Drinking Water Treatment Plants Research Articles

Pepper mild mottle virus intended for use as a process indicator for drinking water treatment: Present forms and quantitative relations to norovirus and rotavirus in surface water

Pepper mild mottle virus (PMMoV) has been proposed as a potential indicator of human enteric viruses in environmental water and for viral removal during drinking water treatment. To investigate the occurrence and present forms of PMMoV and quantitative relations to norovirus GII and rotavirus A (RVA) in surface waters, 147 source water samples were collected from 21 drinking water treatment plants (DWTPs) in Japan between January 2018 and January 2021, and the concentrations of viruses in suspended and dissolved fractions were measured using real-time RT-PCR. PMMoV was detected in 81–100 % of samples in each sample month and observed concentrations ranged from 3.0 to 7.0 log10 copies/L. The concentrations of PMMoV were higher in dissolved fraction compared to suspended fractions, while different partitioning was observed for NoV GII depending on seasons. The concentrations of PMMoV were basically higher than those of norovirus GII (1.9−5.3 log10 copies/L) and RVA (1.9−6.6 log10 copies/L), while in 18 samples, RVA presented higher concentrations than PMMoV. Partial regions of VP7, VP4, and VP6 of the RVA in the 18 samples were amplified using nested PCR, and the genotypes were determined using an amplicon-based next-generation sequencing approach. We found that these source water samples included not only human RVA but also various animal RVA and high genetic diversity due to the existence of animal RVA was associated with a higher RVA concentration than PMMoV. Our findings suggest that PMMoV can be used as an indicator of norovirus GII and human RVA in drinking water sources and that the indicator performance should be evaluated by comparing to zoonotic viruses as well as human viruses.

Phosphate adsorption on dried alum sludge: Modeling and application to treatment of dairy effluents

This study evaluates Alum sludge from drinking water treatment plants for the efficient and cost-effective removal of phosphates from aqueous solutions. Extensive characterization and batch experiments have established that optimal phosphate removal was achieved with a sludge dosage of 20 g L−1 (at an initial phosphate concentration of 100 mg L−1), a pH of 5, a temperature of 23 °C, and a stirring speed of 200 rpm. These conditions significantly reduced phosphate levels, ensuring compliance with legal discharge limits. The Langmuir isotherm, pseudo-second-order kinetic and intraparticle diffusion models best described the adsorption process, highlighting the spontaneous and endothermic nature of the phenomenon. The sludge effectively reduced phosphate concentrations to acceptable levels when applied to dairy effluents. This study underscores the potential of Alum sludge as a viable solution for phosphate management in environmental cleanup efforts.

Technical and economic impact of water reuse as an integrated water resource management measure in rural water supply systems

ABSTRACT Water reuse becomes an alternative in the conventional water supply systems, especially in regions where nonpotable use of drinking water, as for garden and grass irrigation, is predominant. This study evaluates the footprint of reuse on small water supply systems in rural areas, where raw water quality does not meet the drinking water standards, and complicated treatment is needed. Individual facilities for the reuse of potential rainwater, light gray, gray, and domestic wastewater in the households could lead to a decrease in nonpotable tap water use up to 60% and a decrease in households' annual expenses for water supply up to 93 €/household. The installation of individual facilities for common reuse of rainwater and gray wastewater requires the highest investment costs, but the optioǹs operational costs are between 15 and 20% lower than all other options considered. The drinking water treatment plant capacity reduction due to measures’ implementation enables from 48 up to 58% saving in the total operational costs for drinking water supply in the settlement. The shortest payback period and best economic impact of reuse for small-scale water supply systems are observed if rainwater and gray wastewater are reused together.

