The global production of organic wastes and heavy metals (HMs) poses significant environmental risks, along with considerable carbon emissions from waste decomposition. This highlights the significance of synergistic management of both wastes and CO2, which is a vital strategy for mitigating environmental pollution and climate change. Herein, we employed waste protein from wastewater produced during soybean peptide (SP) processing as a carbon matrix to anchor HMs Ni from electroplating wastewater. This mixture was electrospun into a gas diffusion electrode (GDE). This unique GDE design eliminates the need for a separate gas diffusion layer (GDL) and simplifies catalyst production. This versatile GDE consists of nanofibers with uniformly dispersed Ni single atom catalysts (SACs) on the fiber surface. Therefore, boasts a porous structure that facilitates CO2 diffusion and storage. The homogeneous distribution of Ni SACs within the GDE fosters high activity in the electrochemical conversion of CO2 to CO. At 50 mA/cm2 and 2.5 V cell voltage, Ni SACs achieved an excellent Faradaic efficiency of 81%−98% in a membrane electrode assembly (MEA). This technique holds a promise in achieving the collaborative management of carbon mitigation and wastes recovery.
The intensification of climate change action has made air conditioners a key target for emission reductions. This study examines the factors influencing residents’ willingness to buy (WTB) and willingness to pay (WTP) for green air conditioners across six cities in the Pearl River Delta (PRD) region, aiming to understand consumer behavior and inform targeted market strategies. Using a novel Contingent Valuation Method (CVM), this study surveyed 1732 residents through online and face-to-face interviews. Binary logistic and ordered logistic regression analyses identified key factors affecting WTB and WTP, including gender, income, education, knowledge of green air conditioners, and confidence in their emission reduction potential. However, the study reveals significant regional disparities in WTP and payment amounts through the Kruskal–Wallis H and Mann–Whitney U tests. The results also highlight Shenzhen has significant difference and highest payment value than other cities. These findings provide valuable insights into regional disparities and common factors in green consumption, offering guidance for market strategies and policy development aimed at promoting green air conditioners.
While the effectiveness of integrated floating film activated sludge (IFFAS) system filled with surface-modified carriers has been demonstrated in promoting simultaneous nitrification and denitrification (SND) performance, the effect of antibiotic stress on this system remains unexplored. Herein, this study investigated the stress response of SND in IFFAS under short- and long-term exposure to ciprofloxacin (CIP), a commonly used antibiotic. Results indicated the significantly higher semi-inhibitory concentration of CIP in the IFFAS system with modified carriers (36.54 mg/L) than that in IFFAS with conventional high density polyethylene (HDPE) carriers (28.77 mg/L). IFFAS system with modified carriers exhibited improved resistance to CIP toxicity compared to IFFAS using HDPE carriers or conventional activated sludge under long-term exposure to CIP concentrations from 50 to 3000 μg/L. The surface-modified carriers demonstrated a multifaceted strategy to mitigate the inhibitory effects of CIP, such as enhancing production of extracellular polymeric substances (EPS) to serve as a potential protective barrier against CIP toxicity, the less suppression of key enzyme activities involved in nitrogen removal, as well as inducing the upregulation of antibiotic resistance genes (ARGs) (qepA, qnrB/C) and the integrase gene (intI1) to enhance target prevention and efflux pumping mechanisms for resistance to CIP. These findings collectively underscored the efficacy of modified carriers in attenuating CIP toxicity within the SND system.
