application of metallurgical slag to treat geothermal wastewater with high concentrations of arsenic and boron

The reuse of geothermal wastewater for irrigation is an attractive alternative for supplying water demand in agriculture, due to the high volumes generated in geothermal plants. This application is limited by the presence of toxic semimetals such as arsenic and boron, which generally require high-cost commercial adsorbents for removal. This work studies the removal mechanism and process optimization of arsenic and boron, present in high concentrations in synthetic solutions and in geothermal wastewater, using metallurgical slags. The effect of pH, initial concentration of arsenic and boron and slag dose were investigated using a 33 factorial experimental design and response surface method to optimize the operating conditions of the removal of pollutants. Scanning electron microscope analysis showed that the removal mechanism consisted in a dissolution–precipitation reaction rather than adsorption. The effluent produced from wastewater at the optimal operating conditions in a two-step process meets the criteria proposed for both metalloids by the US Environmental Protection Agency for water used for irrigation.

Wetlands for wastewater treatment and subsequent recycling of treated effluent: a review

Due to water scarcity challenges around the world, it is essential to think about non-conventional water resources to address the increased demand in clean freshwater. Environmental and public health problems may result from insufficient provision of sanitation and wastewater disposal facilities. Because of this, wastewater treatment and recycling methods will be vital to provide sufficient freshwater in the coming decades, since water resources are limited and more than 70% of water are consumed for irrigation purposes. Therefore, the application of treated wastewater for agricultural irrigation has much potential, especially when incorporating the reuse of nutrients like nitrogen and phosphorous, which are essential for plant production. Among the current treatment technologies applied in urban wastewater reuse for irrigation, wetlands were concluded to be the one of the most suitable ones in terms of pollutant removal and have advantages due to both low maintenance costs and required energy. Wetland behavior and efficiency concerning wastewater treatment is mainly linked to macrophyte composition, substrate, hydrology, surface loading rate, influent feeding mode, microorganism availability, and temperature. Constructed wetlands are very effective in removing organics and suspended solids, whereas the removal of nitrogen is relatively low, but could be improved by using a combination of various types of constructed wetlands meeting the irrigation reuse standards. The removal of phosphorus is usually low, unless special media with high sorption capacity are used. Pathogen removal from wetland effluent to meet irrigation reuse standards is a challenge unless supplementary lagoons or hybrid wetland systems are used.

Integrated technological and management solutions for wastewater treatment and efficient agricultural reuse in Egypt, Morocco, and Tunisia.

Mediterranean-African countries (MACs) face a major water crisis. The annual renewable water resources are close to the 500 m3 /capita threshold of absolute water scarcity, and water withdrawals exceed total renewable water resources by 30%. Such a low water availability curbs economic development in agriculture, which accounts for 86% of freshwater consumption. The analysis of the current situation of wastewater treatment, irrigation, and water management in MACs and of the research projects targeted to these countries indicates the need for 1) an enhanced capacity to analyze water stress, 2) the development of water management strategies capable of including wastewater reuse, and 3) development of locally adapted water treatment and irrigation technologies. This analysis shaped the MADFORWATER project (www.madforwater.eu), whose goal is to develop a set of integrated technological and management solutions to enhance wastewater treatment, wastewater reuse for irrigation, and water efficiency in agriculture in Egypt, Morocco, and Tunisia. MADFORWATER develops and adapts technologies for the production of irrigation-quality water from drainage canals and municipal, agro-industrial, and industrial wastewaters and technologies for water efficiency and reuse in agriculture, initially validated at laboratory scale, to 3 hydrological basins in the selected MACs. Selected technologies will be further adapted and validated in 4 demonstration plants of integrated wastewater treatment and reuse. Integrated strategies for wastewater treatment and reuse targeted to the selected basins are developed, and guidelines for the development of integrated water management strategies in other basins of the 3 target MACs will be produced. The social and technical suitability of the developed technologies and nontechnological tools in relation to the local context is evaluated with the participation of MAC stakeholders and partners. Guidelines on economic instruments and policies for the effective implementation of the proposed water management solutions in the target MACs will be developed. Integr Environ Assess Manag 2018;14:447-462. © 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Agro-industrial wastewater reuse for irrigation of a vegetable crop succession under Mediterranean conditions

