Conventional Water Treatment Research Articles

A review on the synergistic efficacy of sonication-assisted water treatment process with special attention given to microplastics

The rampant spread of microplastic pollution in both natural and industrial water bodies has emerged as a paramount environmental concern. Regrettably, conventional water treatment methods (e.g., adsorption, membrane filtration, coagulation-flocculation, and electrocoagulation, processes) have been discovered to be inadequately effective in tackling this issue. However, the advent of sonication-assisted water treatment technologies has shown great promise in curbing microplastic pollution. This review article expounds on the latest trends in sonication-assisted water treatment technologies for microplastic removal. A comparison between conventional water treatment methods and sonication-assisted procedures elucidates the pros and cons of each were conducted. Additionally, an exploration of various sonication-assisted techniques and their potent efficacy in removing microplastics was undertaken. Sonochemical, Sonoelectrochemical, Sonophotocatalytic, Sonofenton, and Sonoelectrocatalytic, may be used for microplastics (MPs) removal, it has been demonstrated that ultrasonic frequencies between 100 and 1000 kHz for the sonochemical process are more useful than frequencies below 20 kHz. Generally, sonication methods have good compatibility and attachment to other biological or physical processes and increase the cavitation-induced concentration of the reactive radical in the bulk phase. Also, When Fenton processes are combined with sonication, the number of ferrous ions present in the treated water decreases due to easy handling, quick degradation, and a wide pH range that can be used. The economic aspects are the biggest challenges in synergistic efficacy of sonication-assisted water treatment for microplastics mitigation. The paramount importance of continued research and development to refine and optimize sonication-assisted water treatment technologies for practical implementation was concluded.

Occurrence, efficiency of treatment processes, source apportionment and human health risk assessment of pharmaceuticals and xenoestrogen compounds in tap water from some Ghanaian communities

The occurrence of pharmaceuticals and xenoestrogen compounds (PXCs) in drinking water presents a dire human health risk challenge. The problem stems from the high anthropogenic pollution load on source water and the inefficiencies of the conventional water treatment plants in treating PXCs. This study assessed the PXCs levels and the consequential health risks of exposure to tap water from selected Ghanaian communities as well as that of raw water samples from the respective treatment plants. Thus the PXCs treatment efficiency of two drinking water treatment plants in the metropolises studied was also assessed. The study also conducted source apportionment of the PXCs in the tap water. Twenty six (26) tap and raw water samples from communities in the Cape Coast and Sekondi-Takoradi metropolises were extracted using SPE cartridges and analysed for PXCs using Ultra-fast-HPLC-UV instrument. Elevated levels of PXCs up to 24.79 and 22.02 μg/L were respectively recorded in raw and tap water samples from the metropolises. Consequently, elevated non-cancer health risk (HI > 1) to residential adults were found for tap water samples from Cape Coast metropolis and also for some samples from Sekondi-Takoradi metropolis. Again, elevated cumulative oral cancer risks >10−5 and dermal cancer risk up to 4 × 10−5 were recorded. The source apportionment revealed three significant sources of PXCs in tap water samples studied. The results revealed the inefficiency of the treatment plants in removing PXCs from the raw water during treatments. The situation thus requires urgent attention to ameliorate it, safeguarding public health. It is recommended that the conventional water treatment process employed be augmented with advanced treatment technologies to improve their efficacy in PXCs treatment.

Exploratory studies on the use of peanut shell biochar as a promising adsorbent for ivermectin removal from aqueous solutions: impact of biomass treatment, pyrolisis temperature and duration

The contamination of environmental matrices by chemical compounds poses a significant challenge for humanity, demanding focused attention from researchers and governments. Within aquatic environments, the emerging contaminants with potential ecotoxicological effects, even at low concentrations, have earned global interest among researchers. The persistence of these contaminants is exacerbated by specific physicochemical characteristics, hindering their natural degradation and removal through conventional water treatment methods. Biochar, a carbonaceous material produced through biomass pyrolysis at high temperatures, exhibits properties that effectively remove emerging contaminants from water. In this study, we investigated the impact of acidic biomass treatment on the removal efficiency of ivermectin from aqueous solutions. The materials were derived from untreated biomass, as well as basic and acidic-treated peanut shell (PS), subjected to pyrolysis at temperatures of 300, 400, 500, and 600 °C for 2, 3, and 4 hours. Characterization was conducted using TGA, ATR-FT-IR, SEM-EDS, and XRD. Quantification of ivermectin removal was performed using HPLC-DAD. The results showed that the removal was enhanced by temperature and time of pyrolysis, while the chemical treatments had different effects. The most effective removal tendency was observed with acidic biochar calcinated at 600 °C, demonstrating an average removal yield of 84.70%.