A biopolymer adsorbent was prepared by crosslinking chitosan (CS) and gelatin (GL) with ethylenediaminetetraacetic acid (EDTA) for the separation and recovery of three famous rare earth elements (REEs), i.e., lanthanum (La(III)), cerium (Ce(III)), and europium (Eu(III)), from water. In this adsorbent, the EDTA moiety acts as a crosslinking agent, in addition to aiding in REE adsorption via coordination sites. Various parameters, including contact time, pH, initial REE concentration, reusability, and selectivity, were investigated during the REE recovery from water. The kinetic results fit better with the pseudo-second-order (PSO) kinetics model, confirming the involvement of chemisorption and external film diffusion in the rate-determining step. The isotherm data fit the Langmuir model, indicating a homogeneous surface for REE adsorption. The rate constant (k2) values for PSO kinetics were (9.60 ± 0.05) × 10−4, (8.67 ± 0.04) × 10−4, and (10.30 ± 0.04) × 10−4 g/(mg·min), while the maximum adsorption capacities were 76.70 ± 5.70, 79.10 ± 6.80, and 86.20 ± 5.10 mg/g for La(III), Ce(III), and Eu(III), respectively. The CS-EDTA-GL adsorbent provided a good separation factor (β) in 16 REE mixtures; among them, an optimal β was observed for Eu(III) with values of 1.3838, 1.322, 1.284, 1.351, 1.4896, and 1.2792 for Eu/Sc, Eu/Yb, Eu/Tm, Eu/Y, Eu/La, and Eu/Er, respectively. Adsorption mechanism confirms the electrostatic interactions and coordination complexation role in the REE adsorption. Finally, the adsorbent was used in pure water, tap water, and two industrial wastewater samples collected at real environmental concentrations to determine its suitability for practical applications.
Most research on antibiotics in the environment disregards chiral antibiotics, such as ofloxacin (OF). In this study, tadpoles of Rana nigromaculata were exposed to 1 μg/L OF and levofloxacin (LVFX, an enantiomer of OF) for 75 d. Compared with dextrofloxacin, LVFX treatment had a greater effect on the inhibition of bodyweight, body length, development stage, and pathological liver damage. Therefore, OF exerts a stereoselective inhibitory effect on both growth and development, which is consistent with the results at the systemic metabolism level. Transcriptomic analysis revealed that the differentially expressed genes between OF and LVFX were mainly immune related. Targeted metabolomics showed that the stereoselective biological effect of OF on R. nigromaculata was caused by differences in contents of PE-O 16:0–22:4, PE 16:0–14:0, TAG 45:0–FA16:0, PE-P 18:0–16:0, PE 16:0–16:0, PC 16:0–22:4 + AcO, PE 18:1–18:3, PC 16:1–18:1 + AcO, and PC 18:1–18:3 + AcO. Furthermore, two enantiomers of OF were selectively bound to enzymes related to lipid metabolism. This study provides both theoretical and practical references for the accurate evaluation and scientific control of the ecological risk of chiral antibiotics.
Chlorination plays a vital role in guaranteeing the safety of reused stormwater, but it must be carefully managed due to its potential to react with dissolved organic matter (DOM) in water, forming disinfection by-products (DBPs). This study investigated DOM characteristics in stormwater from different land uses. The results showed that surrounding environments significantly impacted DOM characteristics in stormwater. Commercial stormwater and highway stormwater showed higher DOM concentrations with higher aromaticity than urban village and residential areas. DOM in commercial stormwater and highway stormwater had a high humification while residential stormwater and urban village stormwater had a higher fraction of recently microbially-generated DOM. When compared to other water sources in China, stormwater (rainwater that reaches the ground and washes off pollutants)/rainwater (rainwater without reaching ground surfaces) exhibited higher humification and fewer extracellular substances produced by microorganisms. Stormwater/rainwater was also more hydrophilic, with percentages ranging from 50.77% to 93.73%. However, all water sources contained a significant fraction of low molecular weight DOM, such as < 1 kDa, with stormwater in this study containing 36.45% to 66.39% of DOM < 1 kDa. These findings provide valuable insights into the DOM characteristics of stormwater.
Chlorinating wastewater before it is released into surface water can change the fate of organic pollutants. This transformation is influenced by chlorine residues, bromine-containing wastewater, and solar radiation. Losartan (LOS), one of the earliest sartan antihypertensive drugs produced, is used worldwide and has been found in the environment. However, its transformation mechanisms and environmental risks have not been systematically investigated. This research presents the degradation kinetics, transformation products, and environmental risks of LOS in different scenarios. The results revealed that kapp, HClO (LOS) ranged from 0.47 to 8.30 L/(mol·s) at pH 5.0–8.0. The kapp, HBrO (LOS) values at pH 5.0–8.0 ranged from 8.38 × 103 to 1.55 × 105 L/(mol·s), revealing a faster bromination reaction than chlorination. LOS degrades through direct photolysis, carbonate radicals (CO3•−), and singlet oxygen (1O2) under sunlight exposure. The solar/chlorination process accelerates the reaction rate through radical activity. In addition, chlorination and bromination resulted in halogen addition to the aromatic ring, whereas hydroxylation, hydrogen abstraction, demethylation, ring opening, and hydrolysis reactions were observed across all processes. Some products exhibit high biodegradation resistance and high toxicity, potentially threatening the aquatic environment. This study aims to enhance our understanding of the environmental behavior and resulting risks of LOS by exploring its environmental fate through various transformation processes.
