Chunji Jin

Long-term effects of ZnO nanoparticles on nitrogen and phosphorus removal, microbial activity and microbial community of a sequencing batch reactor

The performance, microbial activity, and microbial community of a sequencing batch reactor (SBR) were investigated under the long-term exposure of ZnO nanoparticles (ZnO NPs). Low ZnO NPs concentration (less than 5mg/L) had no obvious effect on the SBR performance, whereas the removals of COD, NH4(+)-N, and phosphorus were affected at 10-60mg/L ZnO NPs. The variation trend of nitrogen and phosphorus removal rate was similar to that of microbial enzymatic activity with the increase of ZnO NPs concentrations. The richness and diversity of microbial community showed obvious variations at different ZnO NPs concentrations. ZnO NPs appeared on the surface and cell interior of activated sludge, and the Zn contents in the effluent and activated sludge increased with the increase of ZnO NPS concentration. The present results provide use information to understand the effect of ZnO NPS on the performance of wastewater biological treatment systems.

Magnetic Fe3O4 nanoparticles induced effects on performance and microbial community of activated sludge from a sequencing batch reactor under long-term exposure

The performance and microbial community of activated sludge from a sequencing batch reactor (SBR) were investigated under long-term exposure of magnetic Fe3O4 nanoparticles (Fe3O4 NPs). The COD removal showed a slight decrease at 5-60mg/L Fe3O4 NPs compared to 0mg/L Fe3O4 NPs, whereas the NH4+-N removal had no obvious variation at 0-60mg/L Fe3O4 NPs. It was found that 10-60mg/L Fe3O4 NPs improved the denitrification process and phosphorus removal of activated sludge. The microbial enzymatic activities of activated sludge could be affected by Fe3O4 NPs, which had similar variation trends to the nitrogen and phosphorus removal rates of activated sludge. The reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) release demonstrated that Fe3O4 NPs led to the toxicity to activated sludge and destroyed the integrity of microbial cytomembrane. High throughput sequencing indicated that Fe3O4 NPs could obviously affect the microbial richness and diversity of activated sludge.

Performance and microbial community of a sequencing batch biofilm reactor treating synthetic mariculture wastewater under long-term exposure to norfloxacin.

The performance and microbial community of a sequencing batch biofilm reactor (SBBR) treating synthetic mariculture wastewater were evaluated under long-term exposure to norfloxacin (NFX) due to the overuse of antibiotics during the mariculture. The COD and NH4+-N removals had no distinct change at 0-6mgL-1 NFX and were inhibited at 6-35mgL-1 NFX. The specific oxygen uptake rate (SOUR), specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR) and specific nitrate reduction rate (SNRR) of the biofilm kept a decreasing tendency with the increase of NFX concentration from 0 to 35mgL-1. The presence of NFX promoted the microorganisms to secrete more extracellular polymeric substances (EPS) and affected the chemical compositions of EPS. The microbial richness and diversity showed some obvious variations at different NFX concentrations. The present results demonstrated that NFX inhibited the SBBR performance and should decrease the NFX dosage in the mariculture.

Impact of sulfadiazine on performance and microbial community of a sequencing batch biofilm reactor treating synthetic mariculture wastewater

The impact of sulfadiazine on the performance, microbial activity and microbial community of a sequencing batch biofilm reactor (SBBR) were evaluated in treating mariculture wastewater due to the application of sulfadiazine as an antibiotic in mariculture. The COD and nitrogen removals kept stable at 0-6mg/L sulfadiazine and were inhibited at 10-35mg/L sulfadiazine. The microbial activities related to organic matter and nitrogen removals reduced with an increase in sulfadiazine concentration. The presence of sulfadiazine could affect the production and chemical composition of loosely bound extracellular polymeric substances (LB-EPS) and tightly bound EPS (TB-EPS) in the biofilm. High-throughput sequencing demonstrated that sulfadiazine could impact on the microbial richness and diversity of SBBR treating mariculture wastewater. The relative abundances of Nitrosomonas, Nitrospira, Paracoccus, Hyphomicrobium, Rhodanobacter, Thauera and Steroidobacter decreased with an increase in sulfadiazine concentration, indicating that the presence of sulfadiazine decreased the relative abundance of some nitrifying and denitrifying bacteria.

