Dynamic simulation of benzene vapor treatment by a two-phase partitioning bioscrubber. Part I: Model development, parameter estimation, and parametric sensitivity

A dynamic, mechanistic model has been developed to predict the performance of a liquid-liquid, two-phase partitioning bioscrubber (TPPB) for removal, and subsequent biodegradation, of toxic volatile organic compounds (VOCs) from industrial waste gases under various conditions of practical relevance. TPPBs, which contain an immiscible and biocompatible organic liquid phase, allow enhanced biodegradation rates to be maintained by partitioning inhibitory substrates away from microorganisms. The system being considered involves the treatment of benzene vapors by Achromobacter xylosoxidans Y234 using n-hexadecane as the organic phase. The model incorporates the following dynamic elements: volatile substrate and oxygen absorption by both liquid phases, partitioning of dissolved substrate and oxygen between liquid phases, and microbial consumption of dissolved substrate and oxygen in the aqueous phase for both growth and maintenance. Part I focuses on the development of the model equations and estimation of relevant parameters. Using parametric sensitivity analysis, the relative influences of the parameters are identified under transient and steady state conditions. Both the organic phase volume fraction and its properties are predicted to have a significant influence on performance. Biocatalysts capable of maintaining high biodegradation rates under dilute substrate concentrations are predicted to be superior for use in TPPBs.