Leo Mulcahy

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Daniel D. Hutto

University of Wollongong

Galen Strawson

The University of Texas at Austin

Timothy Williamson

University of Oxford

Shaun Gallagher

University of Memphis

Edmund Waldstein, O.Cist.

Phil. -Theol. Hochschule Benedikt XVI. Heiligenkreuz

Angelo Bottone

Dublin Business School

Stephen Kelly

Liverpool Hope University

Michael McClymond

Saint Louis University

Jared Isaac Goff

Ss. Cyril and Methodius Byzantine Catholic Seminary

Jonathan Ciraulo

The Catholic University of America

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Papers by Leo Mulcahy

Discussion of “Fluidized Bed for Biological Wastewater Treatment”

Journal of the Environmental Engineering Division, 1981

Fluidized Bed Biofilm Reactor (FBBR)Kinetics – A Rational Design and Optimization Approach

Water Science and Technology, 1983

A mathematical model is presented for an intrinsic zero order, completely mixed fLuidized bed bio... more A mathematical model is presented for an intrinsic zero order, completely mixed fLuidized bed biofilm reactor(FBBR). Intrabiofilm mass transfer effects are considered. A modified Thiele modulus(ϕm) is defined to relate substrate conversion rate to intrabiofilm mass transfer rate through use of an effectiveness factor(η). For ϕm− < 1.15, intrabiofilm mass transfer is insignificant and intrinsic zero order kinetics is observed. For ϕm > 1.15, the FBBR substrate conversion rate is mass transfer limited and 0.45 order kinetics is observed. It is demonstrated via the FBBR model that media size and density and biofilm thickness are the most significant design parameters affecting FBBR performance. Selection of these parameters can be optimized through use of the equations presented herein. In addition, the effect of other important design parameters such as recycle rate and superficial upflow velocity on reactor performance can be assessed using the FBBR model outlined here.

Experimental Determination of Intrinsic Kinetic Coefficients for Biological Wastewater Treatment Systems

Water Science and Technology, 1986

An experimental procedure which allows for a direct determination of intrinsic kinetic coefficien... more An experimental procedure which allows for a direct determination of intrinsic kinetic coefficients is described. The experimental apparatus(a rotating disk biofilm reactor) used offers a relatively simple, yet rigorous means for examination of factors affecting biokinetics, i.e., simultaneous mass transfer and biochemical reaction. Intrinsic kinetic coefficients of biological denitrification with methanol as the organic carbon source were determined using the proposed experimental procedure and these intrinsic kinetic coefficients were capable of providing an accurate prediction of nitrate-nitrogen profiles observed in a laboratory-scale fluidized bed biofilm reactor receiving the same feed.

Kinetic Model of Biological Denitrification in a Fluidized Bed Biofilm Reactor (FBBR)

Water Pollution Research and Development, 1981

ABSTRACT A kinetic model is proposed for biological denitrification in a fluidized bed biofilm re... more ABSTRACT A kinetic model is proposed for biological denitrification in a fluidized bed biofilm reactor (FBBR). For individual biofilm covered particles within the reactor, an analysis of intra-biofilm diffusion and simultaneous zero order reaction is used to develop an effectiveness factor expression. This individual particle case is then linked to a one dimensional reactor plug flow equation to yield an overall kinetic model describing convective transport and simultaneous biochemical conversion of nitrate within the heterogeneous reactor. A modified Thiele modulus, Φ m , is defined to relate biochemical conversion rate to intra-biofilm diffusion rate. For Φ m > 1.15, FBBR denitrification is diffusion limited and 0.45 order kinetics is observed. For Φ m ≤ 1.15, diffusion limitations are insignificant and intrinsic zero order kinetics is observed. Good agreement was obtained when the nitrate profiles observed in a laboratory scale fluidized bed biofilm reactor under different operating conditions were compared to those predicted by the kinetic model.

Fluidization and reactor biomass characteristics of the denitrification fluidized bed biofilm reactor

Water Research, 1987

Abstract The fluidization and reactor biomass characteristics of the denitrification fluidized be... more Abstract The fluidization and reactor biomass characteristics of the denitrification fluidized bed biofilm reactor (FBBR) were investigated. Experimental evidence obtained indicates that Richardson-Zaki correlation, which was developed for rigid solid particles, provides an excellent description of the fluidization mechanics of a denitrification FBBR. However, correlations for calculation of drag coefficient and expansion index should be modified to account for the FBBR characteristics that the degree of bed expansion increases with increased bioparticle size (i.e. increased biofilm thickness). The fluidization and reactor biomass correlations developed in this investigation are capable of providing a direct and accurate prediction of biomass concentration and bed expansion in FBBRs designed for wastewater treatment applications. Engineering applications of these correlations are discussed.

Mathematical model for the fluidized bed biofilm reactor

Enzyme and Microbial Technology, 1982

The fluidized bed biofilm reactor is a novel biological wastewater treatment process. The use of ... more The fluidized bed biofilm reactor is a novel biological wastewater treatment process. The use of small, fluidized particles in the reactor affords growth support surface an order of magnitude greater than conventional biofilms systems, while avoiding clogging problems which would be encountered under fixed bed operation. This allows retention of high biomass concentration within the reactor. This high biomass concentration, in turn, translates to substrate conversion efficiencies an order of magnitude greater than possible in conventional biological reactors. The primary objective of this research has been the development of a mathematical model of the fluidized bed biofilm reactor. The mathematical model has two major subdivisions. The first predicts biomass holdup and biofilm thickness within the reactor using drag vi TABLE OF CONTENTS

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