Environmental Chemistry Letters最新文献

In the context of climate change and the circular economy, most municipal wastewater treatment plants are not efficient because they generate huge amount of organic sludge, which in turn requires costly post-treatment by biological processes such as anaerobic digestion. An emerging solution is to add biochar to improve anaerobic digestion efficiency by enhancing microbial activity, aiding in the breakdown of complex organic compounds, producing more biogas, and promoting overall reactor stability. Here, we review the effects of adding biochar in anaerobic digestion, with emphasis on digester performance, process stability, biochar properties, and mechanisms. We discuss methane production, lag phase, electrical conductivity, volatile fatty acids, ammonia nitrogen, pH, and oxidation–reduction potential. We also review the process inhibition by biochar addition, with focus on phenols, heavy metals and microbial composition. Biochar properties are controlled by feedstock type, pyrolysis temperature, specific surface area, electrical conductivity, carbon and mineral content, electron exchange capacity, aromaticity, and particle size. We found that 6–16 g/L biochar supplementation consistently yielded higher cumulative specific methane compared to control without biochar, across diverse conditions and substrate types. Biochar’s role is explained by four mechanisms: enhancing functional microbes, facilitating direct interspecies electron transfer, improving the degradation of refractory compounds, and increasing reactor stability.

The contamination of ecosystems by pharmaceuticals and personal care products represents a significant threat to public health, necessitating innovative approaches to clean wastewater before release into aquatic environments. Here, we review the emerging strategies and methods for the remediation of gemfibrozil and carbamazepine, emphasizing toxicological impacts, advanced oxidation processes, membrane-based removal techniques, and the underlying mechanisms driving these removal processes. We found that engineered composites with strong electron transfer capabilities can enhance the removal efficiency as they boost the generation of highly oxidative radicals. For instance, a nano zero-valent ion incorporated carbon–nitrogen composite removes 100% of gemfibrozil within 60 min. Similarly, a ruthenium perovskite-based heterogeneous catalyst achieved 100% elimination of carbamazepine in 7.5 min.

Levels of biological thiols, or “biothiols,” in mitochondria can be used to assess environmental and biological oxidative stress, which can cause health issues such as malignant tumors and neurological diseases. Here, we review fluorescent probes for detecting biothiols, targeting mitochondria, and emitting red and near-infrared light, with focus on nitrogen cation and oxonium ion units as mitochondrial biomarkers. Red-emitting and near-infrared fluorescent probes for detecting biothiols are classified according to the way they target mitochondria. We present the structure, fluorescence behavior, and biological imaging of the probes.

Exposure of wildlife to anticoagulant rodenticides from sewer baiting and bait application is poorly understood. We analyzed residues of eight anticoagulant rodenticides in liver samples of 96 great cormorants, 29 common mergansers, various fish species, and coypu, in different German regions. Results show that hepatic residues of anticoagulant rodenticides were found in almost half of the investigated cormorants and mergansers due to the uptake of contaminated fish from effluent-receiving surface waters. By contrast, exposure of coypu to rodenticides via aquatic emissions was not observed. The maximum total hepatic anticoagulant rodenticide concentration measured in waterfowl specimens was 35 ng per g based on liver wet weight. Second-generation anticoagulant rodenticide active ingredients brodifacoum, difenacoum, and bromadiolone were detected almost exclusively, reflecting their estimated market share in Germany and their continuing release into the aquatic compartment. Overall, our findings reveal that second-generation anticoagulant rodenticides accumulating in wild fish are transferred to piscivorous predators via the aquatic food chain.

