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Cd contamination, especially in farmland soil, can pose serious threats to human health as well as ecological security. Stabilization is an important strategy for agricultural soil Cd remediation. In this study, a Cd-resistant strain (Cupriavidus B-7) was isolated and loaded onto cow manure (CDB), rice straw (RSB) and pine wood biochar (PB) to investigate its effects on Cd stabilization by a 60-day pot experiment. Results indicated that the Cupriavidus B-7-loaded biochar (labelled as CDBB, PBB and RSBB) reduced the CaCl2-extractable Cd by 43.06–59.78%, which was significantly superior to individual applications of Cupriavidus B-7 and biochar. Likewise, the soil physicochemical properties, urease, catalase and phosphatase activities were improved, indicating improved soil health. Consequently, dry weights of pakchoi's shoot and root were increased by 938.9–1230.9% and 149.1–281.2%, respectively, by applying CDBB, PBB and RSBB. Meanwhile, the Cd accumulation in pakchoi shoots decreased by 38.06–50.75%. Notably, the RSBB exhibited an optimal performance on pakchoi growth promotion and Cd accumulation alleviation. The structural equation model indicated the synergistic effect on pakchoi growth promotion and Cd accumulation decreased between biochar and Cupriavidus B-7. Our research provides some new insights into the development of strategies for green and sustainable remediation of Cd-contaminated soil. Highlights: A Cd resistant Cupriavidus B-7 (B-7) was isolated from copper mining soil Biochar, B-7 and their conbination were used to remediate Cd polluted soil Biochar loaded B-7 outperformed individual treatments for Cd stabilization Biochar loaded B-7 alleivated the Cd uptake and promoted pakchoi growth [ABSTRACT FROM AUTHOR]

In wastewater treatment, a low C/N ratio highly inhibits the bioremoval of nitrogen, and commercial external carbon sources are widely used. In order to obtain an economical substitute, fermentation broth of spent mushroom substrates (SMS) was employed here as a carbon source for denitrification in a sequencing batch reactor (SBR). During the domestication process, the SMS fermentation broth-feeding treatment presented comparable nitrogen removal ability (74.44%) with a commercial carbon source group (77.99%). Rhodobacter, Lactobacillus and Pseudomonas were the dominant bacteria in the fermentation broth, and Saccharomycetales Gymnopilus dilepis was the dominant fungi. At the early domestication stage, the relatively high concentration of fermentation broth led to a much lower abundance of typical nitrate reductase genes than the control group. Furthermore, extracellular polymeric substance (EPS) formation was observed in the broth-feeding sample. The microbial structure dynamic was investigated, which showed a high influent effect when 20% fermentation broth was added. As domestication proceeded, similar dominant species in the control and broth-feeding treatments were observed. Overall, SMS fermentation broth can be used as a promising substitute to replace a costly commercial carbon source. [ABSTRACT FROM AUTHOR]

Recently, ClO2-based oxidation has attracted increasing attention to micropollutant abatement, due to high oxidation potential, low disinfection byproduct (DBPs) formation, and easy technical implementation. However, the kinetics, reactive sites, activation methods, and degradation pathways involved are not fully understood. Therefore, we reviewed current literature on ClO2-based oxidation in micropollutant abatement. In direct ClO2 oxidation, the reactions of micropollutants with ClO2 followed second-order reaction kinetics (kapp = 10−3–106 M−1 s−1 at neutral pH). The kapp depends significantly on the molecular structures of the micropollutant and solution pH. The reactive sites of micropollutants start with certain functional groups with the highest electron densities including piperazine, sulfonyl amido, amino, aniline, pyrazolone, phenol groups, urea group, etc. The one-electron transfer was the dominant micropollutant degradation pathway, followed by indirect oxidation by superoxide anion radical (O2•−) or hydroxyl radical (•OH). In UV-activated ClO2 oxidation, the reactions of micropollutants followed the pseudo-first-order reaction kinetics with the rates of 1.3 × 10−4–12.9 s−1 at pH 7.0. Their degradation pathways include direct ClO2 oxidation, direct UV photolysis, ozonation, •OH-involved reaction, and reactive chlorine species (RCS)-involved reaction. Finally, we identified the research gaps and provided recommendations for further research. Therefore, this review gives a critical evaluation of ClO2-based oxidation in micropollutant abatement, and provides recommendations for further research. [ABSTRACT FROM AUTHOR]