Biosolids Engineering

1029

Transcript of Biosolids Engineering

  • Biosolids Management Practices and Regulatory Requirements

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    Biosolids EngineeringBy Michael McFarland

    Publisher: McGraw-Hill Professional Number Of Pages: 800 Publication Date: 2000-12-20 ISBN-10 / ASIN: 0070471789 ISBN-13 / EAN: 9780070471788 Binding: Hardcover

    Book Description:

    Expert help for designing and managing a biosolids program.

    So notoriously complex and occasionally controversial that it has paradoxically reduced biosolids applications in some locales, CFR Part 503 becomes understandable, manageable, and doable with this expert guide from experienced environmental engineer Michael J. McFarland, diplomate of the American Academy of Environmental Engineers and certified Grade IV wastewater and water treatment operator.

    If you have interest in or responsibility for fulfilling the intent of Part 503, putting biosolids and organic residues to beneficial use and decreasing the burden on landfills, Biosolids Engineering can help you:

    *Control the factors in wastewater and biosolids processing that affect usability *Apply soil chemistry and physics to finding safe and appropriate uses for biosolids *Design needed hydraulic, storage, and transport systems *Ensure pathogen and vector attraction reduction *Make biosolids engineering a team effort with agricultural specialists, mining engineers, water treatment officials, and highway, transportation, and timber specialists *Apply sampling and analysis protocols for effectiveness and safety *Increase public awareness of the safety and value of biosolids applications

  • Contents

    Preface xv Acknowledgments xix

    Chapter 1. Biosol ids Management Practices and Regulatory Requirements 1.1

    1.0 Introduct ion 1.1 1.0.1 Summary Statistics tor Sewage Sludge Use and Disposal

    in the United States 1.4 1.0.2 Inst i tut ional Barriers and Liabil i ty Issues 1.6

    1.1 Regulatory Aspects to Biosol ids Management 1.7 1.1.1 R isk-Assessment Basis for the 40 CFR Part 503 Rule 1.8

    ' .2 Land Appl icat ion of Biosol ids 1.11 1.2.1 General Requirements for Lard-Appl ied Biosol ids 1.11 1.2.2 Pollutant Limits 1.13 1.2.3 Management Practices 1.20 1.2.4 Pathogen Levels in Biosol ids 1.22 1.2.5 Vector Attract ion Reduction Requirements 1.29 1.2.6 Mon i to r i rg Frequency 1.30 1.2.7 Recordkeeping 1.30 1.2.8 Report ing Requirements 1.37 1.2.9 Summary of Opt ions for Comply ing wi th Biosol ids Land-

    Appl icat ion Criteria 1.37 1.2.10 Domestic Septage 1.39 1.2.11 Liabi l i ty Issues and Enforcement Oversight 1.49

    1.3 Surface Disposal 1.50 1.3.0 Site Life and Size 1.61 1.3.1 Surface Storage of Biosol ids 1.63 1.3.2 R e g u l a t o r Requirements for Surface Disposal 1.63 1.3.3 Pollutant Limits 1.65 1.3.4 Management Practices 1.67 1.3.5 Pathogen and Vector At t ract ion Reduction Requirements 1.77 1.3.6 Frequency ol Moni tor ing 1.77 1.3.7 Recordkeeping Requirements for Surface-Disposal Sites 1.80 1.3.8 Report ing Requirements for Surface-Disposal Sites 1.81 1.3.9 Regulato'-y Requirements for Surface Disposal of

    Domestic Septage 1.81 ".4 Incineration 1.82

    1.4.1 Use of Auxi l iary Fuels 1.84 1.4.2 Biosol ids Incinerat ion Systems 1.84 1.4.3 General Incinerator Design Requirements 1.95

    vi.

  • viii Contents

    1.4.4 Requlatory Considerat ions tor Biosol ids Incineration 1.97 1.4.5 General Requirements 1.98 1.4.6 Pollutant Limits 1.98 1.4.7 Management Practices for Biosol ids Incineration 1.105 1.4.8 Monitor ing Frequency 1.107 1.4.9 Recordkeeping 1.108

    1.4.10 Report ing Requirements 1.109 1.4.11 USEPA Biosol ids Data Management System 1.109 1.4.12 Cri t ic isms of the 40 CFR Part 503 Rule 1.110

    1.5 Problems 1.111 1 6 References 1.114

    Chapter 2 Biosol ids Characteristics and Production Hates 2.1

    2.0 Introduct ion 2.1 2.1 Wastewater Quality 2.1

    2.1.1 Wastewater Solids 2.3 2.1.2 Odors 2.5 2.1.3 Organic Matter 2.5 2.1.4 Inorganic Wastewater Parameters 2.6 2.1.5 Nutrient Levels in Wastewater 2.7 2.1.6 Toxic Inorganic Compounds 2.8 2.1.7 Wastewater Pathogens 2.8

    2.2 Biosol ids Quality 2.9 2.2.1 Organic Content 2.11 2.2.2 Nutr ients 2.12 2.2.3 Metal Content 2.14 2.2.4 Pathogens in Biosol ids 2.17 2.2.5 Septage 2.19

    2.3 Biosol ids Product ion Rates 2.24 2.4 Primary Wastewater Treatment 2.27

    2.4.1 Design cf Gravity Sedimertat ion Systems 2.27 2.4.2 Primary Clarif ication Tank Design 2.51 2.4.3 Chemical Precipitation 2.58 2.4.4 Sludge Procuct ion from Primary Treatment 2.68 2.4.5 Screening 2.72

    2.5 Secondary Wastewater Treatment 2.72 2.5.1 Act ivated-Sludge Process 2.74 2.5.2 Tr ickl ing Filters 2.122 2.5.3 Rotat ing Biological Contactors 2.142 2.5.4 Combinat ion Suspended-Growth/Fixed-Fi lm Systems 2.158 2.5.5 Septage Generation and Management 2.158

    2 6 Problems 2.180 2.7 References 2.187

    Chapter 3 Biosol ids and Sludge Processing 3.1

    3.0 Introduct ion 3.1 3.1 Thickening 3.1

    3.1.1 Gravity Thickeners 3.3 3.1.2 Flotation Thickening 3.17 3.1.3 Centri fugal Thickening 3.26 3.1.4 Gravity-Belt Thickeners 3.33 3.1.5 Rotary-Drum Thickening 3.34

