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

Impact of water reuse on agricultural practices and human health

Climate change is altering the habits of the population. Extensive drought periods and overuse of potable water led to significant water shortages in many different places. Therefore, new water sources are necessary for usage in applications where the microbiological and chemical water quality demands are less stringent, as for agriculture. In this study, we planted, germinated, and grew vegetables/fruits (cherry tomato, lettuce, and carrot) using three types of potential waters for irrigation: secondary-treated wastewater, chlorine-treated wastewater, and green wall-treated greywater, to observe potential health risks of foodstuff consumption. In this study the waters and crops were analyzed for three taxonomic groups: bacteria, enteric viruses, and protozoa. Enteric viruses, human Norovirus I (hNoVGI) and Enterovirus (EntV), were detected in tomato and carrots irrigated with secondary-treated and chlorine-treated wastewater, in concentrations as high as 2.63 log genome units (GU)/g. On the other hand, Aichi viruses were detected in lettuce. Bacteria and protozoa remained undetected in all fresh produce although being detected in both types of wastewaters. Fresh produce irrigated with green wall-treated greywater were free from the chosen pathogens. This suggests that green wall-treated greywater may be a valuable option for crop irrigation, directly impacting the cities of the future vision, and the circular and green economy concepts. On the other hand, this work demonstrates that further advancement is still necessary to improve reclaimed water to the point where it no longer constitutes risk of foodborne diseases and to human health.

Concentration of potentially harmful elements (PHEs) in eggplant vegetable (Solanum melongena) irrigated with wastewater: a systematic review and meta-analysis and probabilistic health risk assessment

The main objectives of this study were PHEs concentration meta-analysis (Fe, Zn, Cr, Ni, Cu, Pb, and Cd) in eggplant irrigated by wastewater and the following estimation of non-carcinogenic (n-CR) risk for the consumers based on countries. According to the results, the rank order of PHEs concentration in eggplant was Fe (88.3 mg/kg -dry weight) > Zn (10.1 mg/kg -dry weight) > Pb (3.0 mg/kg -dry weight) > Ni (2.7 mg/kg -dry weight) > Cu (1.1 mg/kg -dry weight) > Cd (0.9 mg/kg -dry weight) > Cr (0.05 mg/kg -dry weight). Moreover, n-CR risk showed that all investigated countries (China, India, Pakistan, Turkey, and Jordan) except for United Arab Emirates (UAE) had a considerable n-CR in both age groups (adults and children).

Listeria monocytogenes in Irrigation Water: An Assessment of Outbreaks, Sources, Prevalence, and Persistence

As more fresh fruits and vegetables are needed to meet the demands of a growing population, growers may need to start depending on more varied sources of water, including environmental, recycled, and reclaimed waters. Some of these sources might be susceptible to contamination with microbial pathogens, such as Listeria monocytogenes. Surveys have found this pathogen in water, soil, vegetation, and farm animal feces around the world. The frequency at which this pathogen is present in water sources is dependent on multiple factors, including the season, surrounding land use, presence of animals, and physicochemical water parameters. Understanding the survival duration of L. monocytogenes in specific water sources is important, but studies are limited concerning this environment and the impact of these highly variable factors. Understanding the pathogen’s ability to remain infectious is key to understanding how L. monocytogenes impacts produce outbreaks and, ultimately, consumers’ health.

Assessing the Effect of Irrigation with Reclaimed Water Using Different Irrigation Techniques on Tomatoes Quality Parameters

