Sensivity analysis and design calculations with biofiltration models

Biofiltration is a new technology for biological treatment of volatile organic compounds present in airstreams. It is a complex process and thus, engineering models which attempt to describe it are by necessity very involved and contain a large number of parameters. In this study, two models describing biofiltration of airstreams carrying a single pollutant (VOC) were used in detailed parameter-sensitivity studies. One model concerned biofiltration under steady-state conditions, while the second described the transient behavior of the process. The intent of the sensitivity studies was to determine which model parameters need to be known with accuracy in order to allow for a good prediction of the size of a biofilter needed to achieve a Oven VOC-control objective. Studies with the steady-state biofiltration model have shown that accurate knowledge of the values of two kinetic parameters and the specific area of biofilm (and therefore the packing configuration) are essential. Studies with the transient model have revealed that in regards to transient behavior, the mass transfer coefficient is the most important design parameter. Design calculations were also performed in this study for an integrated process involving soil venting and biofiltration for cleaning a contaminated aquifer. Preliminary results (based on a number of simplifying assumptions) have shown that the proposed concept is plausible in the sense that a reasonable biofilter size is adequate for remediating a site in a relatively short period of time. It was also found that a given mass of contaminant can be treated more efficiently (shorter time, smaller biofilter volume) under constant venting rate if the volume of the aquifer is smaller (i.e., when the residence time of air in the aquifer is larger). This finding could be taken advantage of through faster remediation of a spill (before it spreads), or if seasonal variations affect the size of the aquifer