PubMed | Heilongjiang University, Harbin Institute of Technology and Shenzhen Water Group Co.
Type: Journal Article | Journal: Regulatory toxicology and pharmacology : RTP | Year: 2015
Bromate is a byproduct of water disinfection that is produced when waters contain bromide treated with ozone. To investigate the level of the toxicity of bromate and find the most sensitive indicators in a short time, a series of toxicological assessments were conducted including the acute toxicity, cumulative toxicity, genetic toxicity and subacute toxicity of bromate (using Potassium Bromate to represent bromate). The LD50 of orally administered Potassium Bromate was 215 mg/kg in Wistar rats and 464 mg/kg in ICR mice. The cumulative toxicity of Potassium Bromate was not obvious. The Ames test, mouse bone marrow cell micronucleus test and mouse sperm abnormality test did not indicate mutagenicity. The results of the subacute study did not exhibit significant differences in most of the parameters, except the white blood cell count, which was significantly decreased in male rats. In addition, Potassium Bromate influenced the albumin, creatinine, total cholesterol, triglycerides and glucose levels in male rats to various extents. A thorough analysis of the above tests clearly demonstrates that bromate has toxicity, not obvious cumulative toxicity and the white blood cell count can be used as an indicator to reflect the toxicity of bromate and investigate bromates toxic mechanism.
Huang H.-X.,Huazhong University of Science and Technology |
Huang H.-X.,Shenzhen Water Group Co. |
Chen H.-P.,Huazhong University of Science and Technology |
Hu Z.-F.,Guangdong Key Laboratory of Clean Energy Technology |
Ma X.-Q.,Guangdong Key Laboratory of Clean Energy Technology
Journal of Coal Science and Engineering | Year: 2012
Since the adverse factors such as deficient penetration and long reaction time have restricted the complete microwave-used drying of municipal sludge, the microwave-induced drying is considered, which has advantages in such aspects. The investigation of the microwave-induced drying to uncover the mechanism bears great meaning for its development and utilization. The effects of temperature and microwave cracking in municipal sewage sludge drying characteristics are studied through municipal sewage sludge drying experiment. Experiments shows that higher drying temperature would lead to a more acutely changing drying rate (DR). The DR had increased from 0.005 g/(g·min) to 0.060 g/(g·min), which was 12 times enlarged, while the temperature rose from 70 °C to 160 °C. The higher the temperature was, the earlier the peak value of DR appeared. The experiments indicated that the temperature was the decisive factor affecting the DR. The microwave-induced sludge reached the highest DR at the moisture rate (MR) of 40%, with a 20% grade promotion compared with that of the original one. The molecular fracture caused by microwave radiation had obviously accelerated the drying process and the DR was rising in proportion to the microwave radiation dose. The diffusion coefficient had been calculated according to Fick's law. In comparison to that of the original one, the diffusion coefficient of microwave-induced sludge was obviously enlarged more than two times. By fit examinations, Model Weibull was proven to be the most fit one for thermal thin-layer drying of municipal sludge. By means of Arrhenius equation, the obtained average activation energy of municipal sludge was 37.1 kJ/(mol·K). © The Editorial Office of Journal of Coal Science and Engineering (China) and Springer-Verlag Berlin Heidelberg 2012.
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.
Yin W.-C.,Harbin Institute of Technology |
Zhang J.-S.,Harbin Institute of Technology |
Zhang J.-S.,Shenzhen Water Group Co. |
Liu L.-J.,Shenzhen Water Group Co. |
And 3 more authors.
Journal of Water Supply: Research and Technology - AQUA | Year: 2012
In view of the aesthetic problem and potential threat to safe drinking water caused by invertebrates, a series of different depth sand beds were located under granular activated carbon (GAC) media in five pilot-GAC filtration (GACF) columns to restrict invertebrates' access into the distribution system. During the study period May 2010 to March 2011, seven groups of invertebrates (rotifers and crustaceans as the predominant species) were detected in the filtrates of the five GACF columns. The experimental results indicated that invertebrates could be removed effectively with the added sand beds compared with the sand bed-free GACF column. The mean abundances of invertebrates decreased significantly with the increase in the depth of sand beds, while there were different removal ratios between rotifers (29.8-46.6%) and larger invertebrates (size >200 μm) (41.7-85.5%). Sand sizes had a greater impact on rotifer removal than on larger invertebrates. Also, increasing removal ratios of particle matter were detected with the sand beds added. Further data analysis showed that there was significant correlation between the mean values of particle counts and abundances of invertebrates in the filtrates. The mixed-layer phenomenon between the GAC and the sand media could be controlled effectively under the optimized backwashing procedures. © IWA Publishing 2012.
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.
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.
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.
PubMed | Shenzhen Water Group Co.
Type: Journal Article | Journal: Biofouling | Year: 2015
A novel pure-oxygen pressurized biofilm reactor was operated at different organic loading, mechanical shear and hydrodynamic conditions to understand the relationships between biofilm architecture and its operation. The ultimate goal was to improve the performance of the biofilm reactor. The biofilm was labeled with seven stains and observed with confocal laser scanning microscopy. Unusual biofilm architecture of a ribbon embedded between two surfaces with very few points of attachment was observed. As organic loading increased, the biofilm morphology changed from a moderately rough layer into a locally smoother biomass with significant bulging protuberances, although the chemical oxygen demand (COD) removal efficiency remained unchanged at about 75%. At higher organic loadings, biofilms contained a larger fraction of active cells distributed uniformly within a proteinaceous matrix with decreasing polysaccharide content. Higher hydrodynamic shear in combination with high organic loading resulted in the collapse of biofilm structure and a substantial decrease in reactor performance (a COD removal of 16%). Moreover, the important role of proteins for the spatial distribution of active cells was demonstrated quantitatively.
PubMed | Jinan University and Shenzhen Water Group Co.
Type: | Journal: Water research | Year: 2014
Invertebrate colonization of granular activated carbon (GAC) filters in the waterworks is one of the most frequently occurring and least studied biological problems of water processing in China. A survey of invertebrate colonization of GAC filters was carried out weekly from October 2010 to December 2011 at a reservoir water treatment works in South China. Twenty-six kinds of invertebrates were observed. The abundance was as high as 5600ind.m(-3) with a mean of 860ind.m(-3). Large variations in abundance were observed among different seasons and before and after GAC filtration. The dominant organisms were rotifers and copepods. The average invertebrate abundance in the filtrate was 12-18.7 times of that in the pre-filtered water. Results showed that the GAC filters were colonized by invertebrates which may lead to a higher output of organisms in the filtrate than in the pre-filtered water. The invertebrate abundance in the GAC filters was statistically correlated with the water temperature. Seasonal patterns were observed. The invertebrate abundance grew faster in the spring and summer. Copepods were dominant in the summer while rotifers dominated in all other seasons of the year. There was a transition of small invertebrates (rotifers) gradually being substituted by larger invertebrates (copepods) from spring to summer. Control measures such as backwashing with chloric water, drying filter beds and soaking with saliferous water were implemented in the waterworks to reduce invertebrate abundances in the GAC filters. The results showed that soaking with saliferous water (99%, reduction in percent) was best but drying the filter beds (84%) was more economical. Soaking filter beds with 20g/L saliferous water for one day can be implemented in case of emergency. In order to keep invertebrate abundance in the acceptable range, some of these measures should be adopted.