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Shennan, China

Zhou L.,Tongji University | Zhang Z.,Tongji University | Xia S.,Tongji University | Jiang W.,Shenzhen Water Group Co. | And 8 more authors.
Bioresource Technology | Year: 2014

Effects of the suspended titanium dioxide nanoparticles (TiO2 NPs, 50mg/L) on the cake layer formation in a submerged MBR were systematically investigated. With nanometer sizes, TiO2 NPs were found to aggravate membrane pore blocking but postpone cake layer fouling. TiO2 NPs showed obvious effects on the structure and the distribution of the organic and the inorganic compounds in cake layer. Concentrations of fatty acids and cholesterol in the cake layer increased due to the acute response of bacteria to the toxicity of TiO2 NPs. Line-analysis and dot map of energy-dispersive X-ray were also carried out. Since TiO2 NPs inhibited the interactions between the inorganic and the organic compounds, the inorganic compounds (especially SiO2) were prevented from depositing onto the membrane surface. Thus, the postponed cake layer fouling was due to the changing features of the complexes on the membrane surface caused by TiO2 NPs. © 2013 Elsevier Ltd.

Han X.B.,CAS Research Center for Eco Environmental Sciences | Han X.B.,Shenzhen Water Group Co. | Yuen K.W.Y.,University of Hong Kong | Wu R.S.S.,University of Hong Kong
Environmental Pollution | Year: 2013

Polybrominated diphenyl ethers (PBDEs) have been commonly used as flame retardants and now become ubiquitous in the global environment. Using zebrafish as a model, we tested the hypothesis that PBDEs may affect the reproduction and development of fish. Zebrafish were exposed to environmentally relevant concentrations of DE-71 (a congener of PBDE commonly found in the environment) throughout their whole life cycle, and the effects of DE-71 on gonadal development, gamete quality, fertilization success, hatching success, embryonic development and sex ratio were investigated. Despite gonadal development was enhanced, reductions in spawning, fertilization success, hatching success and larval survival rate were evident, while significant increases in malformation and percentage of male were also observed in the F1 generation. Our laboratory results suggest that PBDEs may pose a risk to reproductive success and alter the sex ratio of fish in environments highly contaminated with PBDEs. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.

Duan L.,Chinese Research Academy of Environmental Sciences | Duan L.,Tsinghua University | Tian Z.,Chinese Research Academy of Environmental Sciences | Song Y.,Chinese Research Academy of Environmental Sciences | And 4 more authors.
Biofouling | Year: 2015

The objective of this study was to investigate the influence of solids retention time (SRT) on membrane fouling and the characteristics of biomacromolecules. Four identical laboratory-scale membrane bioreactors (MBRs) were operated with SRTs for 10, 20, 40 and 80 days. The results indicated that membrane fouling occurred faster and more readily under short SRTs. Fouling resistance was the primary source of filtration resistance. The modified fouling index (MFI) results suggested that the more ready fouling at short SRTs could be attributed to higher concentrations of soluble microbial products (SMP). Fourier transform infrared (FTIR) spectra indicated that the SRT had a weak influence on the functional groups of the total extracellular polymeric substances (TEPS) and SMP. However, the MBR under a short SRT had more low-molecular-weight (MW) compounds (<1 kDa) and fewer high-MW compounds (>100 kDa). Aromatic protein and tryptophan protein-like substances were the dominant groups in the TEPS and SMP, respectively. © 2015 Taylor & Francis.

Gao D.-W.,Harbin Institute of Technology | Gao D.-W.,Northeast Forestry University | Tao Y.,Harbin Institute of Technology | An R.,Shenzhen Water Group Co.
Desalination | Year: 2012

As one of the largest wastewater sources, domestic sewage needs particular attention. This study focuses on how hydraulic retention time (HRT) affects a membrane-based process treating digested sewage. A laboratory-scale combined system, including an anoxic tank (AT) and an aerobic membrane bioreactor (MBR) was operated under decreasing HRTs (8. h, 6. h, 4. h and 2.5. h) for 218. days. HRT variation had a very limited effect on carbon removal but enhanced nitrogen (ammonium and total nitrogen) removal capacity. The biomass concentrations increased by five times until the end of HRT 2.5. h. The 16S rDNA fingerprinting analyses indicated that the microbial diversity decreased and the species belonging to the genera of Nitrospira and Variovorax became to dominate at short HRTs. The filtration resistance at HRT 2.5. h was almost three times higher than the one at HRT 8. h; also, the fouling rate was faster at short HRTs. © 2011 Elsevier B.V.

Zhou L.,Tongji University | Zhang Z.,Tongji University | Jiang W.,Shenzhen Water Group Co. | Guo W.,University of Technology, Sydney | And 5 more authors.
Biofouling | Year: 2014

The effects of low-concentration Cr(VI) (0.4 mg l-1) on the performance of a submerged membrane bioreactor (SMBR) in the treatment of municipal wastewater, as well as membrane fouling were investigated. Compared with the SMBR for control municipal wastewater, the SMBR for Cr(VI)-containing municipal wastewater had a higher concentration of soluble microbial products (SMP) with lower molecular weights, and smaller sludge particle sizes. Furthermore, low-concentration Cr(VI) induced membrane fouling, especially irreversible membrane pore blocking, which markedly shortened the service life of the membrane. © 2013 © 2013 Taylor & Francis.

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