Environmental Science and Ecotechnology最新文献

Seasonal or permanent water scarcity in off-grid communities can be alleviated by recycling water in decentralized wastewater treatment systems. Nature-based solutions, such as constructed wetlands (CWs), have become popular solutions for sanitation in remote locations. Although typical CWs can efficiently remove solids and organics to meet water reuse standards, polishing remains necessary for other parameters, such as pathogens, nutrients, and recalcitrant pollutants. Different CW designs and CWs coupled with electrochemical technologies have been proposed to improve treatment efficiency. Electrochemical systems (ECs) have been either implemented within the CW bed (ECin-CW) or as a stage in a sequential treatment (CW + EC). A large body of literature has focused on ECin-CW, and multiple scaled-up systems have recently been successfully implemented, primarily to remove recalcitrant organics. Conversely, only a few reports have explored the opportunity to polish CW effluents in a downstream electrochemical module for the electro-oxidation of micropollutants or electro-disinfection of pathogens to meet more stringent water reuse standards. This paper aims to critically review the opportunities, challenges, and future research directions of the different couplings of CW with EC as a decentralized technology for water treatment and recovery.

The industrial adoption of microbial electrosynthesis (MES) is hindered by high overpotentials deriving from low electrolyte conductivity and inefficient cell designs. In this study, a mixed microbial consortium originating from an anaerobic digester operated under saline conditions (∼13 g L⁻¹ NaCl) was adapted for acetate production from bicarbonate in galvanostatic (0.25 mA cm⁻²) H-type cells at 5, 10, 15, or 20 g L⁻¹ NaCl concentration. The acetogenic communities were successfully enriched only at 5 and 10 g L⁻¹ NaCl, revealing an inhibitory threshold of about 6 g L⁻¹ Na⁺. The enriched planktonic communities were then used as inoculum for 3D printed, three-chamber cells equipped with a gas diffusion biocathode. The cells were fed with CO₂ gas and operated galvanostatically (0.25 or 1.00 mA cm⁻²). The highest production rate of 55.4 g m⁻² d⁻¹ (0.89 g L⁻¹ d⁻¹), with 82.4% Coulombic efficiency, was obtained at 5 g L⁻¹ NaCl concentration and 1 mA cm⁻² applied current, achieving an average acetate production of 44.7 kg MWh⁻¹. Scanning electron microscopy and 16S rRNA sequencing analysis confirmed the formation of a cathodic biofilm dominated by Acetobacterium sp. Finally, three 3D printed cells were hydraulically connected in series to simulate an MES stack, achieving three-fold production rates than with the single cell at 0.25 mA cm⁻². This confirms that three-chamber MES cells are an efficient and scalable technology for CO₂ bio-electro recycling to acetate and that moderate saline conditions (5 g L⁻¹ NaCl) can help reduce their power demand while preserving the activity of acetogens.

To efficiently remove organic and inorganic pollutants from leachate concentrate, an in situ coagulation-electrochemical oxidation (CO-EO) system was proposed using Ti/Ti₄O₇ anode and Al cathode, coupling the “super-Faradaic” dissolution of Al. The system was evaluated in terms of the removal efficiencies of organics, nutrients, and metals, and the underlying cathodic mechanisms were investigated compared with the Ti/RuO₂–IrO₂ and graphite cathode systems. After a 3-h treatment, the Al-cathode system removed 89.0% of COD and 36.3% of total nitrogen (TN). The TN removal was primarily ascribed to the oxidation of both ammonia and organic-N to N₂. In comparison, the Al-cathode system achieved 3–10-fold total phosphorus (TP) (62.6%) and metal removals (>80%) than Ti/RuO₂–IrO₂ and graphite systems. The increased removals of TP and metals were ascribed to the in situ coagulation of Al(OH)₃, hydroxide precipitation, and electrodeposition. With the reduced scaling on the Al cathode surface, the formation of Al³⁺ and electrified Al(OH)₃ lessened the requirement for cathode cleaning and increased the bulk conductivity, resulting in increased instantaneous current production (38.9%) and operating cost efficiencies (48.3 kWh kg_COD⁻¹). The present study indicated that the in situ CO-EO process could be potentially used for treating persistent wastewater containing high levels of organic and inorganic ions.

