Abstract
Emerging pollutants in the form of pharmaceuticals have drawn international attention during the past few decades. Ciprofloxacin (CIP) is a common drug widely found in effluents from hospitals, industrial and different wastewater treatment plants, as well as rivers. In this work, the lab-scale 3D-BER system was established, and more than 90% of the antibiotic CIP was removed from Low C/N wastewater. The best results were obtained with the current intensity being taken into account, and a different C/N ratio significantly improved the removal of CIP and nitrates when the ideal conditions were C/N = 1.5–3.5, pH = 7.0–7.5 and I = 60 mA. The highest removal efficiency occurred when CIP = 94.2%, NO3−-N = 95.5% and total nitrogen (TN) = 84.3%, respectively. In this novel system, the autotrophic-heterotrophic denitrifying bacteria played a vital role in the removal of CIP and an enhanced denitrification process. Thus, autotrophic denitrifying bacteria uses CO2 and H2 as carbon sources to reduce nitrates to N2. This system has the assortment and prosperous community revealed at the current intensity of 60 mA, and the analysis of bacterial community structure in effluent samples fluctuates under different conditions of C/N ratios. Based on the results of LC-MS/MS analysis, the intermediate products were proposed after efficient biodegradation of CIP. The microbial community on biodegrading was mostly found at phylum, and the class level was dominantly responsible for the NO3−-N and biodegradation of CIP. This work can provide some new insights towards the biodegradation of CIP and the efficient removal of nitrates from low C/N wastewater treatment through the novel 3D-BER system.
Highlights
Worldwide, the various kinds of emerging pollutants such as pharmaceuticals compounds, anti-inflammatory drugs, antibiotics, beta-blockers [1] and the massive amount of NO3− or NO2− have attracted international attention for the last few decades [2]
Antibiotic CIP is readily detectable in man-made aquatic-environments [7]; it occurs at high levels in the effluents of Wastewater Treatment plants (WWTPs) receiving pharmaceutical wastewater and rivers polluted with industrial waste [6,10,11]
We recently introduced a 3D-biofilm electrode reactors (BERs) system for the new advanced technique in the potential benefits of low currents, and there is the best capability to treat toxic substances
Summary
The various kinds of emerging pollutants such as pharmaceuticals compounds, anti-inflammatory drugs, antibiotics, beta-blockers [1] and the massive amount of NO3− or NO2− have attracted international attention for the last few decades [2]. CIP can reach the environment through various pharmaceutical industries, sewage treatment plants, livestock activities, landfills, application of sewage sludge [6], manure or treated wastewater to agricultural land [3,7,8]. Antibiotic CIP is readily detectable in man-made aquatic-environments (usually found in surface water at ng·L−1 to μg·L−1 levels) [7]; it occurs at high levels in the effluents of Wastewater Treatment plants (WWTPs) (up to 6.55–31 mg·L−1) receiving pharmaceutical wastewater and rivers polluted with industrial waste (up to 14 mg·L−1) [6,10,11]. 80–90% of CIP was removed by adsorption to sludge, which stabilizes the substance [3]
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