Showing papers by "Dongsheng Shen published in 2008"

Influence on three categories of metal ions on adsorption of humic acid by activated sludge

Abstract: Activated sludge,as the adsorbent of humid acid in solution,was considered as an environment-friendly material.The effects of three categories of metal ions on sorption of humic acid by activated sludge were studied.The results indicated that the salts(Na~+),hardness(Ca~(2+),Mg~(2+)) and hydrolyzing metal(Al~(3+),Fe~(3+)) ions were able to increase the efficiency of adsorption.In view of coagulant aids,the hardness metal ions would be a better choice at the concentration higher than 10~(-2)(mol/L).Addition of 10~(2)(mol/L) Ca~(2+) and Mg~(2+) to the solution resulted in the concentrations of humid acid of(0.64±0.17)(mg/L) and(2.32±0.40)(mg/L),respectively,in 48 h with corresponding removal efficiencies of 98.4% and 94.2%.Upon increasing the concentrations of Ca~(2+) and Mg~(2+) in the solution to 10~(-1)(mol/L),the removal efficiencies were close to 100% after 48 h. Moreover,the effect of Ca~(2+) was superior to that of Mg~(2+).Decrease in thickness of the electric double layer due to repulsion forces,cationic bridge,destabilization and precipitation might be the major mechanisms to promote the removal of humic acid in solution.On the other hand,the addition of metal irons might have resulted in physical changes in sorption site on the activated sludge,even inactivation,and might have caused negative effects on humid acid adsorption.

[Fenton technique for oxidation treatment of solid-waste containing aniline].

Abstract: The catalytic oxidation of aniline was evaluated to provide the foundation for risk-based treatment of aniline-contaminated solid-waste using Fenton reagent (catalyzed hydrogen peroxide). The operating conditions of Fenton reaction were investigated and the factors of the chemical treatment were analyzed. The optimal conditions were following: 1.1 mL H2O2 per gram of dried solid waste, V (H2O2) 0.5-1.0 mL x min(-1), addition of Fenton reagent twice or three times at pH = 3.0 in 50 grams of waste, and the aniline removal rate is over 99.86% for 30 min reaction after reagent addition. Furthermore, mechanisms of affecting factors in solid-waste were analyzed; the key and controlling steps of reactions were expounded in the system, which provided safeguard for further treatment ranging from stabilization and solidification to landfill.