    3.2 Stabil ization 3.36 3.2.1 Sludge Volume Considerat ions 3.38

  • Contents ix

    3 2 2 Anaerobic Digestion 3.40 3.2.3 Aerobic Digestion 3.92 3.2.4 Autothermal Thermophi l ic Aerobic Digestion

    (ATAD) Process 3.102 3.2.5 Lime Stabil ization 3.112 3.2.6 Chlorine Oxidation 3.116 3.2.7 Vermistabil ization 3.118 3.2.8 Pasteurization 3.120 3.2.9 Sludge Irradiation 3.123

    3.2.10 Compost ing 3.128 3.3 Condi t ion ing 3.148

    3.3.1 Particle Surface Charge and Hydration 3.149 3.3.2 Particle Size 3.149 3.3.3 Compressibi l i ty 3.150 3.3.4 Sludge Temperature 3.150 3.3.5 Ratio of Volatile Solids to Fixed Sol ids (VS/FS) 3.150 3.3.6 Sludge pH 3.151 3.3.7 Chemicals Used in Sludge Condi t ioning 3.151 3.3.8 Selection of Condi t ioning Chemicals 3.163 3.3.9 Elutr iat ion 3.167

    3.3.10 Thermal Condi t ioning 3.168 3.4 Dewatering 3.171

    3.4.1 Strategy for Dewatering Process Selection 3.171 3.4.2 Dewatering Processes 3.172 3.4.3 Belt Press Filtration 3.173 3.4.4 Centr i fugat ion 3.181 3.4.5 Pressure Filtration 3.192 3.4.6 Vacuum Filtration 3.201 3.4.7 Screw Presses 3 204 3.4.8 Air-Drying Processes 3.207 3.4.9 Sand Drying Beds 3.208

    3.4.10 Paved Drying Beds 3.215 3.4.11 Vacuum-Assisted Drying Beds 3.220 3.4.12 Wedgewater Sludge Drying Beds 3.224 3.4.13 Sludge Drying Lagoons 3.227 3.4.14 Sol ids Capture dur ing Sludge Dewatering 3.227 3.4.15 Evaluating Sludge Dewatering Potential 3.228

    3.5 Heat Drying 3.230 3.5.1 General Design of Heat Dryers 3.231 3.5.2 Direct Dryers 3.232 3.5.3 Indirect Dryers 3.234 3.5.4 Infrared or Radiant-Heat Dryers 3.234 3.5.5 Humidity and Moisture Transfer 3.237

    3.6 Problems 3.248 3.7 References 3.255

    C h a p t e r 4 C o n t r o l of B i o s o l i d s Q u a l i t y 4.1

    4.0 Introduct ion 4.1 4.1 The Clean Water Act 4.1

    4.1.1 Industrial Pretreatment Discharge Standards 4.3 4 1 2 Developmert of Wastewater Discharge Limits 4.4

    4.2 Pollutant Generators of Concern 4 40 4.2.1 Industr ial Users 4.40 4.2.2 Commercial Users 4.41

  • x Contents

    4.3 Pol lut ion Prevention 4.41 4.3.1 Pol lut ion-Prevention Plans 4.44 4.3.2 Source Reduction 4.44 4.3.3 Source Reduction in the Metal Finishing Industry 4 46 4.3.4 Recycl ing 4.50 4.3.5 Product Changes 4.56 4.3.6 Pol lut ion-Prevention Resources 4.57

    4.4 Facility Inspect ions 4.59 4.4.1 Inspection Procedures 4.62

    4.5 Pretreatment Noncompl iance 4.63 4.6 Problems 4.63 4.7 References 4.67

    Chapter 5. Transport, Storage, and Facilities Design 5.1

    5.0 Introduct ion 5.1 5.1 Transportat ion of Biosol ids/Sludges 5.1 5.2 Pipeline Transport 5.3

    5.2.1 General Pipeline Design Guidance 5.15 5.2.2 Biosol ids/Sludge Pumps 5.18 5.2.3 Pumping Stations 5.35 5.2.4 Cost Estimation of Pipeline Transport Systems 5.39

    5.3 Dewatered Biosol ids/Sludge Conveyance 5.41 5.3,1 Conveyors 5.41

    5.4 Long-Distance Biosol ids/Sludge Transportat ion 5.44 5.4.1 Truck Transportat ion 5.45 5.4.2 Rail Transport 5.49 5.4.3 Barge Transportat ion 5.51

    5.5 Storage of Biosol ids/Sludge 5.52 5.5.1 Types of Storage 5.52 5.5.2 Dedicated Systems for Liquid Biosol ids/Sludge Storage 5.59

    5.6 Lagoon Systems 5.64 5.6.1 Facultative Sludge Lagoons 5.64 5.6.2 Anaerobic Liquid Sludge Lagoons 5.71 5.6.3 Sludge Drying Lagoons 5.71 5.6.4 Aerated Storage Basins 5.76

    5.7 Storage in a Drying Bed 5.77 5.7.1 Sand Drying Beds 5.78 5.7.2 Reed-Enhanced Sand Drying Beds 5.85 5.7.3 Freeze-Assisted Sa rd Drying Beds 5.88 5.7.4 Paved Sludge Drying Beds 5.96

    5.8 Storage Facilit ies for Dewatered Biosol ids/Sludge 5.102 5.8.1 Conf i red Hoppers or Bins 5.102 5.8.2 Earthen Structures for Dewatered Biosol ids/Sludge Storage 5.105 5.8 3 Unconf ined Stockpi les 5.105

    5.9 Treatment of Sidestreams f rom Biosol ids/Sludge Processing 5.106 5.9.1 Sidestream Quality 5.107

    5.10 Odor Control 5.114 5.10.1 Odors f rom Primary and Seconaary Wastewater Treatment

    Operat ions 5.115 5.10.2 Odors In Sludge Processing 5.116 5.10.3 Septage Handl ing 5.118 5.10.4 Approaches to Odor Control 5.118 5.13.5 Collect on and Treatment of Odorous Air 5.122

  • Contents xi

    5.10.6 Use of Exist ing Biological Stabil ization Processes for Odor Control 5.146

    5.10.7 Use of Odor Modif icat ion. Counteract ion, and Maskants for Odor Control 5.148

    5.11 Corrosion Control 5.149 5.11.1 Corrosion Protect ion 5.150 5.11.2 Venti lat ion and Heating 5.151

    5.12 Problems 5.151 5.13 References 5.154

    C h a p t e r 6. F u n d a m e n t a l s o f S o i l a n d Wa te r I n t e r a c t i o n s 6.1

