Water Reclamation Research Articles

The characteristics of temperature-responsive ionic liquids on the integrated operational effectiveness of water reclamation from semiconductor wastewater using forward osmosis.

Large amounts of wastewater are produced from semiconductor manufacturing, and the production energy consumption has skyrocketed with its global demand in recent years. Forward osmosis (FO) provides unique merits in reclaiming the wastewater if suitable draw solutes with high water flux, low leakage, and limited energy requirement in regeneration are available. Two lower critical solution temperature-ionic liquids (LCST-ILs), tetrabutylphosphonium trimethylbenzensulfonate ([P4444][TMBS]) and tetrabutylphosphonium maleate ([P4444][Mal]) were synthesized and systematically assessed as recycled draw solutes in FO for the water reclamation from the wastewater of Si-ingot sawing. The water flux of [P4444][TMBS] and [P4444][Mal] was 4.12 and 2.67 LMH in the FO for the authentic sawing wastewater, respectively. The characteristics of relatively higher hydrophobic and the structure configuration ensure the lower thermal-stimulus separation energy (Ets) of the spent [P4444][Mal] solution and its relative ease in recycling because of the higher regeneration ratio. The more hydrophilic [P4444][TMBS] based draw solution (DS) exhibits higher osmotic pressure, which is beneficial for water filtration but leads to higher Ets. The estimated energy required for the integrated processes, including FO filtration for the sawing wastewater, thermal separation of draw solute, and the reclaimed water polishing, for the system with [P4444][Mal] as draw solutes is 14.22 kWh m-3. The value significantly reduced to 1.33 kWh m-3 if low-grade waste heat (<100°C) was applied for the thermal separation.

Air gap membrane distillation for nutrient and water recovery from marine culture wastewater for improved water reclamation.

Valuable nutrients such as ammonium and phosphate exist in teensy concentrations in marine-culture wastewater (MCW), causing their recovery challenging with inefficient conventional methods. Air gap membrane distillation (AGMD) is systematically explored for the first time to recover nutrients and pure water from low-nutrient MCW. This study assessed the AGMD performance in resource recovery by conducting a thorough investigation and optimization of various parameter conditions. Concerning the findings, AGMD satisfactorily inhibits ammonia transfer from the feed stream to the permeate stream by optimizing operating parameters specifically feed temperature and pH. A higher feed temperature improves water recovery, and feed pH is critical in nutrient recovery. In particular, high pH promotes the transformation and transport of ammonia through the membrane, whereas low pH inhibits ammonia transport, encouraging the creation of pure water. Maintaining an acidic feed solution decreases membrane fouling by increasing the solubility of calcium phosphate, hence boosting water recovery. Nevertheless, higher pH levels encourage fouling by allowing solid phosphate particles to form more readily. While at lower pH, ammonium phosphate fertilizers might be generated in the retentate solution by improving NH4+ and PO43- recovery under optimal conditions. The findings reveal that the AGMD system provides a novel method for treating MCW while also improving nutrient and pure water recovery.

Ground-Based Green Façade for Enhanced Greywater Treatment and Sustainable Water Management

Urban areas face challenges with water scarcity, and the use of non-conventional water resources for uses not requiring potable quality is being promoted more and more by governments and international agencies. However, non-conventional water resources, such as rainwater and greywater, need to be treated before use to avoid health risks and possible nuisance (smell, bacteria and algae proliferation in storage tanks, etc.). This study is aimed at demonstrating the feasibility of a system reusing treated greywater for toilet flushing, relying on a nature-based treatment technology—ground-based green façades—with limited maintenance requirements which is therefore easily replicable for decentralized treatment systems, like those of greywater reuse at building scales. The demonstrative system has been installed at the University of Jordan’s Al-Zahra dormitory in Amman and uses a degreaser as the primary treatment followed by ground-based green façade technology as a secondary treatment mechanism. The effluent is stored in an underground tank and directed to a tertiary treatment mechanism with UV lamps to remove pathogens before being reused for lawn irrigation and toilet flushing. Samples from influent and effluent were analyzed for various physical, chemical, and microbiological characteristics. The degreaser significantly reduced turbidity, TSS, total BOD5, and total COD levels in greywater. When combined with the green wall façades, the system demonstrated high removal efficiencies, particularly for turbidity, TSS, total COD, and total BOD5. The treated effluent met irrigation reuse standards for all the parameters, including total coliform and E. coli concentrations. The UV disinfection unit proved to be an effective post-treatment step, ensuring that water quality standards for reuse were met. The system’s overall performance highlights its ability to manage low- to medium-strength greywater. Results suggest the applied green wall system has significant potential for wider adoption in urban settings.

