Biofiltration for Odor and VOC Removal INTRODUCTION Conceptual

Biofiltration for Odor and VOC Removal

INTRODUCTION

Conceptual Design of a Typical Biofiltration System H 2 O BIOMASS SUPPORT MEDIA Clean gas outlet H 2 O Waste gas Inlet Blower Humidifying Chamber Pump Biofilter Drain Pump

PROCESS ENGINEERING FUNDAMENTALS

Biofiltration Mechanisms

Simplified Biophysical Model of Biofiltration GAS PHASE Reaction Controlled Zone BIOFILM Reaction Controlled Borderline Situation Diffusion Controlled Zone Diffusion Controlled Reaction Free Zone FILTER MEDIA

Biodegradability of Various Contaminants in Biofilters

Biodegradability of Various Contaminants in Biofilters (Continued)

Typical odor characteristics and odor threshold

Basic Variables involved in Biofiltration Performance

BIOFILTER DESIGN

Summary of Biofilter System Types

Illustrative Full-scale Biofilter Performance Data

Media Selection - Desirable Characteristics

Media Selection - organic vs. inorganic materials

Important Considerations in Deciding Waste Airflow in Biofilters

OPERATIONAL PARAMETERS

Acclimation

Methods to maintain optimal operational factors

Methods to maintain optimal operational factors (cont’d)

ATTACHED GROWTH versus ARTIFICIAL IMMOBILIZATION

Differences between Attached Growth Systems and Entrapment Immobilization Technology

Differences between Attached Growth and Entrapment Immobilization (Cont’d)

Main principles of immobilization processes q 1. Treatment of gases by attached growth systems - Self attachment of microorganisms to the filter bedding material q 2. Treatment of gases by systems that contain microorganisms entrapped within polymer beads -artificial immobilization of the microorganisms to or within the filter bedding material q microencapsulation - wrapping droplets containing microorganisms with a thin membrane; microorganisms can freely move within capsule, consuming substrates that penetrate through membrane q membrane separation - microorganisms are separated from the bulk fluid by the use of sheets of membrane, which allow substrates to penetrate. Usually porous UF membranes (0. 002 -0. 1 m). Selective membranes also used, e. g. those separating CO 2 and H 2 S from CH 4

Main principles of immobilization processes (cont’d) 1. microorganisms entrapment within 3 D polymer matrix - pores in matrix smaller than microbial cells, keeping them trapped within the material, but the pores allow penetration of substrates 2. covalent bonding and covalent crosslinking - creation of covalent bonds between reactive groups on the surfaces of cells and different ligands on the bedding material. Coupling agents used to activate ligands (most common is glutaraldyde; isocynate and amino silane also frequently used).

Advantages and Disadvantages of each method

Advantages and Disadvantages of each method (cont’d)

Comparison between natural polymers and synthetic polymers used for microbial entrapment (for wastewater treatment)

Future Research Needs