    6.0 Introduct ion 6.1 6.1 General Definit ion of Soil 6.1 6.2 Properties of Soils 6.2 6.3 Soil Chemistry 6.4

    6.3.1 Inorganic Soil Species 6.4 6.3.2 Soil Organic Matter 6.9

    6.4 Trace Elements in Soil 6.10 6.4.1 Phytotoxici ty of Trace Elements 6.11

    6.5 Nutrient Cycles in Soil 6.12 6.5.1 Soil Nitrogen 6.13 6.5.2 Estimation of Plant-Available Nitrogen f rom Biosol ids 6.17

    6.6 Phosphorus in Soil 6.22 6.6.1 Phosphorus Control at Biosol ids Land-Appl icat ion Sites 6.23

    6.7 Soil Physics 6.27 6.7.1 Particle Size 6.28 6.7.2 Gradation 6.29 6.7.3 Soil Texture 6.29 6.7.4 Soil Structure 6.30

    6.8 Soil Water 6.31 6.8.1 Soil Moisture Content 6.31 6.8.2 Specific Yield 6.33 6.8.3 Field Capacity and Permanent Wil t ing Point 6.33 6.8.4 Available Water Capacity 6.35

    6.9 Soil Water Properties 6.37 6.9.1 Soil Moisture Potential 6.39 6.9.2 Measurement of Soil Water Potential 6.42 6.9.3 Hydraulic Conduct iv i ty 6.43 6.9.4 Measurement of Hydraulic Conduct iv i ty 6.46

    6.10 Inf i l trat ion 6.47 6.10.1 Measurement of Inf i l trat ion 6.49 6.10.2 Est imating Soil Erosion 6.51

    6.11 Drainage Systems 6.54 6.11.1 Drainage Terminology 6.55 6.11.2 Drainage Requirements at Biosol ids Land-Appl icat ion Sites 6.56 6.11.3 Drainage Invest igat ion 6.58 6.11.4 Surface Runoff Control 6.58 6.11.5 Groundwater Control 6.60 6.11.6 Salinity Management 6.62 6.11.7 Practical Considerat ions in Drainage Design 6.70 6.11.8 Drainage System Design 6.71 6.11.9 Drainage Water Quality Criteria 6.75

    6.12 Problems 6.76 6.13 References 6.B2

  • xi i Contents

    Chapter 7. Beneficial Use of Biosolids 7.1 7.0 Introduct ion 7.1 7.1 Prel iminary Planning Process 7.2

    7.1.1 Public Part ic ipat ion 7.2 7.1.2 Land Area Requirements 7.3 7.1.3 Biosol ids Transport 7.4

    7.2 Phase I Site-Screening Investigation 7.6 7.2.1 Land Use and Availabil ity 7.6 7.2.2 Aesthetics 7.6 7.2.3 Site Acquis i t ion 7.7 7.2.4 Physical Factors 7.7 7.2.5 Contact with Owners of Prospective Sites 7.10

    7.3 Phase II Site Evaluation 7.10 7.3.1 Topographic Limitat ions 7.12 7.3.2 Soil Characterist ics 7.12 7.3.3 Delineation of Flood Plains and Wetlands 7.12 7.3.4 Site Hydrogeology 7.13 7.3.5 Biosol ids Land-Appl icat ion Rates 7.13 7.3.6 Biosol ids Land-Appl icat ion Practices 7.14 7 3 " Preliminary Cost Analysis 7.15 7 3.8 Final Site Selection 7.15

    7.4 Agricultural Land Appl icat ion of Biosol ids 7.16 7.4.1 Crop Select ion, Yields, and Nutrient Requirements 7.19 7.4.2 Est imation of Residual Nutr ient Levels 7.22 7.4.3 Biosol ids Appl icat ion Rates at Agricul tural Sites 7.22 7.4.4 Agronomic Rate Based on Phosphorus 7.31 7.4.5 Biosol ids Appl icat ion Rate Based on Pollutant Limitat ions 7.33 7.4.6 Biosol ids Land-Appl icat ion Equipment 7.35 7.4.7 Land Appl icat ion of Biosol ids to Ar id Land 7.36 7.4.6 Land Appl icat ion of Biosol ids to Rangeland 7.37 7.4.9 Schedul ing of Biosol ids Land Appl icat ion 7.38

    7.4.10 Biosol ids Storage 7.38 7.4.11 Moni tor ing Requirements 7.39

    7.5 Forest Land Biosol ids Appl icat ion 7.39 7.5.1 Effect of Biosol ids Appl icat ion on Tree Growth and Wood

    Properties 7.40 7.5.2 Effect of Biosol ids on Forest Ecosystems 7.41 7.5.3 Equipment for Biosol ids Appl icat ion at Forest Sites 7.44 7.5.4 Determining Biosol ids Appl icat ion Rates for Forests 7.45 7.5.5 Biosol ids Agronomic Rate for Forests 7.48 7.5.6 Scheduling 7.53

    7.6 Biosol ids Use lor Land Reclamation 7.53 7.6.1 Biosol ids Appl icat ion Rates at Reclamation Sites 7.54 7.6.2 Site Investigation 7.56 7.6.3 Vegetation Selection and Management 7.58 7.6.4 Grading 7.60 7.6.5 Biosol ids Storage 7.60 7 6.5 Schedul ing 7.63

    7.6.7 Reclamation of Mining Land 7.63 7.6.8 Biosol ids Appl icat ion Rates 7.65 7.6.9 Monitoring 7.70

    7.6.10 Surface Runoff Storage Volume Required 7.72 7.6.11 Groundwater Leachate Col lect ion and Control 7.72

    7.7 Land Appl icat ion of Biosol ids to Publ ic-Access Sites 7.72 7.7.1 Market ing of Biosol ids 7.75

  • Contents xii i

    7.S

    7.10 7.11

    7.7.2 Marketing Cost Considerat ions 7.7.3 Developing Product Demand

    Land Appl icat ion of Domestic Septage 7.8.1 Domestic Septage Pathogen-Reduction Requirements 7.8.2 Domest c Septage Vector Attraction Reduction 7.8.3 Domest c Septage Management Practices 7.8.4 Domestic Septage Recordkeeping

