Wastewater Treatment Plant Effluent Research Articles

Source-tracing of industrial and municipal wastewater effluent in river water via fluorescence fingerprinting.

Fluorescence fingerprinting is a technique to uniquely characterize water samples based on their distinct composition of dissolved organic matter (DOM) measured via 3D fluorescence spectroscopy. It is an effective tool for monitoring the chemical composition of various water systems. This study examines a river affected by several municipal and industrial wastewater treatment plant (WWTP) effluents and aims to source-tracing them via fluorescence fingerprints based on parallel factor analysis (PARAFAC) components. Additional principal component analysis (PCA) clusters the WWTP effluents according to similarity. The results yield seven PARAFAC components characterizing the WWTP effluents. Considering the ratios among the components, these distinct fluorescence fingerprints are attributable to the studied industrial sectors: leather industry, meat processing, electronics industry, and municipal wastewater treatment. Furthermore, the fluorescence signal of the receiving river is examined by PCA and assessment of flow-weighted fluorescence intensities for source-tracing the fingerprints of the WWTP effluents. An analysis of the contribution of each WWTP effluent shows that during low flow, the fluorescence signal in the river is dominated by WWTP emissions. In contrast, during high flow events, the impact of WWTP emissions is masked by diffuse emissions. The techniques presented in this study have the potential to define generalizable fluorescence fingerprints for WWTP effluents of various industrial sectors and source-trace them in the receiving river. This approach represents a step closer to implementing complex fluorescence monitoring tools in rivers, tracing the impact of municipal and industrial WWTP effluents on riverine OM.

Simultaneous heterogeneous photo-Fenton degradation of azithromycin and clarithromycin in wastewater treatment plant effluent

Simultaneous heterogeneous photo-Fenton degradation of azithromycin and clarithromycin in wastewater treatment plant effluent

Azithromycin removal from water via adsorption on drinking water sludge-derived materials: Kinetics and isotherms studies.

In this study, we utilized drinking water treatment sludge (WTS) to produce adsorbents through the drying and calcination process. These adsorbents were then evaluated for their ability to remove azithromycin (AZT) from aqueous solutions. The L-500 adsorbent, derived from the calcination (at 500°C) of WTS generated under conditions of low turbidity in the drinking water treatment plant, presented an increase in the specific surface area from 70.745 to 95.471 m2 g-1 and in the total pore volume from 0.154 to 0.211 cm3 g-1, which resulted in a significant AZT removal efficiency of 65% in distilled water after 60 min of treatment. In synthetic wastewater, the rate of AZT removal increased to 80%, in comparison, in a real effluent of a municipal wastewater treatment plant, an AZT removal of 56% was obtained. Kinetic studies revealed that the experimental data followed the pseudo-second-order model (R2: 0.993-0.999, APE: 0.07-1.30%, and Δq: 0.10-2.14%) suggesting that chemisorption is the limiting step in the adsorption using L-500. This finding aligns with FTIR analysis, which indicates that adsorption mechanisms involve π-π stacking, hydrogen bonding, and electrostatic interactions. The equilibrium data were analyzed using the nonlinear Langmuir, Freundlich, and Langmuir-Freundlich isotherms. The Langmuir-Freundlich model presented the best fitting (R2: 0.93, APE: 2.22%, and Δq: 0.06%) revealing numerous interactions and adsorption energies between AZT and L-500. This adsorbent showed a reduction of 19% in its AZT removal after four consecutive reuse cycles. In line with the circular economy principles, our study presents an interesting prospect for the reuse and valorization of WTS. This approach not only offers an effective adsorbent for AZT removal from water but also represents a significant step forward in advancing sustainable water treatment solutions within the framework of the circular economy.

Optimization of Odorous Compounds Analysis in Water Using Headspace-SPME and GC-MSD, and Detection Characteristics in the Nakdong River Basin

