Conventional Drinking Water Research Articles

Purification Resistance Index: A new water quality assessment method toward drinking water production

Water quality assessment plays a significant role in ensuring the availability of clean and safe water. The Water Quality Index (WQI) model method has been developed to provide a basis for assessing water quality by integrating various water quality parameters. However, existing WQIs do not “actively” consider the difficulty of water treatment from raw water to specific water use scenarios. This study proposes a novel model framework, named as Purification Resistance Index (PRI), quantitatively evaluating not only the exceedance of pollutants but also how difficult they can be removed in the water treatment process. The framework is built based on the conventional drinking water treatment processes, with sub-indices for coagulation-sedimentation (rc), filtration (rf), disinfection (rd), and advanced treatment (ra). The model considers appropriate weights assigned to each sub-index to calculate the purification resistance, resulting in a comprehensive index for water quality evaluation. Case studies on nationwide and citywide water source reservoirs demonstrated the applicability of PRI approach. PRI breakthrough the traditional water quality risk assessment paradigm and extents to engineering region and provide useful tools for water source supervision, drinking water treatment plant planning and updating, operation control, and other purposes. Water authority, water utility and municipal design institute will all benefit. It is open for more localized practices validation and discussion.

Siamese based few-shot learning lightweight transformer model for coagulant and disinfectant dosage simultaneous regulation

Deep learning (DL) has emerged as a transformative and promising approach to address inefficient resource management due to imprecise chemical dosing in conventional manual-dependent drinking water treatment. However, the scarcity of high-quality data and limited computing resources of embedded devices hinder the development and deployment of state-of-the-art (SOTA) DL models. Herein, a novel lightweight Transformer (LighT) model integrated with the Siamese structure was proposed for simultaneous regulation of coagulant dosage (FeCl3 and PAC) and disinfectant dosage (NaClO) and compared with other attention-based DL models. The results demonstrate that LighT showed robust few-shot learning effectiveness and outperformed other models in multi-output prediction (R2 values of 0.99 and RMSE of 0.20 mg/L, 0.16 mg/L and 0.45 mg/L, respectively). The LighT model also exhibited enhanced cost-effectiveness with a 79.74 % compression in model parameters and a 36.14 % decrease in inference time. The LighT-based chemical dosage prediction program was sustained for one month of operation, which can save chemical dosage by 15.81 % while maintaining satisfactory product water quality, indicating the potential of LighT for economizing chemical dosing strategy in drinking water treatment.

What is the Difference between Conventional Drinking Water, Potable Reuse Water, and Nonpotable Reuse Water? A Microbiome Perspective.

As water reuse applications expand, there is a need for more comprehensive means to assess water quality. Microbiome analysis could provide the ability to supplement fecal indicators and pathogen profiling toward defining a "healthy" drinking water microbiota while also providing insight into the impact of treatment and distribution. Here, we utilized 16S rRNA gene amplicon sequencing to identify signature features in the composition of microbiota across a wide spectrum of water types (potable conventional, potable reuse, and nonpotable reuse). A clear distinction was found in the composition of microbiota as a function of intended water use (e.g., potable vs nonpotable) across a very broad range of U.S. water systems at both the point of compliance (Betadisper p > 0.01; ANOSIM p < 0.01, r-stat = 0.71) and point of use (Betadisper p > 0.01; ANOSIM p < 0.01, r-stat = 0.41). Core and discriminatory analysis further served in identifying distinct differences between potable and nonpotable water microbiomes. Taxa were identified at both the phylum (Desulfobacterota, Patescibacteria, and Myxococcota) and genus (Aeromonas and NS11.12_marine_group) levels that effectively discriminated between potable and nonpotable waters, with the most discriminatory taxa being core/abundant in nonpotable waters (with few exceptions, such as Ralstonia being abundant in potable conventional waters). The approach and findings open the door to the possibility of microbial community signature profiling as a water quality monitoring approach for assessing efficacy of treatments and suitability of water for intended use/reuse application.