As the most important resource for life, water has been a central issue in the international agenda for several decades. Yet, the world’s clean freshwater supply is steadily decreasing due to climate change and extensive agricultural water demand for irrigated lands. Therefore, in addition to rational water use, we should use non-traditional water resources like Reclaimed Wastewater (RW). The present experiment was carried out in China over three years (2017, 2018, and 2019) to study the effects of two types of water qualities (reclaimed wastewater (RW) and clean water (CW)), two types of irrigation methods (Full irrigation (FI) and alternate partial root-zone irrigation (APRI)), and two types of irrigation techniques (Furrow irrigation (FUI) and subsurface drip irrigation (SDI)) on the main tomato fruit quality parameters. The APRI treatments obtained 70% of the FI irrigation water volume. The irrigation treatments of this study were: (1) SDI with APRI; (2) SDI with FI; (3) FUI with APRI; and (4) FUI with FI. These treatments were under RW and CW. Thus, the experiment consisted of eight treatments. The tomato fruit quality parameters studied were vitamin C (VC), total acidity (TA), protein content (PC), and total soluble sugar content (TSS). The results reveal that many measurements under reclaimed water (RW) had the highest values compared with clean water (CW), except in protein content (PC). The vast majority of values measured for PC under CW were slightly greater than the values under RW. Moreover, the results reveal that tomato quality in many measurements under APRI treatments increased compared with FUI. The statistical analysis generally shows that the fruit quality parameters were not significantly (p > 0.05) affected by the interaction between the irrigation treatments. In conclusion, the treatment SDI-APRI under RW can be an efficient irrigation method to reduce the consumption of clean water. Additionally, SDI-APRI offers a safe option because the physical contact between the wastewater, crops, and the farmers is minimized compare with the FUI treatment.

Potential of Flow Cytometric Approaches for Rapid Microbial Detection and Characterization in the Food Industry-A Review

As microbial contamination is persistent within the food and bioindustries and foodborne infections are still a significant cause of death, the detection, monitoring, and characterization of pathogens and spoilage microorganisms are of great importance. However, the current methods do not meet all relevant criteria. They either show (i) inadequate sensitivity, rapidity, and effectiveness; (ii) a high workload and time requirement; or (iii) difficulties in differentiating between viable and non-viable cells. Flow cytometry (FCM) represents an approach to overcome such limitations. Thus, this comprehensive literature review focuses on the potential of FCM and fluorescence in situ hybridization (FISH) for food and bioindustry applications. First, the principles of FCM and FISH and basic staining methods are discussed, and critical areas for microbial contamination, including abiotic and biotic surfaces, water, and air, are characterized. State-of-the-art non-specific FCM and specific FISH approaches are described, and their limitations are highlighted. One such limitation is the use of toxic and mutagenic fluorochromes and probes. Alternative staining and hybridization approaches are presented, along with other strategies to overcome the current challenges. Further research needs are outlined in order to make FCM and FISH even more suitable monitoring and detection tools for food quality and safety and environmental and clinical approaches.

Composting of Olive Mill Pomace, Agro-Industrial Sewage Sludge and Other Residues: Process Monitoring and Agronomic Use of the Resulting Composts

The viability of co-composting of olive mill pomace added to sewage sludge with other organic residues was evaluated and the agronomic use of the final composts was investigated. Two composting piles at different carbon-nitrogen ratios were performed, in which olive mill pomace (OMP), sewage sludge from vegetable processing (SS), fresh residues from artichoke processing residues (AR), and wheat straw (WS) were used. The two composting piles were placed inside a specially built greenhouse and a turning machine pulled by a tractor was used for turning and shredding the organic matrix (every 6 days) during the process. The humidity and temperature of organic matrices have been monitored and controlled during the entire composting process, which lasted 90 days. The process was also monitored to evaluate the microbiological safety of the final compost. The humidity of both piles was always kept just above 50% until the end of the thermophilic phase and the maximum temperature was about 50 °C during the thermophilic phase. The carbon-nitrogen ratio decreased from 21.4 and 28.2, respectively (initial value at day 1 in Pile A and B), to values ranging from 12.9 to 15.1, both composts that originated from the two different piles were microbiologically safe. During a two-year period, the effects of different types of compost on the main qualitative parameters of processing tomato and durum wheat was evaluated. Five fertilization treatments were evaluated for tomato and durum wheat crops: unfertilized control (TR₁); compost A (TR₂); compost B (TR₃); ½ mineral and ½ compost A (TR₄); and mineral fertilizer commonly used for the two crops (TR₅). Concerning the processing tomato yield, TR₅ and TR₄ showed the best results (2.73 and 2.51 kg, respectively). The same trend was observed considering the marketable yield per plant. The only difference was related to the treatments that included the compost (2.32, 1.77, and 1.73 kg/plant for TR₄, TR₃, and TR₂, respectively). As regards the qualitative parameters of tomato, the highest average weight of the fruits was found in the TR₅, TR₄, and TR₃ treatments (respectively, 73.67 g, 70.34 g, and 68.10 g). For durum wheat, only the protein component was differentiated between treatments. Furthermore, wheat grain yield parameters generally increased by combined application of mineral fertilizer and compost.