Objectives : This study developed a simple and automated analytical method using headspace-SPME (solid phase microextraction) and GC (gas chromatography)-MSD (mass selective detector) to simultaneously analyze ten odorous compounds (dimethyl trisulfide (DMTS), 3-hexenylacetate (HA), 2-isopropyl-3-methoxypyrazine (IPMP), 2-methylbenzofuran (MBF), 2-isobutyl-3-methoxypyrazine (IBMP), β-cyclocitral (CC), trans-2-decenal (DCNL), 2-trans-4-trans-decadienal (DENL) 2,4,6-trichloroanisole (TCA) 및 β-ionone (ION)), evaluating their distribution characteristics throughout the Nakdong River basin.Methods : To optimize the extraction efficiency of the headspace-SPME method for ten odorous compounds, we evaluated various SPME fiber materials, extraction temperatures, extraction times, desorption temperatures, desorption times and salt (NaCl) dosages. Additionally, using the optimized headspace-SPME, we investigated the detection concentrations at ten main stream sites and six tributary sites in the Nakdong River basin.Results and Discussion : The most suitable SPME fiber material for the pretreatment of ten odorous compounds was CAR/PDMS/DVB. The optimal SPME extraction temperature and time were 75°C and 60 minutes, respectively, and the optimal desorption temperature and time at the GC injection port were 250°C and 3 minutes. Additionally, the optimal salt (NaCl) dosage for a 10 mL water sample was 2 g. Using the optimized headspace-SPME pretreatment method for GC-MSD analysis, the detection limits and quantification limits for the ten odorous compounds ranged from 2 to 10 ng/L and 5 to 25 ng/L, respectively, with HA exhibiting the highest detection and quantification limits. The evaluation of the distribution characteristics of odorous compounds throughout the Nakdong River basin revealed that only three compounds—DMTS, CC and ION—were detected. Among these, DMTS was found at the highest concentration of 115.5 ng/L in the tributary Jincheon-cheon, while CC was detected at the highest concentration of 30.6 ng/L in the main river at Goryeong. In the case of the Nakdong River basin, there was no contamination by odorous compounds in the upstream area. In the middle reach, influenced by effluent of wastewater treatment plants, the detection concentrations of three odorous compounds increased, but they showed a decreasing trend as they moved downstream.Conclusion : Since odorous compounds can lead to distrust in water quality even at extremely low concentrations in the ng/L range in tap water, regular monitoring of water sources is necessary during algal bloom season, including the dry season. Furthermore, continuous research is needed on various odorous compounds beyond the 10 odorous compounds in this study, including the optimization of analytical methods and the detection characteristics in water sources.

Application of Membrane Distillation for Secondary Effluent Treatment towards Water Recovery

This paper presented the application of Direct Contact Membrane Distillation (DCMD) for the treatment of the secondary effluent of a municipal wastewater treatment plant (WWTP) to produce fresh water. The purification studies conducted at various feed temperatures demonstrated that the permeate water flux increased and that the water flux decreased quickly at the higher feed temperature. However, the electrical conductivity of permeate remained consistent at about 2.0 μS/cm. The majority of pollutants found in the secondary effluent, including SS, COD, nitrate, nitrite, phosphate, and total coliform, were entirely eliminated throughout the MD treatment process using a bi-composite membrane made of polytetrafluoroethylene and polypropylene at different feed stream temperatures. Ammonia had a limited rate of rejection, though. Protein and organic/inorganic aggregates made up the majority of the foulants were found on the membrane surface, not the inner pores. The long-term test, which involved an 18-day operation with a feed solution concentration of ten times, revealed that no wetness issue was seen despite a notable foulant deposit and reduction in water flux.

The abundance, removal efficiency, and characteristics of microplastics in three urban wastewater treatment plants (WWTPs) on the southern coast of the Caspian Sea.

Wastewater treatment plants (WWTPs) are one of the major collection points of microplastics (MPs). The MPs in influents and effluents of WWTPs were assessed for three cities on the southern coast of the Caspian Sea in the winter and spring seasons. The MP removal rate of WWTPs ranged between 71.12 and 88.13% depending on the season and treatment methods. The higher removal efficiency of MPs in the city of Sari compared to that in the other two cities might be attributed to the implementation of more effective treatment techniques at the Sari WWTP. Our findings showed that the presence of MPs in influents was greater in the spring than in the winter, attributed to the increased usage of personal care and washing products during the COVID-19 lockdown period. Conversely, in effluents, the abundance of MPs was higher in the winter than in the spring, likely due to precipitation and inadequate management of sewage overflows. On average, more than 50% of identified MPs had black/grey and white/transparent colours. The majority of the identified MPs that were found in both the influents and effluents of all three investigated WWTPs were smaller than 500µm and had a fibre shape. Our findings indicate that removing plastics with a size smaller than 100µm is more challenging compared to larger-sized plastics in WWTPs. Moreover, a strong correlation was observed between TSS and the abundance of MPs in influents. The predominant types of MP that were identified with spectroscopic analysis in most samples were polyamide (PA), acrylic, polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), and polypropylene (PP). Based on the results of our study, it can be estimated that a total of 132 × 106 and 223 × 106 MPs are discharged per day from the three investigated WWTPs into aquatic environments that ultimately reach the Caspian Sea in the spring and winter, respectively. Our findings enhance our knowledge about the load of MPs from WWTPs into the Caspian Sea, and it provides a foundation for future discussions on management strategies and the reuse of wastewater.