In many countries of the Mediterranean region, characterized by frequent drought periods, agricultural production often occurs under water deficiency or conditions that cause the depletion of the existing water resources. In these areas, the reuse of reclaimed wastewater for crop irrigation could contribute to mitigate/decrease water shortage, support the agriculture sector and protect groundwater resources. In 1.5-year field experiments in Southern Italy (Apulia Region), the effects of irrigation with treated agro-industrial wastewater on soil properties, crops yield and qualitative traits of crop products, including their microbiological safety, were assessed. Groundwater (GW), secondary treated wastewater (SW) and tertiary treated wastewater (TW) from an innovative “on-demand” UV disinfection system were used to irrigate tomato and broccoli, cultivated in succession. The three irrigation water sources and the corresponding irrigated soils, plants and crop products were analyzed for the main physico-chemical characteristics, quali-quantitative parameters and fecal indicators. SW and TW showed higher values of the main physico-chemical parameters than GW. SW irrigated soil resulted in a significant increase of NH4-N, Na+, SAR, EC (below the threshold value beyond which a soil is defined as saline) during the first tomato crop cycle, and of pH during the broccoli growing season. Irrigation with treated wastewater did not significantly affect the marketable yield nor the qualitative traits of tomato and broccoli crops, except for the Na+ and NO3− content (below the threshold levels defined by the European guidelines for vegetables). High levels of E. coli (above the Italian limit for reuse), Fecal coliforms and Fecal enterococci (up to 104 CFU 100ml−1) were observed in the SW and, when chlorination was not done, in the TW. Nevertheless, E. coli was not isolated from any sample of soil, plant and crop product, probably due to its rapid die-off. Moreover, low concentrations of Fecal coliforms and Total heterotrophic count were found in plant and crop product. The drip irrigation system used, which avoided the close contact between water and plant, may have contributed to this. Under the conditions applied in this study, the reuse of treated agro-industrial wastewater for irrigation can be considered an effective way to cope with agricultural water shortage in the Mediterranean area.

Impact of the reusing of food manufacturing wastewater for irrigation in a closed system on the microbiological quality of the food crops

In order to evaluate if the reuse of food industry treated wastewater is compatible for irrigation of food crops, without increased health risk, in the present study a cropping system, in which ground water and treated wastewater were used for irrigation of tomato and broccoli, during consecutive crop seasons was monitored. Water, crop environment and final products were monitored for microbial indicators and pathogenic bacteria, by conventional and molecular methods. The microbial quality of the irrigation waters influenced sporadically the presence of microbial indicators in soil. No water sample was found positive for pathogenic bacteria, independently from the source. Salmonella spp. and Listeria monocytogenes were detected in soil samples, independently from the irrigation water source. No pathogen was found to contaminate tomato plants, while Listeria monocytogenes and E. coli O157:H7 were detected on broccoli plant, but when final produce were harvested, no pathogen was detected on edible part.The level of microbial indicators and detection of pathogenic bacteria in field and plant was not dependent upon wastewater used. Our results, suggest that reuse of food industry wastewater for irrigation of agricultural crop can be applied without significant increase of potential health risk related to microbial quality.

Supply chain analysis for cassava starch production: Cleaner production opportunities and benefits

This research assesses resource efficiency and the loss through the processes of the cassava starch production supply chain in order to find opportunities to improve resource use efficiency, reduce loss and recover resources from waste. The case study was conducted at a cassava starch company in the north of Thailand. The starch supply chain includes cassava cultivation, cassava root transport and processing of cassava starch.In the base case, 25,000 tonne of freshwater was used to produce 1000 tonne of cassava starch. Water consumption in the extraction process accounted for over 60% of freshwater use in the supply chain. The extraction and separation processes were the main hotspots because they consumed a large amount of water and a large portion of cassava mass including cassava pulp was separated out at these stages. Over 81% of energy was used in the starch plant including hot air (53%) and electricity (28%). Diesel used for crop production and transport accounted for only 6% and 12% respectively. Drying process was the hotspot in terms of energy use; the process used heat accounting for over 68% of the total energy use in the supply chain. Fortunately, hot air produced from biogas covered 100% of the hot air requirement and electricity produced from biogas covered 86% of the electricity demand in the plant.The conventional system of cassava starch production was compared with an improved one incorporating changes in practice of crop production, transport and starch production. In the improved scenario, in crop production, several nutrient management practices were applied along with fertilizer optimization. The starch plant was modified to enhance water recycling and reduce loss in order to reduce cassava root input. Starch loss reduction was achieved in the fiber and pulp separation processes where the largest starch loss occurred. The results showed that the scenario of improved technology and management could reduce consumption of all resources and emissions including cassava roots (4%), fertilizers (50%), water (30%), wastewater (40%) as well as energy (8%). All of the cassava pulp could be recovered to produce ethanol instead of using for feed with some ending up in the landfill in the base case. All wastewater could be reused for irrigation in the cassava farms instead of being evaporated. Moreover, recovering cassava pulp for ethanol production led to positive energy balance and net GHG benefit of 107 t CO2eq/y. Net GHG benefit from wastewater reuse for irrigation in the improve scenario was 3 t CO2eq.

Planning for Integrative Management of Wastewater Disposal, Irrigation Water Supply and Fertilizer Use: A Case Study in an Arid Land of China

This work is a trans-disciplinary undertaking aiming at innovative water management in arid and semi-arid regions. Based on field studies on soil bacterial communities and irrigation water quality in an arid region of China where wastewater has been used for agricultural production decade long, this paper is intended to propose an integrative management scheme combining wastewater reuse in agriculture, wise use of wetlands and fertilizer management as an engine toward achieving sustainable development in arid and semi-arid regions. This study was also designed to address a key but very much neglected question about wastewater reuse in irrigation: does wastewater irrigation lead to reduction of chemical fertilizer use and increase of crop yield? Through a questionnaire, it revealed that there was a misperception among farmers about wastewater, which led to no-reduction or even increase in fertilizer use with wastewater irrigation as compared with river water irrigation. It also showed that crop yield was not increased with wastewater irrigation under the current practice. Besides, it sheds some light on an underreported health concern.