An investigation of cyanobacteria, cyanotoxins and environmental variables in selected drinking water treatment plants in New Jersey

Harmful Algal Blooms (HAB) have the potential to impact human health primarily through their possible cyanotoxins production. While conventional water treatments can result in the removal of unlysed cyanobacterial cells and low levels of cyanotoxins, during severe HAB events, cyanotoxins can break through and can be present in the treated water due to a lack of adequate toxin treatment. The objectives of this study were to assess the HAB conditions in drinking water sources in New Jersey and investigate relationships between environmental variables and cyanobacterial communities in these drinking water sources. Source water samples were collected monthly from May to October 2019 and analyzed for phytoplankton and cyanobacterial cell densities, microcystins, cylindrospermopsin, Microcystis 16S rRNA gene, microcystin-producing mcyB gene, Raphidiopsis raciborskii-specific rpoC1 gene, and cylindrospermopsin-producing pks gene. Water quality parameters included water temperature, pH, dissolved oxygen, specific conductance, fluorescence of phycocyanin and chlorophyll, chlorophyll-a, total suspended solids, total dissolved solids, dissolved organic carbon, total nitrogen, ammonia, and total phosphorus. In addition to source waters, microcystins and cylindrospermopsin were analyzed for treated waters. The results showed all five selected New Jersey source waters had high total phosphorus concentrations that exceeded the established New Jersey Surface Water Quality Standards for lakes and rivers. Commonly found cyanobacteria were identified, such as Microcystis and Dolichospermum. Site E was the site most susceptible to HABs with significantly greater HAB variables, such as extracted phycocyanin, fluorescence of phycocyanin, cyanobacterial cell density, microcystins, and Microcystis 16S rRNA gene. All treated waters were undetected with microcystins, indicating treatment processes were effective at removing toxins from source waters. Results also showed that phycocyanin values had a significantly positive relationship with microcystin concentration, copies of Microcystis 16S rRNA and microcystin-producing mcyB genes, suggesting these values can be used as a proxy for HAB monitoring. This study suggests that drinking water sources in New Jersey are vulnerable to forthcoming HAB. Monitoring and management of source waters is crucial to help safeguard public health.

Photocatalytic activation of peroxydisulfate by UV-LED through rGO/g-C3N4/SiO2 nanocomposite for ciprofloxacin removal: Mineralization, toxicity, degradation pathways, and application for real matrix

If trace amounts of antibiotics remain in the environment, they can lead to microbial pathogens becoming resistant to antibiotics and putting ecosystem health at risk. For instance, ciprofloxacin (CIP) can be found in surface and ground waters, suggesting that conventional water treatment technologies are ineffective at removing it. Now, a rGO/g-C3N4/SiO2 nanocomposite was synthesized in this study to activate peroxydisulfate (PDS) under UVA-LED irradiation. UVA-LED/rGO-g–C3N4–SiO2/PDS system performance was evaluated using Ciprofloxacin as an antibiotic. Particularly, rGO/g-C3N4/SiO2 showed superior catalytic activity for PDS activation to remove CIP. Operational variables, reactive species determination, and mechanisms were investigated. 0.85 mM PDS and 0.3 g/L rGO/g-C3N4/SiO2 eliminated 99.63% of CIP in 35 min and mineralized 59.78% in 100 min at pH = 6.18. By scavenging free radicals, bicarbonate ions inhibit CIP degradation. According to the trapping experiments, superoxide (O2•−) was the main active species rather than sulfate (SO4•−) and hydroxyl radicals (•OH). RGO/g-C3N4/SiO2 showed an excellent recyclable capability of up to six cycles. The UVA-LED/rGO-g–C3N4–SiO2/PDS system was also tested under real conditions. The system efficiency was reasonable. By calculating the synergistic factor (SF), this work highlights the benefit of combining composite, UVA-LED, and PDS. UVA-LED/rGO-g–C3N4–SiO2/PDS had also been predicted to be an eco-friendly process based on the results of the ECOSAR program. Consequently, this study provides a novel and durable nanocomposite with supreme thermal stability that effectively mitigates environmental contamination by eliminating antibiotics from wastewater.