    Support ing Facilit ies at Biosol ids Land-Appl icat ion Sites 7.9.1 Access Roads 7.9.2 Site Fencing and Security 7.9.3 Equipment and Personnel Bui ldings 7.9.4 Light ing and Other Util it ies

    Problems References

    7.76 7.77 7.78 7.80 7.80 7.83 7.85 7.85 7.85 7.86 7.86 7.86 7.86 7.92

    C h a p t e r 8. S a m p l i n g a n d Q u a l i t y A s s u r a n c e

    8.0 Introduct ion 8.1 General Sampling of Sludge and Biosol ids

    8.1.1 Representative Samples 8.1.2 Ccmpcsi te Samp e Development 8.1.3 Sampling Location 8.1.4 Sample Size and Sampl ing Equipment 8.1.5 Health and Safety Considerat ions 8.1.6 Sample Packaging and Shipping 8.1.7 Sample Documentat ion

    8.2 Quality Assurance and Sampling Frequency 8.2.1 Quality Assurance Proiect Plan (QAPP) 8.2.2 Data-Quality Objectives (DQO) Process

    8.3 Sampl ing of Biosol ids (40 CFR Part 503 Rule) 8.3.1 Monitor ing Frequency 8.3.2 Sampling Location 8.3.3 Sample Size and Sampling Equipment 8.3.4 Data Quality

    8.4 Environmental Sampling at Beneficial-Use Sites 8.4.1 Soil Sampling Location

    Sampling Equipment Surface and Groundwater Monitor ing Vegetation Monitor ing Monitor ing and Sampling at Land Reclamation Sites

    8.5 a.b

    8.4.2 8.4.3 8.4.4 8.4.5

    Problems References

    8.1

    8.1 8.2 3.2 8.1 3.8 8.9

    8.11 8.12 8.14 8.15 8.16 8.17 8.25 8.27 8.32 8.33 8.33 8.35 8.36 8.37 8.37 8.39 8.39 8.41 8.42

    Appendix A Atomic Masses and Weights A.1 Append.x B Physical Constants 'or Wastewater. Sludge, and Biosol ids

    Management B.1 Append x C Conversion Factors C.1 Appendix D Physical Properties of Water and Air D.1 Appendix E Solubi l i ty of Gases in Water E.1 Append x F Minor Losses in Pipes and Appurtenances F.1 Append x G Standard Normal Probabil i t ies G.1 Index fol lows Appendix G

  • Preface

    Throughout the world, wherever centralized municipal wastewater treatment occurs, an inevitable by-product is residual solids or sewage sludge. With a global emphasis on improving the overall environmen-tal quality of surface and groundwaters, effluent water-quality stan-dards for municipal wastewater treatment plants are becoming more stringent. The acceleration in infrastructure development of Third World nations together with the implementation of more stringent water-quality standards are expected to result in significantly increas-ing the global generation of sewage sludge. The urgency to identify and implement cost-effective means of reusing or disposing of sewage sludge in an environmentally safe and acceptable manner is now rec-ognized worldwide. Depending on the magnitude of sewage sludge pro-duction. the scope of international, national, and local environmental regulations, and the prevailing public attitudes, countries around the world are adopting their own unique approaches to the treatment, dis-posal, and reuse of sewage sludge.

    In 1987, the U.S. Congress amended Section 405 of the Clean Water Act (CWA) and, for the first time, set forth a comprehensive program for reducing the potential environmental and human health risks associated with the beneficial use and disposal of sewage sludge. As amended. Section 405 of the CWA required the U.S. Environmental Protection Agency (USEPA) to establish numeric limits and manage-ment practices that protect public health and the environment from reasonably anticipated adverse effects of pollutants found in sewage sludge. On February 19. 1993, the final 40 CFR Part 503 rule 'Standards for the Use or Disposal of Sewage Sludge) and revisions to the 40 CFR Parts 122, 123, and 501 (State Sludge Management Program Requirements) were published in the Federal Register [58(32):9248-9415]. The USEPA adopted the term biosolids to empha-size the plant nutritional and soil conditioning value of those sewage sludges that meet the regulatory' requirements specified in the 40 CFR Part 503 rule and are. therefore, potentially recyclable.

    XV

  • xvi Preface

    The 40 CFR Part 503 rule affects the generators, processors, users, and disposers of biosolids, both public and privately owned treatment works treating domestic sewage (including domestic septage haulers and nondischargersi, facilities processing or disposing of biosolids, and the users of biosolids and products derived from biosolids. The 40 CFR Part 503 rule establishes the technical requirements and management practices for biosolids that are (1) employed for beneficial purposes, an operational standard for either total hydrocarbons or carbon monoxide emissions.

    The fundamental difference between the U.S. biosolids reuse and disposal regulations and those currently adopted by other nations is that the 40 CFR Part 503 rule is based primarily on the results of sci-entifically conducted risk assessments aimed at identifying what, if any, risks were associated with the use or disposal of sewage sludge (biosolidsi. Those parts of the U.S. biosolids (sewage sludge' regula-tions that are not based on risk assessments were formulated based on either performance- or technology-based standards or on management. monitoring, or recordkeeping practices designed to protect human health and the environment.

    While the United States has adopted a risk assessment'risk man-agement-based paradigm in which regulations for protecting public health and the environment are developed, other parts of the world continue to use background pollutant concentrations as the basis for establishing regulatory levels for the reuse and'or disposal of biosolids (i.e., policy standards). Given the considerable scientific advances in risk-assessment methodology, establishing biosolids (sewage sludge) reuse and/or disposal regulations based on background pollutant con-centrations must be viewed as arbitrary and, in many cases, unneces-sarily conservative. The public health and ecological risk assessments that formed the basis of the 40 CFR Part 503 rule allow a much broader technical understanding of the environmental risks associated with

  • Preface xvii

    biosolids reuse and disposal than the policy-based regulations (which are unrelated to either public health or environmental risks i while, at the same time, highlighting those scientific areas that would benefit most from further research.

