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Doxycycline (DOX), a typical antibiotic, is harmful to aquatic ecosystems and human health. This study presents DOX removal by potassium ferrate (Fe(VI)) and montmorillonite and investigates the effect of Fe(VI) dosage, reaction time, initial pH value, montmorillonite dosage, adsorption pH, time and temperature on DOX removal. The results show that DOX removal increases when increasing the Fe(VI) dosage, with the optimal condition for DOX removal (~97%) by Fe(VI) observed under a molar ratio ([Fe(VI)]:[DOX]) of 30:1 at pH 7. The reaction of DOX with Fe(VI) obeyed second-order kinetics with a rate constant of 10.7 ± 0.45 M−1 s−1 at pH 7. The limited promotion (~4%) of DOX adsorption by montmorillonite was observed when the temperature increased and the pH decreased. Moreover, the synergetic effect of Fe(VI) and montmorillonite on DOX removal was obtained when comparing the various types of dosing sequences (Fe(VI) oxidation first and then adsorption; adsorption first and then Fe(VI) oxidation; simultaneous oxidation and adsorption). The best synergistic effect of DOX removal (97%) was observed under the simultaneous addition of Fe(VI) and montmorillonite, maintaining the Fe(VI) dosage (from 30:1 to 5:1). Five intermediates were detected during DOX degradation, and a plausible DOX degradation pathway was proposed.

The biofilm process has the advantages of strong load impact resistance, low power consumption, easy operation and management, and good treatment effect. The key factor of the biofilm method is the biofilm carrier filler. The performance of the filler will directly affect the operation and treatment effect of the reactor. Aiming at the severely polluted rivers, this paper proposes to use bamboo materials with extensive raw materials, cheap processing, green and pollution-free materials to make biofilm reactor fillers, and conduct laboratory-scale research on them. The results show that, compared with the suspended filler, the bamboo filler has a faster filming speed and a rich microbial population structure on the film, which is beneficial to the removal of pollutants in the water. In addition, the bamboo filler has a degradable carbon source, which helps to further improve the reactor. The denitrification efficiency. The research results will provide technical support for the practical application of bamboo fillers in biofilm reactors and the in-situ remediation of polluted river water quality in my country.