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Chen S.,Shanghai Environment Engineering Design Institute Co. | Song L.,Shanghai Environment Engineering Design Institute Co.
Clean - Soil, Air, Water | Year: 2017

Activated carbon (AC), layered double hydroxide (LDH), and metal ions (MIs) were added to aerobic sequencing batch reactors (SBRs), respectively, to improve the stability of aerobic granular sludge (AGS). The results showed that the addition of AC, LDH, and MIs accelerated the sludge granulation. With the addition of LDH, the AGS was denser and more compact, and the protein and polysaccharide contents of the extracellular polymeric substance (EPS) extracted from AGS were higher. In addition, the removal efficiencies of COD and NH4 +-N in the reactor with LDH addition were higher than those with AC and MIs addition, respectively. These results indicate that the AGS cultivated with LDH addition was more stable and more efficient than those with the addition of AC and MIs. The stimulated EPS secretion, the bridging effect and the binding effect played important roles in improving the AGS stability. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lu X.,Shanghai University | Lu X.,Tohoku University | Chen S.,Shanghai Environment Engineering Design Institute Co. | Luo J.,Shanghai University | And 4 more authors.
RSC Advances | Year: 2016

The application of CO2-stripping system for calcium removal to upgrade organic matter removal and sludge granulation in a leachate-fed EGSB bioreactor was evaluated. Three-dimensional excitation-emission matrix (3D-EEM) spectroscopy combined with parallel factor (PARAFAC) analysis was used to characterize the transformation of the effluent dissolved organic matter (DOM) during the operation. X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and scanning electronic microscopy (SEM) were used to assess the effects of a CO2-stripping unit on the microstructure of the granules. The introduction of the CO2-stripping system reduced the calcium concentration while upgrading methane evolution. The methane yield reached 0.33 L CH4 per g CODremoved in the bioreactor with the CO2-stripping unit compared with 0.31 L CH4 per g CODremoved without the unit as the control. The combined system produced 80% and 50-60% chemical oxygen demand (COD) and total nitrogen (TN) removal under steady-state conditions, which were 6.3% and 41.0% higher than those of the control, respectively. With 3D-EEM-PARAFAC analysis, three fluorescence components, associated as tryptophan protein-like (component 1, Ex/Em = 275-280/355-365 nm) and humic-like substances (component 2, Ex/Em = 240(295, 340)/450 nm and component 3, Ex/Em = 320/320 nm), were identified from the effluent samples. The componential characterizations confirmed the favorable influence of the CO2-stripping unit on the transformation of DOM. Further analysis through XRD, FT-IR and SEM demonstrated that the use of the unit alleviated inactivation of the granules through removing calcium, which might be the core reason for the enhancement of the EGSB performance. © The Royal Society of Chemistry 2016.

Wu L.,Shanghai University | Chen S.,Shanghai Environment Engineering Design Institute Co. | Zhou J.,Shanghai University | Zhang C.,Shanghai University | And 6 more authors.
RSC Advances | Year: 2015

The removal of nitrate and organic matter from landfill leachate has been an arduously difficult challenge in recent years. Iron-carbon internal micro-electrolysis combined with ammonia stripping has been employed for the simultaneous removal of nitrate and organic matter from the biochemically treated landfill leachate. Compared with synthetic wastewater, nitrate removal from practical leachate is much more difficult, with a good removal efficiency only at low pH value. The removal efficiency of organic matter would quickly reach the maximum in 20 minutes, but in 100 minutes for that of nitrate. The higher the initial pH was, the more ammonia could be removed. pH = 11 is a reasonable choice based on total cost and nitrate removal efficiency. The mechanisms of nitrate and organic matter removal by iron-carbon internal micro-electrolysis were investigated. Nitrate reduction to ammonia was the main way for nitrate removal, while adsorption by activated carbon and coagulation by iron ions were the two main ways for organic matter removal (with contribution of about 70% of the total COD removal). These results proved that iron-carbon internal micro-electrolysis followed with ammonia stripping could be a promising option for further nitrate and organic matter removal from biochemically treated leachate. © The Royal Society of Chemistry 2015.

Liu J.-Y.,Shanghai University | Bian H.-D.,Shanghai University | Cao Y.-L.,Shanghai University | Zhong J.-P.,Shanghai University | And 5 more authors.
Journal of Shanghai University | Year: 2011

An expanded granular sludge bed (EGSB) reactor inoculated with anaerobic granular sludge was started up with its COD removal performance, self-balancing of pH, biogas production rate and characteristics of the granular sludge during the start-up period being investigated. The results indicated that the EGSB reactor can be started up successfully in 27 d by increasing the organic loading rate rapidly. The removal efficiency of COD was maintained above 93% with influent COD concentration of 25 000 mg/L and OLR of 37.94 kgCOD/(m 3•d). The EGSB reactor with good pH self-balancing could be fed with fresh leachate of low pH value (4-5). The biogas production rate was closely related with OLR and COD reduction. Every gram of COD fed (consumed) to the reactor produced 0.34 LSTP (0.36 LSTP) biogas with 0.21 LSTP (0.23 LSTP) methane. Thus, 65%-70% of the produced biogas was methane. Sixty one percentage of COD fed to the reactor was converted to methane, another 33% was converted to biomass by metabolism, and the other 6% was left in the liquid phase. The specific methanogenic activity (SMA) of the granular sludge had increased by 92% after 27 d dynamic incubation. The granular sludge in the reactor had good settlement performance with majority diameter of 1-2 mm. © 2011 Shanghai University and Springer-Verlag Berlin Heidelberg.

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