Mitigating risks and maximizing sustainability of treated wastewater reuse for irrigation

A framework to assess pharmaceutical accumulation in crops: from wastewater irrigation to consumption

The reuse of treated wastewater for irrigation can inadvertently introduce a suite of emerging contaminants such as pharmaceuticals into agri-ecosystems. However, current monitoring efforts to characterise exposure usually focus on a limited range of analytes. A modelling framework was developed that employs a sequence of pre-developed models to predict accumulative potential in a model crop, Zea mays (corn), using chemical structure and excretion rate as the only model inputs. Z. mays was selected as the model crop as it is a major food source, stands as one of the highest cultivated crops globally, and is characterised as having a medium uptake potential. The framework was used to predict uptake in Z. mays in three regions characteristic of high wastewater reuse (Australia, the US and the Middle East). Despite regional and plant specific differences, 72.7 % of the calculated concentrations were within a factor of ten of those reported in the literature. Topiramate, furosemide, and gemfibrozil were observed to accumulate to the greatest extent in Z. mays, predicted concentrations ranged between 50.27 and 418.01 ng/g (dw) for the top 10. Acids predominantly accumulated in leaves and fruit whereas a higher proportion of bases were predicted to accumulate in the roots. To the best of our knowledge 56.7 % of the 30 highest-ranked pharmaceuticals have not been previously documented in existing literature or monitoring campaigns. This presented framework demonstrates a method to assess risk posed by pharmaceutical compounds with limited experimental data.

Are we ready for the application of the EU Regulation on wastewater reuse in agriculture? A techno-economic preliminary evaluation based on a case-study

Reuse of reclaimed wastewater (RWW) in agriculture represents one of the key strategies to promote for reducing the pressures on water sources, as also fostered by the EU governance. Indeed, the European Regulation 741/2020 on water reuse, entered into force in 2023, was issued with the aim to extend the reuse of treated water in agriculture under safe conditions. It establishes the minimum quality requirements; it also foresees the possibility to add additional requirements, especially for contaminants of emerging concern (CECs), based on "scientific evidence" and the risk assessment. The present study aims at evaluating from both the technical and economic points of view the potential reuse of RWW for irrigating edible crops in a real case study, considering the requirements set by the EU Regulation 741/2020. The Rieti province in the Lazio region of Italy was selected as the case study, since its territory is devoted to agricultural activities which have an important economic impact (e.g. olive trees, potatoes and maize). Firstly, the wastewater treatment plants (WWTPs) here located were classified based upon the quality of the water produced with respect to the classes listed by the EU Regulation. Then, the nutrients and water demand of the crops grown in the same area were compared with the nutrients and water potentially available through the RWW from the WWTPs. Furthermore, a preliminary assessment was carried out considering only four selected CECs present in the RWW produced by the WWTPs. Combining the quality requirements set by EU Regulation and the results of the preliminary risk assessment, in the investigated territory, there are 17 WWTPs potentially suitable for the irrigation of maize, only 1 plant for potato and 8 plants for olive.

Performance evaluation of a brewery wastewater treatment plant: A case of Heineken Brewery, Addis Ababa, Ethiopia

Untreated wastewater from the brewing industry poses significant environmental risks due to its high organic content. Therefore, this study evaluates the wastewater treatment system at Heineken Brewery in Addis Ababa, Ethiopia. Key parameters analyzed include COD, BOD₅, TSS, pH, ammonia (NH₃), total nitrogen (TN), total phosphorus (TP), electrical conductivity (EC), temperature, turbidity, and volatile fatty acids (VFA). These parameters were analyzed following the procedures of the American Public Health Association's standard. The treatment system demonstrated notable efficiency, with influent temperature decreasing from 29.37 °C to 25.35 °C, remaining well below the acceptable limit of 40 °C. The pH dropped from a mean of 9.3 to 7.5, aligning with the acceptable range of 6-9. COD and BOD₅ were significantly reduced by 97.2 %, achieving levels well below discharge limits of 250 mg/L and 60 mg/L, respectively. TSS levels decreased by 95.7 %, with a mean of 32.3 mg/L. However, TP and TN removal efficiencies were lower at 49.4 % and 57.6 %, respectively, with TP slightly exceeding the limit of 5 mg/L. The system effectively reduced VFA by 94.3 % and turbidity by 71.5 %. While parameters such as pH, temperature, TN, NH₄-N, and EC were within acceptable limits, the high nutrient concentrations in the final effluent indicate potential environmental contamination if discharged untreated. Overall, while the treatment plant shows commendable pollutant removal efficiency, further optimization is needed for improved nutrient management.