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.

Photocatalytic Removal of Emerging Contaminants from Water using Metal Oxide-based Nanoparticles

Abstract: Water contamination resulting from industrial and anthropogenic activities is a major problem in many countries throughout the world. Effective water treatment technologies are necessary to address this issue. Emerging pollutants (EPs) are reaching the aquatic environments from point and diffuse sources constantly. These are the substances that are not regularly monitored, yet have the potential to infiltrate the environment and harm the ecosystem and human health. Because of their ecological and sustainable properties, interest in improved photocatalytic technologies based on metal oxide-based nanomaterials has grown tremendously over the years to address this water contamination. Pollutant degradation, water splitting, carbon dioxide reduction, nitrogen reduction, and microbial inactivation are just a few of the applications of photocatalysis. However, to maintain its environmentally favourable status, new solutions must be found to assure long-term viability. Here we review, emerging organic pollutants, conventional water treatment, advanced oxidation methods, photocatalytic mechanisms, photocatalyst support materials, synthesis, and characterization of metal oxides and metal oxide nanoparticles in the removal of emerging contaminants. The purpose of this review is to reach a broader readership by giving a simple comprehension of the fundamentals and advances of metal-oxide-driven photocatalysis for environmental clean-up.

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 > ozone >> chlorine > permanganate >> 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.

Microcystin removal by microbial communities from a coastal lagoon: Influence of abiotic factors, bacterioplankton composition and estimated functions

Toxic cyanobacterial blooms present a substantial risk to public health due to the production of secondary metabolites, notably microcystins (MCs). Microcystin-LR (MC-LR) is the most prevalent and toxic variant in freshwater. MCs resist conventional water treatment methods, persistently impacting water quality. This study focused on an oligohaline shallow lagoon historically affected by MC-producing cyanobacteria, aiming to identify bacteria capable of degrading MC and investigating the influence of environmental factors on this process. While isolated strains did not exhibit MC degradation, microbial assemblages directly sourced from lagoon water removed MC-LR within seven days at 25 ºC and pH 8.0. The associated bacterial community demonstrated an increased abundance of bacterial taxa assigned to Methylophilales, and also Rhodospirillales and Rhodocyclales to a lesser extent. However, elevated atmospheric temperatures (45 ºC) and acidification (pH 5.0 and 3.0) hindered MC-LR removal, indicating that extreme environmental changes could contribute to prolonged MC persistence in the water column. This study highlights the importance of considering environmental conditions in order to develop strategies to mitigate cyanotoxin contamination in aquatic ecosystems.

Downflow sponge biofilm reactors for polluted raw water treatment: Performance optimisation, kinetics, and microbial community

Water outages caused by elevated ammonium (NH4+-N) levels are a prevalent problem faced by conventional raw water treatment plants in developing countries. A treatment solution requires a short hydraulic retention time (HRT) to overcome nitrification rate limitation in oligotrophic conditions. In this study, the performance of polluted raw water treatment using a green downflow sponge biofilm (DSB) technology was evaluated. We operated two DSB reactors, DSB-1 and DSB-2 under different NH4+-N concentration ranges (DSB-1: 3.2–5.0 mg L−1; DSB-2: 1.7–2.6 mg L−1) over 360 days and monitored their performance under short HRT (60 min, 30 min, 20 min, and 15 min). The experimental results revealed vertical segregation of organic removal in the upper reactor depths and nitrification in the lower depths. Under the shortest HRT of 15 min, both DSB reactors achieved stable NH4+-N and chemical oxygen demand removal (≥95%) and produced minimal effluent nitrite (NO2−-N). DSB system could facilitate complete NH4+-N oxidation to nitrate (NO3−-N) without external aeration energy requirement. The 16S rRNA sequencing data revealed that nitrifying bacteria Nitrosomonas and Nitrospira in the reactor were stratified. Putative comammox bacteria with high ammonia affinity was successfully enriched in DSB-2 operating at a lower NH4+-N loading rate, which is advantageous in oligotrophic treatment. This study suggests that a high hydraulic rate DSB system with efficient ammonia removal could incorporate ammonia treatment capability into polluted raw water treatment process and ensure safe water supply in many developing countries.

