Biochar is a solid substance with a charcoal-like appearances. It is highly flammable and is made from the burning of agricultural and forest-based organic wastes by various controlled processes like pyrolysis. Biochar is rich in carbon and storage of the same in soil is highly recommended to ease off climate change by sequestration of carbon along with enhancing agricultural yield and production of energy. According to the World Health Organization, one of the biggest threats to human life in the present century is livestock water contamination. Among different contaminants, microbial contamination is responsible for several harmful diseases many of which are fatal. The current disinfectant methods are quite useful but they produce harmful by-products which can cause more hazards to human health. Magnetic biochar which is a modification of normal biochar is a green, facile, and cost-effective bacteriocide that has immense antimicrobial potential against water-borne pathogens. Magnetic biochar in conjugation with quaternary phosphonium salt produces Magnetic Biochar-Quaternary phosphonium salt [MBQ], which is a further modification of magnetic biochar that holds much better antimicrobial properties than biochar or magnetic biochar. It can successfully undergo inhibition of water-borne pathogens like Escherichia coli and Staphylococcus aureus. MBQ can disrupt the bacterial membrane and induce oxidative damage inside the bacteria, causing their inactivation and inhibition. MBQ also shows biocidal effects. In this review, we will discuss biochar, its properties, various methods of synthesis of biochar, different methods of modification of biochar, antimicrobial and antibacterial properties of biochar, magnetic biochar, and MBQ. Synthesis, Characterization, and antimicrobial properties of MBQ against waterborne microorganisms are also discussed in detail.

Herein, magnetic biochar coupled with Acinetobacter lwoffii DNS32 immobilized pellets (DMBC-P) were synthesized through sodium alginate embedding and fixation, which could fast and completely eliminate atrazine from contaminated farmland soil. Characterization results revealed that DMBC-P exhibited a significant abundance of three-dimensional network porous structures, thereby enhancing the stability and specific surface area of DMBC-P. The application of 0.5 % DMBC-P could completely remove 22 mg/kg atrazine from soil within 4 d under the condition of moisture content of 60 % and soil pH of 7.4. After 5 d of remediation, DMBC-P could be easily extracted from the soil by magnetic separation and still had 100 % removal efficiency for atrazine after 3 rounds of recycling. Moreover, DMBC-P effectively alleviated the oxidative damage of atrazine to soybean seedlings through significantly decreasing the activities of various plants antioxidant enzymes by 27 % to 79 %. Meanwhile, analysis of 16S rRNA revealed a significant increase in the relative abundance of functional microflora such as Acidobacteriota and Chloroflexi at the phylum level, which promoted the growth of soybean seedlings. Additionally, pore filling, hydrogen bonding, and 7C -7C stacking were identified as the primary mechanisms responsible for atrazine adsorption onto DMBC-P. Subsequently, the degrading bacteria DNS32 immobilized on DMBC-P was employed to catalyze the decomposition of atrazine into non-toxic cyanuric acid based on LC -MS. Overall, this study provided a reasonable design of magnetic carbon -based bacterial pellet for atrazinecontaminated soil remediation, which could efficiently remove atrazine and be effectively recycled after remediation.