Modelling the impacts generated by reclaimed wastewater reuse in agriculture: From literature gaps to an integrated risk assessment in a One Health perspective

The reuse of reclaimed wastewater is increasingly recognized as a viable alternative water source for irrigation. Its application, whether direct or indirect, impacts several interconnected compartments, including groundwater, surface water, soil, crops, and humans. Reclaimed wastewater provides essential resources for crops, like water and nutrients. However, it also introduces pathogens, and contaminants of emerging concern (CECs), defined as chemicals that may pose risks to human health and ecosystems but are not yet fully regulated, such as pharmaceuticals and personal care products, among others. Additionally, reclaimed wastewater may contain antibiotic-resistant bacteria (ARBs) and disinfection by-products (DBPs), all of which present potential health and environmental risks. Therefore, regulatory bodies stress the need for preventive risk assessments to ensure safe reuse. This paper critically reviews available models for assessing the impacts of reclaimed wastewater reuse in agriculture. It identifies gaps in current modelling approaches and outlines future research directions. Key areas requiring further investigation include the fate and transfer of CECs, ARBs and DBPs, and the co-occurrence of multiple risks in such interconnected systems, especially in the indirect reuse. To address these gaps, we proposed a simplified approach to integrate three types of risk associated with CECs in indirect reuse, focusing on risks posed by antibiotics and other pharmaceuticals: human health risk, environmental risk and risk from antibiotic resistance development. This approach aids in identifying the most critical endpoints within the One Health approach, supporting (i) CECs prioritization in regulations based on their critical endpoints and (ii) the adoption of CEC-specific mitigation measures.

Regional Water and Food Security Require Joint Israeli-Palestinian Guidelines for Wastewater Reuse and Food Safety

BACKGROUND

Water and food security in Israel and the Palestinian Authority are deeply interconnected due to the region's arid climate and water scarcity, shared water resources, and interrelated agricultural sectors. Therefore, jointly addressing water reuse is vital to supporting sustainable agricultural production and ensuring food safety.

OBJECTIVES

This paper examines the food safety implications of the cross-border trade of fresh fruits and vegetables between the Palestinian Authority and Israel, with an emphasis on the influence of, water technologies, agricultural practices, and environmental health.

METHODS

This paper provides a comprehensive review of existing data to assess water irrigation quality, food safety, and water reuse regulations in the Palestinian Authority and Israel.

RESULTS

Significant discrepancies in food safety, food quality, and exposure to contaminants from fresh produce result from different water reuse regulations, practices, and socioeconomic conditions. Given the volume of trade, consumer mobility, and environmental sustainability, coupled with geopolitical limitations between the Palestinian Authority and Israel, there is an urgent need for a unified regulatory strategy for wastewater reuse ensuring food safety and security. We propose a single, coordinated approach to overseeing wastewater reuse to enhance public health and address contaminants of emerging concern that are not currently regulated. Navigating the political and legislative complexities in a proactive stance requires both Israeli and Palestinian decision-makers to address the matter conscientiously. Existing data and the precautionary principle are sufficient to propose an interim prohibition on treated wastewater irrigation for leafy vegetables to mitigate pollution risks and act as a catalyst for improving irrigation water quality.

CONCLUSIONS

Our proposed strategy for a unified water reuse regulation emphasizes the necessary steps for its implementation and addresses potential obstacles. This strategy underscores the importance of responsible wastewater management in advancing common goals of environmental sustainability, food safety, and human health.

SHORT SYNOPSIS

We propose a coordinated Israeli-Palestinian approach to wastewater reuse to ensure food safety based on shared environmental and health concerns, economic considerations, and the precautionary principle.

A Call for Joint Israeli-Palestinian Guidelines for Water Recycling to Improve Food Security and Safety.

