● Electrochemical degradations of the organochlorine pollutants are reviewed. ● Materials and mechanisms of the degradation are introduced. ● Different environmental and property of POCPs are compared. ● Development and applications of modified degradation materials are discussed. ● Molecular, electrode material and solution influences are also illustrated.
Pollution from persistent organic chlorinated pollutants (POCPs) in water environments is attributable to historical reasons and the lack of effective discharge regulations. Electrochemical degradation of POCPs, as a key study for POCP degradation, involves the use of electrons as reducing or oxidizing agents. The occurrence of this degradation depends on the environmental characteristics of the POCPs, the electrochemical materials used, and the technology and mechanisms involved. Furthermore, regarding the development of new materials and technologies, such as micro-, nano-, and atomic-sized materials, the degradation of POCPs achieves higher degradation efficiency and maximizes current utilization efficiency. In this review article, we first summarize the current status and future opportunities of the electrochemical degradation of POCPs. Environmental characteristics of POCPs facilitate a comparison of POCP degradation, and a comparison of electrochemical materials and their methods is made. Subsequently, we discuss technologies for the electrochemical degradation of POCPs from three aspects: oxidation, reduction, and a combination of oxidation and reduction. Moreover, the mechanisms were generalized in terms of molecular structure, electrode materials, and solution environment. In addition to maximizing the intrinsic enhancement factors of degradation, strategies to improve environmental accessibilities are equally important. This review article aims to effectively guide the advancement of POCP degradation and the remediation of environmental water pollution.
● Seven glucocorticoids in Jiangsu section of Yangtze River Basin were detected. ● The distributions of those glucocorticoids changed with season and locations. ● The levels of glucocorticoids in Jiangsu are higher than other regions in China. ● Prednison exhibits the highest ecological risk in the studied water environment.
Glucocorticoids, which are one of the most extensively used steroid hormones, are typical endocrine disruptors. In recent years, glucocorticoids have been widely detected in surface waters such as rivers and lakes, but there are relatively few studies focusing on their ecological risk assessment. In this study, the pollution characteristics of seven glucocorticoids were studied in the Jiangsu section of the Yangtze River Basin, and ecological risk assessments were performed using the risk quotient method. The results showed that seven glucocorticoids were detected at different levels at eight sampling sites. Among these glucocorticoids, prednisone had the highest value of 238.27 ng/L in the wet season, with pollution levels significantly higher than those reported in other areas. The ecological risk evaluation showed that prednisone, prednisolone, dexamethasone, and hydrocortisone acetate all had risk quotient values greater than 1 in the studied water environment, posing a high ecological risk. This study provides a scientific foundation for the in-depth study of the pollution characteristics and ecological risk of glucocorticoids in water bodies in the Jiangsu section of the Yangtze River Basin.
● AHL-mediated quorum sensing is widely observed in H2-denitrification systems. ● Inclusion of an external AHL source can enhance the induction of QS. ● C14-HSL and C4-HSL, especially C14-HSL, can enhance biofilm formation. ● Tech to expedite autochthonous microbial biofilm formation has been proposed.
The slow growth rate of autotrophic bacteria and regulation of biofilm thickness are critical factors that limit the development of a hydrogen-based membrane biofilm reactor (H2-MBfR). The acyl-homoserine lactone (AHL) mediated quorum sensing (QS) system is a crucial mechanism regulating biofilm behavior. However, the AHLs that promote biofilm formation in autotrophic denitrification systems and their underlying mechanisms, remain unclear. This study explored the impact of AHL-mediated QS signaling molecules on biofilm development in H2-MBfR. This study revealed that C14-HSL and C4-HSL are potential signaling molecules that enhanced biofilm formation in long-term stable operating H2-MBfR. Subsequent short-term experiments with C14-HSL and C4-HSL confirmed their ability to increase bacterial adhesion to carrier surfaces by promoting the production of extracellular polymeric substances (EPS). Functional gene annotation indicated that exogenous C14-HSL and C4-HSL increased the abundance of signal transduction (increased by 0.250%–0.375%), strengthening the inter bacterial QS response while enhancing cell motility (increased by 0.24% and 0.21%, respectively) and biological adhesion (increased by 0.044% and 0.020%, respectively), thereby accelerating the initial bacterial attachment to hollow fiber membranes and facilitating biofilm development. These findings contribute to the understanding of microbial community interactions in H2-MBfRs and provide novel approaches for biofilm management in wastewater treatment systems.