Treated Wastewater Irrigation—A Review

As the most important resource for life, water has been a central issue on the international agenda for several decades. Yet, the world’s supply of clean freshwater is steadily decreasing due to extensive agricultural demand for irrigated lands. Therefore, water resources should be used with greater efficiency, and the use of non-traditional water resources, such as Treated Wastewater (TW), should be increased. Reusing TW could be an alternative option to increase water resources. Thus, many countries have decided to turn wastewater into an irrigation resource to help meet urban demand and address water shortages. However, because of the nature of that water, there are potential problems associated with its use in irrigation. Some of the major concerns are health hazards, salinity build-up, and toxicity hazards. The objectives of this comprehensive literature review are to illuminate the importance of using TW in irrigation as an alternative freshwater source and to assess the effects of its use on soil fertility and other soil properties, plants, and public health. The literature review reveals that TW reuse has become part of the extension program for boosting water resource utilization. However, the uncontrolled application of such waters has many unfavorable effects on both soils and plants, especially in the long-term. To reduce these unfavorable effects when using TW in irrigation, proper guidelines for wastewater reuse and management should be followed to limit negative effects significantly.

Wild whale faecal samples as a proxy of anthropogenic impact

The occurrence of protozoan parasite, bacterial communities, organic pollutants and heavy metals was investigated in free-ranging species of fin (Balaenoptera physalus, n. 2) and sperm (Physeter macrocephalus, n. 2) whales from the Pelagos Sanctuary, Corsican-Ligurian Provencal Basin (Northern-Western Mediterranean Sea). Out of four faecal samples investigated, two from fin whales and one from sperm whale were found positive to Blastocystis sp. A higher number of sequences related to Synergistetes and Spirochaetae were found in sperm whales if compared with fin whales. Moreover, As, Co and Hg were found exclusively in sperm whale faecal samples, while Pb was found only in fin whale faecal samples. The concentration of both PAH and PCB was always below the limit of detection. This is the first report in which the presence of these opportunistic pathogens, bacteria and chemical pollutants have been investigated in faecal samples of free-ranging whale species and the first record of Blastocystis in fin and sperm whales. Thus, this study may provide baseline data on new anthropozoonotic parasite, bacterial records and heavy metals in free-ranging fin and sperm whales, probably as a result of an increasing anthropogenic activity. This survey calls for more integrated research to perform regular monitoring programs supported by national and/or international authorities responsible for preservation of these still vulnerable and threatened whale species in the Mediterranean Sea.

Water Scarcity and Wastewater Reuse in Crop Irrigation

Due to climate change, two-thirds of mankind will face water scarcity by 2025, while by 2050, global food production must increase by at least 50% to feed 9 billion people. To overcome water scarcity, 15 million m3/day of untreated wastewater is used globally for crop irrigation, polluting the soil with pathogens, heavy metals and excess salts. Since 10% of the global population consumes food from crops irrigated with wastewater, pathogens transmitted through the food chain cause diseases especially in young children and women. In this paper, we discuss the status of water scarcity and the challenges to food security, the reuse of wastewater in agriculture and the possible risks to human and environmental health. The efficiency of different irrigation systems in limiting the risks of wastewater reuse and the latest regulations of the European Commission on effluent recovery are also presented. Hence, we emphasize that irrigation offers real perspectives for large-scale recovery of wastewater, helping to reduce the deficit and conserve water resources, and increasing food safety, with the express mention that investments must be made in wastewater treatment plants and wastewater must be properly treated before recovery, to limit the risks on human health and the environment.

Analysis of Barriers and Opportunities for Reclaimed Wastewater Use for Agriculture in Europe

This paper presents an analysis of the perception regarding reclaimed wastewater reuse in agriculture conducted in the European Union regions. The analysis is based upon a SWOT framework and applies a cluster analysis to reduce the dimension of the responses enabling an assessment of the different perceptions of water reuse. More than one hundred key actors identified among the regions participated in the evaluation of the relevance of aspects identified. The results indicate some groups of countries according to natural conditions (water scarcity) and the strategic role of agriculture as a key factor to determine agent’s perceptions and attitudes. The results indicate that the forthcoming EU regulation of water reuse should focus in the problems of the perceived high cost of reclaimed water for farmers and the sanitary risk perception for irrigated crops by consumers as the critical points for fostering the use of reclaimed water in agriculture and the need for regional implementation of the global regulatory framework.

