Environmental Technology最新文献

Caffeine is considered a pollutant that threatens aquatic life and human well-being, and its anaerobic treatment is typically a slow process. Microbial fuel cells (MFCs) present a sustainable alternative by enabling caffeine degradation while simultaneously generating electricity. This study investigates the anaerobic degradation of caffeine using MFCs as a sustainable wastewater treatment approach under various operational conditions. A two-chambered MFC was established employing synthetic wastewater, sodium acetate as the carbon source, and anaerobic sludge as inoculum. Various concentrations of acetate (0.375 and 1 g/L) and caffeine (10 and 20 mg/L) with and without an external nitrogen source, ammonium chloride, were evaluated for power generation and caffeine degradation efficiency. Results demonstrate that caffeine degradation achieves 100% in 5 days when coupled with external nitrogen sources, whereas degradation without external nitrogen achieves the same within 3 days for both caffeine concentrations. Furthermore, increasing the caffeine loading concentration results in a maximum power density of 5.64, 9.37, and 11.83 mW/m², respectively, for 10 and 20 mg/L caffeine concentrations. Additionally, when the acetate concentration was increased to 1 mg/L without external nitrogen, degradation of 10 and 20 mg/L caffeine requires 3 and 5 days respectively, with a maximum power density of 12.8 mW/m². This investigation underscores the potential of anaerobic bacteria to degrade caffeine utilising it as a nitrogen source while also contributing to power generation in MFCs. Moreover, the results highlight the significant influence of operational parameters on caffeine degradation efficiency and power generation.

Greenhouse gases (GHGs) such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) emanating from coal-fired power plants contribute substantially to the greenhouse effect. In the face of the continual trend of global warming, curbing GHGs emissions has emerged as an essential step to lessen anthropogenic carbon emissions and attain the targets of carbon peak and neutrality. The practical implementation of strategies to reduce carbon emissions from coal-fired power stations necessitates the precise monitoring and recording of associated greenhouse gas emissions. In the study presented herein, a measurement system based on non-dispersive infrared (NDIR) spectroscopy has been devised, enabling the concurrent assessment of CO₂, CH₄, and N₂O concentrations. An investigative case study has been conducted to examine the relationship between the operational conditions of coal-fired power plants and the emissions of greenhouse gases, thereby providing an enriched understanding of the variables that affect these emissions. The findings of this study may act as a significant guide for future enhancements and fine-tuning of measures to control greenhouse gas emissions from coal-fired utility boilers.

This study investigated the presence, distribution, and bioaccumulation of microplastics in surface water and Coptodon rendalli at six sites in Dikgatlhong Dam, Botswana: S1 (Tati River Inflow), S2 (Tati River Midway), S3 (Confluence), S4 (Boundary Wall), S5 (Shashe River Midway), and S6 (Shashe River Inflow). All samples were taken in a single day to ensure consistency. To digest organic materials, water samples were processed with the wet peroxide oxidation method, whereas fish tissues were pre-treated with 10% potassium hydroxide (KOH) before going through the same oxidation procedure to extract microplastics efficiently. Surface water microplastic concentrations ranged from 33.59 ± 5.15 n/L (S5) to 78.32 ± 12.83 n/L (S1), and items per fish ranged from 9.46 ± 2.98 (S4) to 19.33 ± 5.87 (S1). The moderate positive association (r = 0.65) between water and fish microplastic levels suggests that water is the primary exposure channel. However, site-specific variations in microplastic size reveal additional factors such as sediment interactions and feeding behaviours. This study emphasizes the importance of focused mitigation methods for managing microplastic pollution and provides a key baseline for future research on microplastic contamination in Botswana's aquatic systems.

