Sipkema E M, de Koning W, Van Hylckama Vlieg J E, Ganzeveld K J, Janssen D B, Beenackers A A
Department of Chemical Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Biotechnol Bioeng. 1999 Apr 5;63(1):56-68. doi: 10.1002/(sici)1097-0290(19990405)63:1<56::aid-bit6>3.0.co;2-f.
The breakdown of dissolved TCE in a two-step bioremediation system is described. In the first reactor, the organism Methylosinus trichosporium OB3b is grown; in the second reactor, consisting of three 17-L column reactors in series, the cells degrade TCE. A special design allowed both for the addition of air (uG,s = 0.01-0. 04 mm s-1) in the conversion reactor to prevent oxygen limitation while minimizing stripping of TCE, and for the use of methane as exogenous electron donor. In two-step systems presented thus far, only formate was used (excess, 20 mM). We found formate additions could be reduced by 75% (15 degrees C), whereas small amounts of methane (0.02-0.04 mol CH4/g cells) could replace formate and led to equally optimal results. Example calculations show that up to 90% reduction in operating cost of chemicals can be obtained by using methane instead of formate. A model was developed to describe each of the conditions studied: excess formate and optimal methane addition, suboptimal formate addition and suboptimal methane addition. Using parameters obtained from independent batch experiments, the model gives a very good description of the overall TCE conversion in the two-step system. The system presented is flexible (oxygen/methane addition) and can easily be scaled up for field application. The model provides a tool for the design of an effective and low-cost treatment system based on methane addition in the conversion reactor.
描述了在两步生物修复系统中溶解三氯乙烯（TCE）的分解情况。在第一个反应器中培养甲基弯曲菌OB3b；在第二个反应器中，由三个串联的17升柱式反应器组成，细胞降解TCE。一种特殊设计既允许在转化反应器中添加空气（uG,s = 0.01 - 0.04 mm s-1）以防止氧气限制，同时使TCE的汽提最小化，又允许使用甲烷作为外源电子供体。在迄今为止提出的两步系统中，仅使用了甲酸盐（过量，20 mM）。我们发现甲酸盐添加量可减少75%（15摄氏度），而少量甲烷（0.02 - 0.04 mol CH4/g细胞）可替代甲酸盐并产生同样最佳的结果。示例计算表明，使用甲烷而非甲酸盐可使化学品运营成本降低多达90%。开发了一个模型来描述所研究的每种条件：过量甲酸盐和最佳甲烷添加、次优甲酸盐添加和次优甲烷添加。使用从独立批次实验获得的参数，该模型对两步系统中的总体TCE转化给出了很好的描述。所展示的系统具有灵活性（添加氧气/甲烷），并且可以很容易地扩大规模用于现场应用。该模型为基于在转化反应器中添加甲烷设计有效且低成本的处理系统提供了一种工具。