Process innovations and circular strategies for closing the water loop in a process industry

By implementing advanced wastewater treatment technologies coupled with digital tools, high-quality water is produced to be reused within the industry, enhancing process efficiency and closing loops. This paper investigates the impact of three innovation tools (process, circular and digital) in a Solvay chemical plant. Four technologies of the wastewater treatment plant "WAPEREUSE" were deployed, predicting their performance by process modelling and simulation in the PSM Tool. The environmental impact was assessed using Life Cycle Assessment and compared to the impact of the current industrial effluent discharge. The circularity level was assessed through three alternative closed-loop scenarios: (1) conventional treatment and discharge to sea (baseline), (2) conventional and advanced treatment by WAPEREUSE and discharge to sea, (3) conventional and advanced treatment by WAPEREUSE and industrial water reuse through cross-sectorial symbiotic network, where effluents are exchanged among the process industry, municipality and a water utility. Scenario 1 has the lowest pollutants' removal efficiency with environmental footprint of 0.93 mPt/m3. WAPEREUSE technologies decreased COD by 98.3%, TOC by 91.4% and nitrates by 94.5%. Scenario 2 had environmental footprint of 1.12 mPt/m3. The cross-sectorial symbiotic network on the industrial value chain resulted in higher industrial circularity and sustainability level, avoiding effluents discharge. Scenario 3 is selected as the best option with 0.72 mPt per m3, reducing the environmental footprint by 21% and 36% compared to Scenarios 1 and 2, respectively.

Metagenomic profiling of raw wastewater in Portugal highlights microbiota and resistome signatures of public health interest beyond the usual suspects

In response to the rapid emergence and dissemination of antimicrobial resistant bacteria (ARB) and genes (ARGs), integrated surveillance systems are needed to address antimicrobial resistance (AMR) within the One Health Era. Wastewater analyses enable biomarker monitoring at the sewershed level, offering timely insights into pathogen circulation and ARB/ARGs trends originating from different compartments. During two consecutive epidemic waves of the COVID-19 pandemic in Portugal, taxonomic and functional composition of raw urban wastewater from two wastewater treatment plants (WWTPs) representing one million in equivalent population, located in the main urban areas of the country, were profiled by shotgun metagenomics. Hospital wastewater from two central hospitals located in the WWTPs catchment areas were also sequenced. The resistome and virulome were profiled using metagenomic assemblies without taxonomic constraint, and then specifically characterized for ESKAPE pathogens. Urban and hospital wastewater exhibited specific microbiota signatures, Pseudomonadota dominated in the first and Bacteroidota in the latter. Correlation network analyses highlighted 85 (out of top 100) genera co-occurring across samples. The most frequent ARGs were classified in the multidrug, tetracyclines, and Macrolides, Lincosamides, Streptogramins (MLS) classes. Links established between AMR determinants and bacterial hosts evidenced that the diversity and abundance of ARGs is not restricted to ESKAPE, being also highly predominant among emergent enteropathogens, like Aeromonas and Aliarcobacter, or in the iron (II) oxidizer Acidovorax. The Aliarcobacter genus accumulated high abundance of sulphonamides and polymyxins ARGs, while Acinetobacter and Aeromonas hosted the highest abundance of ARGs against beta-lactams. Other bacteria (e.g. Clostridioides, Francisella, Vibrio cholerae) and genes (e.g. vanA-type vancomycin resistance) of public health interest were detected, with targeted monitoring efforts being needed to establish informative baseline data. Altogether, results highlight that wastewater monitoring is a valuable component of pathogen and AMR surveillance in healthy populations, providing a community-representative snapshot of public health trends beyond priority pathogens.

Filling the Knowledge Gap Regarding Microbial Occupational Exposure Assessment in Waste Water Treatment Plants: A Scoping Review

BACKGROUND

Wastewater treatment plants (WWTPs) are crucial in the scope of European Commission circular economy implementation. However, bioaerosol production may be a hazard for occupational and public health. A scoping review regarding microbial contamination exposure assessment in WWTPs was performed.

METHODS

This study was performed through PRISMA methodology in PubMed, Scopus and Web of Science.