Impacts of Reclaimed Water Irrigation on Soil Salinity, Nutrient Cycling, and Landscape Plant Growth in a Coastal Monsoon Environment

This study investigated the impacts of reclaimed water (RW) irrigation on soil properties and landscape plant growth in a coastal monsoon city over a 13-month period. Soil properties in plots irrigated with RW and tap water (TW) were monitored monthly, including electrical conductivity, total nitrogen, total phosphorus, soil organic matter, and overall variations of soil enzyme activities. The results show that RW irrigation led to increased fluctuations in soil salinity indicators, with higher peaks during periods of low rainfall. Rainfall can efficiently mitigate the salinity increase associated with RW irrigation, highlighting the influence of monsoon climate variability on salinity dynamics. RW application increased soil total nitrogen and organic matter and decreased soil total phosphorus. This suggests that RW irrigation induces complex nutrient interactions within the soil–plant system. Furthermore, RW irrigation promoted the activities of soil enzymes related to carbon, nitrogen, and phosphorus cycling, indicating potential alterations in nutrient bioavailability. Plant growth responses varied among species, with Nephrolepis cordifolia and Cordyline fruticose exhibiting signs of salt stress, especially in the initial months of planting in RW plot. Other species demonstrated greater tolerance to RW irrigation, suggesting the importance of species selection for sustainable landscape management with RW. This study demonstrates the challenges and opportunities associated with RW utilization for urban greening.

Microbial community structure and water quality performance in local scrubber reclaim system for water reclamation of the semiconductor industry: A case study of a semiconductor plant in Beijing.

The local scrubber reclaim (LSR) system plays a critical role in water reclamation and in reducing environmental pollution emissions in semiconductor factories. This study monitored the changes in water quality and assessed the key stages of pollutant removal, with a primary focus on evaluating microbial growth and the shifts in microbial community structure and function in the LSR system. The results showed that activated carbon filtration (ACF) effectively removed total organic carbon (TOC) with a removal rate of 59.35%, while ion exchange (IEX) was essential for reducing conductivity, with a removal rate of 87.33%. Furthermore, severe bacterial growth was observed (more than 1000CFU/ml) in the system. Bacteria numbers in the MMF and ACF stages grew dramatically, at least four times higher than that in the influent tank. After chlorination in the storage tank, microbial numbers sharply dropped, yet microbial diversity increased. The dominant microbial group in the LSR system was Patescibacteria (average relative abundance was 32.37%), considered part of the "microbial dark matter" and also known as Candidate Phyla Radiation (CPR). Following the effluent from the storage tank, the biofilm-forming potential of bacteria significantly increased (relative abundance rose from 7.19% to 15.20%), along with a varying increase in the abundance of genes related to metabolism. Measures should be implemented to prevent pipeline blockage and improve water reclamation efficiency.

Synthesis and Characterization of Polysulfone/Peat Clay Hollow Fibre Membranes: The Effect of Composition and Morphology

In this work, Synthesis of polysulfone (PSf) hydrophilic ultrafiltration membrane was prepared by addiction of Peat Clay (PC) as additive via phase inversion method. The polysulfone dope solution was loading by varied calcined peat clay composition, namely 0, 2, 4, and 6 wt%. Therefore, this study aims to study the influence of peat clay on the morphology and efficiency of the modified membranes studied. The prepared peat clay particles and membranes are all characterized by various physicochemical techniques such as Water Contact Angle (WCA), porosity, water absorption, FTIR, XRF, SEM, water flux. The characterization analysis on peat clay used in this study showed a higher value of silica components of 64.4492 wt%. The experimental results showed that the modified membrane showed high hydrophilicity the contact angle of water from 96.31° to 55.97°. The ability of water absorption increased to 42.71%, and membrane porosity increased from 23.66% to 45.63%. Whereas in SEM in the PSf membrane with the addition of peat clay, the top layer is solid with a higher thickness than without the addition of peat clay. The characteristics of the membrane show that the functional group in the addition of peat clay in the absorption of Si-OH and Si-O-Si, but there is a decrease in pure water flux (up to 3.61 kg.m-2.h-1) compared to pure membranes. Based on the results obtained, PSf-Peat Clay hollow fibre membrane shows potential as an innovative water reclamation technology.

