Antibiotics in water are emerging contaminants of concern due to their indiscriminate usage, continuous input, and persistent nature. Fluoroquinolones (FQs) are one of the most widespread classes of antibiotics in aqueous environments all over the world and even at trace levels, FQs can induce antibiotic resistance potentially endangering ecological systems and humans. Norfloxacin (NOR) as one of the most typical and representative FQs was selected as the main target pollutant in this study. Advanced oxidation processes based on persulfate have attracted broad interest in the degradation of organic pollutants. Peroxydisulfate (S2O82-, PDS) is a common oxidant for the remediation of organic contaminants. Because of the low reactivity of oxidation of recalcitrant organic pollutants, metal catalysts are commonly used to activate PDS and produce highly reactive radicals. However, alternative selective non-radical mechanisms and non-metal catalysts are needed because radicals are non-selective and metal catalysts may lead to secondary pollution. Due to its redox catalytic capabilities, biochar is a low-cost, readily available, and environmentally acceptable carbonaceous substance that can be employed for pollutant remediation. The selection of suitable biomass and pyrolysis conditions is particularly important. Pristine biochar has limited active sites and catalytic reactivity, and chemical modifications need to be applied to overcome these drawbacks and enhance the catalytic reactivity. The most advantageous chemical modification methods are heteroatom doping and the use of metal-biochar composites. However, metal-biochar composites often have problems due to metal leaching, while non-metallic heteroatom doping can avoid this problem. Therefore, in this project, we first chose nitrogen-rich cyanobacteria as the biomass to prepare cyanobacterial biochar (CB) for catalytic PDS degradation of NOR. CB at 950 degrees pyrolysis temperature (PT) (CB950) exhibited excellent performance in PDS activation compared to low PT CB and other widely used materials in other studies. NOR at an initial concentration of 5 mg L-1 in an aqueous solution was fully degraded by CB950 within 120 min. Radical quenching tests, electrochemical measurements, and electron spin resonance spectroscopy results revealed two different mechanisms of PDS activation for low and high PT CBs. In low PT CBs/PDS systems, NOR is degraded by organic, hydroxyl, and sulfate radicals, and the presence of MnII further stimulates radical formation. Electron transfer combined with radical processes predominates in high PT CBs/PDS systems. In the next step, CBs doped with non-metallic elements (N, P, S) were prepared by a one-step pyrolysis method. A comparison of the efficiency of catalytic degradation of NOR by activating PDS showed that N and S doping failed to promote catalytic reactivity of CB, which was greatly enhanced by P-doped CBs (PCBs). Moreover, acid washing post-treatment also helped to improve the catalytic reactivity. In particular, the acid-washed cyanobacterial biochar (P2CB950w) prepared at 950 °C with triphenyl phosphate as the P dopant had the highest NOR degradation rate (5 times higher than the undoped CB) and 79% NOR mineralization rate. Multivariate statistical analysis revealed large specific surface area (max. 655 m2/g), high adsorption capacity, pyrolytic conversion of C-O-P to C-P-O bonding, and non-hydroxyl and sulfate radical pathways as the main attributes for PCBs with high catalytic reactivity. The doped P introduced into the carbon structure can efficiently accelerate the transfer of electrons from the adsorbed NOR molecule to PDS through the carbon bridge effect. Finally, the most reactive P2CB950w was selected to activate PDS for removing antimicrobial resistance (AMR) from wastewater treatment plant effluent. PCB950w activating PDS treatment showed excellent bacterial removal with less than 0.02% of surviving bacteria after 1 day of treatment and with no regrowth observed within 9 days. Viable bacteria after PCB950w/PDS treatment proved difficult to regrow in sea water, but regrowth was observed in autoclaved stream water after the same treatment. However, HT-qPCR results showed that antibiotic resistance genes (ARGs) were markedly removed and did not re-increase, with Firmicutes surviving predominantly. Moreover, PCB950w/PDS treatment showed no influence at the level of ARGs/resistant bacteria in stream water. Four strains of Aeromonas survivors after PCB950w/PDS treatment were resistant to different antibiotics. However, Aeromonas did not proliferate in the receiving environment. The results demonstrate the great potential of cyanobacterial biochar with P amendment as an efficient catalyst to remove AMR in wastewater. Overall, this study demonstrates that high PT biochar from algal bloom biomass may find use as catalysts for organic contaminant oxidation and provides a new way for producing efficient Pdoped metal-free biochar as a PDS catalyst. This study presents a basic framework for the design of other carbon-based catalysts for organic pollutants degradation. Moreover, this thesis highlights the promising future of cyanobacterial biochar with phosphorus amendment as an efficient catalyst to remove AMR in wastewater.