Molecular modelling of emerging contaminants adsorption in subunits of metal-organic frameworks

Emerging Contaminants (ECs) are compounds recently introduced in the environment and associated with the modern lifestyle. Many of these substances arrive in water bodies by sewage, presenting toxic effects to living organisms. Since conventional water treatment methodologies are not able to remove them, adsorptive methods using Metal-Organic Frameworks (MOFs) as adsorbents are quite promising for this purpose. Therefore, understanding the adsorptive mechanisms involving these materials is important to design optimized adsorbents. In this work, the adsorption properties of MOF subunits were evaluated for the ECs atrazine, caffeine, and triclosan using computational simulations based on Density Functional Theory. The choice of the metallic subunit showed to be determinant to the MOFs design, since the ECs coordinate in these sites, besides the possibility of establishing hydrogen bonds. The adsorption of possible coexisting species (Cl-, HSO4-, and H2PO4-) was also investigated and observed as relevant interferents to be considered in the adsorptive methodologies.

Carbamazepine Adsorption onto Giant Macroporous Silica and Adaptive Neuro-Fuzzy Inference System Modeling

AbstractThere is an imperative need to eliminate pharmaceutical residues from aquatic environments due to their hazardous properties, including toxicity, mutagenicity, and carcinogenicity, particularly when present in water sources. Conventional water treatment methods have proven insufficient in addressing nano-pollutants such as pharmaceutical residues. Consequently, the ongoing quest for economically viable, sustainable, and environmentally friendly removal mechanisms persists. In this particular study, we employed Giant Macroporous Silica (GMS) derived from marine sponges as a promising biosorbent. GMS exhibits commendable characteristics, including a high specific surface area, swift mass transfer capabilities, and non-discriminatory adsorption qualities. The efficacy of GMS in adsorbing carbamazepine (CBZ), a common drug residue, was scrutinized under diverse experimental conditions, including a sorbate/sorbent ratio ranging from 0.005 to 1.500 weight ratio, contact times spanning from 0 to 240 min, and initial pH values ranging from 5 to 9. Remarkably, at a concentration of 1000 µg L−1, GMS demonstrated an attractive adsorption rate (98.88%) of carbamazepine at pH 7.07, within 90 min. To enhance our understanding, we developed an ANFIS model utilizing the experimental parameters as inputs. The developed model exhibited a high correlation coefficient of 0.9944% and a root mean square error (RMSE) of 1.6693, indicating its dependability in accurately predicting the adsorption of CBZ on GMS. The results of our study highlight the efficacy of GMS in adsorbing CBZ, suggesting its considerable potential for adsorbing other pharmaceutical residues and nano-pollutants. Furthermore, we propose the possibility of developing a solid-phase extraction cartridge from GMS.

Comparison of Conventional Water Treatment and Ultrafiltration Pilot Tests in the Rozgrund Water Treatment Plant

Comparison of Conventional Water Treatment and Ultrafiltration Pilot Tests in the Rozgrund Water Treatment Plant

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.

Nanoremediation and Antioxidant Potential of Biogenic Silver Nanoparticles Synthesized Using Leucena's Leaves, Stem, and Fruits.

Synthetic dyes are persistent organic environmental pollutants that can cause extensive damage to living beings and to the ecosystem as a whole. Cost-effective, sustainable, and efficient strategies to deal with this type of pollution are necessary as it commonly resists conventional water treatment methods. Silver nanoparticles (AgNPs) synthesized using the aqueous extract from the leaves, stem, and fruits of Leucaena leucocephala (Leucena) were produced and characterized through UV-vis, TEM, EDS, SDL, XPS, XRD, and zeta potential, and they proved to be able to promote adsorption to remediate methylene blue and tartrazine pollution in water. The nanoremediation was performed and did not require direct exposure to sunlight or any special lamp or a specific reduction agent. The AgNPs produced using the extract from the leaves exhibited the best performance in nanoremediation and also presented antioxidant activity that surpassed the one from butylated hydroxytoluene (BHT). Consequently, it is an interesting nanotool to use in dye nanoremediation and/or as an antioxidant nanostructure.

