Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
Department of Applied Analytical and Physical Chemistry, Coupure Links 653, B-9000 Gent, Belgium.
Water Res. 2016 Jul 1;98:293-301. doi: 10.1016/j.watres.2016.04.035. Epub 2016 Apr 19.
Biorefinery wastewaters are often treated by means of anaerobic digestion to produce biogas. Alternatively, these wastewaters can be fermented, leading to the formation of carboxylates. Here, we investigated how lab-scale upflow anaerobic sludge blanket reactors could be shifted to fermentation by changing organic loading rate, hydraulic retention time, pH, and salinity. A strong increase in volatile fatty acid concentration up to 40 g COD L(-1) was achieved through increasing salinity above 30 mS cm(-1), as well as a decrease in methane production by more than 90%, which could not be obtained by adjusting the other parameters, thus, indicating a clear shift from methane to carboxylate production. Microbial community analysis revealed a shift in bacterial community to lower evenness and richness values, following the increased salinity and VFA concentration during the fermentation process. A selective enrichment of the hydrogenotrophic Methanomicrobiales took place upon the shift to fermentation, despite a severe decrease in methane production. Particle size distribution revealed a strong degranulation of the sludge in the reactor, related to the high salinity, which resulted in a wash-out of the biomass. This research shows that salinity is a key parameter enabling a shift from methane to carboxylate production in a stable fermentation process.
生物炼制废水通常通过厌氧消化处理以生产沼气。或者，这些废水可以发酵，导致羧酸盐的形成。在这里，我们研究了如何通过改变有机负荷率、水力停留时间、pH 值和盐度，将实验室规模的上流式厌氧污泥床反应器转变为发酵。通过将盐度提高到 30 mS cm(-1)以上，可以使挥发性脂肪酸浓度强烈增加到 40 g COD L(-1)，同时甲烷产量减少 90%以上，这是通过调节其他参数无法实现的，因此，表明甲烷到羧酸盐的生产发生了明显的转变。微生物群落分析显示，随着发酵过程中盐度和 VFA 浓度的增加，细菌群落的均匀度和丰富度值降低。尽管甲烷产量严重下降，但在向发酵转变时，氢营养型 Methanomicrobiales 发生了选择性富集。颗粒大小分布显示出污泥在反应器中的强烈崩解，这与高盐度有关，导致生物量的洗出。这项研究表明，盐度是在稳定的发酵过程中从甲烷到羧酸盐生产转变的关键参数。