Quantification of Particle-Associated Viruses in Secondary Treated Wastewater Effluent

Viruses can interact with a broad range of inorganic and organic particles in water and wastewater. These associations can protect viruses from inactivation by quenching chemical disinfectants or blocking ultraviolet light transmission, and a much higher dosage of disinfectants is required to inactivate particle-associated viruses than free viruses. There have been only few studies of the association of viruses with particles in wastewater, particularly in secondary treated effluent. As secondary effluent is the source water to the reclaimed water treatment system, this study quantified indigenous enteric viruses, and viral indicators associated with particles in secondary effluents collected from five full-scale water reclamation facilities in the United States. Particle-associated viruses were enumerated using a sequential filtration followed by microfluidic digital PCR. This study showed that enteric viruses and viral indicators (crAssphage and pepper mild mottle virus, PMMoV) were attached to particles of different sizes in secondary effluent. Significantly higher concentrations of RNA viruses including PMMoV, norovirus, and enterovirus were detected in filtrate of the sequential filtration, which contained particles < 0.45 µm. DNA viruses including adenovirus and crAssphage were found to be more associated with larger particles in secondary effluent. Overall, high correlations were observed between viral indicators and enteric viruses, supporting the use of crAssphage and PMMoV to evaluate virus removal efficiency in water and wastewater treatment processes. The association of viruses with particles in wastewater has significant implications on wastewater treatment and disinfection processes as well as virus enumeration in wastewater.Graphic

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.

The performance of electrocoagulation process for decolorization and COD removal of highly colored real grey water under variable operating conditions

Grey water (GW) reclamation offers a viable solution to address water scarcity. However, the variation in its quality and quantity makes treatment options big challenges. In the last years, Electrocoagulation (EC) has emerged as an effective method for treating GW. This study assessed the performance of a lab-scale EC reactor in treating GW with high concentrations of chemical oxygen demand (COD) and color (1290mg/L and 2540 Pt-CO, respectively), sourced from various origins. The impact of different operational parameters, including electrode material (Iron 'Fe' and Aluminum 'Al'), electrode spacing (1 and 2cm), and current density (5, 10, 15, and 20mA/cm²), was evaluated. Results showed minimal impact from electrode spacing, possibly due to the short electrolysis time (10minutes). However, Al based electrodes outperformed Fe based electrodes, offering reduced health risks from metal contamination. Operating with Al electrodes at a current density of 5mA/cm² led to substantial removal of COD (≥ 82%) and color (≥ 97%) while maintaining low operational costs. This study further supports the viability of EC as an effective method for treating greywater, even at high contaminant levels.

Mitigation of membrane fouling in dye wastewater using a ternary WO3/CNT/ZnO composite photocatalytic membrane

The membrane filtration has been widely utilized in the water reclamation due to its simplicity in operation and outstanding separation performance. Nevertheless, the membrane filtration always suffers from the fouling issue which deteriorate the permeability of membrane. This study targeted to diminish the membrane fouling using a photocatalytic membrane. A ternary tungsten trioxide/carbon nanotube/zinc oxide (WO3/CNT/ZnO) composite photocatalyst was applied to form a ternary WO3/CNT/ZnO composite photocatalytic membrane via a wet processing technique. The highest efficiency to photodegrade methylene blue (MB) were obtained using the M5 ternary composite photocatalytic membrane. The presence of CNT and WO3 intensifies the photocatalysis in the ternary photocatalytic membrane to degrade MB. The ternary composite photocatalyst in membrane form displayed a competitive effectiveness in degrading MB when compared to particle form. The ternary composite photocatalytic membrane demonstrated a decreased permeation flux, accompanied by an increased rejection toward the MB when increasing the loading of ternary composite photocatalyst in the photocatalytic membrane. The analysis on the antifouling behaviour of the ternary composite photocatalytic membrane showed that approximately 95% of flux recovery ratio (Rfr) and 5% of irreversible fouling ratio (Rif) were obtained.