Enhancing nanoplastics removal by metal ion-catalyzed ozonation

Nanoplastics (NPs), characterized by sizes < 1 µm, are not completely removed in conventional drinking water treatment plants affecting human health. Catalytic ozonation appears as a promising alternative due to its ability to oxidize emerging pollutants by generating hydroxyl radicals with higher removal rate and mineralization than single ozonation. In this work, catalytic ozonation was investigated for the removal of polystyrene nanoplastics (PSNPs) by employing transition metal ion catalysts, Fe3+, Co2+, Ni2+, and Zn2+. The single ozonation of PSNPs, in the absence of catalyst, led to low turbidity reduction (33 %) and low mineralization rate (16 %) even after 2 h reaction time. Nevertheless, the rapid size reduction of PSNPs by >99 % in less than 5 min of ozonation (TOD: 30 mg L−1) was confirmed. This fact could imply a new issue under the ozone disinfection conditions by the formation of smaller-size particles. However, in the presence of Co2+ (1 mM), the highest PSNPs ozonation performance was achieved, decreasing the turbidity up to 65 % and achieving 70 % of mineralization in the same ozonation time. The scavenger experiments with methanol confirmed that direct ozonation and catalyst role were responsible for PSNPs degradation, with the generation of •OH being the most dominant catalytic mechanism. Therefore, although single ozonation at disinfection doses reduced the particle size of PSNPs, the catalytic process demonstrated greater efficacy in the total removal of PSNPs. These results highlight the need to further investigate ozonation of NPs intermediates, and the synergic improvements of catalytic ozonation for their mineralization.

Ultrafiltration and reverse osmosis integrated to conventional drinking water treatment to ensure human right to water in dam break scenarios: From bench- to pilot-scale

Previous events of tailing dam failures were associated with impacts in the water sources of drinking water treatment plants, which involves elevated concentrations of suspended solids and metal(oid)s. This study assesses the effectiveness of conventional treatment processes at a lab-scale, highlighting their limited robustness in treating water with different physicochemical qualities. Subsequently, it validates the integration of ultrafiltration (UF) and reverse osmosis (RO) into an existing water treatment plant to enhance its performance. The processes were conducted at a pilot scale, operating for 660 h under varied turbidity (<2 – 200 NTU) and contaminant (iron, manganese, and arsenic) concentrations. The membranes operated steadily with an average permeate flux of 38.6 ± 0.9 L/m2h and 19.6 ± 0.8 L/m2h for UF and RO, respectively. UF fouling was primarily related to internal pore blocking and attributed to organic matter and inorganic compounds, identified using excitation-emission matrix and energy-dispersive X-ray mapping across the cross-section of its fibers. Due to the limitations of UF in removing dissolved species, RO became necessary and ensured that all parameters analyzed met drinking water standards. The UF-RO contributes to higher robustness to conventional treatment processes and addresses operational challenges associated with a dam rupture event such as the unforeseen alteration in the quality of surface water that hinders the optimization of pre-oxidants and coagulants in conventional treatment process. To reduce costs, energy requirements, and the size of membrane-based systems, a blending strategy was proposed with a focus on achieving drinking water standards. The suggested blends include effluent from sand filters and RO permeate in a 1:1 ratio. That was only possible due to the high quality achieved for RO permeate. Apart from creating more compact systems, the blending strategy promotes the remineralization of RO permeate, mitigating undesirable characteristics such as corrosiveness, taste, and odor. For the concentrate, UF concentrate could be recycled back into the treatment process, improving water recovery in the drinking water facility, while the concentrate from RO adheres to discharge limits. Overall, the study advances investigations on integrating ultrafiltration and reverse osmosis with conventional drinking water treatment to address water quality issues from tailing dam ruptures.

