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Wang L.-L.,Shanghai Municipal Engineering Design Institute Group Co. | Wang L.-L.,Tongji University | Xu G.-M.,Changzhou Drainage Administration | Chen J.,Changzhou Drainage Administration | And 2 more authors.
Journal of Hohai University | Year: 2012

To improve the hydraulic performance of a super sedimentation tank with peripheral inflow and peripheral effluent, the computational fluid dynamics method was used to simulate the hydraulic performance in a preliminary design scheme for a sedimentation tank. A case study was conducted in a sedimentation tank (with a diameter of 60 m) with peripheral inflow and peripheral effluent in a wastewater treatment plant in the south of China. The optimal design parameters were determined through analysis of the flow field characteristics of the sedimentation tank calculated by means of the staggered-grid finite volume method, with the help of the realizable k-ε model provided by the FLUENT 6.3 software package. The results show that the radius of circulation increased to 26 to 28 m in the sedimentation tank with vertical flow and a two-way baffle, the appropriate ratio of diameter to depth (θ) ranged from 8.0 to 10.0, and the gradient (i) should be set at 0.050. The performance of circulation in the sedimentation tank could be improved by taking proper optimization measures. Source

Du E.-D.,Changzhou University | Du E.-D.,Tongji University | Zheng L.,Changzhou Drainage Administration | Zheng L.,Tongji University | And 2 more authors.
Huanjing Kexue/Environmental Science | Year: 2014

Restriction fragment length polymorphism (RFLP) technology was used to investigate the microbial diversity and structure of biological activated carbon (BAC) from different sources in drinking water advanced treatment process. Diversity indices of samples A, B and C, with relatively high tannic acid and humic acid adsorption capacity, were close to each other, which meant higher microbial diversity. However, samples D and E had relatively lower diversity indices with the low tannic acid and humic acid adsorption capacity. There were five species including β-Proteobacteria, α-Proteobacteria, Planctomycetes, γ-Proteobacteria, Bacteroidetes in the phylogenetic tree of BAC samples. Among them, β-Proteobacteria and α-Proteobacteria were the dominant microbial species in these BAC samples, which played an important role in organic matter removal. Planctomycetes, γ-Proteobacteria, and Bacteroidetes were the non-dominant microbial species. Bacteroidetes only existed in samples A, B, C and D, while did not occur in sample E. The BAC samples with the higher tannic acid and humic acid adsorption capacity had higher microbial diversity. This research should deepen the understanding of microbial community in BAC, and provide a theoretical basis for the safety of drinking water. ©, 2014, Science Press. All right reserved. Source

Zheng L.,Changzhou Drainage Administration | Zheng L.,Tongji University | Gao N.,Tongji University | Gan L.,Changzhou Drainage Administration | And 4 more authors.
Chinese Journal of Environmental Engineering | Year: 2015

Predominant species were selected and attached to the activated carbon surface by immobilization method to form immobilized biological activated carbon (IBAC). Therefore, the biofilm formation period on the activated carbon can be accelerated. IBAC process was also used to treat the micro-polluted water. The results show that, compared with the natural biofilm formation period of 24 days, the biofilm formation period of IBAC was reduced 60% to 9 days. The removal of ammonia by IBAC was 90%. Microbe quantity of IBAC was higher than that of the natural BAC. What's more, microbe quantity of IBAC gradually decreased along the water flow direction. The microscopical study found that lots of protozoa and metazoa, including zoogloea, rotifera, and vorticella, appeared on the surface of IBAC. With the rapid biofilm formation period, IBAC can effectively treat micro-polluted water. © 2015, Science Press. All right reserved. Source

Zhou M.,Changzhou University | Chen J.,Changzhou Drainage Administration | Dong L.,Changzhou University | Yang Y.,Changzhou Drainage Administration | Xu G.,Changzhou Drainage Administration
Chinese Journal of Environmental Engineering | Year: 2015

Two kinds of combined sewer overflows (CSOs) from different intensity rainfall were collected from D drainage system in order to understand the pollution characteristics in old urban area in South Jiangsu. Water quality including COD, SS, TN, TP and NH3-N of CSOs was tested. Characteristics of water quality and correlation of different water quality indexes were analyzed. Results show that SS, COD, TN, NH3-N and TP are 37-695 mg/L, 119-1 441 mg/L, 6.2-26 mg/L, 2.3-6.3 mg/L, and 0.07-1.48 mg/L, respectively from high intensity rainfall, and 22-228 mg/L, 180-535 mg/L, 7.9-24.7mg/L, 3.2-24.2 mg/L, and 1.1-1.99 mg/L, respectively from low intensity rainfall. Sewer flushing effects are found to be depended on rainfall intensity. Linear correlation of TN and COD with SS in high intensity rainfall is existing, and the correlation coefficients are 0.6954 and 0.6234, respectively. However, no obvious correlation is found from low intensity rainfall. Removal of SS can effectively reduce COD and TN concentration of CSOs from high intensity rainfall, which may provide practical advice for CSOs pollution control. ©, 2015, Science Press. All right reserved. Source

Jin J.,Tsinghua University | Wu G.,Tsinghua University | He K.,Tsinghua University | Chen J.,Changzhou Drainage Administration | And 2 more authors.
Desalination and Water Treatment | Year: 2014

Abstract: The corrosion behavior of carbon steel in cooling systems using reclaimed wastewater as the makeup water was investigated. Effect of typical ions (Cl−, (Formula presented.) , (Formula presented.) , and (Formula presented.)) on the corrosion of carbon steel in cooling systems was evaluated. The electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy were used to measure the corrosion rate and analyze the corrosion processes. Also scanning electron microscopy, Fourier transform infrared spectrometer and energy dispersive spectroscopy were applied to surface analysis. Among the examined ions, Cl− had the highest influence on the corrosion of the carbon steel, followed by (Formula presented.) , (Formula presented.) , and (Formula presented.). During cooling cycle, the corrosion process of carbon steel was controlled by cathodic reaction. Corrosion rate increased at the initial stage and then decreased thereafter due to the combined effect of ions and corrosion layer. The ions accelerated the initial corrosion of carbon steel in cooling system, while the corrosion layer hindered this effect. The corrosion layer was dense, uniform, and made up of crystalline particles and the main corrosion products were ferric hydroxides and iron oxide. © 2013, Balaban Desalination Publications. All rights reserved. Source

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