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Chongqing, China

Kang J.,Chongqing University | Du G.,Chongqing University | Gao X.,Chongqing Water Group Co. | Zhao B.,Chongqing University | Guo J.,CAS Chongqing Institute of Green and Intelligent Technology
Water Environment Research | Year: 2014

The relationship between soluble microbial products (SMPs) and extracellular polymeric substances is described, and the characteristics of SMPs in the biological wastewater treatment process, including molecular weight distribution, metal-chelating property, biodegradability, biotoxicity, and membrane fouling, are investigated. The SMPs produced by autotrophs are degradable and utilizable for heterotrophs, thereby confirming the biodegradation of SMPs. Soluble microbial product models are designed through three approaches: establishment of SMP kinetic models or combination with Monod equations, incorporation of SMP generation and degradation into the unified theory raised by Laspidou and Rittmann (2002a), and introduction of the concept of SMP into activated sludge models. The effects of process parameters on SMP concentration are elaborated, based on the optimum biological treatment process operating parameters that can effectively minimize SMP production. The progress of SMP research in water biotreatment systems is presented, and suggestions for future studies are made. Source

He Q.,Chongqing University | Hu C.,Chongqing University | Xu Z.,Kunming Chuyun Traffic Engineering Design Co. | Li H.,Chongqing Water Group Co.
Chinese Journal of Environmental Engineering | Year: 2013

The study on the particle size distribution, feature parameters of ultra-fine grit in combines sewer system of mourainous urban in Three Gorges Reserboir Region was processed. The results show that the average particle size of grit is less than 250 μm in combines sewer system of Fuling area in dry-weather and wet-weather. It is belong to ultra-fine grit. The characteristics and gradation of ultra-fine grit vary depending on a number of factors. These include the type of collection system(combined or separate), the physical condition, mountain landscape, rainfall intensity, dry days before rain, the primary activities(commercial, residential, etc) and soil and water loss etc. The ultra-fine grit content is up to 183.9 mg/L and the average particle size is only 182.6 μm in influent of Fuling Wastewater Treatment Plant. The ultra-fine grit is too fine to be removed by grit trap. When lots of ultra-fine grit into the aeration tank, it brings a series of operational issues such as attrition of pump and mechanical equipment, blockages resulting from grit deposition etc. Source

Jiang S.,Chongqing University | Jiang H.,Chongqing Jiaotong University | Xiang P.,Chongqing University | Zhang N.,Chongqing Sino French Water Supply Co. | And 2 more authors.
Chinese Journal of Environmental Engineering | Year: 2013

Because of the algae outbreak in Jialing River water system, the algae in source water was hard to be removed in pretreatment process, which caused more than 10 water factorties' blockage in filter and shorten the backwashing cycle from normal 24 h to 2 h. It seriously affected normal operation and dramatically decreased the producing ability of waterworks. Due to the algae outbreak (the dominant species was synedra acus belonging to Diatoms), the effect of PAFS, PAC, and PFC coagulants on algae removal and turbidity removal was compared, with PAFS presenting the best effects, which was chosen as the optimal coagulant. In addition, different pro-oxidations and coagulant aids were added to enhance flocculation removal effects of algae, the result showed that PDMDAAC combined with PAFC gave the best effect, and other promoting coagulation effect was PPC>ClO2>PAM>H2O2>HCA-1. Using 0.6 mg/L PDMDAAC+25 mg/L PAFS applied to exising plants, the residual algae decreased to 49×104~55×104 cells/L, the algae removal rate could reach up to 70%~75%, which greatly reduced the operation load of the filter and recoved the normal operating mode of the waterworks. Source

Huang L.,Southwest University | Chen Y.,Southwest University | Liu G.,Southwest University | Li S.,Southwest University | And 2 more authors.
Energy | Year: 2015

A constructed wetland plant waste, Arundo donax L. (AD), was pyrolyzed from room temperature to 1000°C under a dynamic high-purity nitrogen atmosphere at different heating rates. Results show that three stages occur during thermal degradation of AD. Mass loss rates associated with lignocellulose degradation were not affected by heating rates. Physical and chemical characterization of ADs pyrolyzed under different temperatures indicated that simultaneous pyrolysis occurred during the lignocellulose devolatilization process. The non-isothermal method indicated that the pyrolysis reaction should conform to a single-step reaction model with average E (activation energy) of 163kJmol-1, calculated by partial least squares linear regression. The most probable mechanism of thermal degradation of AD, determined by the Malek method with the calculated E as the initial value, is described with the random nucleation and later growth (Johnson-Mehl-Avrami (J-M-A) model). It can be written as f(α)=0.28(1-α)[-ln(1-α)]-2.57. Finally, E=163.44±3.50kJmol-1, the reaction order n=0.28±0.031, and the decimal logaritm of pre-exponential factor lg(A)=13.13±0.096lg(s-1) were estimated. © 2015 Elsevier Ltd. Source

Jiang W.-C.,Chongqing University | Jiang H.,Chongqing Jiaotong University | Wu J.-J.,Chongqing University | Tian S.-H.,Chongqing Water Group Co.
Huazhong Keji Daxue Xuebao (Ziran Kexue Ban)/Journal of Huazhong University of Science and Technology (Natural Science Edition) | Year: 2013

The primary object of this work is to study the impact of the corrosion scales and tubercles of iron pipes on drinking water quality. The rule and mechanism of water quality deterioration due to pipe corrosions were explored though a 28 a unlined DN350 gray cast iron pipe. The results show that the turbidity and total iron of pipeline water increase with hydraulic retention time increase, among which the turbidity and the total iron are positively proportional to each other. The iron concentration of water is also found to be positively proportional to the suspended iron. All of the water quality parameters above are associated with water flow rate in the reactor. When the flow rate increases, the water quality deterioration is accelerated in the pipe. The surface morphology of corrosion tumors was analyzed by scanning electron microscopy (SEM). The structure of corrosion tumors in drinking water pipelines of city C could be divided into three layers: surface layer, hard coat layer and inner nuclear layer. The chemical composition of corrosion tumors was analyzed by using energy dispersive spectroscopy (EDS) and X fluorescence spectrometer (XRF), and the main components of corrosion tumors are iron oxide, i.e. α-FeOOH, γ-FeOOH and Fe3O4. All of the results above showed that an important reason causing water quality deterioration in the pipelines is the corrosion tumors, because the physical morphology and mechanical strength of which are susceptible to hydraulic conditions, then the corrosion products is easily detached and released in the water, leading to secondary pollution of water quality in the pipe. Source

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