The volume of wastewater generated by domestic, industrial and commercial sources has increased with population, urbanization, improved living conditions, and economic development. The productive use ...of wastewater has also increased, as millions of small-scale farmers in urban and peri-urban areas of developing countries depend on wastewater or wastewater polluted water sources to irrigate high-value edible crops for urban markets, often as they have no alternative sources of irrigation water. Undesirable constituents in wastewater can harm human health and the environment. Hence, wastewater irrigation is an issue of concern to public agencies responsible for maintaining public health and environmental quality. For diverse reasons, many developing countries are still unable to implement comprehensive wastewater treatment programs. Therefore in the near term, risk management and interim solutions are needed to prevent adverse impacts from wastewater irrigation. A combination of source control, and farm-level and post-harvest measures can be used to protect farm workers and consumers. The WHO guidelines revised in 2006 for wastewater use suggest measures beyond the traditional recommendations of producing only industrial or non-edible crops, as in many situations it is impossible to enforce a change in the current cash crop pattern, or provide alternative vegetable supply to urban markets.
There are several opportunities for improving wastewater management via improved policies, institutional dialogues and financial mechanisms, which would reduce the risks in agriculture. Effluent standards combined with incentives or enforcement can motivate improvements in water management by household and industrial sectors discharging wastewater from point sources. Segregation of chemical pollutants from urban wastewater facilitates treatment and reduces risk. Strengthening institutional capacity and establishing links between water delivery and sanitation sectors through inter-institutional coordination leads to more efficient management of wastewater and risk reduction.
•BACs biodegrade during biological treatment to form the potent NDMA precursor BDMA.•BDMA and NDMA formation were functions of BAC and suspended solids concentrations.•BDMA and NDMA formation was ...reduced at longer reaction times.•BDMA in wastewater effluents accounted for 4 to 38 % of the NDMA precursor pool.
N-nitrosodimethylamine (NDMA) is a carcinogenic disinfection byproduct that forms during chloramine disinfection of municipal wastewater effluents which are increasingly used to augment drinking water supplies due to growing water scarcity. Knowledge of wastewater NDMA precursors is limited and the known pool of NDMA precursors has not closed the mass balance between precursor loading, precursor NDMA yield, and formed NDMA. Benzalkonium chlorides (BACs) are the most prevalent quaternary ammonium surfactants and have antimicrobial properties. The extensive utilization of BACs in household, commercial and industrial products has resulted in their detection in wastewater at elevated concentrations. We report the formation of a potent NDMA precursor, benzyldimethylamine (BDMA) from the biodegradation of BACs during activated sludge treatment. BDMA formation and NDMA formation potential (FP) were functions of BAC and mixed liquor suspended solids concentration at circumneutral pH, and the microbial community source. Sustained exposure to microorganisms reduced NDMA FP through successive dealkylation of BDMA to less potent precursors. BAC alkyl chain length (C8 – C16) had little impact on NDMA FP and BDMA formation because chain cleavage occurred at the C–N bond. Wastewater effluents collected from three facilities contained BDMA from 15 to 106 ng/L, accounting for an estimated 4 to 38 % of the NDMA precursor pool.
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•A sustainable solution for tertiary treatment of urban wastewater was investigated.•Solar photo Fenton with EDDS was the most effective AOP to remove CECs.•N-TiO2/sunlight less ...efficient than homogeneous solar AOPs.•No acute toxicity observed after N-TiO2/sunlight and solar photo Fenton with EDDS.•Solar photo Fenton with EDDS comparatively more sustainable than other solar AOPs.
The release of toxic contaminant of emerging concern from urban wastewater treatment plants (UWTPs) into the environment calls for more effective (tertiary) treatment methods. In this manuscript, homogeneous solar-driven advanced oxidation processes (AOPs), namely H2O2/sunlight, solar photo-Fenton (Fe+2/H2O2/sunlight) and solar photo-Fenton with ethylenediamine-N,N'-disuccinic acid (EDDS) complex (Fe+2/H2O2/EDDS/sunlight) were compared to a new heterogeneous process (supported nitrogen-doped TiO2 (N-TiO2)/sunlight), with the aim of contributing to fill the gap between lab scale tests and full scale applications as well as to provide a sustainable solution for tertiary treatment in small UWTPs. Process efficiency was evaluated in terms of effluent toxicity and degradation of a mixture of three pharmaceuticals (namely carbamazepine (CBZ), diclofenac and trimethoprim), at initial concentration of 200 µg/L each, in deionized water (DW) and real wastewater (WW). Fe2+/H2O2/EDDS/sunlight was found to be the most effective process (98% removal of CBZ from WW in 60 min, 5.6 kJ/L as cumulative solar energy per unit of volume). Conventional solar photo Fenton was drastically and negatively affected by water matrix, due to the spontaneous neutral pH and iron precipitation in real WW. Although N-TiO2/sunlight process was not so affected by water matrix, it was found to be less efficient (30% removal of CBZ in 180 min, 13.3 kJ/L) than Fe2+/H2O2/EDDS/sunlight process. Toxicity values were found to be lower in WW compared to DW matrix. Class weight scores for WW samples showed a toxicity reduction up to the no acute toxicity level for N-TiO2/sunlight and Fe2+/H2O2/EDDS/sunlight treatments, while H2O2/sunlight and Fe2+/H2O2/sunlight increased the final effluent toxicity up to slightly acute levels.
