Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628BC Delft, The Netherlands.
Appl Microbiol Biotechnol. 2013 Mar;97(6):2743-52. doi: 10.1007/s00253-012-4590-2. Epub 2012 Nov 28.
Silicate minerals can be a source of calcium and alkalinity, enabling CO2 sequestration in the form of carbonates. For this to occur, the mineral needs to be first dissolved in an acidifying process such as the biological process of anaerobic fermentation. In the present study, the main factors which govern the dissolution process of an alkaline silicate mineral (wollastonite, CaSiO3) in an anaerobic fermentation process were determined. Wollastonite dissolution kinetics was measured in a series of chemical batch experiments in order to be able to estimate the required amount of alkaline silicate that can neutralize the acidifying fermentation process. An anaerobic fermentation of glucose with wollastonite as the neutralizing agent was consequently performed in a fed-batch reactor. Results of this experiment were compared with an abiotic (control) fed-batch reactor in which the fermentation products (i.e. organic acids and alcohols) were externally supplied to the system at comparable rates and proportions, in order to provide chemical conditions similar to those during the biotic (fermentation) experiment. This procedure enabled us to determine whether dissolution of wollastonite was solely enhanced by production of organic acids or whether there were other impacts that fermentative bacteria could have on the mineral dissolution rate. The established pH profiles, which were the direct indicator of the dissolution rate, were comparable in both experiments suggesting that the mineral dissolution rate was mostly influenced by the quantity of the organic acids produced.
硅酸盐矿物可以作为钙和堿度的来源，使二氧化碳以碳酸盐的形式被捕获。为此，矿物需要首先在酸化过程中溶解，例如厌氧发酵的生物过程。在本研究中，确定了控制碱性硅酸盐矿物（硅灰石，CaSiO3）在厌氧发酵过程中溶解过程的主要因素。通过一系列化学批式实验测量了硅灰石的溶解动力学，以便能够估计可以中和酸化发酵过程所需的碱性硅酸盐量。随后，在分批进料反应器中用葡萄糖进行了含有硅灰石的厌氧发酵。将该实验的结果与非生物（对照）分批进料反应器进行了比较，在该非生物反应器中，以可比的速率和比例将发酵产物（即有机酸和醇）外部供应给系统，以提供类似于生物（发酵）实验期间的化学条件。该程序使我们能够确定硅灰石的溶解是否仅通过有机酸的产生而得到增强，或者发酵细菌是否会对矿物溶解速率产生其他影响。建立的 pH 曲线，是溶解速率的直接指标，在两个实验中都具有可比性，这表明矿物溶解速率主要受到产生的有机酸的数量的影响。
