In order to improve the anaerobic digestion efficiency of waste activated sludge（WAS）,a pretreatment procedure should be carried out so as to disrupt the microbial cell structure,thus releasing intracellular organic...In order to improve the anaerobic digestion efficiency of waste activated sludge（WAS）,a pretreatment procedure should be carried out so as to disrupt the microbial cell structure,thus releasing intracellular organic matters.In this paper,a corona discharge triggered by a DC voltage was employed to pre-treat WAS for various time periods under different temperatures.The magnitude of the DC voltage was 4 k V at both negative and positive polarities.The changes in the soluble chemical oxygen demand,phosphorus and nitrogen content,and p H value within the WAS were utilized to estimate the pretreatment performance of the DC corona.It was found that with increasing treatment time,the pretreatment efficiency tends to be reduced.With increased temperature,the pretreatment efficiency appears to be better.It is suggested that the oxidative species and the active particles generated in the corona discharge play an important role in disrupting the microbial cell structure,which is dependent upon the treatment time and the temperature.展开更多
The effect of nitrogen form on pH and concentration of soluble iron (Fe) in leaf apoplast was investigated in hydrophonically grown sunflower plants (Helianthus annuus L. cv. Frankasol), and the mechanism underlying t...The effect of nitrogen form on pH and concentration of soluble iron (Fe) in leaf apoplast was investigated in hydrophonically grown sunflower plants (Helianthus annuus L. cv. Frankasol), and the mechanism underlying the improved Fe nutrition by ammonium (NH4) supply was also elucidated. Ammonium supply ameliorated Fe nutrition of plants grown without Fe through decreasing apoplastic pH and increasing soluble Fe concentration in apoplastic fluid of young leaves. The soluble Fe concentration in apoplastic fluid and cell sap of young leaves, and xylem exudates of NH4 fed-plants was higher than that of nitrate (NO3) fed-plants, and no typical Fe-deficiency chlorosis in young leaves was observed in NH4 fed plant without Fe supply. The apoplastic pH was 6.15 and 5.94 in young leaves of Fe-deficient plants fed respectively with NO3 and NH4, while in Fe-sufficient plants, the apoplastic pH was 6.43 with NO3, and 5.50 with NH4 supply. In primary leaves, the apoplastic pH was around 6.25 irrespective of nitrogen form and Fe supply. The pH of xylem exudate was 5.72 in Fe-deficient plants fed with NO3 and 5.49 with NH4. Iron nutrition increased the pH of xylem exudate by 0.27 and 0.16 unit under NO3 and NH4 supply respectively.展开更多
基金financially supported by National Natural Science Foundation of China(Grant No.51677127)
文摘In order to improve the anaerobic digestion efficiency of waste activated sludge（WAS）,a pretreatment procedure should be carried out so as to disrupt the microbial cell structure,thus releasing intracellular organic matters.In this paper,a corona discharge triggered by a DC voltage was employed to pre-treat WAS for various time periods under different temperatures.The magnitude of the DC voltage was 4 k V at both negative and positive polarities.The changes in the soluble chemical oxygen demand,phosphorus and nitrogen content,and p H value within the WAS were utilized to estimate the pretreatment performance of the DC corona.It was found that with increasing treatment time,the pretreatment efficiency tends to be reduced.With increased temperature,the pretreatment efficiency appears to be better.It is suggested that the oxidative species and the active particles generated in the corona discharge play an important role in disrupting the microbial cell structure,which is dependent upon the treatment time and the temperature.
基金supported by the National Natural Science Foundation of China(Grant No.30000103)the Fund of Doctoral Station ofthe Ministry of Education of China(Grant No.20010019014).
文摘The effect of nitrogen form on pH and concentration of soluble iron (Fe) in leaf apoplast was investigated in hydrophonically grown sunflower plants (Helianthus annuus L. cv. Frankasol), and the mechanism underlying the improved Fe nutrition by ammonium (NH4) supply was also elucidated. Ammonium supply ameliorated Fe nutrition of plants grown without Fe through decreasing apoplastic pH and increasing soluble Fe concentration in apoplastic fluid of young leaves. The soluble Fe concentration in apoplastic fluid and cell sap of young leaves, and xylem exudates of NH4 fed-plants was higher than that of nitrate (NO3) fed-plants, and no typical Fe-deficiency chlorosis in young leaves was observed in NH4 fed plant without Fe supply. The apoplastic pH was 6.15 and 5.94 in young leaves of Fe-deficient plants fed respectively with NO3 and NH4, while in Fe-sufficient plants, the apoplastic pH was 6.43 with NO3, and 5.50 with NH4 supply. In primary leaves, the apoplastic pH was around 6.25 irrespective of nitrogen form and Fe supply. The pH of xylem exudate was 5.72 in Fe-deficient plants fed with NO3 and 5.49 with NH4. Iron nutrition increased the pH of xylem exudate by 0.27 and 0.16 unit under NO3 and NH4 supply respectively.
