Sandrin T R, Kight W B, Maier W J, Maier R M
Department of Biology and Microbiology, The University of Wisconsin Oshkosh, Oshkosh, WI, 54901, USA.
Biodegradation. 2006 Oct;17(5):423-35. doi: 10.1007/s10532-005-9013-y. Epub 2006 Feb 14.
A series of batch reactor experiments was carried out to examine the effect of a nonaqueous phase liquid (NAPL) on the biodegradation of a hydrophobic solute. A mathematical program model that describes physical processes of solute solubilization and partitioning between the NAPL and aqueous phases as well as microbial degradation and oxygen utilization was used to analyze the test data. The model calculates the cumulative changes in concentration of substrate, cell mass, carbon dioxide, and dissolved oxygen as a function of time. The equations incorporate the effects of solute solubilization, partitioning, biodegradation, as well as oxygen availability. Hexadecane was used as the model NAPL and was not biodegraded in the timeframe of the experiments performed. The model solute was the polyaromatic hydrocarbon, phenanthrene. In agreement with several previous studies, experimental measurements showed that hexadecane increased rates of mineralization of 15 mg phenanthrene when present at low mass but decreased rates at high mass. Model results suggest that partitioning of the phenanthrene into the hexadecane phase limits bioavailability at high NAPL mass. Further the model suggests that mineralization rates were higher with the low NAPL mass because aqueous phenanthrene concentrations were higher in those treatments from ca. 20 to 40 h than in other treatments. Finally, experiments showed that the presence of hexadecane, at all masses tested, resulted in a lower cell yield, effectively increasing the amount of CO(2) produced during the experiment. Model results suggest that this is due to changes in phenanthrene metabolism that are induced by the presence of the hexadecane phase. Model studies aimed at increasing rates of biodegradation by modifying operating conditions are described along with practical approaches to implementing these modifications.
进行了一系列间歇式反应器实验，以研究非水相液体（NAPL）对疏水性溶质生物降解的影响。使用一个数学程序模型来分析测试数据，该模型描述了溶质在NAPL相和水相之间的溶解和分配以及微生物降解和氧气利用等物理过程。该模型计算底物、细胞质量、二氧化碳和溶解氧浓度随时间的累积变化。这些方程纳入了溶质溶解、分配、生物降解以及氧气可用性的影响。十六烷被用作模型NAPL，在进行的实验时间范围内未被生物降解。模型溶质是多环芳烃菲。与之前的几项研究一致，实验测量表明，当十六烷以低质量存在时，可提高15毫克菲的矿化速率，但在高质量时则降低速率。模型结果表明，在高NAPL质量下，菲向十六烷相的分配限制了生物可利用性。此外，模型表明，低NAPL质量时矿化速率更高，因为在约20至40小时的那些处理中，水相菲浓度高于其他处理。最后，实验表明，在所有测试质量下，十六烷的存在导致细胞产量降低，有效地增加了实验期间产生的CO₂量。模型结果表明，这是由于十六烷相的存在诱导了菲代谢的变化。描述了旨在通过改变操作条件提高生物降解速率的模型研究以及实施这些改变的实际方法。