A group of emerging heterocyclic nitrogenous disinfection byproducts: Formation and cytotoxicity of halopyridinols in drinking water

Recently, a new group of halopyridinol disinfection byproducts (DBPs) was reported in drinking water. The in vivo developmental and acute toxicity assays have shown that they were more toxic than a few commonly known aliphatic DBPs such as bromoform and iodoacetic acid. However, many pyridinol DBPs with the same main structures but different halogen substitutions were still unknown due to complicated water quality conditions and various disinfection methods applied in drinking water treatment plants. Studies on their transformation mechanisms in drinking water disinfection were quite limited. In this study, comprehensive detection and identification of halopyridinols were conducted, and five new halopyridinols were first reported, including 2-chloro-3-pyridinol, 2,6-dichloro-3-pyridinol, 2-bromo-5-chloro-3-pyridinol, 2,4,6-trichloro-3-pyridinol and 2,5,6-trichloro-3-pyridinol. Formation conditions and mechanisms of the halopyridinols were explored, and results showed that chlorination promoted their formation compared with chloramination. Halopyridinols were intermediate DBPs that could undergo further transformation/degradation with increasing contact time, disinfectant dose, bromide concentration, and pH. The in vitro cytotoxicity of the halopyridinols was evaluated using human hepatocellular carcinoma cells. Results showed that the cytotoxicity of 3,5,6-trichloro-2-pyridinol was the highest (EC50 = 474.3μM), which was 13.0 and 1.6 times higher than that of 2-bromo-3-pyridinol (EC50 = 6214.5μM) and tribromomethane (EC50 = 753.6μM), respectively. Environmental ImplicationThis study first reported the detection and identification of five new halopyridinol disinfection byproducts (DBPs) in drinking water. Formation of these new halopyridinol DBP under various source water conditions and disinfection scenarios was explored. Furthermore, the relationship between the structure of halopyridinols and their cytotoxicity was elucidated, providing insights for priority control of high-risk DBPs.

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. Environmental ImplicationsOur findings proffer invaluable insights into the critical role of drinking water treatment plants in providing safe and potable water to the public health. They contribute to the deeper understanding of microbial ecological mechanisms and species interactions, providing valuable strategies to improve hygienic safety in drinking water systems.

Secondary risks induced by polyethylene microplastics during the disinfection processes of chlorination, UV irradiation, and ozone treatment

Abstract The presence of microplastics in surface waters poses potential hazards to both organisms and human health. Traditional water treatment processes have proven to be inadequate in effectively removing microplastics. Besides, previous studies have often utilized disinfectant dosages that surpass those commonly employed in drinking water treatment plants (DWTPs), and the biotoxicity changes induced by microplastics after disinfection remain largely unexplored. To address these knowledge gaps, our study aimed to investigate the impact of practical disinfectant dosages on the leaching of organic compounds from microplastics and the formation of disinfection byproducts (DBPs). Furthermore, the resulting acute and genetic toxicity was evaluated through bioassays. Our findings revealed an elevated release of dissolved organic matter (DOM) derived from microplastics. Additionally, both acute and genetic toxicity increased following various disinfection processes. Specifically, chlorination exhibited the highest level of toxicity in short-term disinfection, while the pretreatment of ozonation followed by residual chlorination demonstrated the highest toxicity in the long-term disinfection, which was correlated with the concentration of CHCl3 formed. These findings will advance our understanding of the potential risks associated with microplastics during various disinfection processes, with the ultimate goal of safeguarding water supplies.

Thorough Validation of Optimized Size Exclusion Chromatography-Total Organic Carbon Analysis for Natural Organic Matter in Fresh Waters.

Size exclusion chromatography with total organic carbon detection (HPSEC-TOC) is a widely employed technique for characterizing aquatic natural organic matter (NOM) into high, medium, and low molecular weight fractions. This study validates the suitability of HPSEC-TOC for a simplified yet efficient routine analysis of freshwater and its application within drinking water treatment plants. The investigation highlights key procedural considerations for optimal results and shows the importance of sample preservation by refrigeration with a maximum storage duration of two weeks. Prior to analysis, the removal of inorganic carbon is essential, which is achieved without altering the NOM composition through sample acidification to pH 6 and subsequent N2-purging. The chromatographic separation employs a preparative TSK HW-50S column to achieve a limit of detection of 19.0 µgC dm-3 with an injection volume of 1350 mm-3. The method demonstrates linearity up to 10,000 µgC dm-3. Precision, trueness and recovery assessments are conducted using certified reference materials, model compounds, and real water samples. The relative measurement uncertainty in routine analysis ranges from 3.22% to 5.17%, while the measurement uncertainty on the bias is 8.73%. Overall, the HPSEC-TOC represents a reliable tool for NOM fractions analysis in both treated and untreated ground and surface water.