Is conventional drinking water treatment more economically viable than ultrafiltration in Brazil? A technical, economic, comparative study with risk assessment

Is conventional drinking water treatment more economically viable than ultrafiltration in Brazil? A technical, economic, comparative study with risk assessment

Identification and assessment of Critical parameters affecting drinking water quality: A case study of water treatment plants of India

Water-borne diseases are common in India and are mostly brought on by shortages and poor quality of potable water. Watercourses receive many effluents, generally residential sewage, due to inadequate sanitation and wastewater treatment. Hence, drinking water treatment plants (DWTPs) face difficulties in meeting the drinking water standards. The current study evaluated the water quality before and after the conventional drinking water treatment process. The water quality was analyzed every month from three major DWTPs in Guwahati, Assam, India for one year. The study showed significant variation in river water turbidity and pathogen levels. During monsoon, river water turbidity reached up to 470 ± 20 NTU, and an increase in pathogen concentration was observed during the dry seasons at low flow conditions. Many times, drinking water turbidity and MPN values exceeded the BIS guideline value in drinking water. The total organic carbon (TOC), one major precursor of disinfection by-products observed in treated drinking water, was found to be in a higher range in water before and after treatment. After treatment, the TOC of (3.25 ± 0.5 mg/L) was found. For better understanding, the water quality was evaluated using the Modified Entropy-weight Water Quality Index (MEWQI) which showed very poor status in the raw water collected from the river Brahmaputra. While the plant's water quality after treatment varied in the category of fair to very good in certain months of the year, but never excellent quality was achieved in any of the selected plants. The results of the sensitivity analysis suggest that turbidity and MPN exhibit the greatest contribution to the WQI of raw water followed by TOC in drinking water. By providing accurate water quality data, this study benefits researchers, policymakers, and water scientists. It also facilitates the adoption of clean production methods to mitigate pollution and enhance water quality.

Bacterial assembly and succession patterns in conventional and advanced drinking water systems: From source to tap

Bacteria are pivotal to drinking water treatment and public health. However, the mechanisms of bacterial assembly and their impact on species coexistence remain largely unexplored. This study explored the assembly and succession of bacterial communities in two full-scale drinking water systems over one year. We observed a decline in bacterial biomass, diversity, and co-occurrence network complexity along the treatment processes, except for the biological activated carbon filtration stage. The conventional plant showed higher bacterial diversity than the advanced plant, despite similar bacterial concentrations and better removal efficiency. The biological activated carbon filter exhibited high phylogenetic diversity, indicating enhanced bacterial metabolic functionality for organic matter removal. Chlorination inactivated most bacteria but favored some chlorination-resistant and potentially pathogenic species, such as Burkholderia, Bosea, Brevundimonas, and Acinetobacter. Moreover, the spatiotemporal dynamics of the bacterial continuum were primarily driven by stochastic processes, explaining more than 78% of the relative importance. The advanced plant’s bacterial community was less influenced by dispersal limitation and more by homogeneous selection. The stochastic process regulated bacterial diversity and influenced the complexity of the species co-occurrence network. These findings deepen our understanding of microbial ecological mechanisms and species interactions, offering insights for enhancing hygienic safety in drinking water systems.

The effectiveness and feasibility of ball-milled powdered activated carbon (BPAC) for removal of organic pesticides in conventional drinking water treatment process

In the conventional drinking water treatment process (CDWTP), powdered activated carbon (PAC) is commonly used for removing organic pesticides, or other organic contaminants. However, the hydraulic retention time (HRT) in CDWTP is insufficient for fulfilling PAC adsorption equilibrium to realize its full capacity. This study examined the adsorption kinetics, adsorption thermal dynamics, and removal efficiency for six organic pesticides using the ball-milled PAC (BPAC) with varying particle sizes in CDWTP. Based on the experiments with the pesticides of atrazine, diazinon, dimethoate, fenitrothion, isoproturon and thiometon, the results indicated that as the particle size reduced from around 38 μm for the commercial PAC to 1 μm for the BPAC, the adsorption rates for hydrophobic pesticides increased up to twentyfold. Diffusional adsorption from the bulk solution to the external PAC surface is the most likely predominant mechanism. This could allow a sufficient pesticides’ adsorption within the limited HRT and to achieve a great depth removal of these toxic compounds. However, the addition of BPAC with a diameter of 1 μm was observed to significantly increase residual particles in treated water after the conventional treatment process. With a further systematic evaluation of both adsorption rate and particle penetration, a particle size of around 6 μm BPAC was considered a practical compromise between the adsorption rate and particle penetration for real application. Results from five surface waters of different water quality indicated that, compared to commercial PAC, application of 6 μm BPAC could achieve up to a 75% reduction in adsorbent dosage while maintaining around the same pesticide removal efficiencies. Additionally, thermodynamic analyses suggest that adsorption of these pesticides could be enthalpically or entropically driven depending on the degree of pesticide hydrophobicity.

