Pind Peter F, Angelidaki Irini, Ahring Birgitte K
BioCentrum-DTU, Technical University of Denmark, Building 227, DK-2800 Lyngby, Denmark.
Biotechnol Bioeng. 2003 Jun 30;82(7):791-801. doi: 10.1002/bit.10628.
A complex and fast dynamic response of the anaerobic biogas system was observed when the system was subjected to pulses of volatile fatty acids (VFAs). It was shown that a pulse of specific VFAs into a well-functioning continuous stirred tank reactor (CSTR) system operating on cow manure affected both CH(4) yield, pH, and gas production and that a unique reaction pattern was seen for the higher VFAs as a result of these pulses. In this study, two thermophilic laboratory reactors were equipped with a novel VFA-sensor for monitoring specific VFAs online. Pulses of VFAs were shown to have a positive effect on process yield and the levels of all VFA were shown to stabilize at a lower level after the biomass had been subjected to several pulses. The response to pulses of propionate or acetate was different from the response to butyrate, iso-butyrate, valerate, or iso-valerate. High concentrations of propionate affected the degradation of all VFAs, while a pulse of acetate affected primarily the degradation of iso-valerate or 2-methylbutyrate. Pulses of n-butyrate, iso-butyrate, and iso-valerate yielded only acetate, while degradation of n-valerate gave both propionate and acetate. Product sensitivity or inhibition was shown for the degradation of all VFAs tested. Based on the results, it was concluded that measurements of all specific VFAs are important for control purposes and increase and decrease in a specific VFA should always be evaluated in close relationship to the conversion of other VFAs and the history of the reactor process. It should be pointed out that the observed dynamics of VFA responses were based on hourly measurements, meaning that the response duration was much lower than the hydraulic retention time, which exceeds several days in anaerobic CSTR systems.
当厌氧沼气系统受到挥发性脂肪酸（VFA）脉冲影响时，观察到该系统呈现出复杂且快速的动态响应。研究表明，向运行良好的以牛粪为原料的连续搅拌槽式反应器（CSTR）系统中注入特定VFA脉冲，会影响甲烷产量、pH值和气体产量，并且由于这些脉冲，较高的VFA呈现出独特的反应模式。在本研究中，两个嗜热实验室反应器配备了新型VFA传感器，用于在线监测特定VFA。结果表明，VFA脉冲对工艺产量有积极影响，并且在生物质经历多次脉冲后，所有VFA的水平均稳定在较低水平。丙酸或乙酸脉冲的响应与丁酸、异丁酸、戊酸或异戊酸脉冲的响应不同。高浓度丙酸会影响所有VFA的降解，而乙酸脉冲主要影响异戊酸或2-甲基丁酸的降解。正丁酸、异丁酸和异戊酸脉冲仅产生乙酸，而正戊酸降解则产生丙酸和乙酸。对所有测试的VFA降解均表现出产物敏感性或抑制作用。基于这些结果，得出结论：对所有特定VFA进行测量对于控制目的很重要，特定VFA的增加和减少应始终结合其他VFA的转化以及反应器工艺历史进行评估。需要指出的是，观察到的VFA响应动态是基于每小时的测量，这意味着响应持续时间远低于水力停留时间，而在厌氧CSTR系统中水力停留时间超过数天。