Due to differences in physical and chemical properties, peroxymonosulfate (PMS) and peroxydisulfate (PDS) show distinct reactivity under ultraviolet (UV) activation. Consequently, selecting the appropriate persulfate concentration is critical for optimising the degradation efficiency of the system. This study compared the degradation efficiency of acetaminophen (ACE) in UV light-activated PDS (UV/PDS) and PMS (UV/PMS) systems. Under optimal conditions ([ACE]₀ = 10 mg·L^-1, UV light power = 6 W, [pH]₀ = 7), the ACE removal rate reached 97.8% within 60 min when the dosage of PDS was 8 mM. 91.7% within 60 min with 10 mM PMS in the UV/PMS system, and only 82.4% when the PMS dosage was 8 mM. Quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that the UV/PDS system exhibited higher characteristic peak signal intensities for sulfate radical ($S{O}_4^{\cdot -}$), superoxide radical ($O_2^{\cdot -}$), singlet oxygen (¹O₂), and hydroxyl radical ($\mathrm{OH}\cdot$) compared to the UV/PMS system. In the UV/PDS system, $S{O}_4^{\cdot -}$ and ¹O₂ were identified as the primary contributors to ACE removal, whereas $S{O}_4^{\cdot -}$ was the predominant species in the UV/PMS system. Moreover, the intermediate products generated during the UV/PDS reaction were analyzed using liquid chromatography-mass spectrometry (LC-MS). This study demonstrated the feasibility of UV light-activated persulfate systems for ACE treatment, providing a systematic comparison of the performance and mechanisms of ACE degradation between the two systems. The findings offer valuable insights and practical guidance for selecting persulfates in UV light-activated research and applications.

Taking PAEs in the urban surface soil of Xi'an as the research object, high-performance liquid chromatography (HPLC) was used to detect 6 PAEs (DMP, DEP, BBP, DnBP, DEHP and DnOP) content, that are highly controlled by the United States Department of Environmental Protection (U.S. EPA) in the urban surface soil. The focus was on the accumulation characteristics and composition characteristics of PAEs in urban surface soil. The results show that the average contents of DMP, DEP, BBP, DnBP, DEHP and DnOP in Xi'an's surface soil are 0.10, 0.05, 0.05, 0.52, 0.77, and 0.05 mg·kg^-1, respectively, and the total amount of 6 PAEs (∑6PAEs) ranges In the range of 0.19∼19.15 mg·kg^-1, the average value is 1.37 mg·kg^-1. The average values of DMP, DEP, DnBP and DEHP in the surface soil of Xi 'an exceeded the PAEs control standard of New York State, and the maximum values of DMP, DnBP and DEHP exceeded the PAEs governance standard of New York State. Compared with the PAEs content in other cities, DMP and BBP in the surface soil of Xi'an were at a high level, and DEP, DnBP, DEHP and DnOP were at a medium level. In addition, the distribution of ∑6PAEs in different functional areas is traffic area > Industrial area > mixed area > Park > Cultural and educational area > residential area.

The processing of coffee consists on the separation of the grains from other parts of the fruit, then roasted and extracted to obtain the beverage that is so appreciated worldwide. Several studies have dedicated efforts to treat the residue from coffee processing, while recovering lignols of industrial interest. Given this scenario, the nutrients in the coffee husk can enhance microbial growth, providing optimal conditions for the microorganisms to produce metabolites that may have medicinal properties. Deep eutectic solvents (DES) are a class of solvents and/or catalysts designed on demand for specific uses, being used to enhance extraction processes of coffee husk. Our present study was successful establishing conditions where the coffee husk enhanced the growth of microorganisms from two Brazilian biomes, the endophytic fungus from Cerrado and the actinomycete, from Atlantic Rainforest in Boraceia, São Paulo. The DES composed by ChCl/LA (1:10) was selected as cosolvent for the extraction, while it also optimized microbial cultivation conditions. Coffee husk was an excellent supplement for culture media, once the fungus FE316 produced Fumiquinazoline A, Tripprostatin B and Pseurotin A, while the actinomycete AC154 produced Trichorozin-IV as metabolites only expressed when in addition to the coffee husk. UHPLC-MS/MS analysis enabled the annotation of lignin monomer compounds, such as alkaloids, phenylpropanoids and terpenoids present in the coffee husk, more specifically, caffeic acid, isochlorogenic acid B, chlorogenic acid and coniferyl aldehyde, underscoring the value of this biomass.

The flow channel configuration affects microbial inactivation efficiency in water because it considerably influences hydrodynamics and ultraviolet (UV) light distribution. The ratio of channel length to breadth (α) and the ratio of channel width to depth (β) of a serpentine flow channel on Escherichia coli inactivation efficiency were investigated. Simulations revealed that when α was 1.0, the flow channel had a uniform velocity distribution and performed the longest microbial residence time. Furthermore, biodosimetry tests indicated that when β was 1.0, the reactor resulted in a maximum inactivation efficiency of 3.7 log when the distance between the UV LEDs and the water was 11.5 mm. The optimal aspect ratio β led to the ideal balance between microbial residence time and UV irradiance, resulting in the highest UV fluence (10.6 mJ/cm²) for the bacteria. The inactivation efficiency observed at the aforementioned aspect ratio was approximately 48% higher than that observed at an aspect ratio of 2.56. Additionally, decreasing the distance between the UV LEDs and the water from 11.5 to 3.5 mm enhanced the inactivation efficiency at all aspect ratios because of the considerable increase in UV irradiance in the water.