● A simple and effective SUPR reactor was developed. ● Over 98% of P could be recovered without urine storage or chemical addition. ● Struvite with relatively high purity could be obtained. ● Increased urine dilution led to higher nitrification efficiency.
Leveraging seawater toilet flushing system in Hong Kong, China, a Seawater-based Urine Phosphorus Recovery (SUPR) process that integrates ureolysis and phosphorus (P) recovery was proposed in our earlier work. In this study, a thermodynamic model was applied to evaluate the effects of ureolysis and the seawater-to-urine mixing ratio (S/U ratio) on P precipitation in the SUPR system. The results suggested that effective P recovery was thermodynamically feasible across a wide range of S/U ratios, with elevated pH levels resulting from ureolysis being critical for P precipitation. Furthermore, a SUPR reactor was developed to validate this process. When the hydraulic retention time (HRT) exceeded 3 h and the S/U ratio was lower than 3:1, more than 98% of P could be recovered without urine storage, chemical dosage, or external mixing. Further decrease in the HRT and increase in S/U ratio caused flushing out of fine precipitates, resulting in a relatively low P recovery efficiency. However, this could be advantageous when downstream urine nitrification is implemented, as dilution of urine can alleviate the inhibitory effects of free ammonia and free nitrous acid, as well as overcome the P limitation problem, thus facilitating urine nitrification. Consequently, there is a trade-off between optimizing P recovery and nitrification efficiencies.
● Genotoxicity was higher in upper Yangtze River than that in the lower reaches. ● COVID-19 changed the seasonal regularity of genotoxicity in lower Yangtze River. ● Water samples exhibited more pronounced genotoxicity compared to sediments. ● Direct genotoxicity being the primary factor and related to antiviral drugs and DBPs. ● 65% or 71% of water posed high or medium risk for Paramecium caudatum or Danio rerio.
Abstract The global spread of viruses can lead to the release of large amounts of disinfectants or antiviral drugs into the water environment. The resulting disinfection byproducts (DBPs) and residual antiviral drugs, acting as genotoxic substances or their precursors, may pose risks to aquatic animals and drinking water sources; however, to date, no studies have analyzed the changes in genotoxicity in the Yangtze River before and after the epidemic. In the present study, water and sediment samples from the Yangtze River were collected during different seasons, just before and after the outbreak of COVID-19, and were assessed using the SOS/umu test (with and without liver S9). The results indicated that water samples exhibited more pronounced genotoxicity than did sediments, with direct genotoxicity being the primary factor. Additionally, there were significant regional differences, with notably greater genotoxicity observed in the upper Yangtze River than in the lower reaches before the COVID-19 epidemic. However, this trend was reversed six to ten months later, suggesting the accumulation of DBPs or antiviral drugs after the COVID-19 pandemic. Moreover, the risk quotient indicated that 65% of the water samples posed a high risk for Paramecium caudatum, whereas 71% of the samples posed a medium risk for Danio rerio, thereby representing a potential threat to the ecological security of the Yangtze River. In conclusion, this study, at the basin scale, revealed the impacts of COVID-19 on the Yangtze River, highlighting the need to prevent DBPs and pharmaceutical pollution during similar events in the future.
● Mechanisms for multiple photochemical transformation of tetracyclines were reported. ● The degradation kinetics were dependent on pH and reactivities of dissociated forms. ● Anionic forms reacted faster in the apparent photolysis and photooxidation processes. ● Different pathways and various intermediates occurred for the three reactions. ● The major by-products showed similar or more toxicities than the parent antibiotics.