Determination of oxidation rate constant for nodularin‐r, saxitoxin, dc‐saxitoxin, and neo‐saxitoxin with conventional water treatment plant oxidants and advanced oxidation processes

AbstractThe effectiveness of chemical oxidation depends on the type of cyanotoxins present in the water and varies with the water quality parameters. This study investigated four cyanotoxins to understand their reactions with conventional drinking water treatment plant oxidants and with advanced oxidation. Kinetic rate constants between saxitoxin, and two variants (dcSTX and neoSTX), and nodularin‐R with chlorine, monochloramine, permanganate, ozone, and hydroxyl radicals (UV‐H2O2) were developed under different pH and temperature conditions. Nodularin‐R kinetic rate constants were comparable to peer‐reviewed microcystin‐LR rate constants with reaction rates in the order of OH radicals &gt; ozone &gt;&gt; chlorine &gt; permanganate &gt;&gt; monochloramine. The speciation of saxitoxins with pH had a dominant effect on their reaction rates with the listed oxidants. Chlorine was the only oxidant effective for saxitoxins removal. The reaction rates of saxitoxins with OH radicals varied slightly with pH but were around two orders of magnitude less than microcystin‐LR's.

Applying Recurrent Neural Networks and Blocked Cross-Validation to Model Conventional Drinking Water Treatment Processes

The jar test is the current standard method for predicting the performance of a conventional drinking water treatment (DWT) process and optimizing the coagulant dose. This test is time-consuming and requires human intervention, meaning it is infeasible for making continuous process predictions. As a potential alternative, we developed a machine learning (ML) model from historical DWT plant data that can operate continuously using real-time sensor data without human intervention for predicting clarified water turbidity 15 min in advance. We evaluated three types of models: multilayer perceptron (MLP), the long short-term memory (LSTM) recurrent neural network (RNN), and the gated recurrent unit (GRU) RNN. We also employed two training methodologies: the commonly used holdout method and the theoretically correct blocked cross-validation (BCV) method. We found that the RNN with GRU was the best model type overall and achieved a mean absolute error on an independent production set of as low as 0.044 NTU. We further found that models trained using BCV typically achieve errors equal to or lower than their counterparts trained using holdout. These results suggest that RNNs trained using BCV are superior for the development of ML models for DWT processes compared to those reported in earlier literature.

Impact of harmful algal bloom severity on bacterial communities in a full-scale biological filtration system for drinking water treatment

The occurrence of harmful algal blooms (HABs) in freshwater environments has been expanded worldwide with growing frequency and severity. HABs can pose a threat to public water supplies, raising concerns about safety of treated water. Many studies have provided valuable information about the impacts of HABs and management strategies on the early-stage treatment processes (e.g., pre-oxidation and coagulation/flocculation) in conventional drinking water treatment plants (DWTPs). However, the potential effect of HAB-impacted water in the granular media filtration has not been well studied. Biologically-active filters (BAFs), which are used in drinking water treatment and rely largely on bacterial community interactions, have not been examined during HABs in full-scale DWTPs. In this study, we assessed the bacterial community structure of BAFs, functional profiles, assembly processes, and bio-interactions in the community during both severe and mild HABs. Our findings indicate that bacterial diversity in BAFs significantly decreases during severe HABs due to the predominance of bloom-associated bacteria (e.g., Spingopyxis, Porphyrobacter, and Sphingomonas). The excitation-emission matrix combined with parallel factor analysis (EEM-PARAFAC) confirmed that filter influent affected by the severe HAB contained a higher portion of protein-like substances than filter influent samples during a mild bloom. In addition, BAF community functions showed increases in metabolisms associated with intracellular algal organic matter (AOM), such as lipids and amino acids, during severe HABs. Further ecological process and network analyses revealed that severe HAB, accompanied by the abundance of bloom-associated taxa and increased nutrient availability, led to not only strong stochastic processes in the assembly process, but also a bacterial community with lower complexity in BAFs. Overall, this study provides deeper insights into BAF bacterial community structure, function, and assembly in response to HABs.

