Water Treatment Systems Research Articles

Machine learning-driven prediction of phosphorus adsorption capacity of biochar: Insights for adsorbent design and process optimization

Phosphorus (P) pollution in aquatic environments poses significant environmental challenges, necessitating the development of effective remediation strategies, and biochar has emerged as a promising adsorbent for P removal at the cost of extensive research resources worldwide. In this study, a machine learning approach was proposed to simulate and predict the performance of biochar in removing P from water. A dataset consisting of 190 types of biochar was compiled from literature, encompassing various variables including biochar characteristics, water quality parameters, and operating conditions. Subsequently, the random forest and CatBoost algorithms were fine-tuned to establish a predictive model for P adsorption capacity. The results demonstrated that the optimized CatBoost model exhibited high prediction accuracy with an R2 value of 0.9573, and biochar dosage, initial P concentration in water, and C content in biochar were identified as the predominant factors. Furthermore, partial dependence analysis was employed to examine the impact of individual variables and interactions between two features, providing valuable insights for adsorbent design and operating condition optimization. This work presented a comprehensive framework for applying a machine learning approach to address environmental issues and provided a valuable tool for advancing the design and implementation of biochar-based water treatment systems.

Assessment of process water quality (depending on the presence of process water systems) in car wash facilities across Germany and the Netherlands

ABSTRACT There are around 2,500 car wash lines in Germany, consuming around 30 million m3 of drinking water per year. In view of the increasing scarcity of water, this level of consumption could soon be restricted by law, as it is in some countries. There are only a few systematic studies on process water systems in car wash lines in Middle Europe; we therefore carried out a survey to determine process water quality parameters (COD, turbidity, water hardness, pH, conductivity, dissolved O2, and temperature). Data were collected and analysed from 63 different locations in Germany and the Netherlands. In addition, longitudinal parameters were measured for 1 year at a single state-of-the-art site in Germany. The scatter of the observed values was quite considerable. The average COD in water of car wash sites with biological treatment was found to be significantly lower than in car wash sites working with filter treatment. Overall, the deviation of the pollution parameters was higher than expected. Surprisingly, there is hardly any reliable data on freshwater consumption in the car wash facilities. As most of the long-established facilities do not have a modern water treatment system, freshwater consumption is up to 300 L per car washed.

Insight into critical water quality factors and gill function of large yellow croaker (Larimichthys crocea) during packaging bag transport

To investigate the effects of the interaction between water quality and gill function of large yellow croaker during transportation in packaging bags, a total of 186 large yellow croakers weighing 120.0 ± 28.0 g were randomly divided into two groups: a control group (tanks with a water treatment system to maintain normal water quality) and treatment groups subjected to simulated transport for 0, 6, 12, 18, and 24 hours at a temperature of 20°C. The results revealed that prolonging the transport duration (beyond 6 hours) caused significant changes in dissolved oxygen (DO), total ammonia nitrogen (TAN) and pH levels in the water. Beyond 6 hours of transport, gill tissue damage increased, and the histomorphological characteristics of the gills were altered. Regarding osmoregulation, the activities of Ca2+/Mg2+-ATPase and Na+/K+-ATPase were notably reduced in the treatment groups, indicating compromised osmoregulatory function of the gill tissue during transport. However, changes in lactic acid (LD) and lactate dehydrogenase (LDH) were not statistically significant, and fish did not experience hypoxia during packaging bag transport. In terms of antioxidant activity, the treatment groups exhibited significantly lower activities of catalase (CAT) and superoxide dismutase (SOD) after 24 hours, as well as increased malondialdehyde (MDA) content after 18 hours. This reduction in antioxidant capacity led to cellular membrane damage in the gill tissue. Furthermore, acid phosphatase (ACP) activity showed a notable decline from 12 hours onwards in immune indicators, while lysozyme (LZM) activity experienced a substantial decrease at 24 hours. Correlation analysis revealed a significant correlation between the osmoregulation, antioxidant capacity, and immune response of gill tissue with elevated TAN levels and reduced pH. In conclusion, the levels of TAN and pH experience notable alterations after 6 hours of transportation, which may lead to impairment of gill function in large yellow croakers. Hence, we advise limiting the transportation of large yellow croakers to less than 6 hours at 20°C.