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•Agro-industrial treated wastewater was reused for tomato and broccoli irrigation.•The main physico-chemical properties of wastewater met the Italian standards for irrigation ...reuse.•Quantity and quality of crops were not affected by wastewater.•No impact of wastewater on chemical properties of irrigated soil was observed.•Low level of fecal indicator was found in plants, tomato fruits and broccoli heads.
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.
•Pollutants were removed from wastewater through electrocoagulation (EC).•The optimal values for EC were pH 9, time of 10 min, and current density of 8 mAcm-2.•The maximum removal of color, turbidity ...and COD were 86%, 82% and 59% respectively.•The treated wastewater with EC can be reused in process of wool dyeing.
The possibility of using electrocoagulation for efficient removal of pollutants in the industrial liquid waste of a textile industry was studied. The performance of the process was evaluated through the analysis of color, turbidity, and chemical oxygen demand (COD). The analysis was first done with the wastewater coming from the process of dyeing linen, which is the most polluting of all effluents that reach the residual effluent pool (REP). For the analysis, the MODDE 7.0 software was used to construct a statistical model. With the results obtained from this model and the experimental measurements, response surfaces were obtained. These response surfaces predicted the behavior of electrocoagulation for different values of the studied variables (pH, current density, and treatment time). Based on the obtained results, the wastewater coming from the REP was treated using the optimum values for the operational variables. After the treatment it was possible to remove 86% color, 82% turbidity, and 59% COD. It was demonstrated that reusing the treated water in the process of wool dyeing does not have a negative effect on the quality of the dyed fabric. Thus, it is possible to implement the process in the textile industry to reduce the consumption of water.
Climate change and the subsequent change in agricultural conditions increase the vulnerability of agricultural water use. Wastewater reuse is a common practice around the globe and is considered as ...an alternative water resource in a changing agricultural environment. Due to rapid urbanization, indirect wastewater reuse, which is the type of agricultural wastewater reuse that is predominantly practiced, will increase, and this can cause issues of unplanned reuse. Therefore, water quality standards are needed for the safe and sustainable practice of indirect wastewater reuse in agriculture. In this study, irrigation water quality criteria for wastewater reuse were discussed, and the standards and guidelines of various countries and organizations were reviewed to suggest preliminary standards for indirect wastewater reuse in South Korea. The proposed standards adopted a probabilistic consideration of practicality and classified the use of irrigation water into two categories: upland and rice paddy. The standards suggest guidelines for E. coli, electric conductivity (EC), turbidity, suspended solids (SS), biochemical oxygen demand (BOD), pH, odor, and trace elements. Through proposing the standards, this study attempts to combine features of both the conservative and liberal approaches, which in turn could suggest a new and sustainable practice of agricultural wastewater reuse.
TCM wastewater treatment is a significant environmental issue in China. This study investigated the effectiveness of the UF-MD hybrid system on recycling valuable resources in TCM wastewater. ...Synthetic TCM wastewater was prepared and separated with the self-assemble UF-MD hybrid system. Moreover, the feed temperature (45 °C, 55 °C, 65 °C) and membrane materials' influence on MD performance were also evaluated. Results show that the UF-MD hybrid system is efficient to achieve a complete separation and resources recycle from the TCM wastewater. The MD flux production increased with the increment of feed temperature. However, some bioactive compounds could not be concentrated in MD due to their potential degradation at high temperatures, and membrane wetting might be an issue in long-term operation. Although PP membranes exhibited the highest flux among PP, PTFE and PVDF membranes, considering the wetting and fouling resistance, PTFE membranes would be a better option for long-term MD operation at 65 °C.
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•The UF-MD hybrid system can achieve a complete resource recycle of the TCM wastewater.•Some bioactive compounds could not be concentrated in MD due to degradation at high temperatures.•MD wetting and fouling may be an issue for long-term TCM wastewater treatment.•Flux increase over temperature is mainly caused by the partial vapor pressure increase.•PTFE membranes may be a better option than PP and PVDF ones for long-term operation.