Is monochloramine pre-oxidation a viable strategy for enhancing the treatment efficiency of algae-laden water with conventional drinking water treatment process?

Algal blooms worldwide pose many challenges to drinking water production. Pre-oxidation with NaClO, KMnO4, or ozone is commonly used to enhance algal removal in conventional drinking water treatment processes. However, these currently utilized oxidation methods often result in significant algal cell lysis or impede the operation of the subsequent units. Higher algal removal with pre-chlorination in algal solutions prepared with natural water, compared to those prepared with ultrapure water, has been observed. In the present studies, preliminary findings indicate that ammonium in natural water alters chlorine species to NH2Cl, leading to improved treatment efficiency. NH2Cl with 1.5–3.0 mg∙L−1 as Cl2 with an oxidation time of 3–7 h significantly enhancing algal removal by coagulation. The selective oxidation of surface-absorbed organic matter (S-AOM) by NH2Cl, followed by the subsequent peeling off of this material from the algal surface, leading to an increase in zeta potential from −20.2 mV to −3.8 mV, constitutes the primary mechanism of enhanced algal removal through coagulation. These peeled S-AOM retained their large molecular weight and acted as polymer aids. Compared with NaClO and KMnO4, NH2Cl displays the best performance in improving algal removal, avoiding cell lysis, and decreasing the potential for nitrogenous disinfection byproducts formation under the reaction conditions used in this study. Notably, in major Chinese cities, water purification plants commonly rely on suburban lakes or reservoirs as water sources, necessitating the transportation of raw water over long distances for times up to several hours. These conditions favor the implementation of NH2Cl pre-oxidation. The collective results indicate the potential of NH2Cl oxidation as a viable pretreatment strategy for algal contamination during water treatment processes.

Study on Conventional Drinking Water Treatment for Removing Emerging Contaminants: A Literature Review

Emerging contaminants (ECs) are substances that can be synthetic or natural, or even microorganisms that are usually not monitored in the environment and could be harmful to the environment and human health. These chemicals can include pharmaceuticals, such as ibuprofen and acetaminophen, and industrial chemicals, e.g., perfluorooctanoic acid (PFOA). Common conventional drinking water treatment plants (CDWTP) are not designed to remove emerging contaminants, so these compounds can enter the water system and affect the drinking water treatment process. This study aims to focus on the performance of CDWTP in removing ibuprofen, acetaminophen, and PFOA parameters, as well as determine suitable water treatment units to eliminate these parameters from the system. An extensive literature review was conducted and further analysed using descriptive and qualitative analysis to understand the unit performance in removing emerging contaminants, followed by the simple simulation to determine the types of advanced drinking water treatment facilities that perform better in eliminating ECs. The results show that CDWTP could reduce ibuprofen concentration in water with 40%, 20%, and 36% efficiency through coagulation-flocculation, sand filtration, and disinfection, respectively. Acetaminophen removal is up to 67%, 51%, and 66.45% during coagulation-flocculation, sand filtration, and disinfection, respectively. However, PFOA removal is only up to 5%, 7%, and 2% during coagulation-flocculation, sand filtration, and disinfection, respectively. Membrane treatment technology with reverse osmosis could remove ibuprofen, acetaminophen, and PFOA compounds more effectively with removal efficiencies of 99.99%, 96%, and 100%, respectively.