The effects of divalent copper on performance, extracellular polymeric substances and microbial community of an anoxic–aerobic sequencing batch reactor

The effects of divalent copper (Cu(II)) on the performance, extracellular polymeric substances (EPS) and microbial community of activated sludge were investigated in an anoxic–aerobic sequencing batch reactor (SBR). The removal efficiencies of chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N) decreased with the increase of influent Cu(II) concentration from 0 to 50 mg L−1. The specific oxygen utilization rate (SOUR), specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR), and specific nitrate reduction rate (SNRR) decreased with the increase of influent Cu(II) concentration. The protein (PN) contents in the loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) increased from 3.67 and 4.73 mg g−1 VSS to 32.83 and 50.45 mg g−1 VSS with the increase of influent Cu(II) concentration from 0 to 50 mg L−1, respectively. The polysaccharide (PS) contents in the LB-EPS and TB-EPS increased from 1.44 and 2.68 mg g−1 VSS to 8.51 and 19.84 mg g−1 VSS with the increase of influent Cu(II) from 0 to 50 mg L−1, respectively. The three-dimensional excitation–emission matrix (3D-EEM) fluorescence spectra and Fourier transform infrared (FTIR) spectra illustrated that the addition of Cu(II) to the influent had distinct effects on the functional groups of PN and PS in the LB-EPS and TB-EPS. The sludge volume index (SVI) showed a negative correlation with LB-EPS (or TB-EPS) content at different Cu(II) concentrations. Some microorganisms adapting to high Cu(II) concentration became predominant bacteria, while others without Cu(II)-tolerance capacity gradually depleted or weakened with the increase in Cu(II) concentration.

Long-term impacts of titanium dioxide nanoparticles (TiO2 NPs) on performance and microbial community of activated sludge

The long-term impacts of titanium dioxide nanoparticles (TiO2 NPs) on the performance and microbial community of activated sludge were evaluated in a sequencing batch reactor (SBR). TiO2 NPs impacted the COD and phosphorus removals of activated sludge, whereas the NH4+-N removal efficiency had no distinct change at 0-60mg/L TiO2 NPs. The presence of TiO2 NPs obviously inhibited the organic matter and nitrogen removal rates of activated sludge. The phosphorus removal rate gradually reduced at 0-5mg/L TiO2 NPs and then increased at 10-60mg/L TiO2 NPs. The removal rates of organic matter, nitrogen and phosphorus had the similar varying trends to the corresponding microbial enzymatic activities. High TiO2 NPs concentration promoted more reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) release of activated sludge. The microbial richness and diversity of activated sludge were obviously affected at the phyla, class and genus levels.

Effect of oxytetracycline on performance and microbial community of an anoxic–aerobic sequencing batch reactor treating mariculture wastewater

The performance and microbial community of an anoxic–aerobic sequencing batch reactor (SBR) treating mariculture wastewater were evaluated at different oxytetracycline (OTC) concentrations. The COD and nitrogen removal efficiencies decreased with the increase in OTC concentration from 0 to 12 mg L−1. No apparent NO3−-N accumulation was found during the whole operational period, whereas NO2−-N accumulation occurred at 12 mg L−1 OTC. The specific oxygen uptake rate (SOUR), specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR) and specific nitrate reduction rate (SNRR) decreased with increasing influent OTC concentration. The protein (PN) and polysaccharide (PS) contents in the loosely-bound extracellular polymeric substances (LB-EPS) and tightly bound EPS (TB-EPS) increased with the increase in OTC concentration from 0 to 12 mg L−1, respectively. The appearance of OTC in the influent could obviously affect the functional groups of the PN and PS in the LB-EPS and TB-EPS. X-ray photoelectron spectroscopy (XPS) illustrated that amino, carboxyl and hydroxyl groups in the EPS might be involved in the interaction between the EPS and OTC. The denaturing gradient gel electrophoresis (DGGE) profile indicated that some variations were found in the microbial community of the activated sludge with increasing OTC concentration. Some microorganisms were depleted or weakened with the increase in OTC concentration, whereas others became the predominant microorganisms due to their ability to adapt to the OTC toxicity.