Synthesis and evaluation of a novel ternary quaternary ammonium salts-fluorescent template copolymer: Integrating flocculation, sterilization, and monitoring functions

Developing flocculants with sterilization and monitoring functions is of practical significance for optimizing water treatment agents. In this research, a fluorescent monomer, EtFl, with double bonds was synthesized and copolymerized with acrylamide (AM) and 3-(methacryloyloxy)propyltrimethylammonium chloride (MAPTAC) using a linear anionic template agent. This synthesis successfully produced a multifunctional template copolymer, TP(AM-MAP-EtFl), with flocculation, sterilization and monitoring capabilities. The fluorescence intensity of TP(AM-MAP-EtFl) was measured using a fluorescence spectrophotometer, demonstrating strong performance even with an EtFl monomer mass fraction as low as 0.5 wt‰, resulting in a fluorescence intensity value of 1000 a.u., suitable for analytical detection. In flocculation experiments with simulated wastewater containing E. coli, the introduction of the fluorescent monomer did not affect E. coli flocculation. When flocculation conditions are optimized, the OD600 readings of the clear liquid remaining after treating with TP(AM-MAP-EtFl#0.5) and TP(AM-MAP-EtFl#5) are 0.0297 and 0.0457, respectively, illustrating superior sterilization effects. Interestingly, SEM and 3D-EEM results confirmed TP(AM-MAP-EtFl)’s bactericidal effect on E. coli, with the introduction of the fluorescent monomer not affecting the sterilization capability of quaternary ammonium. This work integrates flocculation, sterilization and fluorescence properties to provide sterilization-type flocculants with monitoring capabilities, enabling accurate calculation of polymer concentration by detecting solution fluorescence intensity, thereby offering potential for online detection and automatic control of water treatment systems, demonstrating good applicability.

Saline water treatment coupled with carbon dioxide capture by bipolar membrane electrodialysis in a continuous feed-bleed mode: The effect of proton leakage

Bipolar membrane electrodialysis (BMED) has emerged as a promising technology for integrating saline water treatment with CO2 capture systems. However, a significant challenge remains in the form of proton leakage, which depletes the OH− ions generated by the bipolar membrane (BPM), thereby directly hindering CO2 absorption efficiency. To unravel the underlying mechanism of proton leakage and optimize BMED performance, a continuous feed-bleed BMED system for both saline water treatment and CO2 capture was proposed. A comprehensive investigation was conducted to assess the influence of key parameters, including current density, alkalinity ion concentration, feedstock salinity, and product concentration on the extent of H+ leakage. Notably, it’s found that increasing current density from 150 to 300 A/m2, the proportion of H+ leakage through the anion exchange membrane (AEM) rose from 65.53 % to 74.77 %, while alkalinity ion concentration has a relatively minor impact. To manage the feedstock salinity and product concentration, the NaCl and H2O feeding rates were precisely regulated in this feed-bleed system. By adjusting these rates to 8–15 mL/min for NaCl and 3–8 mL/min for H2O, respectively, a notable reduction in the H+ leakage rate was achieved, from 71.37 % down to 57.97 %. Furthermore, through the integration of iterative calculations with experimental data, it was discovered that proton leakage predominantly occurs via concentration diffusion mechanisms. This insight into the intricate regulation of proton leakage not only deepens our understanding of the underlying mechanism but also provides valuable guidance for the effective deployment and optimization of BMED technology.

Application of batch electrocoagulation treatment system with aluminium electrodes for simultaneous removal of organic and heavy metal contaminants from Borneo urban rivers