Removal of dissolved organic matter via a combination of UV/persulfate oxidation and biological activated carbon (BAC) process

The combination process of UV/peroxydisulfate (UV/PDS) oxidation and BAC (UV/PDS-BAC) is examined as an advanced treatment for conventional drinking water treatment through a continuous flow experimental apparatus with actual sand filter effluent as feed water. The effect of three key parameters (UV dosage, PDS dosage, and water temperature) on dissolved organic matter (DOM) is evaluated via long-term monitoring data. The removal behavior of DOM in the UV/PDS-BAC process is also compared with that in the O3-BAC process. Further, this study delves into the mechanisms behind the enhanced DOM removal achieved by UV/PDS-BAC. The achieved results reveal that impressive removal rates of 42.1 % for total organic carbon (TOC) and 62.9 % for UV254 could be achieved in the presence of specific conditions: a UV input of 200 mJ/cm2 and a PDS dosage of 0.5 mM. The efficiency of DOM removal by UV/PDS-BAC exhibits a positive correlation with the UV dosage ranging from 50 to 200 mJ/cm2, and the water temperature in the range of 4–30 ℃. While increasing the PDS dosage from 0.01 to 0.5 mM results in improved DOM removal, any further increase yields reduced removal efficiency. In comparison, subjected to similar operating conditions, UV/PDS-BAC outperforms O3-BAC in removing DOM. The superior DOM removal achieved by the UV/PDS-BAC process can be essentially attributed to several factors: firstly, it exhibits excellent mineralization capacity for low molecular weight organics (<1 kDa) and leads to increased biodegradable fraction of organics by oxidatively degrading DOM with a molecular weight >3 kDa. Secondly, the appropriate exposure of activated carbon pores is chiefly maintained by suitably controlling the biomass. Lastly, the enhanced biodegradability of BAC influent stimulated the growth of bacteria proficient in degrading DOM.

An XAS study of Hg(II) sorption to Al-based drinking water treatment residuals

Drinking water treatment residuals (DWTRs) are produced from the coagulation and flocculation processes in conventional drinking water treatment. The abundant metal oxide content of these materials resulting from the use of coagulants, like alum and ferric chloride, has driven strong research interest into the reuse of DWTRs as sorptive materials. Using a suite of aluminum-based DWTRs, we provide new insights into Hg(II) sorption mechanisms. Experiments performed at circum-neutral pH show that sorption capacities are related to the amount of organic carbon/matter present in DWTRs. We found that carbon rich samples can scavenge about 9000 mg/kg of Hg, in contrast to 2000 mg/kg for lime based DWTRs. X-ray absorption spectroscopy (XAS) at the Hg L3 edge further characterizes mercury coordination. X-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) results point to a partial association of mercury with sulfur at low mass loadings, transitioning to a full association with oxygen/carbon at higher concentrations of sorbed Hg(II) and in DWTRs with limited sulfur content. These results suggest that sorption of Hg(II) is primarily controlled by the carbon/organic matter fraction of DWTRs, but not by the coagulants.

Efficiency of coagulation-flocculation and chlorination processes in the removal of endosulfan from water sources

ABSTRACT In this study, the efficiency of conventional drinking water treatment processes (coagulation-flocculation and chlorination) for endosulfan removal and metabolite formation were investigated. Taguchi experimental design and analysis of variance (ANOVA) were applied using Minitab program. The highest removal efficiency was obtained as 65% at 6 mg/L initial endosulfan concentration, 30 mg/L aluminium sulfate dose and pH 7, in the coagulation-flocculation experiments. In chlorination experiments, it was determined that the variables of initial endosulfan concentration, chlorine dose, pH and contact time contributed 55.84%, 21.25%, 5.74% and 3.48% to the endosulfan removal, respectively, according to the ANOVA results. The presence of endosulfan metabolites like endosulfan ether, sulfate, and lactone were also detected and measured. P values were obtained only in endosulfan sulfate formation as a result of chlorination, lower than 0.05 for initial endosulfan concentration, chlorine dose and time parameters; apart from this, P values were not statistically significant in all other experiments.