    The goal of this book is to provide the student, instructor, and pro-fessional practitioner with a comprehensive description of the regula-tory and technical framework that forms the basis of biosolids generation, reuse, and disposal practices in the United States. Although the individual chapters have been constructed to provide concise standalone information, they have been arranged in a specific sequence to facilitate the understanding of the regulatory and process fundamentals necessary for the design of biosolids beneficial-use sys-tems. Chapter 1 introduces the regulatory framework necessary for establishing the technical quality objectives required for the beneficial use. surface disposal, and incineration of biosolids. Chapters 2 and 3 describe the various unit operations found at municipal wastewater treatment plants and their impact on sewage sludge generation rates as well as those unit operations available to process sewage sludge and domestic septage into biosolids. Chapter 4 provides the reader with an introduction to industrial pretreatment with a special emphasis placed on the use of pollution prevention (P2) for improving both biosolids and effluent wastewater quality. Chapter 5 describes the various physical facilities required for the transport, storage, and treatment of sewage sludge (biosolids) both within the wastewater treatment plant and at the beneficial-use, surface disposal, or incin-eration site. Chapter 6 introduces the reader to the fundamentals of soil physics and chemistry with special emphasis placed on the impact of land-applied biosolids on crop production and environmental quality. Chapter 7 provides the design engineer with a step-by-step methodol-ogy for the design, implementation, and monitoring of the four basic types of biosolids beneficial-use systems (i.e., agricultural, forest, land reclamation, and public-accessi. Finally, Chap. 8 introduces the reader to the fundamentals of quality assurance and the development of sta-tistical environmental sampling designs. Emphasis is placed on the use of a systematic data-quality planning process to generate environ-mental data of the appropriate quality for defensible decision making.

    It should be emphasized that the development of environmentally acceptable and cost-effective approaches to sewage sludge i biosolids) reuse and disposal is a continuously evolving process. As better infor-mation regarding the public health and environmental risks associated with sewage sludge (biosolidsi reuse and disposal is generated, regu-lations will be modified that reflect the new level of scientific under-standing. Changes in the legal requirements will, in turn, impact the development and implementation of innovative technologies and

  • xviil Preface

    strategies for more effective biosolids 'sewage sludgei management. Finally, as reported at the 1992 United Nations Conference on Envi-ronment and Development (Rio de Janeiro. Brazil>, the overarching objective in all residual solids management programs should be envi-ronmental sustainability. which demands an increased efficiency in resource use while maintaining adequate protection of the functions and viability of natural systems on which all life depends. It is hoped that the information furnished in this text provides appropriate guid-ance for meeting this important environmental objective.

    Dr. Michael J. McFarland. PE, DEE

  • Acknowledgments

    This book has its roots in the long history of residuals management and. in particular, nutrient recycling for the enhancement of crop pro-duction and soil improvement. Over the years, I have had the privilege of collaborating with many outstanding agricultural, chemical, and environmental engineers and scientists who provided me with valu-able insight into the broad issues impacting residuals management decisions in the United States and abroad. Their professional enthusi-asm and technical acumen highlighted the critical need for a text that collectively addressed the multifaceted field of biosolids engineering.

    From Cornell University, I am particularly indebted to my Ph.D. advisor. Dr. William J. Jewell, who first introduced me to the field of residuals management and provided the technical foundation upon which much of this work is based. Thanks are also due to one of my favorite and most demanding instructors. Dr. Richard Dick of Cornell University, who painstakingly taught me the engineering fundamen-tals of sludge treatment. From the University of Texas at Austin, I am greatly indebted to my postdoctoral research supervisor. Dr. Raymond C. Loehr. who was instrumental in broadening my understanding and appreciation of land-based residuals management systems.

    I would like to recognize and thank Mr. Bob Brobst of the U.S. Environmental Protection Agency [USEPA Region VIIT (Denver)] for submitting a critical and extremely valuable review of an earlier draft of this book. I also would like to acknowledge Mr. Robert K. Bastian of the USEPA's Office of Water (Washington, D.C.) for supplying me with much of the historical and regulatory- material for this text as well as for sharing with me his thoughts and insights on the future of biosolids management. In addition, I would like to recognize and thank a personal friend and colleague, Mr. Clyde Bishop of the USEPA's Office of Research and Development (Washington, D.C). for his mentorship and for the many stimulating discussions we have had on the importance of addressing ecological concerns early in the resid-uals management decision making process.

  • xx Acknowledgments

    I would like to express my gratitude to friends and colleagues at the USEPA Science Advison' Board

  • 1.1

    Biosolids ManagementPractices and

    Regulatory Requirements

    1.0 IntroductionIn 1948, the U.S. Congress enacted the original Federal Water Pollu-tion Control Act (FWPCA). Since its passage, the FWPCA has beenamended many times. Two of the most important amendments were(1) the 1972 FWPCA Amendments and (2) the 1977 Clean Water ActAmendments [10]. These amendments define the basic national frame-work for water quality and water pollution control in the UnitedStates. Today, the comprehensive federal law is simply referred to asthe U.S. Clean Water Act (CWA).

    The primary objective of the CWA is to restore and maintain thechemical, physical, and biological integrity of the nations waters. Toprevent contamination and deterioration of water quality, wastewaterfrom industrial, commercial, and residential activities is treated atwastewater treatment plants (WWTPs) before it is discharged to sur-face water or groundwater (Fig. 1.1).

    At present, there are more than 15,000 municipal wastewater treat-ment plants or publicly owned treatment works (POTWs) in theUnited States that process over 34 billion gallons of domestic sewageand other wastewater each day [21]. Sewage sludge represents thelargest source of residual solids generated during the treatment ofmunicipal wastewater by POTWs as well as by privately and federally

    Chapter

    1Source: Biosolids Engineering

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  • owned wastewater treatment works. The annual amount of sewagesludge (i.e., biosolids) generated during the treatment of domesticsewage is estimated at approximately 47 pounds for every individualin the United States. Figure 1.2 illustrates the collection and treat-ment of domestic and industrial wastewater resulting in the produc-tion, treatment, use, and disposal of sewage sludge.

    In the United States, the use or disposal of sewage sludge has beenregulated under various federal environmental statutes. Land dispos-al and reuse of sewage sludge were regulated initially under the solidwaste disposal regulations of 40 Code of Federal Regulations (CFR)Part 257, which was jointly promulgated under the 1976 ResourceConservation and Recovery Act (RCRA) and Sections 405 and 307 ofthe 1977 CWA Amendments. RCRA (PL 94-580) required that solidwastes be used or disposed in a safe and environmentally acceptablemanner. Sewage sludge was included by definition in the RCRA provi-sions relating to solid waste management. The 1977 CWAAmendments (PL 95-217) contained two major provisions affectingsewage sludge use and disposal. First, Section 405 of the 1977 CWAAmendments required that the U.S. Environmental Protection Agency(USEPA) issue guidelines and regulations for the disposal and reuse ofsewage sludge. Second, Section 307 of the CWA Amendments requiredpretreatment of industrial wastes if such wastes, when discharged

    1.2 Chapter One

    Figure 1.1 Aerial view of typical municipal wastewater treatment plant(WWTP). (Courtesy of Waterlink, Inc.)