The challenges of sludge management and complex water treatment systems hinder the effectiveness of chemical coagulation in treating heavily contaminated urban river water. Realizing these issues, this study aims to develop a batch electrocoagulation system using aluminum electrodes to generate in-situ aluminum hydroxide coagulants for simultaneous removal of organic contaminants and heavy metals from Borneo urban river water. Subsequent, the treatment system achieves a reduction of 91.67 % of turbidity, 98.29 % of color, 95.16 % of total suspended solids (TSS), 97.78 % of iron, 94.21 % of lead, 21.94 % of pH, and 98.58 % of chemical oxygen demand (COD) with an electric current of 5 A and a residence time of 25 min. Besides, the treated water meets the Malaysia National Water Quality Standards for Class I which making it suitable for domestic consumption. The energy consumption cost for the treatment is only RM 1.48 (USD 0.31) per cubic meter of treated water. Additionally, the analysis of the electrocoagulation flocs reveals the presence of carbon, iron, lead, and various dissolved minerals which indicates effective contaminant removal from urban river. Overall, this study demonstrates the potential of the batch electrocoagulation treatment system as an effective and cost-efficient solution for treating urban river water in Borneo industrial areas.

Modelling the predictive analysis of turbidity removal efficiency in the in-line coagulation and flocculation process

Coagulation and flocculation processes are commonly used in conventional water treatment plants to remove suspended solids from water. However, these methods often suffer from drawbacks such as high chemical consumption, sludge generation, and the need for huge areas, leading to high construction costs. To address these limitations, this study investigated the performance of in-line coagulation and flocculation processes as an alternative to conventional methods. The objectives were to determine the efficiency of in-line coagulation and flocculation, understand the underlying mechanisms, establish optimal operating conditions and design criteria, and to develop theoretical models for predicting turbidity removal efficiency in the in-line coagulation-flocculation process. Experiments were conducted using a continuous setup consisting of a static mixer and a 35-m helically coiled hydraulic tube flocculator.Various operating parameters, including water flow rate (100 – 800 L/hr), initial turbidity (20 – 200 NTU), and coagulant types (aluminum sulfate, poly aluminum chloride, aluminum chlorohydrate, and ferric chloride), were examined. The results demonstrated that aluminum sulfate was the appropriate coagulant for the water characteristics studied, and the in-line coagulation and flocculation processes achieved turbidity removal efficiencies of approximately 91 % under all operating conditions, with a notable 97 % removal efficiency achieved at a liquid flow rate of 600 L/hr, with a Gt value of 21,715 and an overflow rate of 2 m/hr. A prediction model of turbidity removal efficiency was developed, showing good agreement between experimental and predicted removal efficiency model, with an average deviation of about 20 %. This model can aid in determining optimal operating conditions and serve as a hybrid process in future water treatment systems, potentially applicable to other separation processes as well.

PH and potential-controlled multi-modal mass transport in block copolymer nanochannel membranes

Inspired by the hydrophobic gating for achieving fast and selective ion/molecular transport in cell membranes, wetting/dewetting transition in solid-state nanopores controlled by external stimuli such as voltage, pH, electrostatics, and light have attracted increasing attention. For an accurate and better understanding, a single nanopore or low-density array of nanopores was preferred to investigate the wetting and dewetting transitions owing to their well-defined chemical functions and physical structures. However, high-density nanochannel membranes capable of processing high-throughput and multi-modal mass transport are more beneficial with the aim of practical use. In this regard, pH- and potential-responsive nanochannel membranes consisting of a polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) are prepared to demonstrate a multi-modal transport system with high-throughput capability. At pH < pKa(P4VP) (pKa ∼ 4.8), the cylindrical P4VP nanodomains are hydrophilic and positively charged, acting as an anion-exchange membrane. In contrast, at pH > pKa(P4VP), the P4VP domains switch to be charge-neutral and hydrophobic, naturally blocking the mass transport through the nanochannels. Applying a sufficiently positive potential to a BCP membrane-coated electrode may induce oxidative wetting in the hydrophobic nanochannels to facilitate mass transport across the membrane with no charge-selectivity. Releasing the bias makes the hydrophobic nanochannel membranes retrieve the original dewetted state, blocking the transport again. In addition, direct observation of the wetting-dewetting transition dynamics in the hydrophobic nanochannels is investigated by monitoring potential-correlated electrochemiluminescence (ECL) signals arising from Ru(bpy)32+ and co-reactant tripropylamine (TPA) under potential modulations. ECL signals tend to decrease with increasing membrane thickness ranging from 0 nm to 820 nm because it requires higher potentials to induce wetting in the nanochannels due to elongated hydrophobic nanochannels. The multi-modal transport system developed in the present work will be useful for applications such as water treatment, biosensors, and smart valve systems like controlled drug release/delivery.