Performance comparison of biofilm and suspended sludge from a sequencing batch biofilm reactor treating mariculture wastewater under oxytetracycline stress.

ABSTRACT The performance, extracellular polymeric substances (EPS) and microbial community of a sequencing batch biofilm reactor (SBBR) were investigated in treating mariculture wastewater under oxytetracycline stress. The chemical oxygen demand and –N removal efficiencies of the SBBR decreased with the increase of oxytetracycline concentration, and no obvious –N and –N accumulation in the effluent appeared at less than 10 mg L−1 oxytetracycline. The specific oxygen utilization rate of the suspended sludge was more than that of the biofilm at different oxytetracycline concentrations. The specific ammonium oxidation rate (SAOR) of the biofilm was more easily affected by oxytetracycline than that of the suspended sludge, whereas the effect of oxytetracycline on the specific nitrite oxidation rate (SNOR) of the biofilm was less than that of the suspended sludge. The specific nitrate reduction rate of both the biofilm and suspended sludge was higher than the sum of the SAOR and SNOR at different oxytetracycline concentrations. The protein and polysaccharide contents in the EPS of the biofilm and suspended sludge increased with the increase of oxytetracycline concentration. The appearance of oxytetracycline in the influent could affect the chemical composition of the loosely bound EPS and tightly bound EPS. The amino, carboxyl and hydroxyl groups might be involved with interaction between EPS and oxytetracycline. The denaturing gradient gel electrophoresis profiles indicated that the variation of oxytetracycline concentration in the influent could affect the microbial communities of both the biofilm and suspended sludge.

Effect of florfenicol on performance and microbial community of a sequencing batch biofilm reactor treating mariculture wastewater

ABSTRACT The effects of florfenicol (FF) on the performance, microbial activity and microbial community of a sequencing batch biofilm reactor (SBBR) were evaluated in treating mariculture wastewater. The chemical oxygen demand (COD) and nitrogen removal were inhibited at high FF concentrations. The specific oxygen utilization rate (SOUR), specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR) and specific nitrate reduction rate (SNRR) were decreased with an increase in the FF concentration from 0 to 35 mg/L. The chemical compositions of loosely bound extracellular polymeric substances (LB-EPS) and tightly bound EPS (TB-EPS) could be affected with an increase in the FF concentration. The high-throughput sequencing indicated some obvious variations in the microbial community at different FF concentrations. The relative abundance of Nitrosomonas and Nitrospira showed a decreasing tendency with an increase in the FF concentration, suggesting that FF could affect the nitrification process of SBBR. Some genera capable of reducing nitrate to nitrogen gas could be inhibited by the addition of FF in the influent, such as Azospirillum and Hyphomicrobium.

Performance evaluation and microbial community shift of a sequencing batch reactor under silica nanoparticles stress

The performance, microbial community and enzymatic activity of a sequencing batch reactor (SBR) were evaluated at different silica nanoparticles (SiO2 NPs) concentrations. SiO2 NPs concentration at 5-30mg/L had a slight inhibitory impact on the nitrogen and COD removals, whereas the phosphorus removal was obviously inhibited at 30mg/L SiO2 NPs. The rates of nitrification, nitrite reduction and phosphorus removal decreased with the increase of SiO2 NPs concentration. The nitrate reduction rate decreased at less than 5mg/L SiO2 NPs and subsequently showed an increase at 10-30mg/L SiO2 NPs. The organic matter, nitrogen and phosphorus removal rates had similar varying tendencies to the corresponding microbial enzymatic activities under SiO2 NPs stress. Some SiO2 NPs were firstly absorbed on sludge surface and subsequently entered the interior of the microbial cells, which could exert the biological toxicity to activated sludge. The microbial community showed some obvious variations under SiO2 NPs stress.