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  • into municipal sewage collection systems, inhibited wastewater treat-ment or the beneficial use of sewage sludge. In addition to RCRA andthe CWA Amendments, the 1972 Marine Protection, Research andSanctuaries Act (MPRSA) regulated the discharging of sewage sludgeto oceans and estuaries until the Ocean Dumping Ban Act of 1988 pro-hibited this disposal practice [10].

    In 1987, Section 405(d) of the CWA was amended to require theUSEPA to establish sewage sludge pollutant standards that adequate-ly protected public health and the environment from any reasonablyanticipated adverse effects of pollutants in sewage sludge that is usedor disposed [21]. These regulations were to include identification of thevarious beneficial uses for sludge while specifying factors to be takeninto account in developing management practices for each type ofreuse or disposal option. The 1987 CWA Amendments also requiredthat any CWA Section 402 (National Pollutant Discharge EliminationSystem, NPDES) permit include sewage sludge use or disposal stan-dards unless these requirements were included in another permit. The1987 CWA Amendments expanded the regulated universe to includeall treatment works treating domestic sewage (TWTDS), even thosenot requiring an NPDES permit. TWTDS include all sewage sludge orwastewater treatment systems used to store, treat, recycle, andreclaim municipal or domestic sewage.

    In summary, to maintain regulatory compliance with the CWArequirements, POTWs must adopt and implement federally mandatedprocedures ensuring the proper treatment, use, and disposal of sewagesludge. Furthermore, as a result of Section 405 of the 1977 and 1987CWA Amendments, increased use of sewage sludge recycling hasbecome a clear objective of U.S. environmental policy.

    Management Practices and Regulatory Requirements 1.3

    Figure 1.2 Schematic illustration of the generation, treatment, use, and disposal ofsewage sludge.

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  • 1.0.1 Summary statistics for sewagesludge use and disposal in the United StatesIn 1988, the USEPA collected information on the use or disposal ofsewage sludge through a two-part National Sewage Sludge Survey(NSSS). In Part I, a questionnaire survey was used to obtain both tech-nical and financial information on the sewage sludge use or disposalpractices employed by POTWs. In Part II, information on the quality ofsewage sludge was obtained by analyzing sewage sludge from severalPOTWs for specific pollutants. Results from the NSSS were used as thebasis for establishing several of the sewage sludge pollutant limitsfound in the 40 CFR Part 503 sludge rule (see Sec. 1.1). The number ofPOTWs and the magnitude of sewage sludge generated (dry-massbasis) as reported in the 1988 NSSS are sumarized in Table 1.1.

    In 1988, POTWs with a design flow rate of over 100 million gallonsper day (MGD) accounted for 30.1 percent of the sewage sludge usedor disposed by POTWs. POTWs with a design flow rate of between 10and 100 MGD used or disposed 38.4 percent of the total annualamount of sewage sludge generated in the United States, whilePOTWs with a flow rate of between 1 and 10 MGD used or disposed24.0 percent of the sewage sludge. In contrast, while they account formore than half of all POTWs in the United States, POTWs with a flowrate of less than 1 MGD generated only 7.5 percent of the annualamount of sewage sludge used or disposed.

    The 1988 NSSS identified four principal categories of practicesemployed by POTWs for the reuse and or disposal of sewage sludge.Table 1.2 illustrates that, in 1988, the most prevalent sludge reuse/dis-posal practice was land application (34.6 percent), followed by sewagesludge codisposal in municipal solid waste landfills. With respect tothe total mass of sewage sludge generated, codisposal in municipallandfills was the preferred disposal practice in 1988, accounting for33.7 percent of the total amount of sludge generated.

    1.4 Chapter One

    TABLE 1.1 Number of Publicly Owned Treatment Works (POTWs), Actual Flow,and Estimated Sewage Sludge Quantities in the United States*

    POTW flow rate Quantity of sewage sludge(MGD) No. of POTWs (dmt) Percent

    100 35 2,120,512 30.110100 459 2,709,604 38.4

    110 2,666 1,692,086 24.01 9,588 530,339 7.5

    TOTAL 12,748 7,052,540 100.0

    *Adapted from ref. [18].MGD, million gallons per day.dmt, dry metric ton (1000 kg) = 0.9072 U.S. ton. (kg = 2.2 lb.)

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  • Due to the increased level to which municipal wastewater is nowrequired to be treated, it is anticipated that the sewage sludge vol-umes have increased significantly since 1988. Some of the regulatoryrequirements that have mandated higher levels of wastewater treat-ment include (1) the reduction in permissible levels of nitrogen andphosphorus in wastewater discharges to surface waters and (2) theconversion of primary treatment-only facilities to full secondary treat-ment [21]. In addition to the increased stringency in federal and localwater quality discharge standards, industrial pretreatment programshave had a significant impact on sewage sludge management. Withthe overall improvement in sewage sludge quality as a result of imple-mentation of industrial pretreatment programs, a large volume ofsewage sludge can now be directed toward beneficial use, such as landapplication and the production and sale of sewage sludge amendmentproducts (e.g., compost, heat-dried pellets, alkaline-stabilized soiladditives, and soil substitute products). To document the impact ofchanging water quality standards on sewage sludge quality and gen-eration rates, the USEPA is currently developing the scope for a sec-ond national sewage sludge survey [2,3].

    Although regulatory compliance issues have led to consideration ofnew approaches to sewage sludge recycling, in some cases, rising trans-portation and labor costs have stimulated changes in sewage sludgemanagement. For example, wastewater treatment authorities recentlyhave been faced with dramatic increases in sewage sludge disposalcosts. In the 1970s, costs for sewage sludge disposal generally were lessthan $100 per dry ton, whereas recent short-term private contracts toimplement land-based sewage sludge disposal alternatives have beenreported to be as high as $800 per dry ton [23]. Such increases in dis-posal costs, along with the difficulties in siting sewage sludge disposalfacilities, have led to situations where long-distance sewage sludgetransport becomes necessary (e.g., New York City sewage sludge trans-ported to Arizona for reuse/disposal). With such high sewage sludgemanagement costs, more attention is being paid to the development andimplementation of innovative approaches to sewage sludge recycling.