Removal of antibiotic resistant bacteria and antibiotic resistance genes by an electrochemically driven UV/chlorine process for decentralized water treatment

The UV/chlorine (UV/Cl2) process is a developing advanced oxidation process and can efficiently remove antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). However, the transportation and storage of chlorine solutions limit the application of the UV/Cl2 process, especially for decentralized water treatment. To overcome the limitation, an electrochemically driven UV/Cl2 process (E-UV/Cl2) where Cl2 can be electrochemically produced in situ from anodic oxidation of chloride (Cl−) ubiquitously present in various water matrices was evaluated in this study. >5-log inactivation of the ARB (E. coli) was achieved within 5 s of the E-UV/Cl2 process, and no photoreactivation of the ARB was observed after the treatment. In addition to the ARB, intracellular and extracellular ARGs (tetA, sul1, sul2, and ermB) could be effectively degraded (e.g., log(C0/C) > 4 for i-ARGs) within 5 min of the E-UV/Cl2 process. Atomic force microscopy showed that the most of the i-ARGs were interrupted into short fragments (< 30 nm) during the E-UV/Cl2 process, which can thus effectively prevent the self-repair of i-ARGs and the horizontal gene transfer. Modelling results showed that the abatement efficiencies of i-ARG correlated positively with the exposures of •OH, Cl2−•, and ClO• during the E-UV/Cl2 process. Due to the short treatment time (5 min) required for ARB and ARG removal, insignificant concentrations of trihalomethanes (THMs) were generated during of the E-UV/Cl2 process, and the energy consumption (EEO) of ARG removal was ∼0.20‒0.27 kWh/m3-log, which is generally comparable to that of the UV/Cl2 process (0.18–0.23 kWh/m3-log). These results demonstrate that the E-UV/Cl2 process can provide a feasible and attractive alternative to the UV/Cl2 process for ARB and ARG removal in decentralized water treatment system.

Optimizing ozone treatment for pathogen removal and disinfection by-product control for potable reuse at pilot-scale

Reclaimed water poses environmental and human health risks due to residual organic micropollutants and pathogens. Ozonation of reclaimed water to control pathogens and trace organics is an important step in advanced water treatment systems for potable reuse of reclaimed water. Ensuring efficient pathogen reduction while controlling disinfection byproducts remains a significant challenge to implementing ozonation in reclaimed water reuse applications. This study aimed to investigate ozonation conditions using a plug flow reactor (PFR) to achieve effective pathogen removal/inactivation while minimizing bromate and N-Nitrosodimethylamine (NDMA) formation. The pilot scale study was conducted using three doses of ozone (0.7, 1.0 and 1.4 ozone/total organic carbon (O3/TOC) ratio) to determine the disinfection performance using actual reclaimed water. The disinfection efficiency was assessed by measuring total coliforms, Escherichia coli (E. coli), Pepper Mild Mottle Virus (PMMoV), Tomato Brown Rugose Fruit Virus (ToBRFV) and Norovirus (HNoV). The ozone CT values ranged from 1.60 to 13.62 mg min L−1, resulting in significant reductions in pathogens and indicators. Specifically, ozone treatment led to concentration reductions of 2.46–2.89, 2.03–2.18, 0.46–1.63, 2.23–2.64 and > 4 log for total coliforms, E. coli, PMMoV, ToBRFV, and HNoV, respectively. After ozonation, concentrations of bromate and NDMA increased, reaching levels between 2.8 and 12.0 μg L−1, and 28–40.0 ng L−1, respectively, for average feed water bromide levels of 86.7 ± 1.8 μg L−1 and TOC levels of 7.2 ± 0.1 mg L−1. The increases in DBP formation were pronounced with higher ozone dosages, possibly requiring removal/control in subsequent treatment steps in some potable reuse applications.

