The mechanisms responsible for the fast granulation of anaerobic sludge caused by Mg2+ and Ca2+ addition was examined in four lab-scale expanded granular sludge bed(EGSB) reactors. Results indicated that both Mg2+ and...The mechanisms responsible for the fast granulation of anaerobic sludge caused by Mg2+ and Ca2+ addition was examined in four lab-scale expanded granular sludge bed(EGSB) reactors. Results indicated that both Mg2+ and Ca2+ accelerated the sludge-granulation process and increased the amount of polysaccharides and proteins in the sludge. Energy dispersive x-ray spectrometry(EDX) analysis revealed that, in a mature granule, both Mg2+ and Ca2+ composed as phosphate and calcium was distributed primarily in the periphery of the granule, while magnesium distributed mainly in the interior. The addition of Mg2+ was more favorable for the nuclei formation, whereas the addition of Ca2+ was more favorable for subgranule growth and maintaining the granules' rigid structure. Results showed that the addition of Mg2+ in the nuclei formation stage and Ca2+ in the granule-growth stage accelerated granulation more than adding only one of them in the granulation process.展开更多
Sulfate reducing bacteria(SRB)is identified as the primary organisms responsible for the treatment of heavy metal wastewater.However,most heavy metals can inhibit the growth of SRB during heavy metal treatment process...Sulfate reducing bacteria(SRB)is identified as the primary organisms responsible for the treatment of heavy metal wastewater.However,most heavy metals can inhibit the growth of SRB during heavy metal treatment processes.Sulfide is a metabolic product of SRB and it can precipitate or reduce heavy metals.This study focused on the effects of sulfide on SRB resistance to Cu(II),Hg(I)and Cr(VI)toxicity.First,we considered the existence style of various heavy metals with and without sulfide addition by sequential extraction experiments.Second,the particle size distribution was evaluated and the cell structure during the metabolism of a SRB culture,containing different heavy metals,was analyzed by particle size distribution and TEM analyses.Third,the evolution of sulfate under the influence of different concentrations of heavy metals with and without sulfide addition was investigated to evaluate SRB activity.The results indicated that sulfide played an important role in alleviating and even eliminating the toxicity of Cu(II),Hg(II)and Cr(VI).We also discuss the mechanism of sulfide on SRB resistance to Cu(II),Hg(I)and Cr(VI)toxicity.展开更多
基金supported by the National Natural Science Foundation of China(21307134)the National High-Tech R&D Program of China(2011AA060702 and 2011AA060904)the Open Funding Project of the National Key Laboratory of Biochemical Engineering(2012KF-07)
文摘The mechanisms responsible for the fast granulation of anaerobic sludge caused by Mg2+ and Ca2+ addition was examined in four lab-scale expanded granular sludge bed(EGSB) reactors. Results indicated that both Mg2+ and Ca2+ accelerated the sludge-granulation process and increased the amount of polysaccharides and proteins in the sludge. Energy dispersive x-ray spectrometry(EDX) analysis revealed that, in a mature granule, both Mg2+ and Ca2+ composed as phosphate and calcium was distributed primarily in the periphery of the granule, while magnesium distributed mainly in the interior. The addition of Mg2+ was more favorable for the nuclei formation, whereas the addition of Ca2+ was more favorable for subgranule growth and maintaining the granules' rigid structure. Results showed that the addition of Mg2+ in the nuclei formation stage and Ca2+ in the granule-growth stage accelerated granulation more than adding only one of them in the granulation process.
基金supported by the National Natural Science Foundation of China(20877075)the National High-Technology R&D Program of China(2006BAC02A05)the National Key Basic Research Program of China(2007CB613501)
文摘Sulfate reducing bacteria(SRB)is identified as the primary organisms responsible for the treatment of heavy metal wastewater.However,most heavy metals can inhibit the growth of SRB during heavy metal treatment processes.Sulfide is a metabolic product of SRB and it can precipitate or reduce heavy metals.This study focused on the effects of sulfide on SRB resistance to Cu(II),Hg(I)and Cr(VI)toxicity.First,we considered the existence style of various heavy metals with and without sulfide addition by sequential extraction experiments.Second,the particle size distribution was evaluated and the cell structure during the metabolism of a SRB culture,containing different heavy metals,was analyzed by particle size distribution and TEM analyses.Third,the evolution of sulfate under the influence of different concentrations of heavy metals with and without sulfide addition was investigated to evaluate SRB activity.The results indicated that sulfide played an important role in alleviating and even eliminating the toxicity of Cu(II),Hg(II)and Cr(VI).We also discuss the mechanism of sulfide on SRB resistance to Cu(II),Hg(I)and Cr(VI)toxicity.