    Management Practices and Regulatory Requirements 1.5

    TABLE 1.2 Use and Disposal Practices of Sewage Sludge in the United States*

    Percentage of POTWs Percentage of total Use/disposal practice using a particular practice sewage sludge generated

    Land application 34.6 33.5Codisposal landfill 22.2 33.7Incineration 2.8 16.1Surface disposal 10.1 10.4Unknown transfers 30.3 6.3

    *Adapted from refs. [21,23].Ocean disposalbanned in 1988.

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  • 1.0.2 Institutional barriers and liability issues

    Although the technological feasibility of innovative methods for recy-cling sewage sludge can be demonstrated repeatedly, in many cases,achieving public acceptance of new sludge management methodsbecomes insurmountable. The reluctance to accept the results oftechnological innovation directly influences the numerous political,regulatory, and financial policy barriers that wastewater treatmentauthorities must address in developing sludge management pro-grams. The skepticism recorded about the proposed changes in cur-rent sludge disposal/recycling practices and policies includedlegitimate public concerns over protecting public health, the environ-ment, and tax revenue. In recent years, potential liability associatedwith the beneficial use of sewage sludge has become a concern to bothproponents and opponents of sewage sludge recycling [30].

    Under federal law, anyone responsible for a hazardous substancerelease that is not federally permitted is liable for the costs of cleaningup the release under the 1980 Comprehensive EnvironmentalResponse, Compensation and Liability Act (CERCLA, or Superfund).Potential Superfund liability has created concerns over the potentialfor future liability associated with sewage sludge use/disposal prac-tices for both sludge generators and landowners. In addition, groupssuch as the Farm Credit Bank and various food processing organiza-tions also have raised concerns over potential liabilities [21]. Thepotential for litigation brought on behalf of food processors and/or thepublic has created significant psychological and financial barriers tofarmers who would otherwise use sewage sludge as either a low-costfertilizer or soil amendment.

    To ease some of the liability concerns, the 40 CFR Part 503 sludgerule clarifies that Superfund liability does not apply to the beneficialuse of sewage sludge [21]. Moreover, the Farm Credit Bank in con-junction with the USEPA has developed an indemnification state-ment that is currently being employed by several companies toclarify the legal responsibilities of the sludge preparer, land applier,and farmer when sewage sludge reuse/disposal projects are in com-pliance with applicable standards and management practices of the40 CFR Part 503 rule [21].

    Finally, overcoming the nontechnical issues such as public percep-tion and legal liability fears may prove to be the greatest barrier fac-ing sewage sludge management authorities in the future. Studies ofpublic acceptance and institutional barriers to changes in sewagesludge management practices suggest that techniques such as (1)providing adequate public involvement in the decision-makingprocess, (2) addressing public nuisance concerns early, (3) use of

    1.6 Chapter One

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  • stakeholder advisory groups, and (4) aggressive education programsmay minimize opposition to implementation of innovative sludgemanagement practices.

    1.1 Regulatory Aspects to BiosolidsManagementIn compliance with the requirements of Section 405(d) of the 1987 CWAAmendments, on February 19, 1993, the final version of 40 CFR Part503, Standards for the Use or Disposal of Biosolids, was published inthe Federal Register [22]. In the 40 CFR Part 503 rule, the termbiosolids was introduced as a replacement for the term sewage sludge.The new term was designed to reflect the beneficial characteristics ofthe residual solids generated from municipal wastewater treatment.The 40 CFR Part 503 rule defines biosolids as the final solid, semisol-id, or liquid residue generated during the treatment of domestic sewagein a municipal wastewater treatment plant [19]. The 40 CFR Part 503rule applies to biosolids generated from the treatment of domesticwastewater as well as domestic septage.

    Biosolids permitting requirements apply to all TWTDS, i.e., facili-ties that generate, treat, or provide disposal of biosolids, includingnondischarging and biosolids-only (i.e., sludge) facilities. A TWTDSfacility must apply for a federal biosolids permit from the USEPA or anapproved state biosolids program if it manages biosolids that are ulti-mately subject to the 40 CFR Part 503 rule. In other words, if thebiosolids are applied to land, placed in a surface disposal site, inciner-ated, or sent to a municipal solid waste monofill, the TWTDS facilityrequires a permit under the 40 CFR Part 503 rule.

    The 40 CFR Part 503 rule does not apply to materials such as greasetrap residues or other nondomestic wastewater residues pumped fromcommercial facilities such as solids produced by industrial wastewatertreatment facilities or grit and screenings from publicly owned treat-ment works (POTWs). Wastewater biosolids disposed in municipal solid waste landfills or used as landfill cover material are regulated byfederal and local solid waste regulations [21].

    The 40 CFR Part 503 rule was designed to protect public health andthe environment from any reasonably anticipated adverse effects of pol-lutants that may be present in biosolids. A schematic diagram illus-trating the various components of the 40 CFR Part 503 rule is providedin Fig. 1.3. The provisions of the 40 CFR Part 503 rule are consistentwith USEPAs policy of promoting beneficial uses of biosolids. Most ofthe requirements contained in the 40 CFR Part 503 rule were generat-ed based on results from extensive multimedia risk-assessment studiesconducted by the USEPA [28].

    Management Practices and Regulatory Requirements 1.7

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  • 1.1.1 Risk-assessment basis for the 40 CFR Part 503 ruleThe Part 503 rule was developed with the realization that the use ordisposal of biosolids may result in measurable changes in the envi-ronment. The biosolids risk-assessment process provided a scientificbasis for determining acceptable environmental change whenbiosolids were used or disposed. Acceptable environmental change hasbeen defined by the USEPA as any measurable change that still main-tains adequate protection for public health and the environment. Therisk-assessment procedures used in developing the sludge rule (40CFR Part 503) were based on the methodology formulated by theNational Academy of Science, which included the following four steps:(1) hazard identification, (2) exposure assessment, (3) dose-responseevaluation, and (4) risk characterization [28].

    To evaluate both the human health and environmental risks associ-ated with biosolids reuse and disposal practices, the USEPA analyzedthe health impacts on humans, animals, plants, and soil organismsresulting from exposure to pollutants found in biosolids. The USEPAevaluated 14 various exposure pathways in which human beings andthe environment may be exposed to pollutants contained in land-applied biosolids. Similarly, the USEPA evaluated two exposure path-ways through which human beings and the environment may be

    1.8 Chapter One

    Figure 1.3 Various components of the 40 CFR Part 503 sludge rule.

