[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.
Wang
Qi
Q
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
Liu
Bo
B
Yan
Dong-Dong
DD
Li
Song
S
Chen
Ze-Zhi
ZZ
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