RESULTS

28 papers were selected for data extraction. The WWTPs' most common sampled sites are the aeration tank (42.86%), sludge dewatering basin (21.43%) and grit chamber. Air sampling is the preferred sampling technique and culture-based methods were the most frequently employed assays. Staphylococcus sp. (21.43%), Bacillus sp. (7.14%), Clostridium sp. (3.57%), Escherichia sp. (7.14%) and Legionella sp. (3.57%) were the most isolated bacteria and Aspergillus sp. (17.86%), Cladosporium sp. (10.71%) and Alternaria sp. (10.71%) dominated the fungal presence.

CONCLUSIONS

This study allowed the identification of the following needs: (a) common protocol from the field (sampling campaign) to the lab (assays to employ); (b) standardized contextual information to be retrieved allowing a proper risk control and management; (c) the selection of the most suitable microbial targets to serve as indicators of harmful microbial exposure. Filling these gaps with further studies will help to provide robust science to policy makers and stakeholders.

Impacts of vegetable processing and cheese making effluent on soil microbial functional diversity, community structure, and denitrification potential of land treatment systems

The cheese making and vegetable processing industries generate immense volumes of high-nitrogen wastewater that is often treated at rural facilities using land applications. Laboratory incubation results showed denitrification decreased with temperature in industry facility soils but remained high in soils from agricultural sites (75% at 2.1°C). 16S rRNA, phospholipid fatty acid (PLFA), and soil respiration analyses were conducted to investigate potential soil microbiome impacts. Biotic and abiotic system factor correlations showed no clear patterns explaining the divergent denitrification rates. In all three soil types at the phylum level, Actinobacteria, Proteobacteria, and Acidobacteria dominated, whereas at the class level, Nitrososphaeria and Alphaproteobacteria dominated, similar to denitrifying systems such as wetlands, wastewater resource recovery facilities, and wastewater-irrigated agricultural systems. Results show that potential denitrification drivers vary but lay the foundation to develop a better understanding of the key factors regulating denitrification in land application systems and protect local groundwater supplies. PRACTITIONER POINTS: Incubation study denitrification rates decreased as temperatures decreased, potentially leading to groundwater contamination issues during colder months. The three most dominant phyla for all systems are Actinobacteria, Proteobacteria, and Acidobacteria. The dominant class for all systems is Nitrosphaeria (phyla Crenarchaeota). No correlation patterns between denitrification rates and system biotic and abiotic factors were observed that explained system efficiency differences.

Dissemination of antibiotic resistance genes through soil-plant-earthworm continuum in the food production environment

Treated municipal wastewater (TMW) can provide a reliable source of irrigation water for crops, which is especially important in arid areas where water resources are limited or prone to drought. Nonetheless, TMW may contain residual antibiotics, potentially exposing the crops to these substances. The goal of this study was to investigate the dissemination of antibiotics resistance genes (ARGs) in the soil-plant-earthworm continuum after irrigation of spinach and radish plants with TMW containing trimethoprim, sulfamethoxazole, and sulfapyridine in a greenhouse experiment, followed by feeding of earthworms with harvested plant materials. Our results showed that antibiotic resistance genes (ARGs) were enriched in the soil-plant-earthworm microbiomes irrigated with TMW and TMW spiked with higher concentrations of antibiotics. The number of ARGs and antibiotic-resistant bacteria (ARB) enrichment varied with plant type, with spinach harboring a significantly higher amount of ARGs and ARB compared to radish. Our data showed that bulk and rhizosphere soils of spinach and radish plants irrigated with MilliQ water, TMW, TMW10, or TMW100 had significant differences in bacterial community (p < 0.001), ARG (p < 0.001), and virulence factor gene (VFG) (p < 0.001) diversities. The abundance of ARGs significantly decreased from bulk soil to rhizosphere to phyllosphere and endosphere. Using metagenome assembled genomes (MAGs), we recovered many bacterial MAGs and a near complete genome (>90 %) of bacterial MAG of genus Leclercia adecarboxylata B from the fecal microbiome of earthworm that was fed harvested radish tubers and spinach leaves grown on TMW10 irrigated waters, and this bacterium has been shown to be an emerging pathogen causing infection in immunocompromised patients that may lead to health complications and death. Therefore, crops irrigated with TMW containing residual antibiotics and ARGs may lead to increased incidences of enrichment of ARB in the soil-plant-earthworm continuum.