Kim Moonil, Ahn Young-Ho, Speece R E
Department of Civil & Environmental Engineering, Vanderbilt University, Nashville, TN 37235, USA.
Water Res. 2002 Oct;36(17):4369-85. doi: 10.1016/s0043-1354(02)00147-1.
The comparative process stability and efficiency of mesophilic (35 degrees C) and thermophilic anaerobic digestion (55 degrees C) has been evaluated for four different reactor configurations, which are: daily batch-fed single-stage continuously stirred tank reactor (CSTR), continuously fed single-stage CSTR, daily batch-fed two-phase CSTR, and daily batch-fed non-mixed single-stage reactor. The results are discussed for three periods: (1) start-up, (2) steady state, and (3) organic loading rate (OLR) increase until reactor failure (pH below 5.5). During the start-up, the single-stage CSTRs at both temperatures showed the least stability, while the non-mixed single-stage reactors reached steady state in the shortest time with relatively stable pH and low volatile fatty acid (VFA). In the case of the thermophilic non-mixed reactor, efficient removal of propionate occurred but supplementation of nutrients (Ca, Fe, Ni, and Co) was required when VFA increased. The results imply the importance of inorganic nutrients bioavailability. The comparative results of the reactor performance at steady state clearly showed the superior performance of the thermophilic non-mixed reactor with respect to lower VFA, higher gas production and volatile solids removal implying that microbial consortia proximity can alleviate the problem of poor effluent quality in thermophilic system. During the OLR increase until reactor failure, all thermophilic reactors except the thermophilic non-mixed reactor showed increases in propionate concentrations as the OLR increased, while all mesophilic reactors except the mesophilic two-phase system showed little increase in VFA concentrations. When all reactors had the same conditions with OLR increase, the continuously fed reactors showed the lowest gas production, while the non-mixed reactors showed the highest gas production at both temperatures. It is hypothesized that the non-mixing reactor configuration has closer microbial consortia proximity than others. Therefore, the results in this study indicated the importance of microbial consortia proximity. A proposed model for the effect of the distance between two syntrophic bacteria reasonably matched the data in this study.
针对四种不同的反应器配置，评估了中温（35摄氏度）和高温厌氧消化（55摄氏度）的比较过程稳定性和效率，这四种配置分别为：每日分批进料单级连续搅拌槽式反应器（CSTR）、连续进料单级CSTR、每日分批进料两相CSTR和每日分批进料非混合单级反应器。针对三个阶段讨论了结果：（1）启动阶段，（2）稳定状态阶段，以及（3）有机负荷率（OLR）增加直至反应器失效（pH值低于5.5）。在启动阶段，两种温度下的单级CSTR稳定性最差，而非混合单级反应器在最短时间内达到稳定状态，pH值相对稳定，挥发性脂肪酸（VFA）含量较低。对于高温非混合反应器，丙酸得到了有效去除，但当VFA增加时需要补充营养物质（钙、铁、镍和钴）。结果表明了无机营养物质生物可利用性的重要性。稳定状态下反应器性能的比较结果清楚地表明，高温非混合反应器在较低的VFA、较高的产气量和挥发性固体去除方面具有卓越性能，这意味着微生物群落的紧密程度可以缓解高温系统中出水水质差的问题。在OLR增加直至反应器失效的过程中，除高温非混合反应器外，所有高温反应器的丙酸浓度均随OLR增加而升高，而除中温两相系统外，所有中温反应器的VFA浓度几乎没有增加。当所有反应器在相同条件下增加OLR时，连续进料反应器的产气量最低，而非混合反应器在两种温度下的产气量最高。据推测，非混合反应器配置的微生物群落比其他配置更紧密。因此，本研究结果表明了微生物群落紧密程度的重要性。一个关于两种互营细菌之间距离影响的模型合理地匹配了本研究中的数据。
