Kaksonen Anna H, Franzmann Peter D, Puhakka Jaakko A
Institute of Environmental Engineering and Biotechnology, Tampere University of Technology, P.O. Box 541, FIN-33101 Tampere, Finland.
Biotechnol Bioeng. 2004 May 5;86(3):332-43. doi: 10.1002/bit.20061.
The effects of hydraulic retention time (HRT) and sulfide toxicity on ethanol and acetate utilization were studied in a sulfate-reducing fluidized-bed reactor (FBR) treating acidic metal-containing wastewater. The effects of HRT were determined with continuous flow FBR experiments. The percentage of ethanol oxidation was 99.9% even at a HRT of 6.5 h (loading of 2.6 g ethanol L(-1) d(-1)), while acetate accumulated in the FBR with HRTs below 12 h (loading of 1.4 g ethanol L(-1) d(-1)). Partial acetate utilization was accompanied by decreased concentrations of dissolved sulfide (DS) and alkalinity in the effluent, and eventually resulted in process failure when HRT was decreased to 6.1 h (loading of 2.7 g ethanol L(-1) d(-1)). Zinc and iron precipitation rates increased to over 600 mg L(-1) d(-1) and 300 mg L(-1) d(-1), respectively, with decreasing HRT. At HRT of 6.5 h, percent metal precipitation was over 99.9%, and effluent metal concentrations remained below 0.08 mg L(-1). Under these conditions, the alkalinity produced by substrate utilization increased the wastewater pH from 3 to 7.9-8.0. The percentage of electron flow from ethanol to sulfate reduction averaged 76 +/- 10% and was not affected by the HRT. The lowest HRT did not result in significant biomass washout from the FBR. The effect of sulfide toxicity on the sulfate-reducing culture was studied with batch kinetic experiments in the FBR. Noncompetitive inhibition model described well the sulfide inhibition of the sulfate-reducing culture. (DS) inhibition constants (K(i)) for ethanol and acetate oxidation were 248 mg S L(-1) and 356 mg S L(-1), respectively, and the corresponding K(i) values for H(2)S were 84 mg S L(-1) and 124 mg S L(-1). In conclusion, ethanol oxidation was more inhibited by sulfide toxicity than the acetate oxidation.
在处理含酸性金属废水的硫酸盐还原流化床反应器（FBR）中，研究了水力停留时间（HRT）和硫化物毒性对乙醇和乙酸利用的影响。通过连续流FBR实验确定了HRT的影响。即使在HRT为6.5 h（乙醇负荷为2.6 g L⁻¹ d⁻¹）时，乙醇氧化率仍为99.9%，而当HRT低于12 h（乙醇负荷为1.4 g L⁻¹ d⁻¹）时，乙酸在FBR中积累。部分乙酸的利用伴随着出水溶解硫化物（DS）浓度和碱度的降低，当HRT降至6.1 h（乙醇负荷为2.7 g L⁻¹ d⁻¹）时，最终导致工艺失败。随着HRT的降低，锌和铁的沉淀速率分别增加到超过600 mg L⁻¹ d⁻¹和300 mg L⁻¹ d⁻¹。在HRT为6.5 h时，金属沉淀率超过99.9%，出水金属浓度保持在0.08 mg L⁻¹以下。在这些条件下，底物利用产生的碱度使废水pH值从3升高到7.9 - 8.0。从乙醇到硫酸盐还原的电子流百分比平均为76±10%，且不受HRT的影响。最低的HRT并未导致FBR中有明显的生物量流失。在FBR中通过批次动力学实验研究了硫化物毒性对硫酸盐还原培养物的影响。非竞争性抑制模型很好地描述了硫化物对硫酸盐还原培养物的抑制作用。乙醇和乙酸氧化的（DS）抑制常数（K(i)）分别为248 mg S L⁻¹和356 mg S L⁻¹，H₂S的相应K(i)值为84 mg S L⁻¹和124 mg S L⁻¹。总之，硫化物毒性对乙醇氧化的抑制作用比对乙酸氧化的抑制作用更强。