This study focuses on the removal and risk assessment of twenty emerging contaminants (ECs) and heavy metals in a REMIX water treatment plant (RWTP) that produces drinking water from combination of ...wastewater reuse and desalination. The membrane biological reactor (MBR) exhibit removal rates exceeding 95% of pharmaceuticals like acetaminophen, trimethoprim, diclofenac, naproxen, and emtricitabine. The efficiency of brackish reverse osmosis (BWRO) in removing ECs is highlighted, showing substantial efficacy with reduction rates of 99.5%, 75.5%, and 51.2% for sulfamethoxazole, venlafaxine, and benzotriazole, respectively. The advanced oxidation process based on Fenton process reveals removal (>95%) of emtricitabine, efavirenz, and carbamazepine. The study confirms that the combination of treatment units within the RWTP effectively removes heavy metals (>90%), complying with acceptable limits. Risk quotient (RQ) calculations indicate the efficiency of the RWTP in EC removal, serving as benchmarks for public acceptance of reclaimed water. In the context of heavy metals, the study concludes negligible cancer risks associated with reclaimed water consumption over a lifetime. Quantitative structure-activity relationship and occurrence, persistence, bioaccumulation and toxicity (OPBT) models were used to assess EC risk. The study screened and identified potential persistant, bio accumulating and toxic PBT ECs. Critical control points (CCPs) in the RWTP are identified, with brackish and seawater reverse osmosis (BWRO and SWRO) and advanced oxidation process (AOP) recognized as pivotal in hazard management. The study provides valuable insights on the removal of ECs and heavy metals in a wastewater reuse process and demonstrates potential of adopted process configuration in supplying safe drinking water from wastewater recycling.
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•A novel process combining wastewater reuse and desalination studied for EC removal.•OPBT based risk assessment carried out for EC occurrence in recycled water.•Heavy metals in recycled water were within limits, removal >90% and HQ < 1.•Critical control points (CCPs) in the process for EC removal were identified.
Water reuse is rapidly becoming an integral feature of resilient water systems, where municipal wastewater undergoes advanced treatment, typically involving a sequence of ultrafiltration (UF), ...reverse osmosis (RO), and an advanced oxidation process (AOP). When RO is used, a concentrated waste stream is produced that is elevated in not only total dissolved solids but also metals, nutrients, and micropollutants that have passed through conventional wastewater treatment. Management of this RO concentratedubbed municipal wastewater reuse concentrate (MWRC)will be critical to address, especially as water reuse practices become more widespread. Building on existing brine management practices, this review explores MWRC management options by identifying infrastructural needs and opportunities for multi-beneficial disposal. To safeguard environmental systems from the potential hazards of MWRC, disposal, monitoring, and regulatory techniques are discussed to promote the safety and affordability of implementing MWRC management. Furthermore, opportunities for resource recovery and valorization are differentiated, while economic techniques to revamp cost-benefit analysis for MWRC management are examined. The goal of this critical review is to create a common foundation for researchers, practitioners, and regulators by providing an interdisciplinary set of tools and frameworks to address the impending challenges and emerging opportunities of MWRC management.
To study the effect of water quality and operating parameters on membrane fouling, a comparative analysis of wastewater (WW) and seawater (SW) fouled reverse osmosis (RO) membranes was conducted. ...Membranes were harvested from SWRO and WWRO pilot plants located in Vilaseca (East Spain), both using ultrafiltration as pretreatment. The SWRO unit was fed with Mediterranean seawater and the WWRO unit was operated using secondary effluent collected from the municipal wastewater treatment plant. Lead and terminal SWRO and WWRO modules were autopsied after five months and three months of operation, respectively. Ultrastructural, chemical, and microbiological analyses of the fouling layers were performed. Results showed that the WWRO train had mainly bio/organic fouling at the lead position element and inorganic fouling at terminal position element, whereas SWRO train had bio/organic fouling at both end position elements. In the case of WWRO membranes, Betaproteobacteria was the major colonizing species; while Ca, S, and P were the major present inorganic elements. The microbial population of SWRO membranes was mainly represented by Alpha and Gammaproteobacteria. Ca, Fe, and S were the main identified inorganic elements of the fouling layer of SWRO membranes. These results confirmed that the RO fouling layer composition is strongly impacted by the source water quality.
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•Comparison of fouling profiles of seawater and wastewater RO membranes.•Chemical, ultrastructural and microbiological characterization of fouling layers.•Impact of source water quality: A key factor in the membrane fouling phenomenon.
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