Microplastics (MPs), an emerging group of pollutants, not only have direct toxic effects on aquatic organisms but also cause combined toxicity by absorbing other pollutants. Triphenyltin (TPT), one of the most widely used organotin compounds, has adverse effects on aquatic organisms. However, little is known about the combined toxicity of MPs and TPT to aquatic organisms. To investigate the individual and combined toxicity of MPs and TPT, we selected the common carp (Cyprinus carpio) for a 42-day exposure experiment. Based on the environmental concentrations in a heavily polluted area, the experimental concentrations of MPs and TPT were set at 0.5 mg L⁻¹ and 1 μg L⁻¹, respectively. The effects of MPs combined with TPT on the carp gut–brain axis were evaluated by detecting gut physiology and biochemical parameters, gut microbial 16S rRNA, and brain transcriptome sequencing. Our results suggest that a single TPT caused lipid metabolism disorder and a single MP induced immunosuppression in carp. When MPs were combined with TPT, the involvement of TPT amplified the immunotoxic effect induced by MPs. In this study, we also explored the gut–brain axis relationship of carp immunosuppression, providing new insights for assessing the combined toxicity of MPs and TPT. At the same time, our study provides a theoretical basis for evaluating the coexistence risk of MPs and TPT in the aquatic environment.

It is well recognized that carbon dioxide and air pollutants share similar emission sources so that synergetic policies on climate change mitigation and air pollution control can lead to remarkable co-benefits on greenhouse gas reduction, air quality improvement, and improved health. In the context of carbon peak, carbon neutrality, and clean air policies, this perspective tracks and analyzes the process of the synergetic governance of air pollution and climate change in China by developing and monitoring 18 indicators. The 18 indicators cover the following five aspects: air pollution and associated weather-climate conditions, progress in structural transition, sources, inks, and mitigation pathway of atmospheric composition, health impacts and benefits of coordinated control, and synergetic governance system and practices. By tracking the progress in each indicator, this perspective presents the major accomplishment of coordinated control, identifies the emerging challenges toward the synergetic governance, and provides policy recommendations for designing a synergetic roadmap of Carbon Neutrality and Clean Air for China.

Due to the accumulation of an enormous amount of plastic waste from municipal and industrial sources in landfills, landfill leachate is becoming a significant reservoir of microplastics. The release of microplastics from landfill leachate into the environment can have undesirable effects on humans and biota. This study provides the state of the science regarding the source, detection, occurrence, and remediation of microplastics in landfill leachate based on a comprehensive review of the scientific literature, mostly in the recent decade. Solid waste and wastewater treatment residue are the primary sources of microplastics in landfill leachate. Microplastic concentration in raw and treated landfill leachate varied between 0–382 and 0–2.7 items L⁻¹. Microplastics in raw landfill leachate are largely attributable to local plastic waste production and solid waste management practices. Polyethylene, polystyrene, and polypropylene are the most prevalent microplastic polymers in landfill leachate. Even though the colors of microplastics are primarily determined by their parent plastic waste, the predominance of light-colored microplastics in landfill leachate indicates long-term degradation. The identified morphologies of microplastics in leachate from all published sources contain fiber and fragments the most. Depending on the treatment method, leachate treatment processes can achieve microplastic removal rates between 3% and 100%. The review also provides unique perspectives on microplastics in landfill leachate in terms of remediation, final disposal, fate and transport among engineering systems, and source reduction, etc. The landfill–wastewater treatment plant loop and bioreactor landfills present unique difficulties and opportunities for managing microplastics induced by landfill leachate.

Trees are spread worldwide, as the watchmen that experience the intricate ecological effects caused by various environmental factors. In order to better understand such effects, it is preferential to achieve finely and fully mapped global trees and their environments. For this task, aerial and satellite-based remote sensing (RS) methods have been developed. However, a critical branch regarding the apparent forms of trees has significantly fallen behind due to the technical deficiency found within their global-scale surveying methods. Now, terrestrial laser scanning (TLS), a state-of-the-art RS technology, is useful for the in situ three-dimensional (3D) mapping of trees and their environments. Thus, we proposed co-developing an international TLS network as a macroscale ecotechnology to increase the 3D ecological understanding of global trees. First, we generated the system architecture and tested the available RS models to deepen its ground stakes. Then, we verified the ecotechnology regarding the identification of its theoretical feasibility, a review of its technical preparations, and a case testification based on a prototype we designed. Next, we conducted its functional prospects by previewing its scientific and technical potentials and its functional extensibility. Finally, we summarized its technical and scientific challenges, which can be used as the cutting points to promote the improvement of this technology in future studies. Overall, with the implication of establishing a novel cornerstone-sense ecotechnology, the co-development of an international TLS network can revolutionize the 3D ecological understanding of global trees and create new fields of research from 3D global tree structural ecology to 3D macroecology.