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Wu C.,South China University of Technology | Wu C.,The Key Laboratory of Pollution Control | Wu C.,Eco Remediation of Guangdong Regular Higher Education Institutions | Wang L.,South China University of Technology | And 3 more authors.
Journal of Environmental Sciences (China) | Year: 2013

The growth rate and size of floc formation is of great importance in water treatment especially in coagulation process. The floc formation kinetics and the coagulation efficiency of synthetic water were investigated by using an on-line continuous optical photometric dispersion analyze and the analysis of water quality. Experimental conditions such as alum dosage, pH value for coagulation, stirring intensity and initial turbidity were extensively examined. The photometric dispersion analyze results showed that coagulation of kaolin suspensions with two coagulants (alum and polyaluminium chloride) could be taken as a two-phase process: slow and rapid growth periods. Operating conditions with higher coagulant doses, appropriate pH and average shear rate might be particularly advantageous. The rate of overall floc growth was mainly determined by a combination of hydraulic and water quality conditions such as pH and turbidity. The measurement of zeta potential indicates that polyaluminium chloride exhibited higher charge-neutralizing ability than alum and achieved lower turbidities than alum for equivalent Al dosages. Under the same operating conditions, the alum showed a higher grow rate, but with smaller floc size. © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences.

Ju F.,South China University of Technology | Ju F.,The Key Laboratory of Pollution Control | Hu Y.,South China University of Technology | Hu Y.,The Key Laboratory of Pollution Control | And 3 more authors.
Desalination | Year: 2011

Iron hydroxides prepared from microelectrolysis process were applied to remove EDTA-chelated copper from aqueous solution through adsorption-coprecipitation. To eliminate the occurrence of adverse reactions, Fe(II)-rich effluent of microelectrolysis was pretreated by continuously flushing N 2 for 15min to eliminate dissolved oxygen, then iron hydroxides were generated in less than 30s. The experimental results showed that Fe(II) yields could achieve 530.00-748.00mg/L after 60-min operation of microelectrolysis process at the initial pH of 2.0-2.3. The uptake rate of Cu(II) by iron(II) hydroxides was so rapid under nitrogen-aerated condition that 100% of Cu(II) was removed within only 5min at an initial Fe(II) concentration of 374.0mg/L. However, Cu(II) would desorb from iron hydroxides when iron(II) hydroxides were gradually oxidized into iron(III) hydroxides by oxygen, indicating that iron(II) hydroxide had much higher adsorptive capacity for chelated Cu(II) than iron(III) hydroxide. In addition, iron(II)/(III) hydroxides prepared from microelectrolysis process exhibited a higher removal efficiency of Cu(II) than iron hydroxides prepared from FeSO 4 7H 2O, especially under air-aerated condition. This research provided a novel method for efficient removal of both Cu(II) and EDTA from Cu(II)-chelated wastewater. © 2011 Elsevier B.V.

Ke L.,South China University of Technology | Ke L.,City University of Hong Kong | Ke L.,The Key Laboratory of Pollution Control | Zhang C.,City University of Hong Kong | And 4 more authors.
Marine Pollution Bulletin | Year: 2011

The influence of different environmental stresses, including salinity (5-35‰), tidal cycle (6/6, 12/12 and 24/24h of high/low tidal regimes) and nutrient addition (1-6 times background nitrogen and phosphorus content) on Bruguiera gymnorrhiza and Aegiceras corniculatum grown in sediment contaminated with spent lubricating oil (7.5Lm-2) were investigated. The oil-treated 1-year-old mangrove seedlings subject to low (5‰) and high (35‰) salinity had significantly more reduction in growth, more release of superoxide radical (O2-) and higher activity of superoxide dismutase (SOD) than those subject to moderate salinity (15‰). Extended flooding (24/24h of high/low tidal regime) enhanced O2- release and malondialdehyde (MDA) content in both oil-treated species but had little negative effects on biomass production (P>0.05) except the stem of A. corniculatum (P=0.012). The addition of nutrients had no beneficial or even posed harmful effects on the growth and cellular responses of the oil-treated seedlings. © 2011 Elsevier Ltd.

Wu R.-R.,South China University of Technology | Wu R.-R.,Purdue University | Dang Z.,South China University of Technology | Dang Z.,The Key Laboratory of Pollution Control | And 6 more authors.
Journal of Hazardous Materials | Year: 2011

The promotion of hexadecane biodegradation activity by an n-alkane degrading strain of Burkholderia cepacia (GS3C) with yeast extract amendment was studied using various carbon, nitrogen, vitamin, and amino acid amendments. Cytochrome P450 monooxygenase enzymes play a very important role and are especially required to introduce oxygen in n-alkane degradation. These enzymes from GS3C were located and detected using amino acid amendments. It was shown that biodegradation activity was promoted with amino acids amendments. However, only specific amino acids ( l-phenylalanine, l-glutamic acid, l-proline, l-lysine, l-valine and l-leucine) have biodegradation promoting ability for GS3C. Cell protein concentration and cytochrome P450 activity were promoted significantly with the addition of l-phenylalanine and yeast extract. Furthermore, a significant positive linear relationship between cytochrome P450 activity and biodegradation efficiency of GS3C was observed. The results indicate that amino acid is the primary factor of nutrient amendment in promoting hexadecane biodegradation by influencing cytochrome P450 activity in GS3C. © 2010 Elsevier B.V.

Wu Y.,South China University of Technology | Wu Y.,The Key Laboratory of Pollution Control | Wu Y.,Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control | Luo H.,South China University of Technology | And 9 more authors.
Journal of Colloid and Interface Science | Year: 2014

This work describes the preparation of an effective and low-cost porous graphene oxide/sawdust composite by a freeze-drying method. The composite exhibits a strong ability to adsorb nickel ions. The nickel ions adsorbed on graphene oxide/sawdust composite was reduced by sodium borohydride to generate a catalyst which was used in the degradation of phenol in water. The composite and the catalyst were characterized by XPS, FTIR, XRD and SEM. The adsorption of nickel ions by graphene oxide/sawdust composite was initially very fast and then slowly reached equilibrium in around 30. min. The adsorption of nickel ions by the composite could be well-described by the Freundlich isotherm model and the pseudo-second order kinetic model. The performance of the catalyst in phenol degradation was studied as a function of reaction time, dosage, temperature and initial pH. It was found that the catalyst optimally improved the degradation rate at pH 10 with a dose of 2. g/L in about 30. min. The results show that the degradation of phenol was an endothermic reaction and was a good fit to the Langmuir isotherm model. © 2014 Elsevier Inc.

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