Slow feature‐constrained decomposition autoencoder: Application to process anomaly detection and localization

SummaryDetecting anomalies in manufacturing processes is crucial for ensuring safety. However, noise significantly undermines the reliability of data‐driven anomaly detection models. To address this challenge, we propose a slow feature‐constrained decomposition autoencoder (SFC‐DAE) for anomaly detection in noisy scenarios. Considering that the process can exhibit both long‐term trends and periodic properties, the process data is decomposed into trends and cycles. The repetitive information is mitigated by slicing and randomly masking certain trends and cycles. Dependencies among slices are constructed to extract intrinsic information, while high‐frequency noise is reduced using a slow feature‐constrained loss. Anomalies are detected and localized through a reconstruction error strategy. The effectiveness of SFC‐DAE is demonstrated using data from a sugar factory and a secure water treatment system.

Superior microplastic removal and gravity-driven membrane filtration optimization: The role of octadecyl-quaternium hybrid coagulant and molecular dynamics insights

Microplastics (MPs) contamination in surface water poses significant environmental and health threats, particularly in rural areas without centralized water treatment systems. Although pre-coagulated gravity-driven membrane (GDM) is a promising decentralized drinking water treatment technology, the impact of MPs on its performance has not been clearly understood yet. In this study, octadecyl-quaternium hybrid coagulant (OQHC) is proposed as an innovative solution for the efficient removal of MPs. Specifically, the effectiveness and mechanisms of OQHC in removing MPs are investigated, and the performance of a GDM pre-coagulated with OQHC is comprehensively evaluated. The findings reveal that OQHC achieves a superior MPs removal efficiency of 93.45 % in surface water, outperforming conventional coagulants such as PACl and AlCl3. Molecular dynamics simulations suggest that OQHC primarily removes MPs through hydrophobic interactions facilitated by its long octadecyl carbon (C18) chains, with humic acid (HA) enhancing the electrostatic interactions. Furthermore, the stability and permeability of GDM filtration pre-coagulated with OQHC are influenced by the cake layer’s zeta potential in the initial stage (0–90 h) and porosity in the late stage (90–120 h). Moreover, the presence of MPs increases the quantity of particles smaller than 6 µm, resulting in lower porosity of the cake layer and steeper flux decline rates during prolonged filtration. Overall, this study establishes OQHC pre-coagulated GDM filtration as a promising approach for addressing MPs contamination in surface water, offering an efficient solution for ensuring safe drinking water in rural areas.

Multi-Scale Development and Integration of Granular Activated Carbon Electrodes in Multiphase Electrochemical Systems

Providing clean water remains a significant challenge in underserved areas that lack access to public water systems or are affected by extreme natural events like hurricanes. Electrochemical technologies show promise for developing affordable and effective water treatment systems due to their ability to efficiently oxidize contaminants. Particularly, the electrochemical synthesis of in-situ reagents, such as H2O2, systems can oxidize contaminants over the full range of pH with high oxidation potential, leaving only water and oxygen at the end of process, making it a safe and effective method for water treatment. This study is focused on integrating carbon-based electrodes into electrochemical water treatment systems emphasizing their scalability, cost effectiveness, and the efficient generation of reactive oxygen species (ROS). By employing multiscale computational approaches, we develop a comprehensive mechanistic understanding and optimization of ROS generation at the surface of granular activated carbon (GAC) electrodes. Using reactive molecular dynamics simulations, the thermodynamic and transport properties of water-based electrolyte (e.g., adsorption, viscosity, and diffusion) are investigated as a function of the GAC particle size and chemistry. The obtained results show that tuning the GAC particle structure at nanoscale can improve the local diffusion rates by three times. Subsequently, multiphase continuum simulations are used to integrate the GAC electrodes in full electrochemical systems through optimizing the dispersion and the solid-liquid-gas interactions in a reactive environment. The computational findings reveal that higher production of H2O2 and are observed at optimized electrode porosity values when the GAC electrodes are integrated at the system level. These observations are linked to the complex reactive solid-fluid interactions. Specifically, the electrochemical oxygen bubble splitting and coalescence are minimized by optimizing the electrode porosity, which improves the dispersion mass transfer processes by at least one order of magnitude. This leads to higher generation rates of ROS and enhanced degradation of water contaminants. These mechanistic observations will help in designing and scaling up carbon-based electrodes for developing efficient and cost-effective electrochemical water treatment reactors.

