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Wheat straw (WS) has long been subjected to rough treatment by traditional incineration, which not only results in the waste of biomass resources but also poses a risk of atmospheric pollution and is not conducive to the sustainable utilization of natural resources. With great humification potential, WS can be utilized as a valuable composting material. The study optimized the C/N ratio by mixing WS and chicken manure (CM) as composting raw materials, and found that this method could significantly improve the compost quality. In comparison to the conventional poplar woodchip (PW) conditioning, the incorporation of WS resulted in an elevated composting temperature, an extended high-temperature period, a more expeditious lignocellulose degradation, a notable enhancement in the organic matter content, a suppression of hydrogen sulfide production under low C/N ratio, and a promotion of elemental sulfur conversion, collectively contributing to an enhanced overall quality and environmental friendliness of the compost. Correlation analysis of microbial communities and environmental factors demonstrated that the mixed compost facilitated the growth of actinomycetes and sulfur-transforming bacteria. Additionally, structural equation model indicated that parameters such as temperature and pH value played a key role in the composting process. [ABSTRACT FROM AUTHOR]

Vanadium-bearing steel slag is a typical solid waste in the steel industry and a valuable secondary resource for vanadium production. In this paper, a direct alkaline leaching process was proposed to extract valuable vanadium and achieve comprehensive utilization of the residue by incorporating the new process into the conventional Bayer alumina production process. The leaching mechanism showed the feasibility of alkaline leaching. The effects of alkaline concentration, temperature, particle size, liquid-solid ratio (mass ratio), and stirring speed on the process were investigated, and the recovery of vanadium was found to achieve 68.4% under optimal conditions. Both the internal diffusion and the interface reaction were found by kinetic analysis to be the controlling steps of the leaching reaction, and the apparent reaction activation energy value of 26.67 kJ/mol was calculated. The valence state of the vanadium in the steel slag was analyzed in detail, finding that low-valent (V3+) and high-valent (V4+ and V5+) vanadium were both present in the steel slag. By introducing oxygen into the reaction system, the recovery could be improved to 85.6%, which was 17.2% higher than that of non-oxidative leaching. [ABSTRACT FROM AUTHOR]

A sequencing batch biofilm reactor under intermittent micro-aerobic or anaerobic conditions was investigated to remove pyridine at various concentrations from synthetic wastewater. The results showed that over 98% of pyridine (influent concentration ≤200 mg L−1) was degraded under intermittent micro-aerobic condition, while about 21% of pyridine was removed under anaerobic condition. Additionally, at least 60% of nitrogen located in the pyridine ring was transformed to ammonium. At the same time, the sulphate reduction was obviously inhibited under intermittent micro-aerobic conditions. The microscopic observation showed that abundant microorganisms were attached on the surface or inside of porous biocarriers under intermittent micro-aerobic conditions after a short-term period of operation. High-throughput sequencing analysis demonstrated that Azotobacter, Rhodobacteraceae and Tolumonas were the dominant species in the intermittent micro-aerobic system. The kinetic study at steady period showed that pyridine degradation was fitted well with the pseudo-first-order model (R2 > 0.96). The two possible intermediate products were identified and the possible biodegradation pathway of pyridine was proposed under micro-aerobic condition. [ABSTRACT FROM AUTHOR]