Transformation of persistent organic micropollutants by UV and UV/H2O2 in wastewater treatment plant effluent

ABSTRACT Photochemical and advanced oxidation processes (AOPs) are promising options to simultaneously disinfect wastewater treatment plant (WWTP) effluent and degrade organic micropollutants (OMPs). In the present study, kinetic experiments with UV alone and the combination of UV and hydrogen peroxide (H2O2) as an AOP were conducted in WWTP effluent (with and without ultrafiltration) to assess the degradation of 24 OMP, 13 of which were examined for the first time, in a flow-through batch reactor setup. Four parameters were systematically varied to quantify their impacts on OMP degradation: H2O2 concentrations, UV source, water matrix, and flow rate. Most of the studied OMPs (e.g., trimethylammonium, 1,3-di-o-tolylguanidine, carbamazepine) were only significantly degraded in the presence of UV radiation and H2O2. The highest pseudo-first-order rate constants were found for diclofenac, acesulfame, diatrizoate, and sulfamethoxazole. The experiment with the highest degradation also showed the strongest abatement of UV absorbance at 254 nm. Only three of the 24 substances (cyanoguanidine, melamine, and oxipurinol) were not degraded; UV alone even increased their concentrations. Overall, upgrading a UV disinfection to an AOP using H2O2 allows the degradation of a wide range of OMP, making it an interesting process for water reuse.

Research on Impact of Equity Costs and Environmental Costs on Supply-Side Classified Water Pricing

The classified water pricing system is an effective measure for promoting the rational utilization of water resources under market mechanisms. Studying the water prices of three different types of water sources, including reservoir water, river water, and wastewater treatment plant effluent, is the basis for promoting the use of reclaimed water. However, there remains a spectrum of viewpoints on how to establish a pricing mechanism for reclaimed water at present. This study primarily focuses on the multi-level quality-separated water supply system in Yiwu City, China. It analyzes the limitations of the current water pricing formation mechanism and the externality of integrating reclaimed water into the unified allocation of multiple water sources. Based on the principles of full-cost water pricing and externality theory, a supply-side classified water pricing permit cost and pricing calculation model, covering the entire process of the social water cycle, is proposed. It focuses on the analysis of the impact of equity costs and environmental costs on supply-side classified water pricing. The Shapley value method is used for the technology of cost allocation among stakeholders to reasonably distribute the calculated water pricing of reclaimed water. The price of reclaimed water varies depending on the user type, with residential users paying 2.93 CNY/t, industrial users 4.00 CNY/t, and government allocations at 8.52 CNY/t. Compared with the classified water prices of various stakeholders on the user side of reservoir water, reclaimed water has a significant price advantage. This research demonstrates that the supply-side classified water pricing model, which includes a permit cost and pricing calculation framework, can encourage the supply of higher-quality water at corresponding higher prices, while also providing the internalization of external costs. Furthermore, the Shapley value method of cost allocation can realize the fair burden of stakeholders on the calculated water price and maintain the competitive advantage of reclaimed water prices.

Occurrence, fate, and ecological risk of PAEs, PFASs, antibiotics in industrial, urban and rural WWTPs in Shaanxi Province, China

The wastewater treatment plants (WWTPs) were considered as a hub of transit from human activities as a source to the aquatic ecosystems as a sink of emerging contaminants (ECs). This study investigated the fate of phthalate esters (PAEs), per- and polyfluoroalkyl substances (PFASs) and antibiotics in the influent and effluent of WWTPs in industrial, urban and rural in Shaanxi province (China). The first most abundant monomer of these three types of ECs were the same in industrial, urban and rural WWTPs. The composition of PAEs in the influent of urban and rural WWTPs were quite different from that of industrial WWTPs. The removal efficiency of PAEs and PFASs in urban WWTPs were higher than those in rural and industrial WWTPs. The annual mass load of PFASs in rural WWTPs was lower than that in industrial and urban WWTPs. The risk quotient (RQ) of PAEs was high, with most of them exceeding 1. While the RQ of PFASs was low, exceeding 0.1 only in some industrial WWTPs. The frequency of high risk of total antibiotics in urban and rural WWTPs was higher than that in industrial WWTPs. This study provided field survey data and guidance to strengthen the management of ECs in the region.