Most antibiotics contain ionizable groups that undergo acid-base dissociation giving rise to diverse dissociated forms in aquatic systems depending on the pH of the system. In sunlit surface waters, photochemical transformation plays a crucial role in determining the fate of antibiotics. This study presents a comprehensive examination of the photo-transformation degradation kinetics, pathways and photoinduced toxicity of three widely detected tetracyclines (TCs): tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC). Under simulated sunlight (λ > 290 nm), their apparent photolysis followed pseudo-first-order kinetics, with rate constants significantly increasing from H2TCs0 to TCs2–. Through competition kinetic experiments and matrix calculations, it was found that the anions HTCs– or TCs2– (pH ~ 8–10) were more reactive toward hydroxyl radicals (•OH), while TCs2– (pH ~ 10) reacted the fastest with singlet oxygen (1O2). Considering the dissociated species, the total environmental photo-transformation half-lives of TCs were determined, revealing a strong dependence on the water pH and seasonal variation in sunlight. Generally, apparent photolysis was the dominant photochemical process, followed by 1O2 and •OH oxidation. Different transformation pathways for the three reactions were determined based on the key photoproducts identified using HPLC-MS/MS. Toxicity tests and ECOSAR software calculations confirmed that the intermediates produced by the •OH and 1O2 photo-oxidation processes were more toxic than the parent compounds. These findings significantly enhance our understanding of the complex photochemical fate and associated risks of TCs in aqueous environments.
● A novel 3D electro-Fenton method was developed to treat nitrobenzene wastewater. ● Electrochemical oxidation combined with Fenton improves degradation efficiency. ● The new method is cost-effective and produces less sludge than conventional Fenton.
Traditional Fenton oxidation is an effective method for reducing pollutants that are difficult to degrade. Owing to the large amounts of Fe(II), acids, and alkalis added in the reaction, large amounts of Fenton sludge are produced, increasing treatment costs and restricting the method’s application. In this study, we developed a three-dimensional electro-Fenton system by adding iron-carbon filler and investigated the effects of different electrolytic cell structure arrangements, particle electrode dosages, sponge iron (SI) to granular activated carbon (GAC) dosage ratios, current densities, H2O2 dosages, and cathodic aeration on nitrobenzene (NB) wastewater treatment. The optimal system conditions were a particle electrode dosage of 100 g/L, SI:GAC mass ratio of 3:1, current density of 30 mA/cm2, H2O2 dosage of 50 mmol/L, cathodic aeration of 0.8 L/min, and hydraulic retention time of 120 min. The average NB removal rate and chemical oxygen demand reached 67.38%±1.05% and 70.60%±1.15%, respectively, for which the increase in Fenton sludge was 891.8 mg/L. Different from the traditional Fenton process, additional Fe(II) was not required in the process used herein, reducing iron sludge accumulation and lowering the operating costs of using Fenton sludge as a hazardous waste treatment. In addition, the process applied in this study was able to reduce the chemical amounts used and increase the treatment efficiency. The reductions in sludge treatment costs and secondary pollutants make the proposed process an efficient and sustainable alternative for treating NB wastewater.
● Temperature, relative humidity and wind field are influential meteorological factors. ● OH radical chain length and OPE are dominated by the NO x decline. ● The O3 formation is controlled by VOCs and NO x in 2020 summertime.
Changes in ozone (O3) can be evaluated to inform policy effectiveness and develop reasonable emissions reduction measures. This study investigated the causes of summertime maximum daily 8-h average (MDA8) O3 variation between 2015 and 2020 in Nanjing, China, a megacity in the Yangtze River Delta (YRD) region, from the perspective of meteorological conditions and anthropogenic emissions of O3 precursors (VOCs and NOx). Compared with 2015, the observed MDA8 O3 decreased by 19.1 μg/m3 in August 2020. The indirect and indirect impacts of meteorological conditions contributed 44% of the decline, with temperature, relative humidity, and wind playing important roles in the O3 variation. The O3 drop by 10.7 μg/m3 (56% of the total decrease) may have been due to the decreases in anthropogenic emissions of VOCs and NOx by 7.8% and 11.7%, respectively. The longer hydroxyl (OH) radical chain length and higher ozone production efficiency (OPE) indicated that the reduction of anthropogenic emissions accelerated the ROx (ROx = OH + HO2 + RO2) and NOx cycles in O3 production, making O3 more sensitive to NOx. This corresponded to the O3 formation shifting from a VOC-limited regime in 2015 to a transition regime in 2020 and O3 decrease with anthropogenic emission reduction. Hence, the joint control of O3 precursor emissions can effectively mitigate O3 pollution in Nanjing.