Risk-Yuck Factor Nexus in Reclaimed Wastewater for Irrigation: Comparing Farmers’ Attitudes and Public Perception

The successes and failures of water reuse schemes are shaped by complex interrelationships between technological, economic, and socio-political factors. However, it has long been recognized that the main challenges to more effective water management are largely social rather than technical. This article reviews the recent literature (2007–2017) to analyze driving factors associated with farmers’ concerns and public perception of reclaimed wastewater for irrigation. The aim of the paper is to synthetize how both environmental and health risks and the yuck factor could be addressed in order to promote mutual understanding between farmers and the public. Results show: (1) how farmers and the public perceive environmental and health risks in a similar way, (2) how the yuck factor is more noticeable for the public than farmers, and (3) how constructed wetlands, reclaimed water exchange consortiums, product certification, and direct site visits to water reuse infrastructure could be promoted in order to foster understanding between farmers and the public. The article concludes by providing key research questions for managers and public authorities relating to how to focus on the study of technical and social issues related to water reuse.

Potentialities and Limits of Some Non-thermal Technologies to Improve Sustainability of Food Processing

In the whole food production chain, from the farm to the fork, food manufacturing steps have a large environmental impact. Despite significant efforts made to optimize heat recovery or water consumption, conventional food processing remains poorly efficient in terms of energy requirements and waste management. Therefore, in the few last decades, much research has focused on the development of alternative non-thermal technologies. Some of them, such as membrane separation processes, hydrostatic or dynamic high pressure, dense phase or high-pressure carbon dioxide, and pulsed electric fields (PEFs) have been extensively studied for cold pasteurization, concentration, extraction, or food functionalization. However, it is still difficult to evaluate the actual advantages or limits of these innovative processing technologies to replace conventional processes. Thus, the overall aim of this paper is to present an overview of the most relevant studies dealing with the potentialities and limits of these non-thermal technologies to improve sustainability of food processing. After a brief presentation of the physical principles of these technologies, the paper illustrates how these technologies could play a decisive role for sustainable food preservation or valorization of raw materials and by-products.

Effects of irrigation with secondary treated wastewater on physicochemical and microbial properties of soil and produce safety in a semi-arid area

Water scarcity is becoming one of the largest problems worldwide. Agricultural reuse of wastewater has been considered a valuable and reliable alternative, alleviating the pressure on freshwater resources in arid and semi-arid regions such as the Middle East. Inadequate microbial quality of treated wastewater is a challenge for developing countries, which limits agricultural reuse of wastewater. This study assessed the impact of irrigation with secondary treated wastewater (STWW) on soil properties as well as the safety of various types of crops as compared with tap water (TW) irrigation through a furrow system. Total and fecal coliforms and Escherichia coli were monitored as indicator bacteria in STWW, irrigated soil and harvested crops. The presence of pathogenic E. coli O157, Salmonella and Shigella was also monitored in all samples using a combination of culture and molecular methods. The microbial quality of wastewater in terms of E. coli concentration (4.18 Log MPN/100 ml) failed to meet the world health organization (WHO) recommendation for irrigation of root and leafy crops (≤103 and ≤ 104E. coli per 100 ml for root and leafy crops, respectively). No significant effects on physicochemical properties of the soil irrigated with STWW was found in comparison with control plots, except for electrical conductivity (EC) and sodium adsorption ratio (SAR), which were slightly higher in STWW soil samples. Although the microbial quality of soil was affected by STWW irrigation, a relatively low concentration of E. coli was detected in soil. No microbial contamination in terms of E. coli was found on harvested maize and onion. E. coli contamination of lettuce and spring onion was found for both irrigation schemes. No STWW, soil or crop samples were found positive for pathogenic bacteria. According to the analyzed parameters, STWW could be safely used as an alternative source for irrigation of root and leafy crops.