1st Edition
Waste Sites as Biological Reactors Characterization and Modeling
Where and how wastes disappear, and how the environment is affected by the process, are issues that affect cities and towns around the world. Recent investigations have convincingly shown that waste poses water, air, and public health dangers that necessitate highly efficient engineered controls. An inexpensive, effective, method for assessing impacts and risks of a system and devising management plans is to develop mathematical and quantitative models that are sufficiently representative to allow examination of physical systems as units subject to environmental factors.
Providing detailed coverage of the biological, chemical, and physical characteristics of solid waste sites, Waste Sites as Biological Reactors: Characterization and Modeling describes the parameters required to understand, model, and assess the capacity of a waste disposal site as an open biodegradation system. The authors present original analyses of waste and reactor kinetics, decomposition, temperature, and moisture effects, and heat properties. They discuss landfill gas and leachate chemicals generation with detailed composition and property data. Tables and figures provide easy access to the information, and the authors explore various site management options.
The simplicity, ugliness, and beauty of a waste disposal site confronts us with a microcosm of nature at its most basic, yet functioning in its most elegant form. Where and how wastes disappear and how the environment is affected are issues of concern to cities and towns around the world. Waste Sites as Biological Reactors: Characterization and Modeling deconstructs the mystery of the waste site in such a way that it can be modeled using familiar tools and the information obtained can then be applied to site remediation.
The Nature and Control of Waste Disposal Sites
The Bioreactor Concept
Reactor Configurations of Relevance to Practical Description of a Waste Site
The Waste Site as a Biological Reactor
PHYSICAL CHARACTERISTICS OF WASTE SITES
Waste Site Bioreactor Concepts
Porosity of a Waste Site
Density and Other Properties of Mixed Soil and Waste Materials
Applicability of Conductivity and Permeability Relations for Packed Beds
Permeability k of a Mixed Porous Media
Permeability (k) Correction for Packed Bed Flow
Correction of Packed Column Pressure Drop for Wall Effects
Corrections for Pressure Drop Relations for Fluid Flow through a Waste Site
Waste Site Particle Properties: Size and Shape
References
CHARACTERIZATION OF DISPOSED WASTES: PHYSICAL AND CHEMICAL PROPERTIES, AND BIODEGRADATION FACTORS
Determination of Physical and Chemical Characteristics of Wastes
MSW Composition vs. Landfill Layer Depth or Age: Data for Initialization
Individual Wastes and Characteristics
Characteristics of Paper Wastes
Characteristics of Food Wastes
Characteristics of Yard Wastes
Characteristics of Plastics Wastes
Plastics Deterioration in Landfills
Landfill Leachate and Landfill Gas Characteristics
WASTE SITE ECOLOGY
Influence of the Waste Site Environment on Types of Organisms Present
Species Competition for Food at a Waste Site
The Range of Organisms at Waste Sites
Organisms Found in Compost Piles
Trophic Relations and Environmental Factors Determining Organisms at Waste Sites
Influence of Site Environmental factors on Organism Types
The Waste Site as an Environment for Organisms
Definition of Impact of Organisms at Disposed Waste Site
Organisms Reported at Landfills, Dumps, and Other Waste Sites: Considerations
Waste Site Scavengers
Waste Removal Impact of Animals at Disposal Sites
Waste Removal by Insects and Soil Mesofauna
References
MOISTURE AND HEAT FLOWS
Moisture as a Control of Processes in the Waste Site
Water Film Thickness on Solid Materials under Sorption Regime
Method 1 for Liquid Film Thickness Determination
Method 2 for Moisture Film Thickness
Water Potential vs. Water Activity of Soils and Solid Porous Materials
The Issue of Mixed Water Saturation or Varied Water Potential in Wastes
Maximum Moisture Sorption by a Material
Effect of Waste Moisture Content on Soil Organisms
Water Availability to Organisms
Hydraulic Conductivity
Capillary Effects in Waste Sites
Waste Site Moisture Retention Characteristics
Full Range Moisture Capillarity
Middle Moisture Content Range
Moist to Saturation of Wet Moisture Content Section of Curve
Moisture Retention Curve in the Dry Range for Landfilled Waste
Boundary Conditions
Estimation of Constants Full-Range (Wet to Dry)
Reliability of Estimated Values
Relevance of the Lower Curve Junction to Bioreactor Simulation
Development of Moisture Capillarity-Hydraulic
Summary of Extended Range Conductivity Relationships
Moisture Inflow and Moisture Balance
Locations Used for Landfill Cover Moisture Impact Simulations
Microorganism Rate vs. Water Content and Water Activity
Limitations of Applying Water Potential Concepts
Discussion
References
HEAT GENERATION AND TRANSPORT
Introduction
The Heat Model
Definition of Waste Site System Heat Capacity
Heat Content of System: Landfill Gas or Air as Saturating Fluid
The Volumetric Heat Generation Term q'''
Heat Impact of Moisture Uptake and Flows
Evaporation Enhancement Due to Thermal Gradient in Pore Structure
Temperature vs. Water Vapor Diffusion, Latent Heat and Density Variation
Definitions of Waste Site System Tortuosity
Energy Balance at Atmospheric Boundary of Bioractor
Effect of Surface Albedo
Incoming Longwave Radiation
Outgoing Longwave Radiation
Latent Heat Flow of a Bioreactor System
Temperature Variation with Depth
Sensible Heat Flow from the Bioreactor System
Development of the Heat Generation Model
Solution to the Heat Equation
Temperature at the Waste Site Surface
Variables of the Heat Generation Model
Landfill Thermal Conductivity Km
Thermal Conductivity and Diffusivity Values
Estimating the Mean Thermal Conductivity of Mixed Waste Materials
References
THE KINETICS OF DECOMPOSITION OF WASTES
Introduction
Anaerobic and Aerobic Decomposition Patterns
Anaerobic Decomposition
The Kinetics of Aerobic Decomposition at a Waste Site
Aerobic Hydrolysis Product Generation, Incorporation and Use
Diffusivity Coefficients for Liquid and Gas Solutes
A Stoichiometric Approach to Decomposition
Values of Decompositiom Kinetic Constants
References
DECOMPOSITION ISSUES
Introduction
Information from Previous Waste Site Studies
Landfill Soils Sampling Studies
Landfill Soil Microorganism Studies
Mass Transfer Considerations
Application of Transport Model to Gas Flux
Gas-Liquid Transfers
Mass Flux
Removal of Chemical in Liquid Film
Application of Transport Model to Gas Chemicals Flux
Mass Transfer Rate at Interface
Biodegradation Rates for Landfill Organic Chemicals
Partitioning Between Gas and Liquid
Waste Site Settlement
References
SENSITIVITY ANALYSIS AND CONCLUSIONS
Introduction
Information in Database for MSW Fractions as Substrate
Range of Anaerobic and Hydrolysis Rates
Chemical Characterization of Waste Fractions
Moisture Sorption Factors for Municipal Waste Materials
Moisture Response of Materials to the Environment
Testing Approach
Other Properties Estimated for the Database
Constants for Aerobic and Anaerobic Decomposition
Soil Moisture Content
Moisture Inflow Effect of Cover
Temperature as a Decomposition Factor
Biofiltration Effect
Settlement Effect
Discussion
Moisture Input
Conclusions
Appendix 1: Waste-Properties
Appendix 2: Landfill Gas Properties
Biography
Percival A. Miller, Nicholas L. Clesceri