● The milestones underlying studies and mechanisms are summarized. ● Problematic biofilms can be removed by nanozymes through multiple strategies. ● Surface reactivity regulation can improve the antibiofilm efficiency of nanozymes. ● Machine learning-assisted nanozyme design can help improve treatment efficiency.
Current microbial control strategies face challenges in keeping up with the escalation of microbial problems due to the presence of biofilms. Therefore, there is an urgent need to develop effective and robust strategies to control problematic biofilms in water treatment and reuse systems. Nanozymes, which have intrinsic biocatalytic activity and broad antibacterial spectra, hold promise for controlling resilient biofilms. This review summarizes the milestones of nanozyme studies and their applications as antibiofilm agents. The mechanisms behind the antibacterial, quorum quenching, and depolymerizing properties of nanozymes with different enzyme activities are discussed. Notably, the surface and composition of nanozymes are crucial for their efficacy in biofilm control; thus, rationally designed nanozymes can increase their effectiveness. Additionally, the challenges of nanozymes as antibiofilm agents in realistic scenarios are investigated along with proposed strategies to overcome these challenges. Prospects of nanozyme-based biofilm control, such as machine learning-assisted nanozyme design, are also discussed. Overall, this review highlights the potential of nanozymes as antibiofilm agents and provides insights into the future design of nanozymes for biofilm control.
● Potential binding potency of 29 ECs on Gobiocypris rarus transthyretin were tested. ● The Gobiocypris rarus TTR binding affinity of 3 ECs was higher than that of T4. ● High throughput screening classification models for fish and human TTR were derived. ● “TTR Profiler” can predict the potential fish and human TTR disrupting effects data.
Emerging contaminants (ECs) have drawn global concern, and the endocrine disrupting chemicals is one of the highly interested ECs categories. However, numerous ECs lacks the basic information about whether they can disturb the endocrine related biomacromolecules or elicit endocrine related detrimental effects on organism. In this study, the potential binding affinity and underlying binding mechanism between 29 ECs from 7 chemical groups and Gobiocypris rarus transthyretin (CrmTTR) are investigated and probed using in vitro and in silico methods. The experimental results demonstrate that 14 selected ECs (11 disinfection byproducts, 1 pharmaceuticals and personal care product, 1 alkylphenol, 1 perfluoroalkyl and polyfluoroalkyl substance) are potential CrmTTR binders. The CrmTTR binding affinity of three ECs (i.e., 2,6-diiodo-4-nitrophenol (logRP(T4) = 0.678 ± 0.198), 2-bromo-6-chloro-4-nitrophenol (logRP(T4) = 0.399 ± 0.0908), tetrachloro-1,4-benzoquinone (logRP(T4) = 0.272 ± 0.0655)) were higher than that of 3,3′,5,5′-tetraiodo-L-thyronine, highlighting that more work should be performed to reveal their potential endocrine related harmful effects on Gobiocypris rarus. Molecular docking results imply that hydrogen bond and hydrophobic interactions are the dominated non-covalent interactions between the active disruptors and CrmTTR. The optimum mechanism-based (for CrmTTR), and high throughput screening (for CrmTTR, little skate-TTR, seabream-TTR, and human-TTR) binary classification models are developed using three machine learning algorithms, and all the models have good classification performance. To facilitate the use of developed high throughput screening models, a tool named “TTR Profiler” is derived, which could be employed to determine whether a given substance is a potential CrmTTR, little skate-TTR, seabream-TTR, or human-TTR disruptor or not.
● Recent progress on three non-radical oxidation systems was summarized. ● The challenges of identifying non-radical pathway were discussed. ● The key factors determining the generation of non-radicals were reviewed. ● The application prospect of non-radical oxidation system was envisaged.