Application of algae and zeolite in wastewater treatment: Effects on maize properties and soil fertility

ABSTRACT As a consequence of fresh water shortage, non-conventional water resources have become increasingly demandable in semi-arid and arid areas due to the increase in population and urbanization. In Egypt, the reuse of drainage water provides a demanding supplement to irrigation water. This research aims to present natural treatment process for drainage wastewater to be reused in irrigation to support water resources and water quality control. Two biological and chemical wastewater treatment techniques (Algae and Zeolite), under different conditions, were applied to allow the reuse of wastewater to be utilized in the agriculture of very economically important crop which is maize, and comparing the production and the chemical components of the crop with the one irrigated by fresh Nile water. Water, soil and plant analyses were performed. Zeolite was characterized by XRD, SEM and FTIR. Enzymes activities were assigned also (dehydrogenase, phosphatase and nitrogenase activities) and finally the statistical analysis was determined by CoStat software. The treated wastewater chemical and biological analyses showed much better results than El-Rahawy drain wastewater analyses. The plants growth parameters results showed the higher ones with plants subjected to the chemical and biological treatments. Protein and carbohydrate levels, which are the most important plant quality indicators, showed higher concentrations in the treated ones than that irrigated with Nile water. NPK concentration of both seeds and leaves also recorded better levels. The results of the enzymes activities in cases of T4, dehydrogenase, phosphatase, and nitrogenase enzyme activity were 127.66, 40.89, and 79.58, respectively, which increased when compared with control treated with Nile water which were (112.44, 28.4, and 41.39) for dehydrogenase, phosphatase and nitrogenase enzymes respectively.

Circular Water and Wastewater Management in State College, Pennsylvania

In recent years, great attention has been paid to activities aimed at implementing a circular economy (CE) in the management of water resources around the world. One of the possibilities for the practical implementation of CE, based on the sustainable management of primary and secondary resources (waste), is the circular management of water and wastewater generated in urban wastewater treatment plants (WWTPs). This work presents examples of good practices in the implementation of CE in the college town of State College, Pennsylvania (United States of America). There are two WWTPs here – one belonging to Penn State University (Water Reclamation Facility) and another operated by the municipality (University Area Joint Authority). Both facilities implement CE goals through various initiatives dedicated to water, raw materials and energy recovery. The scope of these activities include using reclaimed water for irrigation of green areas, production of renewable energy, as well as recovery of biogenic components by processing sewage sludge in compost. This approach, where the university and municipality propose solutions in the environmental and social areas, is consistent with the idea of building social responsibility of units, which is a path to sustainability. Further actions to implement the CE model are expected to counteract ongoing climate change in various regions.

Impact of fish farm drainage water reuse for irrigation on barley yield and water productivity: Field study and simulation using the SALTMED model

AbstractCountries such as Egypt, which are situated in semi‐arid regions and have water constraints, primarily aim to repurpose unconventional water resources for irrigation. The aim of this research was to examine the feasibility and advantages of irrigating barley with fish farm drainage water (DWFF) rather than fresh irrigation water (IW). Four degrees of deficit irrigation [100% FI (full irrigation), 80% FI, 60% FI and 40% FI] were studied for the irrigation of barley via two types of water (DWFF and IW). The response of crops to a deficit irrigation approach involving the use of IW in the two seasons of 2020–2021 and 2021–2022 was demonstrated by the results. The yield of the barley produced with DWFF irrigation was greater than that produced with IW irrigation, ranging from 9% to 12% in 2020–2021 and from 9% to 13% in 2021–2022. This resulted from the higher concentration of dissolved biological nitrogen and other nutrients in DWFFs. There was a strong correlation between the observed and simulated crop yield values for both growing seasons, with R2 values of 0.963 and 0.960, respectively, for all the treatments. The SALTMED model was used to simulate the soil moisture content, water application efficiency, barley dry matter, yield and water productivity for all the treatments. The study concluded that DWFF is a useful irrigation substitute for IW. Higher yields were also attained with the use of less IW and chemical fertilisers because of the DWFF. In addition, there are other advantages, such as increasing farmer income and lowering discharge to the drainage network.