Characteristics of particle formation in O3-UBAC filter and effects of operational parameter on particles

The ozone oxidation and up-flow biological activated carbon (O3-UBAC) process has been recognized for its ability to extend the operating cycle of biological activated carbon (BAC) filters by expanding the carbon layer and maintaining a dynamic balance of the carbon biofilm. However, the primary focus of O3-UBAC is the removal of organic pollutants, often overlooking the treatment of particles. To address this gap, a pilot-scale study was conducted using sedimentation basin effluent samples from a drinking water treatment plant (DWTP), which were added into BAC columns. The study aimed to investigate the seasonal variation of effluent particles during the UBAC operating cycle, including particle counts, size distribution, and mass composition. Based on particle characteristics and the combined effects of adsorption and biodegradation, the UBAC operation cycle was divided into three periods. Results revealed that hydraulic impacts and biofilm desorption on carbon could increase the proportion of particles >5 μm in effluent. Pre-ozonation demonstrated significant effects on particle counts and Heterotrophic Plate Count (HPC) levels (p < 0.05), with the addition of 1 mg/L O3 resulting in a reduction in particle counts in the effluent. Moreover, particle removal could be achieved by adjusting the upward flow velocity, necessitating comprehensive consideration of pollutants. Furthermore, microbial community analysis under optimal operating conditions unveiled significant changes in the microbial diversity of UBAC-treated water particles. Although the influent and effluent exhibited similarities at different phylum levels, the dominant bacteria differed significantly at various levels.

Ferrate as a sustainable and effective solution to cope with drinking water treatment plants challenges

Surface water quality is declining due to climate change, leading to increased concentrations of soluble metals, natural organic matter (NOM), turbidity, and algal blooms. These changes pose challenges to traditional water treatment plants, needing innovative approaches. Ferrate(VI) was explored as a potential solution to address climate change-related water emergencies, either alone or in combination with conventional reagents to producing potable water. Resultsshow that Fe(VI) was more effective to remove soluble manganese compared to a conventional oxidant (permanganate), while requiring a lower stoichiometric dosage (<2 mol of Fe(VI) per 3 mol of Mn(II)) as the reaction byproducts of Fe(VI) reduction (eg., Fe3+) contributed to manganese removal. A slightly alkaline environment (pH >8.5) was crucial to maximize manganese oxidation since pH closer to neutral caused the reduction of Fe(VI) to Fe(III), thus decreasing its reduction potential. Fe(VI) was also effective toward NOM although its activation was necessary to provide noticeable effects. In combination to conventional coagulant/flocculant agents, Fe(VI) was able to provide noticeable increases in removal of turbidity (<0.30 NTU) while involving a simultaneous decrease in other chemicals requirement (>50 %). Besides, Fe(VI) was also capable of providing algae removal of approximately 80 % higher than conventional oxidizing agent, through simultaneous oxidation and flocculation.This study demonstrated that employing Fe(VI) as a treatment method for drinking water is very promising as it can serve as an alternative or complement conventional approaches in tackling the challenges presented by climate change and sustaining high-quality standard potable water.

Detection and characterisation of microplastics in tap water from Gauteng, South Africa

