Van Ginkel Steven W, Logan Bruce
Department of Civil and Environmental Engineering, The Pennsylvania State University, 212 Sackett Building, University Park, PA 16801, USA.
Water Res. 2005 Oct;39(16):3819-26. doi: 10.1016/j.watres.2005.07.021.
An experimental matrix consisting of reactor hydraulic retention time (HRT) and glucose loading rate was tested to understand the effect of organic loading on H2 production in chemostat reactors. In order to vary the glucose loading rate over a range of 0.5-18.9 g/h, the glucose concentration in the feed was varied from 2.5 to 10 gCOD/L under conditions where the HRT varied from 1 to 10 h (30 degrees C, pH=5.5). Decreasing the glucose loading rate over this range increased the hydrogen yield from 1.7 to 2.8 mol-H2/mol-glucose. High yields of hydrogen were consistent with a high molar acetate:butyrate ratio of 1.08:1 as more hydrogen is produced with acetate as a product (4 mol-H2/mol-acetate) than with butyrate (2 mol-H2/mol-butyrate). It was thought that the decrease in yield with organic loading rate resulted from an overall decreased rate of hydrogen production. As the rate of gas production is reduced, H2 supersaturation in the liquid phase is likely reduced, relieving inhibition due to H2. Flocculation was also an important factor in the performance of the reactor. At the 5-10 gCOD/L influent glucose concentrations, substantial flocculation was observed particularly as the feeding rate was increased due to a reduction in the HRT from 10 to 2.5 h. At the HRT of 2.5 h, biomass concentrations reached as much as 25 g/L. The flocculant nature of the biomass allowed reactor operation at low HRTs with steady H2 production and >90% glucose removal. However, when the HRT was reduced to 1 h at a glucose feed concentration of 2.5 gCOD/L, there was little flocculation evident resulting in wash-out of the culture. These results suggest that hydrogen yields will be optimized for more dilute feeds and lower organic loading rates than have typically been used in biohydrogen reactor studies.
为了了解有机负荷对恒化器反应器中氢气产生的影响，对一个由反应器水力停留时间（HRT）和葡萄糖负荷率组成的实验矩阵进行了测试。为了使葡萄糖负荷率在0.5 - 18.9 g/h范围内变化，在HRT从1到10 h（30℃，pH = 5.5）的条件下，将进料中的葡萄糖浓度从2.5 gCOD/L变化到10 gCOD/L。在此范围内降低葡萄糖负荷率，氢气产率从1.7 mol-H₂/mol-葡萄糖提高到2.8 mol-H₂/mol-葡萄糖。高氢气产率与高摩尔乙酸盐:丁酸盐比例1.08:1一致，因为以乙酸盐作为产物产生的氢气（4 mol-H₂/mol-乙酸盐）比丁酸盐（2 mol-H₂/mol-丁酸盐）更多。据认为，随着有机负荷率增加产率下降是由于氢气产生的总体速率降低。随着产气速率降低，液相中氢气的过饱和度可能降低，从而减轻了氢气的抑制作用。絮凝也是反应器性能的一个重要因素。在进水葡萄糖浓度为5 - 10 gCOD/L时，观察到大量絮凝现象，特别是当进料速率增加时，这是由于HRT从10 h降低到2.5 h所致。在HRT为2.5 h时，生物质浓度高达25 g/L。生物质的絮凝性质使得反应器能够在低HRT下运行，稳定地产生氢气并实现>90%的葡萄糖去除率。然而，当在葡萄糖进料浓度为2.5 gCOD/L时将HRT降低到1 h，几乎没有明显的絮凝现象，导致培养物被冲出。这些结果表明，与生物制氢反应器研究中通常使用的相比，对于更稀的进料和更低的有机负荷率，氢气产率将得到优化。