A Cost–Benefit Analysis of Reclaimed Water and Desalinated Seawater for Irrigation in Axarquia, Southern Spain

In water-scarce regions, policymakers resort to reclaimed water (RW) and desalinated seawater (DSW) to supply economic agents when conventional resources are not available. This paper develops a proposal for a simple methodology to apply a cost–benefit analysis (CBA) approach to RW and DSW as a support to the evaluation of water policy goals. To test the method, it applies a CBA to RW and DSW in Axarquia (southern Spain), a water-scarce region suffering a long and extreme drought that is impacting urban supply and the agricultural sector. The benefit-to-cost ratio (BCR) of 17.02 estimated for reclaimed water highlights its high return on investment, suggesting that it offers substantial economic and environmental benefits. This high BCR indicates that reclaimed water as a resource for irrigation is highly cost-effective, particularly if it is combined with nutrient management. By contrast, the estimated BCR of 4.05 for desalinated water, although positive, is considerably lower, suggesting that desalinated water is a feasible but less cost-effective solution due to its high energy requirements and associated costs. This methodology may be extended to other hydrological systems, such as aquifer basins, to promote the generation of more comprehensive insights.

2D Vermiculite Nanolaminated Membranes for Efficient Organic Solvent Nanofiltration

AbstractMembrane separation technology has found widespread application in molecular sieving and water reclamation. Its use in organic solvent nanofiltration (OSN) has been limited by the modest permeation rates and stability of existing membranes. In this study, 2D clay nanolaminated membranes are engineered, derived from the stacking of exfoliated vermiculite nanosheets, as a potential solution for OSN. The as‐synthesized clay membrane displayed limited stability in both water and solvents due to rapid hydration or solvation of the nanosheets. To enhance the membrane's stability and sieving capabilities, cations of various valences (K+, Na+, Mg2+, Ca2+, Fe3+) are intercalated into the interlayer of the clay nanosheets. The resulting cation‐treated clay membranes display considerable enhancement in structural stability in both aqueous and organic media. Subsequently, the solvent transport behavior and separation performance of these clay membranes are evaluated and described by molecular dynamic simulation and experiments. It is identified that Fe‐intercalated nanolaminates demonstrate controllable stacking order, resulting in enhanced sieving performance with a rejection rate of over 95% for Methyl Orange and a methanol permeation rate of ≈165 L m−2 h−1 bar−1 [LMHB]. The findings of this work pave the way for the practical applications of 2D nanolaminated clay membranes in OSN.

Sustainable capacitive deionization process for enhanced chromium reclamation using functionalized biochar electrode

Water pollution, driven by urbanization and industrial growth, poses a significant threat, with chromium (Cr(VI)) discharge from industries like electroplating and tanneries. To address this issue, capacitive deionization (CDI) is explored for its low energy consumption and efficient removal of ionic contaminants. However, CDI faces challenges related to electrode costs and internal resistance. So, it is necessary to find a low-cost sustainable, functional electrode for the hazardous Cr(VI) reclamation without conventional additives to prevent internal resistance. Industrial Biochar, a product of pyrolysis enriched with carbon content, replaces conventional activated carbon and possesses better physicochemical properties. Similarly, Chitosan is a natural derived functional material enriched with functional groups that can adsorb the Cr(VI) ions. Apart from their functionality, they also improve the electrochemical stability and capacitance of the electrode. In response, the present study focuses on developing cost-effective functional electrodes using a biochar/chitosan (BC-CS) composite. The utilization of the chitosan enriches the physico-electrochemical properties and replaces the requirement of binder for the electrode development. The crosslinked BC-CS composite demonstrates a three-fold increase in specific capacitance compared to biochar electrode. Optimizing the ratio, the 1:1 BC-CS composite achieves a remarkable 96.7% chromium removal from a 100 ppm Cr(VI) solution in 3 h at 2 V. The composite also exhibits promising regeneration capabilities and shows potential in treating real-time chrome wash effluent from electroplating industries, indicating its viability for chromium water reclamation.