Antibiotic resistance genes and virulence factors in the plastisphere in wastewater treatment plant effluent: Health risk quantification and driving mechanism interpretation

Microplastics (MPs) are ubiquitous in wastewater treatment plants (WWTPs) and provide a unique niche for the spread of pollutants. To date, risk assessments and driving mechanisms of pathogens, antibiotic resistance genes (ARGs), and virulence factors (VFs) in the plastisphere are still lacking. Here, the microbiota, ARGs, VFs, their potential health risks, and biologically driving mechanisms on polythene (PE), polyethylene terephthalate (PET), poly (butyleneadipate-co-terephthalate) and polylactic acid blends (PBAT/PLA), PLA MPs, and gravel in WWTP effluent were investigated. The results showed that plastisphere and gravel biofilm harbored more distinctive microorganisms, promoting the uniqueness of pathogens, ARGs, and VFs compared to WWTP effluent. The abundance of major pathogens, ARGs, and VFs in the plastisphere was 1.01–1.35 times higher than that in the effluent. The high health risk of ARGs (HRA) calculated by fully considering the abundance, clinical relevance, pathogenicity, accessibility and mobility, and the high proportion of resistance contigs with mobile genetic elements confirmed that the plastisphere posed the highest potential health risk. Candidatus Microthrix and Candidatus Promineifilum were the essential hosts of ARGs and VFs in the plastisphere and gravel biofilm, respectively. High metabolic activity such as amino acid metabolism and biosynthesis of secondary metabolites, and highly expressed key genes increased the synthesis of ARGs and VFs. The primary mechanisms driving ARG enrichment in the plastisphere were enhanced microbial metabolic activity, increased frequency of horizontal gene transfer, heightened antibiotic inactivation and efflux, and reduced cell permeability. This study provided new insights into the ARGs, VFs, and health risks of the plastisphere and emphasized the importance of strict control of wastewater discharge.

Community-level responses and environmental fate of metformin in freshwater mesocosms.

The type 2 diabetes drug metformin is among the most frequently prescribed, dispensed, and consumed pharmaceuticals worldwide; and its heavy use and poor breakdown means it is consequently detected in various wastewater treatment plant (WWTP) effluents and surface waters. The resulting environmental concentrations of metformin can have adverse impacts on aquatic ecosystems. An 8-week in-lake mesocosm experiment was conducted in a freshwater boreal lake at the IISD-Experimental Lakes Area (Ontario, Canada) to determine the environmental fate and effects of metformin. Mesocosms were assigned to nominal concentrations of 0, 5, or 50μgL-1 metformin, in replicates of four. Biotic communities (i.e. microbial, phytoplankton, zooplankton, benthic macroinvertebrate) were assessed and complementary Lemna gibba and Daphnia magna bioassays were conducted in the laboratory. Metformin was extremely stable during the 8-week experiment, with mean measured concentrations of 0.00, 5.42, and 42.79μgL-1 in mesocosm surface waters for the 0, 5, and 50μgL-1 treatments, respectively. While trace amounts of metformin were detected in mesocosm sediments, the compound was primarily found in the water column. After over 1year following metformin additions, the mean loss of metformin from surface water was 94.0% and 91.0% for the 5 and 50μgL-1 treatment groups, respectively. No adverse effects of metformin treatment on the diversity, abundance, or biomass of microbial, phytoplankton, zooplankton, or benthic macroinvertebrate communities were found. Additionally, no survival or reproductive effects were observed in the 21-d Daphnia magna bioassays and no significant effects were observed in the 7-d Lemna gibba growth assays. No substantial metformin transformation to guanylurea was observed in mesocosm surface waters or sediments, likely due to a lack of bacterial degradation occurring within mesocosms relative to WWTPs.

A probabilistic deep learning approach to enhance the prediction of wastewater treatment plant effluent quality under shocking load events

A probabilistic deep learning approach to enhance the prediction of wastewater treatment plant effluent quality under shocking load events

Hybrid modeling techniques for predicting chemical oxygen demand in wastewater treatment: a stacking ensemble learning approach with neural networks.