This study reports the presence, concentration, and characteristics of microplastics (MPs) in tap water in three suburbs in Gauteng Province in South Africa. Physical characterisation was conducted using stereomicroscopy and scanning electron microscopy following staining of MPs with the Rose Bengal dye. The concentrations of MPs in all samples ranged from 4.7 to 31 particles/L, with a mean of 14 ± 5.6 particles/L. Small-sized (<1 mm) and fibrous-shaped MPs were most abundant in all samples. Fibers accounted for 83.1% of MPs in samples from all the three areas, followed by fragments (12.4%), pellets/beads (3.1%), and films (1.5%), with a minor variation in the distribution of shapes and sizes in samples from each area. Raman microspectroscopy was used for chemical analysis, and five polymers were identified, namely: high-density polyethylene, polyurethane, polyethylene terephthalate, poly(hexamethylene terephtalamide), and poly(acrylamide-co-acrylic acid). C.I Pigment Red 1, C.I. Solvent Yellow 4, Potassium indigotetrasulphonate, and C.I Pigment Black 7 were the colourants detected. These colourants are carcinogenic and mutagenic and are potentially toxic to humans. The prevalence of MPs in tap water implies their inadequate removal during water treatment. For instance, the presence of poly(AM-co-AA) suggests that drinking water treatment plants may be a potential source of MPs in tap water. Other polymers, e.g., high-density polyethylene may be released from pipes during the transportation of drinking water. The estimated daily consumption of MPs from tap water was 1.2, 0.71, and 0.50 particles/kg.day for children, men, and women, respectively. The findings of this study provide evidence of the presence of MPs in drinking water in South Africa, thus giving some insights into the performance of treatment plants in removing these contaminants and a benchmark for the formulation of standard limits for the amount of MPs in drinking water.

Occurrence and health risk assessment of organic amine pesticides in drinking water of the Yangtze River delta urban agglomeration

Organic amine pesticides (OAPs) are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways. However, there is a lack of data on the occurrence of OAPs in drinking water and their potential human health risks. In this study, tap water (TW) and bottled water (BW) samples were collected from eight cities in the Yangtze River Delta urban agglomeration in China, and their OAP levels were analyzed using high-throughput organic analysis testing coupled with high-volume solid-phase extraction (Hi- throat/Hi-volume SPE techniques). This study is the first to systematically characterize the trace levels of OAPs in drinking water in China. Our findings indicated that the total concentration of OAPs (∑OAPs) in TW (average 11.06 ± 4.99 ng/L) was 29.4 % higher than in BW (average 8.55 ± 3.98 ng/L) and fewer kinds (7) of OAPs were detected in BW. Furthermore, the long-term intake of TW in some areas was linked to carcinogenic risks even at an acceptable OAP range, particularly in males, with molinate being the major contributor (61.3 %) to OAP exposure. Further analysis revealed that the occurrence and health risks of OAPs in drinking water were mainly influenced by the quality of water sources and the technologies adopted in drinking water treatment plants (DWTPs). Furthermore, our findings demonstrated that advanced treatment technologies such as nanofiltration could more effectively remove OAPs in raw water (up to 87.5 %). Therefore, our findings highlighted the importance of selecting appropriate advanced treatment technologies in DWTPs.

Precious metal-based Catalytic Membrane Reactors for continuous flow catalytic hydrodechlorination

This work is focused on the development of Catalytic Membrane Reactors (CMRs) comprising precious metals as active phases for a comparative assessment in continuous-flow catalytic hydrodechlorination (HDC). HDC has proved its remarkable potential for application as polishing step in drinking water treatment plants, but studies operating in continuous mode are scarce. Preliminary experiments were conducted in batch operation using Pd/Al2O3, Rh/Al2O3 and Pt/Al2O3 powder catalysts to evaluate the influence of the active phase on the removal of prochloraz (PCZ) (100μgL-1), a pesticide listed on the EU Watch List (2022/1307), by HDC. PCZ removal was successfully described by a pseudo-first order kinetic equation and reaction pathways were proposed. Among the catalysts tested, Pt-based suffered a significant deactivation, not warranting the elimination of this micropollutant. Pd/Al2O3 exhibited a faster removal of PCZ than Rh/Al2O3, while this catalyst resulted in further hydrogenation of the non-chlorinated reaction product. Accordingly, different CMRs were developed by decorating cylindrical inert porous alumina membranes with Pd, Rh, and a combination of Pd-Rh as active phases (~1% wt.). All CMRs showed a remarkable stability along 100h on stream, being Pd/CMR be the most effective, with a pseudo-first order rate constant value of 0.062 min-1. An assessment of the impact of operating conditions (aqueous flow rate, PCZ initial concentration, temperature and H2 flow rate) was conducted using the Pd/CMR, which notably remained stable for 450h on stream. The versatility of the system was finally demonstrated in tap water, achieving a steady-state PCZ conversion close to 95%.