Synthesis and characterization of multi-responsive iron oxide nanoparticles: Evaluation of antibacterial properties and photocatalytic activity

Cape gooseberry (CG) plant leaf extract-mediated iron oxide nanoparticles (CG-IO NPs) were fabricated for antibacterial research. The ideal concentration of the precursor salt, pH (11) of the reaction mixture, reducing agent to precursor salt ratio, and the production time of iron oxide nanoparticles were 5 mM, 9.0, 3:7, and 25 min, respectively. The iron oxide nanoparticles were tested using ultraviolet–visible absorption spectroscopy, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric/differential thermal analysis (TG/DTA), and Fourier transform infrared (FTIR) spectroscopy. FTIR spectroscopy was used to identify functional groups of the compounds, including the carbonyl, CH, and OH bands that reduced and produced nanoparticles. The size and shape of the synthesized CG-IO NPs were determined by TEM and dynamic light scattering, with the median and mean size of 13.9 nm and 15.8 nm, respectively. The thermal stability of the synthesized CG-IO NPs was assessed using TG/DTA in a nitrogen atmosphere. The elements and oxidation states of the CG-IO NP components were examined by XPS. The luminosity of the CG-IO NP was examined using PL spectroscopy. The synthetic CG-IO NPs exhibited strong antibacterial effects against dangerous bacteria, such as Salmonella enterica (S. entirica), Escherichia coli (E. coli), Streptococcus agalactiae, and Staphylococcus aureus. CG-IO NPs assisted in water reclamation by decomposing Malachite Green dye under solar light irradiation.

Biofouling evolution driven by autoinducer-2 quorum sensing in reverse osmosis (RO) for water reclamation

Membrane biofouling remains a key challenge for reverse osmosis (RO) technology in water reclamation. This study investigated the biofouling development with time on RO membrane surface. During the biofouling evolution, the biofilm was examined through confocal laser scanning microscopy (CLSM) observation and foulant composition analysis. Results showed that organic/biofouling was the key contributor, and autoinducer-2 (AI-2), quorum sensing (QS) signaling molecules, were found to play an important role in coordinating community-level behaviors associated with RO membrane fouling. In the initial stage of fouling layer development, the attached cell and biopolymer contents increased with rising AI-2 activity. As development continued, the microbial community changed remarkably, exhibiting peak AI-2 activity as the membrane surface became fully covered with cells and the EPS matrix. However, in later stages, despite a decrease in AI-2 content and biological activity, the rate of increase in fouling resistance accelerated significantly due to continually accumulating foulants. As a result, the AI-2 QS was crucial during early phases of biofilm development in RO systems. This study helps to look deeply into the biological fundamentals of AI-2 mediated QS in RO fouling, enhancing the understanding of the mechanisms behind RO membrane fouling in water reclamation, and may facilitate the development of anti-fouling strategies.

The influence of urbanization and water reclamation plants on fecal indicator bacteria and antibiotic resistance in the Los Angeles River watershed: A case study with complementary monitoring methods.

Urban land use and water reclamation plants (WRPs) can impact fecal indicator bacteria (FIB) and antimicrobial resistance (AMR) in coastal watersheds. However, there is a lack of studies exploring these effects on the US West Coast. Additionally, there is limited research using a complementary approach across culture-, qPCR-, and metagenomics-based techniques for characterizing environmental AMR. In this study, sixteen locations were sampled in the Los Angeles River, encompassing both upstream and downstream of three WRPs discharging into the river. Culture-dependent methods quantified Enterococcus, total coliforms, E. coli, and extended spectrum beta-lactamase-producing E. coli as a low-cost screening tool for AMR, while qPCR measured selected antibiotic resistance genes (ARGs): sul1, ermF, tetW, blaSHV, along with intI1 and 16S rRNA genes. Bacteroides HF183 and crAssphage markers were quantified via ddPCR. All samples underwent shotgun sequencing to investigate gene abundance and mobility and an overall risk score for AMR. Results reveal downstream sites contain ARGs at least two orders of magnitude greater than upstream locations. Developed areas had the highest ARG sequence abundances and the most ARG classes as indicated by metagenomic analysis. WRP effluent exhibited elevated ARGs and co-location of ARGs, mobile genetic elements, and pathogens. A culture-based assessment of AR in E. coli and Pseudomonas aeruginosa revealed increased resistance ratios for most antibiotics from upstream to downstream a WRP discharge point. This study highlights the impacts of land use and WRPs on ARGs and FIB, offering a multi-pronged analysis of AMR.

Optimizing the Nonconventional Water Supply across the Water-Energy-Food Nexus for Arid Regions Using a Life Cycle Assessment

Optimizing the Nonconventional Water Supply across the Water-Energy-Food Nexus for Arid Regions Using a Life Cycle Assessment