Biofilm density, porosity, and thickness are biofilm architecture properties that are important but often difficult to measure. In this study, wet and dry biofilm densities and biofilm porosity in shredded tire biofilters were determined using conventional methods but using a new porosity equation. Methods for determining the surface area and mean biofilm thickness covering tire chips were developed on the basis of box and ellipsoid shape models using the length, width, and thickness data for the tire chips making up the filter medium, as measured with a digital caliper, and the tire chip volume calculated from their measured weight (VMW). The methods were evaluated and compared, via linear regression analysis, with the results from accurate X-ray computed tomography scanning. Results indicate that an ellipsoid shape model, combined with a modified form of th elength-width-thickness data, derived from digital caliper measurements, and the value of VMW, is the best combined model to compute the surface area and biofilm thickness. The combined method may be applicable for biofilm thickness measurement in attached growth systems packed with other irregular shaped media.
Citation: Environmental Science & Technology
Pub Type: Journals
Biofilms, density, porosity, thickness, shape model, X-ray computed tomography, particle shape, length, width, thickness