稀土元素(La3+)对厨余垃圾暗发酵产氢性能影响研究

通过在厨余垃圾暗发酵产氢过程中添加不同质量浓度的稀土元素La3+,考察稀土元素对产氢性能的影响。结果表明,添加一定质量浓度的La3+能促进厨余垃圾产氢效率,而高质量浓度则有抑制效应。添加La3+质量浓度为0.5 mg/L时效果最佳,产氢量和总有机酸量达到最大,分别为43.11 mL/gVS和11 871.7 mg/L,分别是对照组的1.45倍和1.24倍。添加一定量的稀土元素也能同时促进产氢污泥的胞外多聚物的生成。

Effects of rare earth element (La3+ ) on the anaerobic fermentation of kitchen wastes through hydrogen generation

This paper is aimed to present its experimental results of effects of rare earth element(La3+) on the anaerobic fermentation of kitchen waste through hydrogen generation.For this purpose,different concentrations of La3+(0,0.05 mg/L,0.1 mg/L,0.5 mg/L,1.0 mg/L and 5.0 mg/L) were added to the fermentation group in the process of hydrogen generation from the kitchen waste.The results of our experiments indicate that it was possible for the hydrogen yield to get improved by adding certain La3+ ingredients.We have also found that the hydrogen accumulation at first increased with addition concentration,and then would decrease about 0.5 mg/L.In contrast to the control group, the group added with 0.5 mg/L show the better behavior,with the total hydrogen yield reaching 43.11 mL/gVS,that is,1.45 times against the control group.However,when the added concentration was 5.0 mg/L,the hydrogen yield tended to be only 20.60 mL/gVS.The order of the kinetic parameters of Rim turned to be 31.37(0.5 mg/L group)>29.08(0.1 mg/L group)>27.30(control)> 25.36(0.05 mg/L group)>19.50(1.0 mg/L group)>14.67(5.0 mg/L group).Analyzing the metabolites during hydrogen generation,we have found that the metabolites in all the bottles was likely to increase greatly in 5-20 h.However,it was also likely to remain stable during a period of 20-30 h,accordingly.But when the hydrogen increased during the period of 5-20 h,little variation could be observed in the period of 20-30 h.This can probably suggest that the hydrogen was generated along with the occurrence of metabolites.In such a situation,the maximal metabolites can be reached when the reaction reached 11 871.7 mg/L at the presence of La3+ 0.5 mg/L,1.24 times as that of the control group.Besides,the butyric acid and acetic acid proved to remain the chief components in the total metabolites after hydrogen fermentation in all the bottles,which indicated that there had occurred a butyrate-type hydrogen process in the experiment.Further studies have shown that the concentration of the extracellular polymeric substances(EPS) may firstly get improved with the addition of the concentration of La3+,but later dropped from 0.5 mg/L in 10th h.The maximal concentration of the EPS would reach 71.87 mg/gVS,and in turn promoted it to get improved by 3.66 times in comparison with the control group.Thus it can be concluded that adding 0.5 mg/L La3+ tends to be one of the approaches to enhancing the hydrogen accumulation from kitchen wastes by anaerobic fermentation.