To ensure operational efficiency, promote sustainable wastewater treatment practices, and maintain compliance with environmental regulations, it is crucial to evaluate the parameters of treated effluent in wastewater treatment plants (WWTPs). Artificial neural network (ANN) analysis is a promising tool to predict the wastewater characteristics, as a substitute to tedious laboratory techniques. It enables proactive decision-making and contributes to the overall effectiveness of the treatment processes. The primary aim of this work is to develop a robust model for predicting chemical oxygen demand (COD), a key parameter for evaluating the operational efficiency of WWTPs. The research employed a dataset consisting of 527 samples and 22 features, derived from daily sensor readings in an urban WWTP. Additionally, to enhance the efficiency of the ANN framework for regression modeling, the dataset was augmented to 1054 samples using a robust synthetic data generator known as generative adversarial networks (GAN). In this study, K-means clustering combined with principal component analysis (PCA) is employed for feature selection and anomaly detection, aiming to enhance the regression model's performance by incorporating advanced ANN extensions, including polynomial, additive, and radial basis networks. Moreover, the model optimizes ANNs using advanced heuristic techniques such as genetic algorithms (GA), ant colony optimization (ACO), and particle swarm optimization (PSO). Furthermore, the performance of the models was assessed using the R2 (coefficient of determination), MSE (mean squared error), and loss value metrics along with visual performance indicators. The proposed model stacked ensemble method resulted in an MSE of 0.0012 and an R2 score of 0.95 and the GA_ANN model, despite undergoing optimization, achieved only an R2 score of 0.70, indicating considerable potential for improvement. In contrast, the ACO_ANN and PSO_ANN models showed significant performance boosts, with near-perfect R2 scores of about 0.98 and 0.99, respectively, making them the top-performing models overall. The results outlined in this article introduce an ANN stacking ensemble regression mode framework that can aid researchers in improving the operational efficiency of treatment plants.

Recent depositional history of noble and critical elements in sediments from a wastewater-impacted bay (Vidy Bay, Lake Geneva, Switzerland)

Opposing trends in environmental pollution have been observed in recent years, with a growing awareness of the need to reduce emissions to the environment being accompanied by a concomitant increase in the use of polluting substances, which can potentially end up in the environment and harm humans and ecosystems. In order to assess the temporal evolution of loadings of seldom monitored trace elements, including noble metals and some technology critical elements, we analyzed a sediment core taken from the Bay of Vidy (Lake Geneva), impacted by the effluent of an urban wastewater treatment plant (WWTP). The temporal profiles of the chemical elements show essentially two patterns linked to the implementation of the WWTP, with some elements increasing sharply (e.g. Au, In, Ba, Sb, Sn, platinum group elements), while others (e.g. Ga, Ge, rare earth elements) show decreasing concentrations due to dilution by additional effluent particle loads. The origin of the elements showing a marked increase is attributed to local sources (photographic industry and municipal incinerator). There is (still?) no evidence in the sedimentary record of concentration increases linked to the growing use of technologically critical elements by industry.

Enhancing biomass fuel properties of municipal sewage sludge with carbon-rich and low ash energy crops common reed and miscanthus

Wastewater treatment plant effluents, sewage sludge, and purified water are important resources for producing renewable energy and implementing a carbon-neutral green energy policy due to their richness in organic matter and nutrients for energy crops. In the present study, the biomass energy potential, fuel quality, and combustion emission characteristics of sewage sludge and the energy plants Arundo donax and Miscanthus×giganteus and their mixtures were investigated to improve the combustion properties of sewage sludge. The plant biomass is produced using sewage treatment plant effluent as a nutrient source. The proximate and ultimate analysis results showed that adding plant biomass shifted the fuel value of the mixtures, mainly reducing the ash content and increasing the volatile matter and carbon content in the solid biofuel. The regression analysis showed that heating values of 25, 50, and 75 % biomass in sewage sludge mixtures linearly increased HHV and LHV values. The increase in volatile matter significantly improved the ignitability index of sewage sludge, reaching the optimum value of 35 at 75 % biomass mixtures for both crops. The NOx and SO2 emissions of the mixtures were lower than those of sewage sludge. Overall, the results indicate a synergistic effect between the combustion of biomass from energy crops and sewage sludge. A comprehensive comparison of proximate, ultimate, heating value, fuel indices, and gaseous emissions shows that the mixed fuels of 50 % biomass and 50 % sewage sludge can promote combustion and reduce emissions. Arundo had better biofuel properties than Miscanthus.