The recent discovery of nanoplastics in most ecosystems is a major, yet poorly known health issue. Here, we review nanoplastics with focus on their presence in the environment, their methods of detection, and their impact on the nitrogen cycle. Nanoplastics are widely distributed in ecosystems; however, their real concentrations are not known due to the limitation of actual detection methods. Detection methods include techniques based on mass spectrometry, optical instruments, and total organic carbon. Total organic carbon-based methods involve first membrane filtration and oxidation as pretreatment, then the measurement of total organic carbon as the total concentration of nanoplastics. Total organic carbon-based methods are easy and cost-effective, compared with other methods. Nanoplastics negatively impact ecosystems and nitrogen removal. Nanoplastics can adsorb on microbial cell membranes then disrupt the membrane integrity. Nanoplastics can also induce oxidative stress. Nitrogen cycling is substantially inhibited by nanoplastics during laboratory tests.

The rising aquaculture industry has induced an increase in aquaculture waste, calling for advanced methods to recycle waste in the context of the circular economy. Here, we review methods to treat aquaculture wastewater such as the biofloc technique, aquaponic-aquaculture, rice-fish co-culture, microalgae culture, algal–bacterial culture, membrane and moving bed bioreactors, and electrochemical techniques. We discuss nitrogen cycling, resources recovery, and nitrous oxide emission and mitigations. We observed that aquaculture wastewater irrigation allows for enhanced plant biomass, and biofloc technology improves fish biomass. Nitrogen removal processes, including anammox and partial nitrification, show improved performance. Nitrous oxide emission is mainly dependent on the total ammonia and nitrite concentration.

Pyrolysis of modern biomass is a sustainable technique to produce chemicals, yet efficient and selective conversion remains challenging. We studied biomass pyrolysis catalyzed by graphene oxide for the production of levoglucosan, a chemical with potential applications in biodegradable plastics and surfactants. We tested model compounds containing 40–100 wt% cellulose, poplar biomass, and we modelled the role of graphene oxide by calculations using the density functional theory. Results for model compounds show that levoglucosan production is higher for compounds containing less than 50% cellulose. By contrast, levoglucosan yield are reduced for model compounds having more than 60 wt% cellulose, because graphene oxide induced the breakdown of levoglucosan. Experiments show that pyrolysis of poplar biomass with 5 wt% graphene oxide increased about three times the yield of levoglucosan, compared to non-catalyzed pyrolysis. Enhanced levoglucosan formation is explained by the formation of a six-membered ring intermediate.

Toxic metals and metalloids pollution is a major ecological and human health issue, yet classical detection methods are limited. Here we review surface-enhanced Raman spectroscopy-based sensors using nanomaterial-based substrates for metal detection, with emphasis on substrate composition, functionalization, and assembly; metal sensing strategies; and analytical performance. Substrates include nobel metals, semiconductors, and composites. Substrate assembly can be done in solution or on solid supports. Sensing strategies comprise direct sensing, reporter recognition, reporter migration, substrate aggregation, and substrate modification. In general, the physicochemical properties of the substrates determine sensor sensitivity through electromagnetic and chemical enhancements of Raman scattering, whereas substrate surface functionalization, or lack thereof, determines sensor selectivity and the sensing mechanism. The main elements analyzed are mercury, lead, copper, arsenic, and chromium.

Water contamination is a major health issue that can be addressed by using carbonaceous materials to adsorb and filter pollutants, yet adsorption mechanisms need to be better understood to improve the adsorption efficiency. Here we review the models that are used to study the mechanisms of adsorption of drugs, dyes and metal ions on carbonaceous materials, with emphasis on classical and advanced isotherms. We discuss the fitting frequency, lignocellulosic and fossil fuel-derived adsorbents, biomass composition, activating agents, surface functions, the carbonization temperature, the medium temperature effect and the use of several isotherms to explain the same mechanism. The adsorption capacity can reach up to 2651 mg of contaminant per g of lignocellulosic materials and 1274 mg of contaminant per g of fossil materials. Isotherm validation commonly depends on several parameters. The adsorption on lignocellulosic carbonaceous materials is best described by the Langmuir isotherm. In contrast, adsorption on fossil materials is best described by the Redlich-Peterson isotherm. Advanced and classical isotherms are in good agreement in 44% of reports.