厌气反应器对基质扰乱的响应

5套 37℃的扰乱试验实施在 3台厌气完全混合反应器中。三反应器分别处理着以丙酸、丁酸和混合脂肪酸为基质的废水。扰乱由脉冲添加丙酸、丁酸或甲酸来建立。结果表示 ,扰乱立即导致了相应的酸和氢分压(pH2 )的浓度积累。但所有反应器能完全地恢复在 2 0 0h之内。混合液相中丙酸和丁酸的积累没有导致pH的重大变化。但是 ,PH2 的增加限制了丙酸和丁酸的转换 ;各自的阈值分别为 2 1× 10 - 4及 1 1× 10 - 3atm。异丁酸和二高分子羟基酸 ,valerate和caproate ,被检出存在于一些被扰乱的反应器流出水中。对于丁酸异构化pH2 的作用是非决定性的。实验数据的热力学分析表示 ,valerate和caproate的形成或归结于pH2 的增加或独立于pH2 的增加。在后者 ,形成直接地归结于混合液相中丙酸或丁酸的浓度增加。

Responses of Anaerobic Reactors to Substrate Perturbations

Five sets of perturbation experiments were conducted at 37 ℃ in three anaerobic complete-mix reactors treating wastewaters containing propionate,butyrate and mixed-fatty-acids,respectively. Perturbation was created by a pulse addition of either propionate,butyrate or formate. Results showed that the perturbation caused immediate concentration buildup of the corresponding acid and partial pressure of hydrogen (pH2). But all reactors were able to fully recover within 200 hours. The accumulation of propionate and butyrate was not severe enough to cause significant variation of pH in the mixed liquor. However,increase of pH2 suppressed conversion of propionate and butyrate; the respective threshold levels were 2.1×10-4 and 1.1×10-3atm. Isobutyrate,and two higher-molecular-weight carboxylic acids,valerate and caproate,were found in some reactor effluents after perturbation. Effect of pH2 on butyrate isomerization was inconclusive. Analysis of experimental data according to chemical thermodynamics showed that the formation of valerate and caproate could be either due to the increase pH2 or independent of pH2. In the latter case,the formation was directly due to the increase of propionate/butyrate concentrations in the mixed liquor.