Enhanced biodegradation of ciprofloxacin by enriched nitrifying sludge: assessment of removal pathways and microbial responses

Abstract

Antibiotics are mostly collected by sewage systems, but not completely removed within wastewater treatment plants. Their release to aquatic environment poses great threat to public health. This study evaluated the removal of a widely used fluoroquinolone antibiotic ciprofloxacin in enriched nitrifying culture through a series of experiments by controlling ammonium concentrations and inhibiting functional microorganisms. The removal efficiency of ciprofloxacin at an initial concentration of 50 μg L−1 reached 81.86 ± 3.21% in the presence of ammonium, while only 22.83 ± 8.22% of ciprofloxacin was removed in its absence. The positive linear correlation was found between the ammonia oxidation rate (AOR) and ciprofloxacin biodegradation rate. These jointly confirmed the importance of the AOB-induced cometabolism in ciprofloxacin biodegradation with adsorption and metabolic degradation pathways playing minor roles. The continuous exposure of AOB to ciprofloxacin led to decreases of ammonia monooxygenase (AMO) activities and AOR. The antibacterial effects of ciprofloxacin and its biodegradation products were further evaluated and the results revealed that biodegradation products of ciprofloxacin exhibited less toxicity compared to the parent compound, implying the potential application of cometabolism in alleviation of antimicrobial activity. The findings provided new insights into the AOB-induced cometabolic biodegradation of fluoroquinolone antibiotics.

Degradation of Chloroquine by Ammonia-Oxidizing Bacteria: Performance, Mechanisms, and Associated Impact on N2O Production

“…For example, atenolol biodegradation was observed to be linked to the activity of AOB in a lab-scale enriched nitrifying sludge system, 19 and AOB-induced cometabolism contributed significantly to the degradation of ciprofloxacin. 20 Activated sludge in full-scale nitrification processes could appreciably eliminate natural and synthetic estrogen. 21 Owing to the possession of the nonspecific ammonia monooxygenase (AMO), AOB can cometabolically catalyze the biodegradation of various organic substrates in the obligatory presence of ammonium.…”

“…It is worth noting that activated sludge has already been shown to be capable of degrading pharmaceuticals, such as estrogen, atenolol, sulfadimethoxine, triclosan, and ranitidine, to varying extents. , Among all microorganisms contained in conventional activated sludge, ammonia-oxidizing bacteria (AOB) that mediate the key first step for biological nitrogen removal (BNR) from wastewater, i.e., partial nitrification (NH 4 + → NO 2 – ), have been known to enable the efficient removal of pharmaceuticals in studies of different scales. For example, atenolol biodegradation was observed to be linked to the activity of AOB in a lab-scale enriched nitrifying sludge system, and AOB-induced cometabolism contributed significantly to the degradation of ciprofloxacin . Activated sludge in full-scale nitrification processes could appreciably eliminate natural and synthetic estrogen .…”

Adsorption and partition of the antibiotic ciprofloxacin in poultry litter

“…23,24 Wide dispersion in varying concentrations can lead to the generation of resistant microorganisms. [25][26][27] This fact represents a public health problem as the number of untreated infectious diseases increases, which demands new, broad-spectrum and consequently more costly compounds. 28,29 There are several classes and types of antibiotics in veterinary medicine.…”

“…Once in the soil, antibiotics and other drugs can persist on surface horizons or leach into the surface and underground water bodies 23,24 . Wide dispersion in varying concentrations can lead to the generation of resistant microorganisms 25‐27 . This fact represents a public health problem as the number of untreated infectious diseases increases, which demands new, broad‐spectrum and consequently more costly compounds 28,29 .…”

Adsorption Isotherms and Kinetics of Acebutolol and Metoprolol on Magnetic Nanocomposite Fe3O4@MIL‐101(Cr)

“…Various methods such as membrane filtration, [9] biodegradation, [10] photodegradation, [11,12] electrochemical oxidation, [13] nanofiltration [14] and adsorption, [15] have been extensively used for the removal of β‐blockers. Among these methods, adsorption has received remarkable attention owing to its captivating features, such as simplicity, cost‐effectiveness, and facile operation [16,17] .…”