Enhanced removal efficiency of bensulfuron-methyl by a novel boron doping biochar-based Acinetobacter YH0317 at a lower temperature

Mechanistic insights into δ-MnO2/biochar-activated persulfate-treated wastewater containing antibiotics and heavy metals: Nonradical pathway and pivotal role of Cu(Ⅱ) at low temperature

Herein, we present a high efficiency system based on biochar loaded with layered manganese dioxide to remove tetracycline and heavy metals from livestock wastewater. Under the optimal conditions, the degradation efficiencies of TC in the δ-MnO2/BC/PS system were 85.5% at 25 °C and 38.5% at 5 °C. Radical quenching experiments revealed that radical reactions in the δ-MnO2/BC/PS system were weak under 15 °C. Adsorption degradation experiments showed that the system maintained good adsorption performance at 5 °C. Galvanic cell experiments and cyclic voltammetry showed that the δ-MnO2/BC material had good electrochemical activity and high stability in response to temperature, indicating that TC was degraded by a nonradical pathway that was not limited by temperature, such as electron transfer. Copper ion was important coadsorbent and coactivator of the reaction system. Furthermore, FTIR, XPS, and X-ray diffraction (XRD) analyses showed that Cu(II) in the system was involved in changing the manganese valence state in the δ-MnO2/BC material and increasing the -OH content of BC. Comparison of the different products generated during metabolic testing revealed that the reaction pathway of the system at low temperature (5 °C) differed from that at normal temperature (25 °C). The δ-MnO2/BC material demonstrated good removal ability for antibiotics and heavy metals at normal and low temperatures in actual biogas slurry. The study provides insight for improving the efficiency of environmentally friendly treatments of aquaculture wastewater in cold regions, which is of great significance for resource utilization.

Simultaneous achievement of removing bensulfuron-methyl and reducing CO2 emission in paddy soil by Acinetobacter YH0317 immobilized boron-doping biochar

Herbicide residue and greenhouse gas (GHG) emission are two main problems in the paddy rice field, which have barely been considered simultaneously. Herein, a bensulfuron-methyl (BSM)-degrading bacterium named Acinetobacter YH0317 was successfully immobilized on two kinds of biochars and subsequently applied in the paddy soil. The BSM removal rate of Acinetobacter YH0317 immobilized boron-doping biochar (BBC) was 80.42% after 30 d, which was significantly higher than that of BBC (39.05%) and Acinetobacter YH0317 (49.10%) applied alone. BBC acting as an immobilized carrier could enable Acinetobacter YH0317 to work in harsh and complex environment and thus improve the BSM removal efficiency. The addition of Acinetobacter YH0317 immobilized BBC (TP5) significantly improved the soil physicochemical properties (pH, SOC, and NH4+-N) and increased the diversity of soil microbial community compared to control group (CG). Meanwhile, Acinetobacter YH0317 immobilized BBC reduced the CO2-equivalent emission by 41.0%. Metagenomic sequencing results revealed that the decreasing CO2 emission in TP5 was correlated with carbon fixation gene (fhs), indicating that fhs gene may play an important role in reducing CO2 emission. The work presents a practical and supportive technique for the simultaneous achievement on the soil purification and GHG emission reduction in paddy soil.