The substantial generation of building waste had precipitated significant environmental issues in China, attributable to urban expansion. Recycled concrete aggregate (RCA) produced from building waste had been used as an alternative material in green roofs as substrates. However, the biological dynamics of RCA are unknown. Thus, the column test was performed to investigate the effects of different biochar types and application ratios on the biochemical properties and bacterial communities of RCA. Results show that the nutrients of RCA have been improved by biochar addition regardless of biochar types and application ratios. This led to the increase in plant weight and height by at least 227% and 38% in biochar amended RCA. However, biochar application reduced bacterial richness and α-diversity, while enhancing plant growth. This indicated that biochar application directly improves certain bacterial species that promote plant growth and productivity. Biochar application reduced the Proteobacteria abundance and enhanced the percentage of Acidobacteriota in RCA, indicating that biochar application shaped the bacterial communities into raw soil composition. The outcome of this research suggests that biochar application improved RCA biochemical performance as a substrate for green roofs, which provides a potential method to consume substantial RCA.
The investigation of microplastics (MPs) from the basin level is essential to understanding the fate and transport of MPs and for future modeling studies. This study explored the MPs in the Upper Ponnaiyar Basin, situated in Tamil Nadu, India, and examined their characteristics and sources in the terrestrial environment. The extraction of samples was performed using wet peroxide oxidation and subsequent density separation. The physical and chemical characteristics of extracted samples were analyzed using a stereomicroscope and Raman spectroscopy. The total concentration of MPs was found to be 1941.75 particles/kg, varying from 6.75 to 274.5 particles/kg. Urban regions contributed significantly higher concentrations of MPs compared to agricultural regions. The population showed a positive correlation to MPs concentration in agricultural regions. However, in rural and urban areas, the correlation was negative and non-existent, respectively. This observation indicated that the improperly disposed wastes in the urban and rural areas were disintegrated due to the heat and photo-induced fragmentation, highlighting the need to develop waste disposal systems in these regions. The results suggested an evident disparity in the distribution of MPs between the cultivated (24.75 ± 10.45 particles/kg) and uncultivated (18 ± 12.26 particles/kg) agricultural fields, which can be attributed to fertiliser, manure and ploughing. The findings of this study can serve as a reference for future studies.
Hypoxia is one of the most pressing global challenges affecting aquatic ecosystems and is primarily driven by global warming and eutrophication. 17α-ethinylestradiol (EE2), a representative endocrine-disrupting chemical, is widely used in hormone therapy and contraceptives. Both hypoxia and EE2 affect embryonic development by disrupting endocrine signaling and their interactions may induce effects significantly different from their individual impacts. However, the combined exposure of aquatic animals to EE2 under hypoxic conditions remains poorly understood. In this study, marine medaka (Oryzias melastigma) were exposed to combined stressors of EE2 and hypoxia to investigate their interactive effects on embryonic development compared to individual exposures. The key parameters assessed were heart rate, hatching time, hatching rate, and larval locomotion. Our findings indicate that combined exposure to EE2 and hypoxia resulted in an additive effect eye pigmentation development and an antagonistic effect on hatching time. These results highlight the diverse trends in the effects induced by the interaction of multiple stressors, suggesting that in-depth omics-based analyses are required to explore the underlying molecular mechanisms.