Unlocking the potential of carbon quantum dots: Versatile photocatalysts for methylene blue degradation—A comprehensive review of synthesis, catalytic mechanisms, and environmental applications

AbstractCarbon Quantum Dots (CQDs) are nanoscale carbon‐based particles with unique quantum properties. Because of their customizable size, optical properties, and surface functions, CQDs are frequently used in a wide range of applications. The present thorough analysis delves into the crucial function of CQDs in the photocatalytic breakdown of Methylene Blue (MB), providing valuable perspectives on their production, attributes, and catalytic processes. The effects of pH, wavelength, intensity, and other variables on the effectiveness of MB degradation are covered in detail. An analytical review of the kinetic models used to estimate the deterioration process is given. For improved stability and recyclability, the synergistic effects of CQD‐based composites and developments in catalyst immobilization techniques are examined. Prospects for the future center on reactor designs, integration into large‐scale water treatment systems, and optimization of CQD features. The research highlights the revolutionary potential of CQDs in transforming wastewater treatment and advancing environmentally sound solutions.

(Invited) Electrolysis of Liquid Dairy Cow Manure into Clean Reusable Water

Livestock wastewater management is a critical concern in the United States, with an annual production of 1.2 to 1.37 billion tons of waste, surpassing human waste by three to twenty times. This mismanagement poses significant threats to freshwater sources, ecosystems, and public health. Agriwater’s project proposes an innovative solution using electrocoagulation (EC) treatment. The EC technique is a process involving the intentional corrosion of aluminum or iron electrodes to introduce trivalent ions, facilitating the co-precipitation and coagulation of contaminants, making their removal as sludge easier. The project's primary objective is to use electrolysis to convert liquid animal waste into clean water for irrigation, drinking, and farm maintenance. This solution is vital for various farms, including those facing drought, zero-discharge, and EPA-permitted farms discharging manure into rivers. Preliminary research shows EC's potential to significantly reduce turbidity and phosphate levels in livestock wastewater, forming the basis for scalable on-site treatment. The project team, with expertise in electrolysis, wastewater treatment, and agricultural engineering, ensures the development of an industrial-grade water treatment system. This project is in collaboration with Oak Ridge National Laboratory and the University of Tennessee's Dairy Farm and addresses immediate environmental challenges that contribute to a more sustainable and responsible agricultural industry.

Photothermal ZrN composite membranes for solar-driven water distillation

Many regions around the world, including the Arabian Peninsula, face a scarcity of freshwater resources and depend heavily on non-renewable energy sources for energy-intensive desalination processes, emphasizing the need for sustainable water treatment methods. To tackle this challenge, solar energy-driven membrane distillation is a promising and compatible solution for desalinating seawater. In this work, a solar-powered photothermal air gap membrane distillation (AGMD) system has been tested to treat brine by utilizing plasmonic-based composite membranes. Polyvinylidene fluoride (PVDF) membranes were prepared by incorporating low-cost zirconium nitride (ZrN) nanoparticles at varying concentrations to facilitate solar energy harvesting. ZrN-modified PVDF composite membranes significantly boost the solar absorption up to 75 % in the wavelength range of 250–800 nm, when compared to pristine PVDF membranes. The composite membranes with 56 % enhancement in porosity resulted in a permeate flux of 0.36 L m−2 h−1 and a rejection rate of ∼99 %. The developed photothermal water treatment system provides a highly effective and scalable solution for water treatment. Moreover, next-generation materials exhibiting photothermal effects have the potential to exploit solar renewable energy for decentralized off-grid desalination by converting sunlight into heat for a unique and favourable water-energy nexus.

Quaternary Ammonium Salts-Based Materials: A Review on Environmental Toxicity, Anti-Fouling Mechanisms and Applications in Marine and Water Treatment Industries.

The adherence of pathogenic microorganisms to surfaces and their association to form antibiotic-resistant biofilms threatens public health and affects several industrial sectors with significant economic losses. For this reason, the medical, pharmaceutical and materials science communities are exploring more effective anti-fouling approaches. This review focuses on the anti-fouling properties, structure-activity relationships and environmental toxicity of quaternary ammonium salts (QAS) and, as a subclass, ionic liquid compounds. Greener alternatives such as QAS-based antimicrobial polymers with biocide release, non-fouling (i.e., PEG, zwitterions), fouling release (i.e., poly(dimethylsiloxanes), fluorocarbon) and contact killing properties are highlighted. We also report on dual-functional polymers and stimuli-responsive materials. Given the economic and environmental impacts of biofilms in submerged surfaces, we emphasize the importance of less explored QAS-based anti-fouling approaches in the marine industry and in developing efficient membranes for water treatment systems.