Upgrading the eastern wastewater treatment plant effluent quality in Egypt for reuse by means of in-line coagulation followed by ultrafiltration

ABSTRACT Providing clean water to Egyptian citizens is one target of the 2030 sustainable development goals. Ultrafiltration (UF) has been investigated as an advanced treatment of the largest treatment plant in Alexandria. Although UF membranes have been widely used to treat secondary effluent, fouling remains a major challenge. The effects of green and conventional coagulants on controlling ultrafiltration fouling were examined. Two different dosages of each coagulant and a combination of ferric chloride and sodium ferrate were studied in a bench-scale setup that was built and operated under identical circumstances. The results showed that the combined ferrate and ferric chloride pretreatment had the highest performance in terms of the removal of organics and turbidity as well as the reduction of membrane fouling. Fouling can be managed in terms of the normalized flux drop with only 0.5 mg/L of ferrate, which performs similarly to 2.5 mg/L of ferric chloride. The higher the dosage of alum used, the lesser the fouling control observed. The green coagulant, when used as an in-line coagulant aid/oxidant with ferric chloride at very low doses, has a favorable potential to reduce membrane fouling and improve permeated wastewater quality, making it suitable for Grade A for reuse purposes.

In Situ Calibration of a Tube Passive Sampler in Wastewater Effluent with Adjustable Volumetric Flow for the Assessment of Micropollutants with Fluctuating Concentrations.

We present a versatile flow-through tube passive sampling device (TPS), with a controllable feedwater volumetric flow, that can be calibrated in situ against the feedwater load of organic micropollutants (OMPs). This semipassive approach has the advantage of a determinable water load feeding the sampling device. The design of the TPS allows for new sampling scenarios in closed piping while providing stable and controlled sampling conditions. The calibration referencing an OMP's feedwater load can describe the uptake behavior from wastewater treatment plant effluent with potentially highly fluctuating OMP concentrations. The TPS and its load-dependent calibration under realistic environmental conditions proves possible for a variety of organic trace substances in a challenging matrix. Nine of the 20 monitored representative OMPs could be calibrated load-dependently, leading to a good agreement between the calculated concentration from the TPS and the average concentration of corresponding direct measurements. Due to the simple measuring principle and the membrane-less discs, many influencing factors such as diffusion, turbulence, and lag time phenomena can be neglected. The TPS could support the existing online measurement analytics in a (process-) water treatment plant by delivering integrated water concentrations for discharge monitoring.

Enzymatic removal of the sulfa drugs sulfamethoxazole and sulfamerazine from synthetic wastewater by soybean peroxidase.

Sulfa drugs are a broad family of antibiotics widely used in the treatment of a range of infections. They have been found in surface and groundwater, as well as in sewage and effluent (treated sewage and sludge) of municipal or industrial wastewater treatment plants in concentrations of ng/L to >g/L. The continued presence of these so-called emerging contaminants (ECs) and their metabolites can cause adverse ecological effects, including bacterial resistance, even at very low concentrations. In this study, the first aim was to explore the feasibility of oxidation processes catalyzed by soybean peroxidase as an eco-friendly and economically advantageous alternative method for the conversion of the sulfonamides, sulfamethoxazole, and sulfamerazine. Optimum conditions were determined for 0.2 and 0.1 mM of the respective substrates. Optimum pHs were 1.6 and 3.6, respectively. Optimum molar peroxide ratios were 3.0 and 2.5 for the respective substrates. Enzyme activities of 4 and 2 U/mL showed 83 and 76% removal. With the redox mediator hydroxybenzotriazole, optimum pH was 3.6 for both substrates, optimum peroxide ratios were 1.5 and 1.25, and the optimum enzyme requirement decreased 40-fold. A time course study was conducted under optimal mediated conditions to determine the initial first-order rate constant and half-life of each substrate, from which half-lives were 0.0804 and 0.0608 min, normalized for substrate concentration. These two values were among the lowest when compared to 25 other compounds studied with the same enzyme. Finally, the oligomerization products of enzymatic treatment were characterized by mass spectrometry and showed the formation of oxidative dimers and azo compounds.

