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Wang C.,CAS Chongqing Institute of Green and Intelligent Technology | Liu H.,CAS Chongqing Institute of Green and Intelligent Technology | Sun Z.,Guangzhou Municipal Engineering Design and Research Institute
International Journal of Photoenergy | Year: 2012

Great efforts have been exerted in overcoming the drawbacks of the Fenton reaction for water treatment applications. The drawbacks include pH confinement, handling of iron sludge, slow regeneration of Fe(II), and so forth. This paper highlights the recent developments in the heterogeneous photo-Fenton reaction which utilizes nanosized iron oxides as catalyst for maximizing the activity due to the enhanced physical or chemical properties brought about by the unique structures. This paper also summarizes the fundamentals of the Fenton reaction, which determine the inherent drawbacks and associated advances, to address the advantages of iron oxides and nanosized iron oxides. Tips for applying this method in water treatment are also provided. Given that the environmental effect of nanosized iron oxides is not yet well established, rapid research growth may occur in the near future to advance this promising technology toward water treatment once it is smartly coupled with conventional technologies. © 2012 Chuan Wang et al. Source

Li Y.,Southwest Jiaotong University | Cai X.,Southwest Jiaotong University | Cai X.,Guangzhou Municipal Engineering Design and Research Institute | An W.,Southwest Jiaotong University | And 2 more authors.
Zhongguo Tiedao Kexue/China Railway Science | Year: 2011

The determination of structural stiffness parameters is very important in the overall design of long-span bridges. Taking a long-span railway dedicated suspension bridge as an engineering example, the effect of the stiffness of girder, tower and cable on the performances of bridge was analyzed from the aspects of the structural dynamic characteristics, train running performance and wind induced buffeting response. The stiffness assessment index for long-span railway suspension bridge was studied. Results indicate that the increase of the truss width can notably raise the transverse bending fundamental frequency of the bridge. The transverse periodic vibration of bridge would occur on condition that the truss width is too small, and the proposed limit value of the width-span ratio is 1/20~1/35. The vertical acceleration of train can be remarkably increased with the decrease of truss depth, and the proposed limit value of the depth-span ratio is 1/70~1/100. The increase of main cable stiffness can obviously improve the torsional and vertical fundamental frequency of the bridge. In addition, the effect of tower stiffness and dead load is limited. Source

Sui J.,Guangzhou Water Investment Group Co. | Luo F.,Harbin Institute of Technology | Li J.,Guangzhou Municipal Engineering Design and Research Institute
Environmental Technology (United Kingdom) | Year: 2016

Short-cut nitrification (SCN) is shown to be an attractive technology due to its savings in aeration and external carbon source addition cost. However, the shortage of excluding nitrite nitrogen as a model state in an Activated Sludge Model limits the model predictive control of biological nitrogen removal via SCN. In this paper, a two-step kinetic model was developed based on the introduction of pH and temperature as process controller, and it was implemented in an SBR reactor. The simulation results for optimizing operating conditions showed that with increasing of dissolved oxygen (DO) the rate of ammonia oxidation and nitrite accumulation firstly increased in order to achieve a SCN process. By further increasing DO, the SCN process can be transformed into a complete nitrification process. In addition, within a certain range, increasing sludge retention time and aeration time are beneficial to the accumulation of nitrite. The implementation results in the SBR reactor showed that the data predicted by the kinetic model are in agreement with the data obtained, which indicate that the two-step kinetic model is appropriate to simulate the ammonia removal and nitrite production kinetics. © 2016 Taylor & Francis Source

Wen Q.,Hunan University | Hua X.G.,Hunan University | Chen Z.Q.,Hunan University | Yang Y.,Hunan University | Niu H.W.,Guangzhou Municipal Engineering Design and Research Institute
Journal of Bridge Engineering | Year: 2016

This article describes the research work relating to the assessment and control of human-induced vibration of an unusual curved cable-stayed bridge with separate road and pedestrian decks. Dynamic simulations of human-induced vibration were performed with a mode-by-mode approach, and the results showed that a total of eight lateral and vertical modes of the bridge may suffer from excessive vibrations at the design crowd density. A hybrid control scheme was developed for control of human-induced vibration, which consists of steel braces fitted between the road bridge deck and the pedestrian deck to improve structural stiffness and eddy current tuned mass dampers to enhance damping ratios of lively modes. The modal properties of the bridge with steel braces were experimentally obtained by dynamic tests and used for parameter tuning of mass dampers. The performance of the hybrid control strategy was evaluated by group tests of up to 400 pedestrians. It is shown that the critical number of pedestrians triggering synchronous lateral excitation is generally in good agreement with the empirical model developed from measurements on the London Millennium Bridge, but the measured vertical acceleration amplitude is only about 40% of the prediction under the same pedestrian density. The damping ratios for both the vertical and lateral modes increase appreciably after installation of tuned mass dampers and no evidence of large-amplitude vibrations has been observed. © 2016 American Society of Civil Engineers. Source

Wang W.,Heilongjiang Institute of Technology | Chen Q.,Harbin Institute of Technology | Wang C.,Guangzhou Municipal Engineering Design and Research Institute | Peng Y.,Harbin Institute of Technology
Huagong Xuebao/CIESC Journal | Year: 2015

By adjusting the distribution ratio of influent flow into anaerobic and anoxic zones, the removal efficiency of pollutants in low C/N(COD/total nitrogen)<3.5 municipal sewage using modified step feed process was analyzed. Keeping the following conditions unchanged: hydraulic retention time (HRT) 10 h, sludge retention time (SRT) 10-15 d, volume of anaerobic zone:volume of total anoxic zones:volume of total aerobic zones 4:9:9, when the actual efficiency obtained and material balance calculation results were utilized to increase gradually the water ratio distributing to the first stage i.e. anaerobic zone, the best operating conditions could be found and 4 kinds of operating conditions determined. The results show that, at given C/N ratio, concentration of nitrogen oxides in anaerobic zone does not decrease with the increase of the water ratio entered into anaerobic zone, even appears the opposite situation. The simultaneous nitrification and denitrification(SND)and microbial assimilation effect intensity play crucial role in TN removal. The rise of water ratio entered into anaerobic zone improves the removal rate of phosphate due to the phosphorus release effect of phosphorus-accumulating bacteria is enhanced in anaerobic zone. Both nitrogen and phosphorus removals as well as subsequent optimization space are considered, one of optimized water distribution ratio is 6:3:1, and at this condition, the effluent concentration of COD, ammonia nitrogen, TN, phosphate is 45.98, 0.04, 17.47 and 2.43 mg·L-1 respectively. ©, 2015, Chemical Industry Press. All right reserved. Source

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