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AbstractWetlands are an important carbon sink for greenhouse gases (GHGs), and embedding microbial fuel cell (MFC) into constructed wetland (CW) has become a new technology to control methane (CH4) emission. Rhizosphere anode CW–MFC was constructed by selecting rhizome-type wetland plants with strong hypoxia tolerance, which could provide photosynthetic organics as alternative fuel. Compared with non-planted system, CH4 emission flux and power output from the planted CW–MFC increased by approximately 0.48 ± 0.02 mg/(m2·h) and 1.07 W/m3, respectively. The CH4 emission flux of the CW–MFC operated under open-circuit condition was approximately 0.46 ± 0.02 mg/(m2·h) higher than that under closed-circuit condition. The results indicated that plants contributed to the CH4 emission from the CW–MFC, especially under open-circuit mode conditions. The CH4 emission from the CW–MFC was proportional to external resistance, and it increased by 0.67 ± 0.01 mg/(m2·h) when the external resistance was adjusted from 100 to 1000 Ω. High throughput sequencing further showed that there was a competitive relationship between electrogenic bacteria and methanogens. The flora abundance of electrogenic bacteria was high, while methanogens mainly consisted of Methanothrix, Methanobacterium and Methanolinea. The form and content of element C were analysed from solid phase, liquid phase and gas phase. It was found that a large amount of carbon source (TC = 254.70 mg/L) was consumed mostly through microbial migration and conversion, and carbon storage and GHGs emission accounted for 60.38% and 35.80%, respectively. In conclusion, carbon transformation in the CW–MFC can be properly regulated via competition of microorganisms driven by environmental factors, which provides a new direction and idea for the control of CH4 emission from wetlands. Graphical Abstract

Abstract A pilot-scale anaerobic co-digestion research study is presented to elucidate the feasibility of developing anaerobic digestion (AD) as an effective disposal method for municipal biomass waste (MBW) in China, focusing on biogas production and greenhouse gas (GHG) reduction. Food waste, fruit–vegetable waste, and dewatered sewage sludge were co-digested in a continuous stirred-tank reactor for biogas production. Stable operation was achieved with a high biogas production rate of 4.25 m3 (m3 d)−1 at organic loading rate of 6.0 kgVS (m3 d)−1 and hydraulic retention time of 20 d. A total of 16.5% of lipids content was beneficial to the biogas production of the feedstock without inhibition to anaerobic digestion. Compared with the landfill baseline, GHG reduction is an important environmental benefit from MBW digestion. Therefore, anaerobic co-digestion is a promising alternative solution for MBW because it contributes significantly to the sound management of municipal solid waste in China.

Ion exchange resins are employed extensively in the nuclear industry to remove the radioactive contaminants such as neutron activation products and fission products which may have leaked from fuel elements. The spent radioactive ion exchange resins have been produced during the operation of the nuclear facilities in the nuclear industry. The resins loaded with radioactive nuclides could not be regenerated and reused. These waste resins should be properly treated and disposed in order to minimize their potential hazard to the environments. In this paper, different technologies used for the treatment and disposal of spent radioactive resins were summarized and compared, including immobilization (such as cementation, bituminization and plastic solidification), advanced oxidation processes (such as incineration, pyrolysis, acid boiling degradation, the Fenton or Fenton-like reaction, supercritical water oxidation and plasma technology) and super compaction. Some supplementary methods, such as acid stripping, microbial conversion treatment and high integrity container were also mentioned. The principle of treatment methods, their characteristics and applications were briefly introduced, the future research directions were discussed.

AbstractThermoelectric materials are highly promising for waste heat harvesting. Although thermoelectric materials research has expanded over the years, bismuth telluride‐based alloys are still the best for near‐room‐temperature applications. In this work, a ≈38% enhancement of the average ZT (300−473 K) to 1.21 is achieved by mixing Bi0.4Sb1.6Te3 with an emerging thermoelectric material Sb2Si2Te6, which is significantly higher than that of most BiySb2−yTe3‐based composites. This enhancement is facilitated by the unique interface region between the Bi0.4Sb1.6Te3 matrix and Sb2Si2Te6‐based precipitates with an orderly atomic arrangement, which promotes the transport of charge carriers with minimal scattering, overcoming a common factor that is limiting ZT enhancement in such composites. At the same time, high‐density dislocations in the same region can effectively scatter the phonons, decoupling the electron‐phonon transport. This results in a ≈56% enhancement of the thermoelectric quality factor at 373 K, from 0.41 for the pristine sample to 0.64 for the composite sample. A single‐leg device is fabricated with a high efficiency of 5.4% at ΔT = 164 K further demonstrating the efficacy of the Sb2Si2Te6 compositing strategy and the importance of the precipitate‐matrix interface microstructure in improving the performance of materials for relatively low‐temperature applications.