The large amount of refractory organic wastewater produced from industry and agriculture sectors poses a significant threat to both water ecosystems and human health, necessitating the exploration of cost-efficient and efficacious removal techniques. Persulfate, when activated by various catalysts, can produce oxidative species, demonstrating promising potential in remediating organic wastewater. In recent years, numerous studies have unveiled that persulfate can be readily decomposed into non-radicals, which exhibits high selectivity toward pollutants and robust performance in complex wastewater environments. However, the challenges in identifying non-radicals and the unclear catalytic mechanism hinder its further application. This paper critically reviews the research progress on non-radical oxidation in persulfate-based heterogeneous catalytic system. The main advancements and existing challenges in three non-radical oxidation pathways, i.e., singlet oxygen, electron transfer, and high-valent metal oxides, are summarized, and the key factors influencing the production of non-radicals are elaborated. The engineering aspects of non-radical oxidation system are further discussed, and the future prospects of this technology in wastewater treatment are envisaged. This review aims to bridge the knowledge gaps between current research and future requirements.
● We integrate omics data to analyze the aquatic toxicodynamics of nanoplastics. ● Transcriptomics is the primary omics tool in aquatic nanoplastic toxicology research. ● Metabolic disruption, oxidative stress, & photosynthesis inhibition are key effects. ● Variations in molecular responses to nanoplastics are underscored among species. ● Recommendations are made to advance the multi-omics approach in nanoplastic research.
Amidst increasing concerns about plastic pollution’s impacts on ecology and health, nanoplastics are gaining global recognition as emerging environmental hazards. This review aimed to examine the complex molecular consequences and underlying fundamental toxicity mechanisms reported from the exposure of diverse aquatic organisms to nanoplastics. Through the comprehensive examination of transcriptomics, proteomics, and metabolomics studies, we explored the intricate toxicodynamics of nanoplastics in aquatic species. The review raised essential questions about the consistency of findings across different omics approaches, the value of combining these omics tools to understand better and predict ecotoxicity, and the potential differences in molecular responses between species. By amalgamating insights from 37 omics studies (transcriptome 22, proteome six, and metabolome nine) published from 2013 to 2023, the review uncovered both shared and distinct toxic effects and mechanisms in which nanoplastics can affect aquatic life, and recommendations were provided for advancing omics-based research on nanoplastic pollution. This comprehensive review illuminates the nuanced connections between nanoplastic exposure and aquatic ecosystems, offering crucial insights into the complex mechanisms that may drive toxicity in aquatic environments.
● Toxicological effects of copper pyrithione on aquatic organisms were reviewed. ● Copper pyrithione causes copper-induced oxidative stress and cell death. ● Copper pyrithione induces severe deformities in fish. ● Long-term effects and associated risks of copper pyrithione remain unknown.
Copper pyrithione (CuPT) is an alternative to tributyltin that is widely used as an antifoulant and biocide in paint for ship hulls, fishing nets, and other marine environmental facilities. It gradually leaches from antifouling coatings into the aquatic environment, posing health risks to aquatic organisms. In recent years, there have been increasing concerns regarding the impacts of CuPT and its degradation products on organisms, as well as the associated health risks. Although the ecotoxicity of CuPT and its degradation products in various species has been studied, there are no comprehensive reviews in the literature that have collated and interpreted these data. This review provides a comprehensive summary of the ecotoxicological effects of CuPT and its degradation products on microorganisms, plants, invertebrates, fish, and mammals. CuPT and its degradation products can affect the light utilization of plants, thereby altering primary production in ecosystems. It can disrupt cell membranes, antioxidant capacity, and cellular pH gradients in animals, leading to developmental toxicity, deformities, morphological damages, endocrine disruption, reproductive toxicity, hepatotoxicity, and neurotoxicity. Mitochondria are believed to be the primary target of CuPT-induced toxicity in aquatic animals; however, further investigations are warranted to reveal the long-term (e.g., multigenerational and transgenerational) impacts and associated molecular mechanisms of CuPT and its degradation products—particularly at environmentally realistic levels. This will facilitate a more comprehensive understanding of the health effects (both in terms of toxicity and hormesis) and environmental risks of CuPT and its degradation products, facilitating more effective regulation and mitigation.
