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The efficient and selective removal of refractory antibiotics from high-strength antibiotic production wastewater is crucial but remains a substantial challenge. In this study, a novel ozone micronano-bubble (MNB)-enhanced treatment system was constructed for antibiotic production wastewater treatment. Compared with conventional ozone, ozone MNBs exhibit excellent treatment efficiency for oxytetracycline (OTC) degradation and toxicity decrease. Notably, this study identifies the overlooked singlet oxygen (1O2) for the first time as a crucial active species in the ozone MNB system through probe and electron paramagnetic resonance methods. Subsequently, the oxidation mechanisms of OTC by ozone MNBs are systematically investigated. Owing to the high reactivity of OTC toward 1O2, ozone MNBs enhance the selective and anti-interference performance of OTC degradation in raw OTC production wastewater with complex matrixes. This study provides insights into the mechanism of ozone MNB-enhanced pollutant degradation and a new perspective for the efficient treatment of high-concentration industrial wastewater using ozone MNBs. In addition, this study presents a promising technology with scientific guidance for the treatment of antibiotic production wastewater.

Incomplete mineralization of antibiotics in biological sludge systems poses a risk to the environment. In this study, the toxicity associated with ciprofloxacin (CIP) biodegradation in activated sludge (AS), anaerobic methanogenic sludge (AnMS), and sulfur-mediated sludge (SmS) systems was examined via long-term bioreactor tests and a series of bioassays. The AS and AnMS systems were susceptible to CIP and its biotransformation products (TPs) and exhibited performance deterioration, while the SmS system exhibited high tolerance against the toxicity of CIP and its TPs along with excellent pollutant removal. Up to 14 TPs were formed via piperazinyl substituent cleavage, defluorination, decarboxylation, acetylation, and hydroxylation reactions in AS, AnMS, and SmS systems. Biodegradation of CIP in the AS, AnMS, and SmS systems, however, could not completely eliminate its toxicity as evident from the inhibition of Vibrio fischeriluminescence along with Escherichia coliK12 and Bacillus subtilisgrowth.The anaerobic systems (AnMS and SmS) were more effective than the aerobic AS system at CIP biodegradation, significantly reducing the antibacterial activity of CIP and its TPs in the aqueous phase. In addition, the quantitative structure–activity relationship analysis indicated that the TPs produced via decarboxylation and hydroxylation (TP2 and TP4) as well as by cleavage of piperazine (TP12, TP13, and TP14) exhibited higher toxicity than CIP. The findings of this study provide insights into the toxicity and possible risks associated with CIP biodegradation in biological wastewater treatment.

ABSTRACT

Inoculum plays an important role in establishing a bacterial community in biological treatment reactors. Two identical anaerobic-aerobic-anoxic sequencing batch reactors (SBRs) were inoculated with sludge from a municipal (R1) or pharmaceutical (R2) wastewater treatment plant (WWTP) to investigate the influence of inoculum on the start-up of SBRs by comparing the pollutants removal efficiencies and bacterial community. Both SBRs were successfully started up within 30 d. Comparably high chemical oxygen demand (97% ± 2%), total nitrogen (89% ± 8%) and ammonia (96% ± 6%) removals were achieved in both SBRs. But R1 performed much better in total phosphorus removal (95% ± 6% vs. 69% ± 7%) than R2 due to a higher relative abundance of phosphorous-accumulating organisms (5.5% vs. 0.4%) in R1 at the end of the experiment. The bacterial community structures were distinctly different in the inoculating sludge, and no trend of becoming similar was observed all the time. Candidatus Competibacter was enriched to be the most dominant bacteria in both R1 (27.3%) and R2 (19.8%) during the start-up. However, Candidatus Moranbacteria (16.2%) and Roseiflexus (4.2%) were only dominant in R1, whereas Zoogloea (10.5%) and Anaerolineaceae (9.7%) were only dominant in R2 finally. These results indicated that inoculating sludge is one deciding factor shaping the microbiomes in bioreactors, and activated sludge from municipal WWTPs was a potential inoculum to start-up industrial wastewater biotreatment reactors with desirable performances.

Ciprofloxacin (CIP) removal in sulfur-mediated bioprocesses, e.g., sulfate-reducing bacteria (SRB)-mediated process and sulfur-oxidizing bacteria (SOB)-mediated process, was examined for the first time. The sludge properties (compositions and structure of extracellular polymeric substances (EPS), zeta-potential and surface functional groups) affecting CIP adsorption in these two sludge systems were determined.