The efficacy of wastewater treatment plant on removal of perfluoroalkyl substances and their impacts on the coastal environment of False Bay, South Africa

Per- and polyfluoroalkyl substances (PFASs), which have their origins in both industrial processes and consumer products, can be detected at all treatment stages in wastewater treatment plants (WWTPs). Quantifying the emissions of PFAS from WWTPs into the marine environment is crucial because of their potential impacts on receiving aquatic ecosystems. In this study, the levels of five PFAS were measured in both influent and effluent sewage water samples obtained from a municipal WWTP, the discharges of which flow into False Bay, on the Indian Ocean coast of Cape Town, South Africa. Additionally, seawater, sediment, and biota samples from eight sites along the False Bay coast were also analysed. Results showed high prevalence of PFAS in the different environmental matrices. Perfluorononanoic acid was most dominant in all these matrices with maximum concentration in wastewater, 10.50 ng/L; seawater, 18.76 ng/L; marine sediment, 239.65 ng/g dry weight (dw); invertebrates, 0.72–2.45 µg/g dw; seaweed, 0.36–2.01 µg/g dw. The study used the chemical fingerprint of five PFASs detected in WWTP effluents to track their dispersion across a large, previously pristine marine environment and examined how each chemical accumulated in different marine organisms. The study also demonstrates that primary and secondary wastewater treatment processes cannot fully remove such compounds. There is thus a need to improve effluent quality before its release into the environment and promote continuous monitoring focusing on the sources of PFAS, including their potential transformation products, their environmental fate and ecological risks, particularly in areas receiving effluents from WWTP.

Acoustic cavitation assisted synthesis of PCDs@PVA composite film for UV shielding, intelligent pH detection, information encryption and food packing applications

Excessive exposure to UV and high-energy blue light (HEBL) can severely damage the skin and eyes. Therefore, it is essential to protect our bodies from UV and HEBL radiation. We created PEG-derived carbon dots (PCDs) using the acoustic cavitation approach in order to completely block UV and HEBL. The influence of different experimental parameters such as sonication time, amplitude, and temperature on the PCDs is examined. The optimized PCDs are found to have an average diameter ranging from 5 to 9 nm, contingent upon the preparation circumstances, and to have a quantum yield (QY) of 14–16 %. The PCDs vivid colour and simultaneous UV and HEBL absorption properties allowed the PVA film containing 0.120 wt% of PCDs to demonstrate outstanding blocking efficiency, with 99.9 % blocking in HEBL and 100 % blocking in UV-C, UV-B, and UV-A. The photoluminescence (PL) behaviour of PCDs is greatly reduced by Fe3+ ions because of strong excited state electron transfer. This fluorescent “turn-off” behaviour towards Fe3+ is highly selective and sensitive with a limit of detection (LoD) of 0.366 μM. Paper-based sensors incorporating PCDs are developed for the rapid and accurate detection of Fe3+ in surface water, wastewater treatment plant effluent, and tap water, leveraging their excellent sensitivity and selectivity towards Fe3+. The characteristics of ink-free patterned substrates are displayed by PCDs scattered across a PVA matrix, which makes them useful for the non-destructive acquisition and recognition of latent fingerprints (LFPs). A flexible, transparent film is produced when a LFP is exposed to a PCDs@PVA solution. In this film, a steady luminous fingerprint with specific ridge characteristics that aid in personal recognition is seen. This method shows promise for lifting and identifying long-exposed LFPs from various surfaces without causing damage. It is believed that the interfacial segregation of PCDs inside the PVA matrix during the film production process serves as a mechanism for LFP collection and visualization. The YOLOv8x program, which utilizes deep convolutional neural networks, is employed to analyze the discernible features present in fingerprints (FPs). Notably, their exceptional flexibility, foldability, and sustainability create new opportunities for use in the anti-counterfeiting (AC) field. Because of its remarkable fluorescence stability, it may be a viable substitute for conventional fluorescent inks. Fresh green apples are observed over time after being coated with 0.120 wt% PCDs@PVA and PVA. Virtual assessments indicated that the 0.120 wt% PCDs@PVA film coating significantly reduced weight and moisture loss, effectively inhibiting fungal growth and spoilage for over 25 days at room temperature (RT). Overall, the results clearly show that the PCDs@PVA film is easy to make, flexible, safe for the environment, and resistant to photodegradation. Hemolysis, and blood clotting exhibited favorable biocompatibility and nontoxicity.