Estimating national sludge generation and disposal from US drinking water and wastewater treatment plants

In the United States (U.S.), the management of sludges generated from drinking water and wastewater treatment are overseen by the state agencies and much of that information, especially quantities incinerated or landfilled, are not communicated to the U.S. Environmental Protection Agency (U.S. EPA). Instead, estimates of beneficial use or disposal of sludges have been periodically quantified through time- and resource-intensive surveys of facility operators. Simple methods to estimate annual sludge generation and disposal, informed by publicly available state-level data, were developed. The generation of drinking water treatment plant (DWTP) sludge was estimated using water supply data and a sludge generation factor (SGF) based on existing literature. A process-averaged SGF, 1.3% as wet-weight per gallons treated, resulted in 35–40 mmt dw sludge/year from 2000-2015, yielding 150 kg DWTP sludge dw/person-year. Based on publicly available data from 15 states, WWTP sludge was approximately 1–2% of landfilled waste composition. State-level data regarding the (1) generation or (2) disposal of municipal wastewater treatment plant (WWTP) sludges were used to extrapolate national estimates. From 2010-2020, the US generated (1) 7.5-6.8 or (2) 7.9–7.1 mmt dw WWTP sludge/year. National figures for WWTP sludge incineration could not be estimated based on limited data. The development of transparent and simple estimation methods that utilize publicly-available data will help improve generation, disposal, and recycling estimates at the national level.

N-nitrosamines in electroplating and printing/dyeing industrial wastewater treatment plants: Removal efficiency, environmental emission, and the influence on drinking water

The discharge of industrial wastewater containing high concentrations of N-nitrosamines to the aquatic environment can impair downstream source waters and pose potential risks to human health. However, the transport and fate of N-nitrosamines in typical industrial wastewater treatment plants (IWWTPs) and the influence of these effluents on source water and drinking water are still unclear. This study investigated nine N-nitrosamines in four full-scale electroplating (E-) and printing/dyeing (PD-) IWWTPs, two drinking water treatment plants (DWTPs) in the lower reaches of these IWWTPs, and the corresponding tap water in South China. The total concentrations of N-nitrosamines (∑NAs) were 382–10,600, 480–1920, 494–789, and 27.9–427 ng/L in influents, effluents, source water, and tap water, respectively. The compositions of N-nitrosamine species in different influents varied a lot, while N-nitrosodi-n-butylamine (NDBA) and N-nitrosodimethylamine (NDMA) dominated in most of the effluents, source water, and tap water. More than 70 % N-nitrosamines were removed by wastewater treatment processes used in E-IWWTPs such as ferric-carbon micro-electrolysis (Fe/C-ME), while only about 50 % of N-nitrosamines were removed in PD-IWWTPs due to the use of chlorine reagent or other inefficient conventional processes such as flocculation by cationic amine-based polymers or bio-contact oxidation. Therefore, the mass fluxes of N-nitrosamines discharged from these industrial wastewaters to the environment in the selected two industrial towns were up to 14,700 mg/day. The results based on correlation and principal component analysis significantly demonstrated correlations between E-and PD-effluents and source water and tap water, suggesting that these effluents can serve as sources of N-nitrosamines to local drinking water systems. This study suggests that N-nitrosamines are prevalent in typical IWWTPs, which may infect drinking water systems. The findings of this study provide a basis data for the scientific evaluation of environmental processes of N-nitrosamines.