There is little research that focused on both nutrient removal and sludge reduction based on an anaerobic/anoxic/oxic(A2/O) process. In this study, two systems that consisted of an A2/O process combined with a modified oxic-settling-anaerobic (MOSA) reactor were run for 200 d at the lab-scale to evaluate their effect on sludge reduction and their influence on nutrients removal. The MOSA reactor was run a hydraulic retention time of 5 d and interchange rate of 10%. Our results showed that A2/O-MOSA system performed as well as an A2/O system for removing Chemical Oxygen Demand (COD), ammonia, total nitrogen, and total phosphorus. The A2/O-MOSA system removed an average of 92% of the influent COD, slightly higher than that in the A2/O (90%) system. As for sludge reduction efficiency, the A2/O-MOSA process achieved a sludge reduction of 24%and sludge decay contributed 58% to this sludge reduction.

Layered double hydroxides (LDH) consist of positively-charged metal hydroxide layers and negatively-charged anions and water in the interstitial layers. Due to the unique properties of LDH including (i) tunable basicity, (ii) tailorable acidity, (iii) cation-exchange ability of the Brucite-like layer, (iv) anion-exchange ability of the interlayer space, (v) thermal stability, and (vi) large adsorption capacity, LDH-based materials could offer significant breadth for the conversion of biomass, either directly as catalysts or active supports in multifunctional catalysts. This review specially concentrates on the relationship between properties and their performances in the transformation (e.g.oxidation, hydrogenation, dehydration, isomerization, steam reforming and so on) of biomass-derived model molecules. This review demonstrates that LDH and their derived metal oxides (DMO) can be successfully applied over a broad spectrum for the conversion of biomass with advantages such as improved activity, selectivity, and metal dispersion, less waste production, and an improved recuperation of immobilized catalysts. LDH and their DMO are also excellent materials for designing bifunctional redox-base catalysts or controlling the acid–base properties around a heterogenized metal center.

The removal of eight typical pharmaceuticals (PhACs) (i.e., ibuprofen (IBU), ketoprofen (KET), diclofenac (DIC), sulfadiazine (SD), sulfamethoxazole (SMX), trimethoprim (TMP), ciprofloxacin (CIP) and enoxacin (ENO)) in sulfur-driven autotrophic denitrification (SdAD) process were firstly investigated vialong-term operation of bioreactor coupled with batch tests. The results indicated that IBU and KET can be effectively removed (removal efficiency > 50%) compared to other six PhACs in SdAD bioreactor. Biodegradation was the primary removal route for IBU and KET with the specific biodegradation rates of 5.3±0.7∼18.1±1.8 µg g−1-VSS d−1at initial concentrations of 25-200 µg/L. The biotransformation intermediates of IBU and KET were examined, and the results indicated that IBU was biotransformed to three intermediates viahydroxylation and carboxylation. KET biotransformation could be initiated from the reduction of the keto group following with a series of oxidation/reduction reactions, and five intermediates of KET were observed in this study. The microbial community composition in the system was markedly shifted when long-term exposure to PhACs. However, the functional microbes (e.g., genus Thiobacillus) showed high tolerance to PhACs, resulting in the high efficiency for PhACs, N and S removal during long-term SdAD reactor operation. The findings provide better insight into PhACs removal in SdAD process, especially IBU and KET, and open up an innovative opportunity for the treatment of PhACs-laden wastewater using sulfur-mediated biological process.

AbstractThe performance of an oxic-settling-anaerobic (OSA) system in terms of sludge reduction was investigated for various anaerobic hydraulic retention times (HRTs) (7 d, 5 d, 3 d, 1 d, 12 h, and 6 h) for a sequencing batch reactor (SBR)-OSA system. Compared to the traditional SBR system, the rates of sludge reduction in the 7d, 5d-1, 5d-2, 3d, and 1d OSA systems were observed to be 66.6, 57.7, 52.5, 50.0, and 48.5%, respectively. In terms of the apparent yield and actual yield of sludge, the OSA systems with longer HRTs exhibited lower sludge yields and better sludge reduction performance. The systems with an HRT > 1 d achieved a considerable increase in sludge reduction, whereas those with an HRT < 1 d did not. The anaerobic HRT was observed to be an important factor in determining the sludge reduction of OSA systems.

The performance of an oxic-settling-anaerobic (OSA) system in terms of sludge reduction was investigated for various anaerobic hydraulic retention times (HRTs) (7 d, 5 d, 3 d, 1 d, 12 h, and 6 h) for a sequencing batch reactor (SBR)-OSA system. Compared to the traditional SBR system, the rates of sludge reduction in the 7d, 5d-1, 5d-2, 3d, and 1d OSA systems were observed to be 66.6, 57.7, 52.5, 50.0, and 48.5%, respectively. In terms of the apparent yield and actual yield of sludge, the OSA systems with longer HRTs exhibited lower sludge yields and better sludge reduction performance. The systems with an HRT > 1 d achieved a considerable increase in sludge reduction, whereas those with an HRT < 1 d did not. The anaerobic HRT was observed to be an important factor in determining the sludge reduction of OSA systems.