Impact of Flooding and Drought Risks on the Cost of Bond Financing for Water Utilities.

The global water cycle has experienced significant changes due to the interplay of climate shifts and human activities, resulting in more frequent and severe droughts and floods. These shifts have started to impact the operational efficiency of water treatment and delivery systems. This, in turn, has implications for the economic performance of these assets and the climate-impacted cost of their financing through the issuing of municipal bonds. Analyzing a decade of water bond data (2009-2019), this study offers empirical evidence for the impact of flood and drought risks on bond investor demand to offset water risks. The results reveal that bond markets factored in coastal flood risks between 2013 and 2019, adjusting by 3-6 basis points (bps) per risk score unit, and riverine flood risks from 2009 to 2013, with a 5-11 basis points increase per risk score unit. These effects were primarily driven by bonds issued in the Pacific Coast and Great Plains regions, respectively. In contrast, the pricing of drought risks in the bond market followed a more nuanced pattern. Additionally, we show the channeling effects of water consumption and investor perceptions of climate change on water risk pricing in the bond market. These findings have significant implications for water risk management in the public sector as regions with heightened water risk exposure are perceived as riskier by market participants, leading to a higher cost of capital for municipalities and water agencies.

Life cycle assesment on water treatment: Case study in Cau Do water treatment plant – Da Nang city - VietNam

Abstract Production, transportation, use, and disposal consumes resources, energy, and chemicals and causes emissions and waste, contributing to various impacts on the environment, such as heat, global warming, and acidification. Applying the Life Cycle Assessment (LCA) method can identify environmental impacts, to have solutions to control energy use and reduce waste. Research applied at Cau Do water supply plant - Da Nang city with an exploitation flow of 290,000 m3/day shows the results that the plant’s water treatment system has impacts within the allowable limits for with the geological environment in the area, but exploitation requires strict assessment to prevent possible unusual impacts. Assess the environmental impact of using electricity and chemicals in the system by estimating CO2 emissions from the electricity and chemical production process, which indirectly contribute to global warming. Direct sources of greenhouse gases come from the treatment of sludge and wastewater. The impacts discussed in this study are Global Warming, Acidification, depletion of fossil resources and Water Consumption. The amount of electricity consumed at Cau Do plant in 2018 was 16,742,752 kWh/year. The results of the analysis using the Life Cycle Assessment (LCA) method, show that the largest impact on the environment is Water Consumption 1.101 m3/m3 clean water, followed by Global Warming 0.158 kg CO2 eq/m3 Acidification 1.06 × 10−3 kg SO2 eq/m3.

Characterization of solar-derivate ultraviolet radiation for water solar treatment applications

Water resources are under increasing pressure from ever-increasing demand from industry and society. However, water is a limited resource that must be sustainable and protected. This problem is highlighted in desert areas, where water quality and abundance are scarce. Solar-powered water treatment systems are an inexpensive solution to ensure water quality for human consumption. This research analyzes solar ultraviolet radiation (UVR) in three populated Chilean cities to study the potential feasibility of the solar-powered photo-Fenton process for wastewater remediation. To generate long-term UVR values, satellite and reanalysis data and the Radiative Transfer Model were used. Results show high daily levels of solar ultraviolet irradiation, 1299.95kJm−2 for Antofagasta. The shortest treatment time for summer operation was observed in Santiago (21 min), followed by Antofagasta (34 min), and Concepción (35 min). Santiago presented the lowest volume of photoreactors during the summer (297 L) and Antofagasta during the winter (1589 L). This is the first preliminary analysis showing the possibilities of exploiting the potential of UVR in Chilean cities to provide tools for integrating water treatment technologies. This research motivates further studies on spectral radiation and emerging advanced oxidation technologies and the development of prospects for water and wastewater treatment.