Mechanistic insight into efficient PPCPs removal on waste biological activated carbon for low-carbon emission reutilization

Over 3.9 × 107 t/a of biological activated carbon (BAC) waste was generated from Chinese drinking water treatment plants. Traditional disposal methods, such as thermal regeneration and incineration, contributed significantly to high energy consumption and CO2 emissions. To tackle this issue, a low-carbon-emitting reutilization approach was proposed to reutilize waste BAC used for eight years (BAC-8Y) to efficiently remove pharmaceuticals and personal care products (PPCPs) from wastewater. The long-term operation of a BAC-8Y column demonstrated excellent removal efficiencies of tetracycline hydrochloride (TC, >98%) and diclofenac sodium (DS, >90%) with the original concentrations of 2–5 mg/L in the artificially prepared wastewater. Even for the real sewage with the addition of 2 mg/L DS/TC, BAC-8Y could also achieve >99 % removal efficiency for both within 40 days. The results of the adsorption control test using thimerosal to inhibit microbial activity showed that adsorption contributed 94.94% of the TC removal by BAC-8Y, while the DS removal benefitted from the combined effect of adsorption (69.10%) and biodegradation (30.90%). Microbial analysis revealed that Acidobacteriota and Dadabacteria was the dominant phyla, while norank_f__Blastocatellaceae and norank_f__Oxalobacteraceae was the key genera. Moreover, compared to traditional methods, the carbon emission from reutilizing 1 t waste BAC in this study was negligible (4.18 kgCO2), which was mainly from transportation. This was also aligned with China's carbon peaking and carbon neutrality goals.

Human and ecotoxicological risk assessment of heavy metals in polymer post treatment sludge from Barekese Drinking Water Treatment Plant, Kumasi

The disposal of polymer post-treatment sludge (PTS) from Barekese Water Treatment Plants (WTPs) as organic fertilizer and aquatic feed is a common practice in Ghana, necessitating a thorough evaluation of its ecological and human health risks. This study aims to assess the suitability of PTS samples for soil amendment and fish feed, scrutinizing potential hazards to consumer health and soil. PTS samples were collected from five distinct lateral sections of three clariflocculator tanks. Potentially toxic metals such as Cd, Zn, Pb, Cu, Ni, and Cr were determined using a flame atomic absorption spectrophotometer. The mean concentration of 7.82 ± 2.43, 0.31 ± 0.021, and 0.78 ± 0.042 mg/kg for Mn, Zn, and Pb respectively. The concentrations of Ni, Cr, and Cd were below their detection limits (BDL) in all PTS samples. Upon detailed exposure assessment, ingestion emerged as the primary exposure route for both adults and children, with non-cancer risks (NCR) determined to be below 1 for both age groups. Additionally, an exploration of potential cancer risks (CR) associated with heavy metal exposure in the PTS samples revealed values below the tolerable intake levels ranging from 10−4 to 10−6 for both adults and children (10−8 and 10−9, respectively). This study also employs various ecological indices, such as Nemerow's synthetic pollution index (PN), single factor pollution index (PI), geo-accumulation index (Igeo), contamination factor (CF), potential ecological risk index (PERI), pollution load index (PLI), polymetallic contaminant index (IPD), and ecological risk index (ERI). These indices consistently highlight a low contamination status and ecological sensitivity. Consequently, the study indicates that the presence of metals in the PTS samples does not pose a significant threat to the surrounding environment and human health. Furthermore, this research underscores the inadequacy of relying solely on regulatory limit values in assessing the health risks of waste materials. Such comprehensive assessments are crucial for safeguarding aquatic and human populations.

Ondokuz Mayıs University drinking water treatment plant carbon footprint: emission sources and strategies for sustainability

In this study, it was aimed to calculate the carbon footprint of the drinking water treatment facility within Samsun Ondokuz Mayıs University and to determine the greenhouse gas emission sources within the facility. The total daily CO2 emission of the drinking water treatment plant is calculated as 85.05 kg CO2e/d. The analyses show that off-site CO2 emissions are higher than on-site CO2 emission values. It has been determined that the primary source of off-site emissions arises from the electrical energy consumption used in the units, constituting approximately 86.4% of the total CO2 emissions. The second important contribution parameter arises from the reaction of coagulants in mechanical mixing processes. This study emphasizes the importance of taking measures that support greener and sustainable production to reduce the current greenhouse gas emissions of the facility. In addition, calculating the carbon emissions of the drinking water treatment plant is important in informing the relevant institutions in the European Union’s efforts to achieve the goal of zeroing carbon emissions by 2050.