Aseptic containers, widely known as Tetra Paks, are multi-layered packages used in the food industry. These shelf-stable containers preserve the freshness and taste of products, such as beverages, and simplify their distribution and storage. However, the recycling of these packages is notoriously difficult and limited due to their multilayer structure, with recycling rates close to zero in many developing countries and rarely reaching 50% in industrialized nations. Nevertheless, various methods have been proposed to recycle such packages, including the recovery of paper through the hydropulping process and the separation of aluminum from plastic using solvents. The current study focuses on recycling the Al-PE composite residue after hydropulping. Nine solvents, namely xylene, toluene, ethanol, formic acid, distilled water, isopropyl alcohol, acetic acid, methanol, and ethyl acetate, were tested, and the percentage of polyethylene dissolution was determined for each. After identifying xylene and toluene as the most effective solvents, it was hypothesized for the first time that gasoline, a widely available solvent containing a high percentage of both xylene and toluene, could prove effective. Further investigations revealed that using the solvent mixture xylene:toluene:water (53:37:10, v/v) leads to 95% dissolution, while gasoline alone was 85% effective. Finally, Gas Chromatography-Mass Spectrometry (GC-MS) and Hansen Solubility Parameters (HSPs) were used to examine gasoline as a solvent more closely. The analyses showed that, in addition to BTEX, there are many constituents in gasoline that can aid the recycling process.
The utilization of black soldier fly larvae (BSFL) in food waste treatment has garnered significant attention because of its alignment with the principles of a circular economy. However, in rural areas, inadequate management of waste segregation and a high proportion of difficult-to-decompose materials in food waste have reduced the treatment rate by BSFL. After a year-long investigation into rural food waste, we designed a BSFL continuous self-separation reactor, which incorporated microorganisms to enhance waste degradation. The reactor also maintained heat retention, facilitated leachate collection, and enabled the continuous feeding and automated separation of adult black soldier flies. Both single-batch and multi-batch continuous operation modes of the reactor consistently and effectively treated food waste. In the single-batch mode, operation for 10 d resulted in a 38.9% reduction in the wet weight of food waste, with a larval biomass yield of 80.9 g/kg. In the multi-batch continuous mode, operation for 32 d led to a 56.6% reduction in the wet weight of food waste, with a larval biomass yield of 64.7 g/kg. In addition, a 24-h sufficient consumption experiment revealed that the degradation of organic matter in rural food waste was significantly affected by the combined efforts of BSFL and microorganisms. The harvested larvae exhibited high levels of crude protein and crude fat, making them a valuable high-protein, high-fat animal feed. Overall, the reactor demonstrated notable space efficiency and effective waste reduction, providing key insights into the use of BSFL for food waste management.
Partial nitrification (PN) is a highly promising strategy for energy- and carbon-efficient wastewater treatment. Effectively suppressing nitrite-oxidizing bacteria (NOB) is a critical challenge for stable PN operation. This work presents a NOB inhibition strategy on the basis of intrinsic substances in wastewater, namely salt and free ammonia (FA). Three different start-up strategies were adopted: 1) first increasing NH4+-N and then increasing salinity, 2) first increasing NH4+-N and then increasing salinity, and 3) increasing NH4+-N and salinity simultaneously. Either FA or salinity alone caused a temporary decrease in nitrite oxidation efficiency, resulting in a nitrite accumulation rate (NAR) < 35%. Under their combined effect, NAR > 80% was achieved beginning on day 8 (0.61 mg FA/L and 5 g NaCl/L), with a sustained increase in NAR, demonstrating the synergistic inhibitory effect of salinity and FA on NOB activity. In contrast, the enzymatic activity of ammonia-oxidizing bacteria (AOB) increased by 159.5%–203.9% due to the increased concentration of the substrate NH4+-N. In response to the three combined inhibition strategies, polysaccharide excretion was stimulated in all stratified extracellular polymeric substances, while the synergistic effect of FA and salinity further enhanced protein excretion. Following PN initiation with the three strategies, Nitrospira, the only NOB observed, was nearly washed out, and Nitrosomonas became the dominant AOB. The strategy of simultaneously increasing FA and salinity led to the greatest abundance of Nitrosomonas (28.42%). This study offers a novel strategy to achieve PN, which is beneficial for promoting PN-based carbon-efficient wastewater treatment.
