[Effect of ethanol on sulfate reduction and methanogenesis].
Base on the different niche characteristics of sulfate-reducing bacteria (SRB), acidogenic bacteria (AB) and methane-producing bacteria (MPB), this experiment used two-stage anaerobic treatment and circular gas stripping. Sucrose and ethanol were used as organic substrate (COD = 6 000 mg x L(-1). The effect of ethanol concentration on sulfate reduction, COD removal and methanogenesis, the effect of sulfide stripping and the best recycle ratio were investigated respectively at different COD/SO4(2-) ratios. The results indicate that the addition of ethanol promotes SO4(2-) reduction, reduces inhibition of competition resulted from COD/SO4(2-) decreasing, and makes SRB, AB and MPB in good synergetic metabolism. The efficiency of the system was improved obviously after ethanol/SO4(2-) ratio enhanced from 0 to 2. When the ratios of COD/SO4(2-) were 12, 6 and 4, SO4(2-) reduction efficiencies increased from 7.7%, 8.1%, 14.1% to 84.7%, 87.6%, 82.5%, COD removal efficiencies increased from 83.3%, 76.5%, 69.6% to 92.8%, 93.5%, 89.7%, and CH4/COD increased from 225.7, 204.6, 178.6 mL x g(-1) to 278.5, 253.7, 236.1 mL x g(-1), respectively. Dilution at a recycle ratio of 10 and stripping 30%-55% sulfide controlled sulfide concentrations less than 27.8, 38.4, 52.4 mg x L(-1), which inhibited effectively the toxicity of H2S. But higher recycle ratio (r = 20) made substrate gradient too little and SO4(2-) reduction efficiency reduced, while lower recycle ratio (r = 5) made sludge bed shrunken and COD removal efficiency reduced.
Engineering Center of Water Treatment and Environment Remediation, Ministry of Education, National Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093, China. qw_127@163.com
Qi
Q
Wang
Bo
B
Liu
Dong-Dong
DD
Yan
Song
S
Li
Ze-Zhi
ZZ
Chen
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D000431:Ethanol / Q000494:pharmacology*; D008697:Methane / Q000378:metabolism*; D017014:Methanobacterium / Q000378:metabolism; D010084:Oxidation-Reduction; D013431:Sulfates / Q000737:chemistry*; D016999:Sulfur-Reducing Bacteria / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods*
D013431:Sulfates; D000431:Ethanol; D008697:Methane