Valorization of Field-Spent Granular Activated Carbon as Heterogeneous Ozonation Catalyst for Water Treatment.

Developing sustainable cost-effective strategies for valorization of field-spent granular activated carbon (s-GAC) from industrial water treatment has gained much interest. Here, we report a cost-effective strategy for the regeneration of s-GAC as an adsorbent in a large-scale drinking water treatment plant and used as an efficient and durable ozonation catalyst in water. To achieve this, a series of samples is prepared by subjecting s-GAC to thermally controlled combustion treatments with and without pyrolysis. The catalytic performance of the optimized sample is evaluated for oxalic acid degradation as the model pollutant under batch (>15 h) and continuous flow operations (>200 h). The partially deactivated catalyst upon reuse is restored by thermal treatment. Electron paramagnetic resonance and selective quenching experiments show the formation of singlet oxygen (1O2) during catalytic ozonation. The GAC-ozonation catalyst is efficient to minimize the formation of chlorinated disinfection by-products like trihalomethanes and haloacetic acids in an urban wastewater effluent.

Spent ion-exchange resin as a new aggregate to enhance specific heat capacity of composite building materials: A case study on gypsum plaster

Spent ion exchange resin (SIER) is a by-product derived from drinking water treatment plants, possessing intriguing physicochemical properties that render it a promising ingredient for composite building materials. Surprisingly, there has been a luck of research investigating its impact on the performance of such materials. This study addresses this gap by characterizing unfired and fired gypsum-based composites with varying SIER weight ratios (10–50 wt%) and firing temperatures (300, 600, and 900°C). X-ray diffraction, scanning electron microscopy, and the hot disk method were employed to explore the effects of SIER on the composites’ thermal-mechanical features. The results revealed the significance of SIER as a promising waste-based aggregate to enhance the specific heat capacity (cp) of gypsum-based composites. With increasing SIER content and firing temperature, the composites demonstrate improved cp, reduced thermal conductivity, and decreased compressive strength. Both unfired and fired composites exhibited an increase in cp, up to 74.4% and 331.8%, respectively. The composite material achieved a noteworthy reduction in thermal conductivity, reaching 0.132 W/m.K, and a specific heat capacity increase to 4491.35 J/kg.K, which surpasses that of the control sample by more than four times (1040 J/kg.K). These newly developed composites hold significant promise as thermal energy storage materials for low-temperature building applications.

Comparative analysis of chlorine-resistant bacteria after chlorination and chloramination in drinking water treatment plants

Chlorine-resistant bacteria (CRB) in drinking water treatment plants (DWTPs) jeopardize water quality and pose a potential risk to human health. However, the specific response of CRB to chlorination and chloramination remains uncharacterized. Therefore, we analyzed 16 S rRNA sequencing data from water samples before and after chlorination and chloramination taken between January and December 2020. Proteobacteria and Firmicutes dominated all finished water samples. After chloramination, Acinetobacter, Pseudomonas, Methylobacterium, Ralstonia, and Sphingomonas were the dominant CRB, whereas Ralstonia, Bacillus, Acinetobacter, Pseudomonas, and Enterococcus were prevalent after chlorination. Over 75% of the CRB e.g. Acinetobacter, Pseudomonas, Bacillus, and Enterococcus were shared between the chlorination and chloramination, involving potentially pathogens, such as Acinetobacter baumannii and Pseudomonas aeruginosa. Notably, certain genera such as Faecalibacterium, Geobacter, and Megasphaera were enriched as strong CRB after chloramination, whereas Vogesella, Flavobacterium, Thalassolituus, Pseudoalteromonas, and others were enriched after chlorination according to LEfSe analysis. The shared CRB correlated with temperature, pH, and turbidity, displaying a seasonal pattern with varying sensitivity to chlorination and chloramination in cold and warm seasons. These findings enhance our knowledge of the drinking water microbiome and microbial health risks, thus enabling better infectious disease control through enhanced disinfection strategies in DWTPs.