Investigation of the removal of diclofop methyl herbicide by peroxy electrocoagulation process and kinetic and cost analysis

Pesticides containing chlorine, which are released during agricultural activities, are chemical substances that mix with surface and underground waters and have toxic, carcinogenic, and mutagenic effects on the entire living ecosystem. Due to their chemically stable structure, conventional water and wastewater treatment techniques such as coagulation, flocculation, and biological oxidation do not entirely remove these chemical substances. Therefore, before releasing them into the environmental receptor, these chemical substances must be transformed into harmless products or mineralized through advanced oxidation processes. When we look at the literature, there are not many studies on methods of removing diclofop methyl from aquatic media. Our study on the removal of diclofop methyl herbicide from aquatic media using the peroxy electrocoagulation method will provide the first information on this subject in the literature. In addition, this treatment method will contribute significantly to filling an important gap in the literature as an innovative approach for diclofop methyl removal. Moreover, peroxy electrocoagulation, which produces less sludge, provides treatment in a short time, and is economical, has been determined to be an advantageous process. The effects of conductivity, pH, H2O2 concentration, current, and time parameters on the removal of diclofop methyl were investigated using a GC–MS instrument. Kinetics, energy consumption, and cost calculations were also made. Under the optimum conditions determined (pH = 5, H2O2 = 500 mg/L, NaCl = 0.75 g/L, current density = 2.66 mA/cm2), the peroxydic electrocoagulation process resulted in a diclofop methyl removal efficiency of 79.2% after a 25-min reaction. When the experimental results were analyzed, it was found that the results fitted the pseudo-second-order kinetic model.

Characterization of novel solar based nitrogen doped titanium dioxide photocatalytic membrane for wastewater treatment

The increasing presence of microbial and emerging organic contaminants pose detrimental effects on the environment and ecosystem such as diseases, pandemics and toxicity. Most of these synthetic pollutants are biorecalcitrant and therefore persist in the environment. Conventional water treatment methods are not effective thereby necessitating the development of advanced techniques such as photocatalysis and membrane processes. In this study, visible light-driven photocatalytic membrane was synthesized through the immobilization of nitrogen-doped nanoparticles onto the polyvinylidene fluoride (PVDF) membrane and performance evaluated with E.coli microbial contaminant removal. Characterization was done using Fourier transform infrared spectra, X-ray diffraction (XRD), water contact angle, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The Nitrogen-doping of titanium dioxide red-shifted the light absorption to a visible range of 440 nm from 400 nm. Nitrogen dopant was detected at 1420 cm−1and 1170 cm−1 for nitrogen doped nanoparticles and 1346-1417 cm−1 for nitrogen doped titanium dioxide PVDF membrane. SEM-EDX confirmed presences of nitrogen in nitrogen doped titanium dioxide nanoparticles on membrane surface with nitrogen elemental composition of 0.01 % wt. The water contact angle reduced by 81.39o from 120.14o to 38.75o because of PVA immobilization of nitrogen-doped titanium dioxide and glutaraldehyde crosslinking. Nitrogen doping resulted in visible light active photocatalytic membranes with better hydrophilicity and fouling resistance. 8.42 E.coli log removal and a relative flux of 0.35 was obtained within 75 min. The developed photocatalytic membrane enables the use of sunlight hence a less costly method for decontamination of wastewater.

Life Cycle Assessment of a Vegetable Tannin-Based Agent Production for Waters Treatment

