A model to quantify removal and inactivation of microorganisms occluded in effluent wastewater particles using filtration and disinfection systems

Department

Civil Engineering

Document Type

Article

Publication Title

Journal of Environmental Engineering

ISSN

0733-9372

Volume

136

Issue

10

DOI

10.1061/(ASCE)EE.1943-7870.0000235

First Page

1153

Last Page

1160

Publication Date

10-1-2010

Abstract

A model is presented to quantify microbial occlusion in effluent particles and improve understanding of the removal and inactivation of occluded microorganisms in filtration and disinfection systems. Microbial occlusion in particles is described in the model as a function of the particle size distribution, the microbial density (��1) (N1), which is the average quantity of target microorganisms within the subset of particles that contain microorganisms, and the frequency of association (��2) (N2), which is the ratio of particles that contain at least one target microorganism. To demonstrate the model, undisinfected secondary effluent samples were collected from an extended aeration treatment facility and analyzed to determine values for the model variables, ��1N1 and ��2N2 for heterotrophic bacteria and aerobic endospores and ��2N2 for total coliform bacteria. Heterotrophic bacteria were present in most effluent particles (73–100%) at high densities (7–93 per particle), whereas aerobic endospores and total coliform bacteria were only present in a small percentage of effluent particles (0.1–6%) and the density of aerobic endospores in effluent particles was not appreciably higher than one per particle.

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