Zeolite ion-exchange column system has been suggested as a viable option for the removal of total ammonia nitrogen (TAN) from explosives-impacted mining wastewater (EIMWW) in cold regions. The objective of this bench-scale study was to compare the effectiveness of several NaOCl, NaOCl-NaCl and NaCl regeneration solutions on the performance of a zeolite column loaded with a synthetic EIMWW. The NaOCl experiments confirmed that effluent pH, total chlorine level, and free chlorine levels during the chlorine regeneration were positively related, thus indicating that ammonia is oxidized to nitrogen gas accompanied by production of hydrogen ions. This led to the regeneration of TAN-containing sites but it also regenerated sites containing K and Ca, this appears to be accomplished through the Na ions in the NaOCl solution and H⁺ ions generated in the breakpoint chlorination reaction. The three regeneration schemes worked effectively, they did not significantly impact TAN uptakes and TAN selectivity. The NaOCl-NaCl regeneration scenario was superior to the NaOCl regenerations as it was faster and resulted in shorter low-pH periods that may damage the zeolite. And unlike the NaCl regeneration, the NaOCl-NaCl used regenerant was essentially TAN free, so it permits regenerant reuse and avoids creating a secondary waste stream. Thus, zeolite column treatment coupled with NaOCl-NaCl regeneration is a practical approach for the treatment of TAN-laden EIMWW.

Co-contamination of heavy metals and chlorobenzenes (CBs) presents a significant environmental challenge, yet the impact of metal ions on CB biodegradation remains unclear. This study investigates the effects of Cd²⁺, Hg²⁺, Zn²⁺, and Fe³⁺ on the CB degradation ability of Burkholderia strain TF-2. The results indicate that metal ions inhibit CB biodegradation, with the most pronounced inhibitory effects observed at concentrations of 10.0  mg/L (Zn²⁺), 50.0  mg/L (Fe³⁺), 2.5  mg/L (Cd²⁺), and 3.0  mg/L (Hg²⁺). Han-Levenspiel modelling identified critical inhibitory concentrations for Zn²⁺, Cd²⁺, and Hg²⁺ as 9.198, 2.891, and 2.234  mg/L, respectively, while Fe³⁺ was not applicable to this model. Toxicity assessments, expressed as EC50 values, ranked the metal ions as follows: Hg²⁺ (0.451 mg/L) > Cd²⁺ (0.505  mg/L) > Zn²⁺ (5.531  mg/L) > Fe³⁺ (10.37  mg/L). These findings identify Hg²⁺ and Cd²⁺ as the strongest inhibitors of CB degradation by Burkholderia TF-2 and offer insights to optimise bioremediation strategies for heavy metal-organic co-contaminated sites.

The purpose of this study is to investigate and compare the ICT sector's carbon emission responsibility under production-based (PBA), consumption-based (CBA), income-based accounting principle (IBA) and shared-responsibility approach (SRA), focusing on the case of China. We utilise the environmentally extended multiregional input-output (EE-MRIO) model based on China's 2012 and 2017 provincial MRIO table. The empirical finding demonstrate that emission responsibilities assigned to the ICT sector under CBA is greater than those under SRA, IBA and PBA. Regional emissions are highly concentrated under the PBA and IBA. The absolute amount of ICT emission responsibility increased under all accounting method, but the increase in the national share varied significantly. The inter-sectoral carbon emission transfer pattern, shows ICT sector exhibits dual carbon lock-in effects, demonstrates strong supply-chain dependencies, upstream procurement anchored in energy-intensive sectors (S23, S14, S13), while downstream consumption shows path-dependent concentration in S23, S29. Inter-regional transfer exhibits significant regional heterogeneity. In economically developed provinces like Guangdong, Beijing and Zhejiang, the ICT sector has a significant downstream-pushing effect and notable upstream-pulling effect on other regions. Conversely, in less developed northeastern and northwestern provinces, the ICT sector, mainly serving local consumption, leads to minimal upstream and downstream carbon emissions effect. These results provide supportive references for China to develop a more integrated policies, supporting common but differentiated emission reduction targets.