The scarcity of natural resources makes it essential to develop products that meet environmental requirements. This is also true for the water and wastewater treatment business, where even consolidated processes, such as coagulation and flocculation, must be improved, opening opportunities for searching for alternative options to conventional processes. Among the existing options, tannin-based agents (TBAs) have been highlighted in recent years due to their biodegradability and proven efficiency. However, little is known about the impacts of the production process of these agents on an operational/industrial scale. In this study, an examination of the environmental impacts of the full-scale production (more than 500 tons yearly) of a TBA from Acacia spp. (known as black acacia or mimosa) was carried out. To accomplish this, a life cycle assessment (LCA) was developed using openLCA version 2.0.0 to assess a cradle-to-gate system of 1 kg of packed TBA produced. Additionally, a comparison was made between the impacts of the production of TBA and a conventional water treatment agent, aluminum sulfate, to verify the benefits of producing the former. The most relevant impacts resulting from the production of 1 kg of TBA are observed in the following categories: global warming (1.52 kgCO2-eq); terrestrial (7.67 kg1.4-DCB-eq), freshwater (0.06 kg1.4-DCB-eq), and marine (0.08 kg1.4-DCB-eq) ecotoxicities; carcinogenic (0.10 kg1.4-DCB-eq) and non-carcinogenic (1.36 kg1.4-DCB-eq) human toxicities; and water use (0.02 m3). The main contributors to the impacts were the chemicals ammonium chloride and formaldehyde used, the transport of inputs, and the energy used. The aluminum sulfate showed better performance than the TBA for a greater number of categories; however, the normalization of the impacts showed the TBA as a very interesting option. The results obtained here can be used by TBA producers to act on the most impactful categories so that the production process becomes increasingly sustainable.

Occurrence of forever chemicals in Chennai waters, India

BackgroundPer- and polyfluoroalkyl substances (PFAS) are considered ‘contaminants of emerging concern’ due to their environmental persistence, bio-accumulative potential, and adverse effects on human health. They are widely employed in producing various goods used in daily life, such as non-stick cookware, cleaning agents, and many industrial applications in aerospace, automotive, construction, electronics, and military, all of which ultimately end up in different environmental matrices. India’s rapid economic growth necessitates a comprehensive understanding of its PFAS contamination levels and potential human and ecological exposure.ResultsThe present study reports the quantification of one long-chain and two short-chain perfluoroalkyl acids and three long-chain and two short-chain perfluorosulfonic acids and qualitative analysis using suspect screening in the waters of Chennai, Tamil Nadu, India. Samples were collected from surface and groundwater sources, including the Adyar river, Buckingham canal, Chembarambakkam lake, and the water treatment plant. The concentrations analyzed in all the samples ranged from 0.10 ng/L to 136.27 ng/L. Groundwater had some of the highest concentrations of PFAS. L-PFBS (up to 136.27 ng/L) and PFOA (up to 77.61 ng/L) are present in all the samples. The concentrations of all the target PFAS increased in the 5 to 103% range in the final treated water compared to the raw water of the water treatment plant. This treated water is distributed as a source of drinking water for the residents of Chennai. Additionally, the dominance of short-chain compounds (4–7 carbons) over long-chain compounds (> 7 carbons) was observed. Suspect screening revealed numerous precursors and other fluorinated compounds abundantly present in the samples.ConclusionsOur study revealed PFAS levels up to 136.27 ng/L in both surface and groundwater samples from Chennai. These findings raise concerns about potential risks to ecosystems and human well-being. The dominance of short-chain PFAS coupled with abundant precursors and unidentified fluorinated compounds indicates an ongoing shift toward alternatives. Conventional water treatment is ineffective in eliminating these chemicals from the water system; rather, increasing the PFAS concentrations from raw water to treated water necessitates advanced polishing steps. Industrial emissions, untreated domestic wastewater discharge, and open dump sites have been suspected as the significant sources of contamination, highlighting the need for further investigation to fully assess the extent of PFAS contamination in Chennai.Graphical

AN OVERVIEW ON THE SYNTHESIS OF PHOSPHORYLATED CHITOSAN DERIVATIVES FOR THE ADSORPTION OF EMERGING CONTAMINANTS IN WATER

Safe water for human consumption and for aquatic life is of paramount importance. The emergence of new kinds of contaminants like surfactants, pharmaceutical drugs, hormones, foods and additives, laundry detergents, etc., are posing new and serious challenges to the conventional primary and secondary waste water treatment, because of the inability to remove or degrade these toxic pollutants efficiently and hence, the need for cost effective tertiary treatment method. Adsorption is a promising method worldwide for the removal of emerging contaminants, since it is highly-efficient and has a simple operating system. This review seeks to investigate the suitable preparation methods of soluble phosphorylated chitosan derivatives as efficient adsorbent for effective removal of emerging contaminants in water. Hence, the goal of this study, is to review some synthesis of the phosphates of chitosan under various chemical conditions to produce soluble chitosan derivatives which can be effectively used for the removal of emerging contaminants in water by adsorption technique.