Techniques and mechanisms of bacteria immobilization on biochar for further environmental and agricultural applications

Integrated remediation and detoxification of triclocarban-contaminated water using waste-derived biochar-immobilized cells by long-term column experiments

Triclocarban (TCC), an antibacterial agent commonly used in personal care products, is one of the top ten contaminants of emerging concern in various environmental media, including soil and contaminated water in vadose zone. This study aimed to investigate TCC-contaminated water remediation using biochar-immobilized bacterial cells. Pseudomonas fluorescens strain MC46 (MC46), an efficient TCC-degrading isolate, was chosen, whereas agro-industrial carbonized waste as biochar was directly used as a sustainable cell immobilization carrier. According to the long-term TCC removal performance results (160 d), the biochar-immobilized cells consistently exhibited high TCC removal efficiencies (84-97%), whereas the free MC46 removed TCC for 76-94%. At 100 days, the detachment of the MC46 cells from the immobilized cell column was observed. The micro-Fourier-transform infrared spectroscopy results indicated that extracellular polymeric substance (EPS) was produced, but polysaccharide and protein fractions were washed out of the column. The lipid fraction of EPS adhered to the biochar, promoting TCC sorption for long-term treatment. The shortening of MC46 cells improved the tolerance of TCC toxicity. The TCC-contaminated water was successfully detoxified by the biochar-immobilized MC46 cells. Overall, the waste-derived biochar-immobilized cell system proposed in this study for the removal of emerging contaminants, including TCC, is efficient, economical, and aligned with the sustainable development concept of value-added utilization of waste.

Biochar loaded with ferrihydrite and Bacillus pseudomycoides enhances remediation of co-existed Cd(II) and As(III) in solution

Bioremediation is one of the effective ways for heavy metal remediation. Iron-modified biochar (F@BC) loaded with Bacillus pseudomycoides (BF@BC) was synthesized to remove the coexistence of cadmium (Cd) and arsenic (As) in solutions. The results showed that B. pseudomycoides significantly increased the removal rate of Cd(II) by enhancing the specific surface area and Si-containing functional groups of biochar (BC). The surface of F@BC was enriched with Fe-containing functional groups, significantly improving As(III) adsorption. The combination of ferrihydrite and strains on BF@BC enhanced the removal of Cd(II) and As(III). It also promoted the oxidation of As(III) by producing an abundance of hydroxyl radicals (·OH). The maximum saturated adsorption capacity of BF@BC for Cd(II) and As(III) increased by 52.47% and 2.99 folds compared with BC, respectively. This study suggests that biochar loaded with Fe and bacteria could be sustainable for the remediation of the coexistence of Cd(II) and As(III) in solutions.

Efficient Adsorption of Nitrogen and Phosphorus in Wastewater by Biochar

Nitrogen and phosphorus play essential roles in ecosystems and organisms. However, with the development of industry and agriculture in recent years, excessive N and P have flowed into water bodies, leading to eutrophication, algal proliferation, and red tides, which are harmful to aquatic organisms. Biochar has a high specific surface area, abundant functional groups, and porous structure, which can effectively adsorb nitrogen and phosphorus in water, thus reducing environmental pollution, achieving the reusability of elements. This article provides an overview of the preparation of biochar, modification methods of biochar, advancements in the adsorption of nitrogen and phosphorus by biochar, factors influencing the adsorption of nitrogen and phosphorus in water by biochar, as well as reusability and adsorption mechanisms. Furthermore, the difficulties encountered and future research directions regarding the adsorption of nitrogen and phosphorus by biochar were proposed, providing references for the future application of biochar in nitrogen and phosphorus adsorption.