Improving conventional household greensand treatment for efficient Mn(II) removal from drinking water

Geogenic contaminants pose a global threat to ensuring access to safe drinking water. Manganese (Mn) is a naturally-occurring redox-active element which in its reduced form, Mn(II), is a widespread groundwater contaminant. Prolonged consumption of water containing high levels of Mn has been linked to adverse effects on memory, attention, motor skills, and nervous system function, particularly in vulnerable groups including pregnant individuals and young children. In addition, Mn can lead to aesthetic issues such as altered taste, clogging, and damage to plumbing systems. While Mn has historically been regulated as an aesthetic concern, a mounting body of evidence linking health issues to Mn exposure through drinking water has heightened the challenges of using groundwater to meet drinking water needs. Recently, Health Canada established a health guideline which set a maximum acceptable concentration for total Mn in drinking water of 120 μg/L. Greensand (GS) filters are commonly used in conventional drinking water treatment systems for Mn(II) removal due to their cost-effectiveness and high exchange capacity. However, under certain conditions conventional GS systems may have a low Mn(II) removal efficiency (Galangashi et al. 2021) and encounter challenges related to Mn leaching (Outram et al. 2018), resulting in failure to meet health-related standards. Furthermore, GS filters typically undergo regeneration using potassium permanganate (KMnO4), a mild oxidant that results in the release of additional Mn waste byproducts during the regeneration of the filter. Recent research suggests that Mn-containing materials can effectively activate peroxymonosulfate (PMS) and produce reactive oxygen species (ROS) that facilitate contaminant degradation. This study aims to investigate whether PMS may be used to improve greensand treatment systems and enhance Mn(II) removal from drinking water. Batch experiments were performed to test the Mn(II) removal efficiency across a range of PMS concentrations (0-500 μM) and GS mass (0.1-3 g). Aqueous Mn concentrations were measured over time using inductively coupled plasma optical emission spectrometry (ICP-OES). Solid-phase reaction products were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The mechanisms of Mn oxidation were identified by quenching experiments and electron paramagnetic resonance (EPR) spectroscopy. The activation of PMS by greensand significantly increased the removal efficiency of Mn(II) compared to the conventional method (e.g., 96.83(±3.77)% at PMS = 500 µM vs. 5.77(±11.1)% at PMS = 0 µM). Our results attribute the mechanism underlying increased Mn removal in our improved treatment method to advanced oxidation processes that involve free radicals (e.g., hydroxyl radical (·OH) and sulfate radical (SO4·-)) and non-free radical pathways, with Mn oxides as the main oxidation products. This study provides a new treatment method for more efficient Mn(II) removal while simultaneously reducing Mn wastes produced during the regeneration cycle which allows for a more sustainable and holistic management of invaluable groundwater resources.

Is Genotoxicity Associated with Disinfection Byproducts in Potable Reuse and Conventional Drinking Water Additive?

Is Genotoxicity Associated with Disinfection Byproducts in Potable Reuse and Conventional Drinking Water Additive?

Consumo de agua embotellada en México ante una economía circular

The objective is to analyse bottled water consumption in Mexico in view of a circular economy. The paper evaluates the rates of bottled water consumption and the key causal factors. Furthermore, it compares the role played by the private and public sectors in exacerbating demand for bottled water. The paper implemented a systematic review that identified articles mainly from the Web of Science and Scopus databases from November 01 to December 31, 2022. There were utilised three strategies for the search process, including keying in free-text words, implementing Boolean operators, and citation searching. The systematic review was conducted in line with the PRISMA statement/methodology. Forty-eight articles were identified after the complete search. The summations direct that bottled water consumption is high in Mexico due to the below-par conventional drinking water supply. Most customers cited organoleptic and health reasons as key factors influencing their preference for bottled drinking water. Conversely, the demand for bottled water contributes to high Polyethylene Terephthalate bottles, which contribute to environmental degradation. The implementation of the circular economy can reduce the associated negative effects through decreasing and optimization strategies. There were conglomerates findings from various articles while defining the key gaps and areas for improvement. The paper is seminal in bridging the dearth of knowledge on the circular economy and its application in the water industry while providing recommendations for policymakers.