生物制氢反应系统的启动负荷与乙醇型发酵

START-UP OF HYDROGEN BIO-PRODUCTION REACTOR AND ETHANOL-TYPE FERMENTATION

采用连续流搅拌槽式反应器(CSTR),以糖蜜废水为底物,研究了COD容积负荷对生物制氢反应系统启动过程中形成的乙醇型发酵产氢能力的影响。研究表明,在污泥接种量不小于6.24 gVSS/L、启动负荷为7.0 kgCOD/m3.d、水力停留时间(HRT)为6 h、系统pH、氧化还原电位(ORP)分别在4.0~4.3、-440^-470mV之间等条件下,可在30 d内完成乙醇型发酵菌群的驯化,实现生物制氢反应系统的快速启动。由不同启动负荷(3.0、7.0、10.0 kgCOD/m3.d)条件下形成的乙醇型发酵菌群,在相同的运行条件下其产氢能力存在着差异。当系统容积负荷为30 kgCOD/m3.d时,由启动负荷为7.0 kgCOD/m3.d条件下驯化形成的乙醇型发酵菌群比由启动负荷为3.0 kgCOD/m3.d条件下驯化形成的乙醇型发酵菌群产氢能力高56%。

To find out the law of rapid start-up the natural response of an continuous stirred-tank reactor (CSTR) for hydrogen bio-production using molasses wastewater as substrate was investigated. Emphasis was placed on assessing organic loading rate (OLR) on the ethanol-type fermentation during the system's start-up process. It was found that at an initial biomass of 6.24 gVSS/L and an OLR of 7.0 kgCOD/m3 d, an equilibrial microbial community in the ethanol-type fermentation could be established within 30 days while the hydraulic retention time (HRT) was controlled at 6 h, pH and ORP were kept within the ranges of 4.0-4.3 and-440 - -470 mV, respectively. Following that, hydrogen production rates in the reactors were relatively stable and the rapid start-up of hydrogen bio-production reactor was finished. When the initial OLR were set at different levels (3.0, 7.0 and 10.0 kgCOD/ m3 d), the rates of hydrogen production after 30 days of start-up were quite different. Specifically, when OLR was achieved at 30 kgCOD/m3 d, the hydrogen production rate of ethanol-type fermentative bacteria initially acclimated with 7.0 kgCOD/m3 d loading was 56% higher than that acclimated with 3.0 kgCOD/m3 d.