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Feng X.,Changzhou University | Du E.,Changzhou University | Liu X.,Tsinghua University | Guo Y.,Changzhou University | And 2 more authors.
Chinese Journal of Environmental Engineering | Year: 2015

Three typical carbon materials, including granular activated carbon (GAC), powdered activated carbon (PAC), and carbon nanotubes (CNTs), were used to adsorb and remove colored dissolved organic matter (CDOM) in waters of Taihu Lake and sewage plant outlet. The adsorption characteristics were also investigated. The combination of fluorescence spectrum and parallel factor (PARAFAC) analysis was carried out to extract three PARAFAC fluorescent components, including C1 (humic-acid like), C2 (tryptophan protein-like), and C3 (tyrosine protein-like). PAC and CNTs have high adsorption capacity for large molecular organics with developed meso-porous structure. The micro-porous structure of GAC is not conducive to the adsorption of large molecular organics, such as humid acid. The adsorption rate of PAC was the largest with the adsorption rates of component C1, C2, C3 in Taihu Lake samples being 0.278 and 0.358, 0.359 min-1, while the rate of GAC was much lower than that of PAC and CNTs. The research illustrated the adsorption characteristics of complex and mixed organic matter in waters, which might present the technical reference for the parameter optimization of adsorption technology. ©, 2015, Science Press. All right reserved.

Jiang S.,Tongji University | Zhang Y.,Tongji University | Wang P.,Changzhou Academy of Environmental Science | Zheng M.,Tongji University
Water Science and Technology | Year: 2013

The spatiotemporal characterization of unknown sources of groundwater pollution is frequently encountered in environmental problems. This study adopts a simulation-optimization approach that combines a contaminant transport simulation model with a heuristic harmony search algorithm to identify unknown pollution sources. In the proposed methodology, an almost-parameter-free harmony search algorithm is developed. The performance of this methodology is evaluated on an illustrative groundwater pollution source identification problem, and the identified results indicate that the proposed almost-parameter-free harmony search algorithm-based optimization model can give satisfactory estimations, even when the irregular geometry, erroneous monitoring data, and prior information shortage of potential locations are considered. © IWA Publishing 2013.

Du E.,Changzhou University | Zhang S.,Changzhou University | Feng X.,Changzhou University | Gu L.,Changzhou Academy of Environmental Science | And 2 more authors.
Chinese Journal of Environmental Engineering | Year: 2014

Photocatalytic degradation of endocrine disrupting chemical bisphenol A (BPA) by TiO2 was studied in a reactor. Response surface methodology (RSM) and central composite design (CCD) were employed to construct RSM model and optimize three parameters, viz. TiO2 concentration, initial BPA concentration, and UV light intensity. The quadratic model can be used to simulate the experimental results and navigate the design area. The optimized conditions of photocatalytic degradation of BPA were as follows: TiO2 concentration of 1.80 g/L, initial BPA concentration of 41.08 mg/L, UV light intensity of 6.61 mW/cm2. Under these conditions, the maximal BPA removal efficiency of 82.3% was achieved. Also, a polynomial expression modeling the reaction was obtained. The model fitted well with the experimental data, indicating the suitability of the model and the success of response surface methodology (RSM) in optimizing the conditions of photocatalysis. The study has the reference value in development of photocatalytic technology engineering application and photoreactor design. ©, 2014, Science Press. All right reserved.

Yang F.,Nanjing Agricultural University | Guo J.,Nanjing Agricultural University | Dai R.,Changzhou Academy of Environmental Science | Lan Y.,Nanjing Agricultural University
Geoderma | Year: 2014

Cr(III)-cit and Cr(III)-tar were synthesized and purified, and then their stability in the presence of δ-MnO2 was further investigated in batch experiments under different conditions to predict the potential oxidation behaviors of Cr(III)-organic acid complexes in the environment. The results indicated that although the rates and extents of Cr(III)-cit and Cr(III)-tar oxidation by δ-MnO2 were much lower than those of aqueous Cr(III), Cr(VI) could be gradually released through the whole reaction. The oxidations of Cr(III)-cit and Cr(III)-tar were affected by the initial concentrations of δ-MnO2, pH and co-existing ions. Lower pH and higher concentrations of δ-MnO2 markedly enhanced the production of Cr(VI). Ammonium ions significantly improved the oxidation of Cr(III)-cit and Cr(III)-tar, but phosphate ions demonstrated an opposite effect due to the formation of more stable CrPO4. The oxidation process of Cr(III)-cit and Cr(III)-tar by δ-MnO2 can be divided into two phases. At the initial phase, a relatively rapid reaction obeyed the first-order model, and then a zero-order one was followed. It was observed that in all the cases the extent of Cr(III)-cit oxidation was lower than that of Cr(III)-tar. Thus, it was concluded that the stability of Cr(III)-cit was higher than that of Cr(III)-tar. © 2013 Elsevier B.V.

Shang L.,CAS Nanjing Institute of Geography and Limnology | Shang L.,University of Chinese Academy of Sciences | Feng M.,CAS Nanjing Institute of Geography and Limnology | Liu F.,CAS Nanjing Institute of Geography and Limnology | And 6 more authors.
Environmental Sciences: Processes and Impacts | Year: 2015

As harmful cyanobacterial proliferation threatens the safety of drinking water supplies worldwide, it is essential to establish a safety threshold (ST) for cyanobacteria to control cyanobacterial density effectively in water sources. For this purpose, cyanobacterial abundance, microcystin (MC) production, and environmental parameters were monitored monthly from September 2011 to August 2012 in one drinking water source of Lake Chaohu. The cyanobacterial density ranged from 1400 to 220000 cells per mL with the succession of two dominant species Microcystis and Dolichospermum, which was determined by water temperature and nutrient loading. The MC concentrations were correlated significantly with the cyanobacterial density and they varied between 0.28 and 8.86 μg L-1. Therefore, the characteristics of MC cell quotas were classified according to four stages of the development of cyanobacteria, namely: recruitment, multiplication, decline and dormancy. The ST for cyanobacteria was established for different periods based on the MC cell quota and its guideline wherein three commonly monitored MC congeners (MC-LR, -RR and -YR) were considered in the present study. Its reliability was verified in the water source using the data collected between June 2013 and May 2014. The results highlighted the necessity to classify the ST-values in different periods referring to the main MC congeners rather than MC-LR, which will facilitate the management and control of toxic cyanobacterial proliferation in drinking water sources. © 2015 The Royal Society of Chemistry.

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