The Science of Composting

FROM THE PREFACE The main objective of composting is to transform organic materials into a stable usable product. Often organic materials which may have limited beneficial use in their raw state or have regulatory disposal constraints can be transformed by composting into marketable products. The limits on beneficial reuse may be regulations or they may be due to the potential for materials to be putrescible or pathogenic. Composting can be a solution for each of these. The implementation of composting on a large scale (in contrast to home or backyard composting) involves materials handling. Technological implementation of composting must be consistent with the biological demand of the system. If the biological system is violated, conditions will not be optimized for composting, and problems such as odor generation, insufficient aeration or moisture, or a combination of these conditions may result. Past problems and closure of facilities have been largely due to violations of the biological systems. Product quality with respect to particle size, inclusions, moisture content and other physical aspects are a function of engineering design. A well designed system must have the biological and engineering principles in harmony at all times.

Table of Contents:
Preface Composting: A Prospective Composting and Recycling History Philosophical Aspects and the Future of Composting in the United States Advantages and Disadvantages of Composting Conclusion References Basic Concepts Introduction Oxygen and Aeration Moisture Temperature Nutrients: Carbon, Nitrogen, pH Summary References Microbiology Introduction Microbial Populations Temperature Moisture Nutrients Inoculants Summary References Biochemistry Introduction Organic Matter Biochemical Manifestations Occurring during Composting Biochemical Manifestations Occurring When Compost Is Applied to Soil Humus Formation Summary References Stability, Maturity, and Phytotoxicity Introduction Stability and Maturity: Chemical Methods Carbon/Nitrogen Ratio (C/N) Nitrogen Species pH Cation Exchange Capacity (CEC) Organic Chemical Constituents Humification Parameters Humification Index Relative Concentrations of Humic Acid to Fulvic Acid Humic Substance Functional Groups Optical Density Physical Methods Temperature and Heat Output Color, Odor, Structure and Specific Gravity Plant Assays Microbiological Tests and Activities Respiration-Carbon Dioxide Evolution Respiration-Oxygen Uptake Microbial Changes Enzyme Activity Phytotoxicity Summary References Trace Elements, Heavy Metals, and Micronutrients Introduction Essentiality and Toxicity Arsenic (As) Boron (B) Cadmium (Cd) Copper (Cu) Lead (Pb) Mercury (Hg) Molybdenum (Mo) Nickel (Ni) Selenium (Se) Zinc (Zn) Occurrence in the Environment Environmental Consequences Leachate Characteristics of Compost Soil-Plant Interactions Type of Trace Element and Chemical State Soil Acidity Organic Matter Cation Exchange Capacity (CEC) Reversion to Unavailable Forms Other Aspects Effect of Compost on Trace Element Uptake Summary References Organic Compounds Introduction Organic Compounds in Various Compost Materials and Feedstocks Fate of Organic Compounds during Composting Reactions and Movement of Toxic Organics in Soil Uptake by Plants and Potential Entry into the Food Chain Conclusion References Pathogens Introduction Primary Pathogens in Wastes and Compost Worker Health Risks of Solid Waste Composting The Effect of Composting on Pathogen Destruction Survival of Pathogens in Soils and on Plants Conclusions References Bioaerosols Introduction Aspergillus Fumigatus Morphology Pathogenicity Occurrence in the Environment Occurrence in and Around Composting Facilities Dickerson, Maryland Site II, Maryland Westbrook, Maine Windsor, Ontario Hampton Roads, Virginia Beltsville, Maryland Camden, New Jersey Yard Waste Composting Facilities MSW Composting Facility Other Studies Endotoxin and Organic Dusts Conclusions References Odors and Volatile Organic Compounds Introduction Odorous Compounds and Odors Emitted by Composting Facilities Volatile Organic Compounds Air Dispersion Modeling for Composting Facilities Regulatory Models Model Parameters Gassian Dispersion and Dispersion Parameters Treatment of Terrain Reliability of Model Results Peak-to-Mean Conversion for Assessing Odor Impacts Examples of Dispersion Modeling for Composting Facilities Conclusion References Soil Physical and Chemical Manifestations Introduction Effect of Compost Application on Soil Physical Properties Soil Structure Bulk Density Soil Strength Water Relations-Soil Water Retention and Available Water to Plants Runoff and Soil Erosion Soil Temperature Effect of Compost Application on Soil Chemical Properties Cation Exchange Capacity Soil pH Electrical Conductivity (EC) Nitrogen Availability in Soil Nitrogen Leaching Summary References Utilization of Compost Introduction Horticulture Ornamental Flowering and House Plants Sod Production and Turf Grass Establishment Agricultural Crops Field Crops Vegetable Crops Silviculture Conclusion References Compost Utilization II Introduction Plant Pathogen Destruction during Composting Plant Disease Suppression Biofiltration Basic Concepts Moisture Content pH Nutrients Temperature Microbiology Application Summary References Regulations Introduction Concepts and Approaches to Regulations United States Federal Regulations State Regulations in the United States New York Tennessee Composting Facility General Requirements Facility Design and Construction Compost Standards California Canada Europe Austria Denmark Germany Italy Netherlands Criteria for Compost Quality and Facility Design: Compost Quality Criteria Facility Design Criteria Conclusion References Index

About the Author :
Epstein, Eliot