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  • affected by the surface disposal of biosolids, while the impact ofbiosolids incineration on human health was modeled assuming oneprincipal exposure pathway [25]. Figure 1.4 summarizes the variousexposure pathways evaluated by the USEPA in the development of the40 CFR Part 503 rule.

    Employing human health and environmental risk assessments to establish permissible biosolids use and disposal standards repre-sents a paradigm shift away from the policy-driven methodologyemployed by many European countries and Canadian provinces.

    Management Practices and Regulatory Requirements 1.9

    Figure 1.4 Various exposure pathways evaluated by the USEPA in developingthe 40 CFR Part 503 rule: (a) exposure pathways for land-applied biosolids; (b)exposure pathways for surface disposal and incineration of biosolids.

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  • Policy-driven approaches used to establish biosolids quality standardsallow only small, incremental increases of pollutants into the environ-ment. A typical example of a policy-driven biosolids land-applicationstandard might include a mandate requiring that the soil metal con-centrations resulting from biosolids land application shall not be per-mitted to exceed the 95th percentile of background soil concentrations.Unfortunately, these policy-driven approaches to establishing environ-mental standards not only result in overly conservative pollutant lim-its but often have neither a scientific nor technical basis.

    In most cases, the USEPA determined that risk-based pollutant lim-its could be calculated to achieve the goal of protecting public healthand the environment. However, in three cases, risk-assessmentmethodologies were not sufficiently developed to provide a reasonableestimate of risk. These cases included establishing (1) pathogen reduc-tion criteria for land-applied biosolids, (2) vector attraction reductioncriteria for land-applied biosolids, and (3) total hydrocarbon (THC)limits in biosolids incineration emissions. In lieu of developing a risk-based pollutant limit for these cases, the USEPA adopted technology-based biosolids management requirements to ensure an adequatemargin of protection for human health and the environment [19,25].

    Once risk assessments were completed, the basic approach adoptedby the USEPA to establish the permissible pollutant concentrationswas to use the lower of either (1) the risk-derived concentration or (2)the 99th percentile concentration derived from the 1988 USEPA NSSS[18]. The NSSS summarized pollutant concentration data in biosolidsgenerated from 186 statistically representative POTWs. In the case ofthe pollutants chromium and selenium, the 99th percentile concentra-tion found in the 1988 NSSS was lower than the concentration derivedfrom risk assessments. Therefore, the initial limiting concentrationspecified for both metals for land-applied biosolids was the 99th per-centile concentration found in the 1988 NSSS.

    The USEPA received many comments from both the regulated com-munity and the public after the initial promulgation of the 40 CFR Part503 rule [30]. In addition to public comments, several industry groupsand POTWs initiated lawsuits against the USEPA contending that theland-application pollutant limits set for chromium and selenium in therule were overly stringent [30]. In these particular lawsuits, theDistrict of Columbia Circuit Court concluded that Section 405 of theCWA mandated that only risk-based pollutant concentrations could bepromulgated in the 40 CFR Part 503 rule. Since the maximum chromi-um level reported in the 1988 NSSS and subsequently investigated inthe USEPA risk assessments did not pose a significant risk to humanhealth and the environment, the USEPA decided to delete all chromi-um limits for land-applied biosolids from the 40 CFR Part 503 rule.Moreover, the USEPA revised the selenium pollutant concentration

    1.10 Chapter One

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  • limits, concluding that it could not legally adopt a more stringent con-centration limit for selenium in land-applied biosolids than the risk-assessment-based concentration of 100 mg/kg (dry solids basis).

    1.2 Land Application of BiosolidsLand application of biosolids includes all forms of applying bulk orbagged biosolids to land for beneficial use. Beneficial uses includebiosolids application to (1) agricultural land for food production, (2)agricultural land for production of feed and fiber crops, (3) pasture and range land, (4) nonagricultural land (e.g., forests), (5) disturbed lands (e.g., highway embankments, mine reclamation,etc.), (6) construction sites and gravel pits, (7) public contact sites (e.g.,parks and golf courses), and (8) home lawns and gardens. Figure 1.5presents photographs depicting the land application of various types ofbiosolids for agricultural production.

    The 40 CFR Part 503 rule requires that any person applyingbiosolids to land or any person who prepares biosolids for beneficialuse must obtain a permit. The 40 CFR Part 503 rule defines a personas an individual, association, partnership, corporation, municipality,state or federal agency, or any individual working on behalf of one ofthese entities. The self-implementing nature of the 40 CFR Part 503rule requires that biosolids land appliers comply with the rule even ifthey have not applied for and/or have not been issued a permit cover-ing biosolids use. Similarly, USEPA (or an approved state regulatoryagency) can take enforcement actions directly against persons who vio-late the 40 CFR Part 503 requirements regardless of whether or notthey have been issued a biosolids permit [21,30].

    Regardless of the land-application end use (i.e., agricultural or non-agricultural), seven types of requirements must be met to legally applybiosolids to land: (1) general requirements, (2) pollutant limits, (3)management practices, (4) operational standards covering pathogenand vector attraction reduction requirements, (5) frequency of moni-toring requirements, (6) recordkeeping requirements, and (7) report-ing requirements. Each of these requirements is discussed in furtherdetail in the following sections.

    1.2.1 General requirements for land-applied biosolids

    Subpart B of the 40 CFR Part 503 rule specifies the legal requirementsfor land applying biosolids and/or any material derived from biosolids(e.g., land application of biosolids composted with yard wastes).General requirements mandate that the preparer of bulk biosolids pro-vide any subsequent preparer and any land applier of biosolids withthe appropriate notice and information certification necessary to

    Management Practices and Regulatory Requirements 1.11

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  • comply with Subpart B. Subpart B requirements (i.e., pollutant limits,class of pathogen control, and vector attraction reduction) are designedto ensure that all preparers of biosolids that do not meet specific qual-ity requirements have written agreement with any biosolids landapplier before land application of biosolids commences.

    In addition to having a written contract with the land applier, thepreparers of land-applied biosolids must provide the state regulatoryauthority with information pertaining to the site location, time peri-od of application, and the name, address, telephone numbers, andNPDES permit number of the biosolids applier. The regulation alsorequires all land appliers of bulk biosolids that are subject to thecumulative pollutant limits to provide written notification to the per-mitting authority for the state in which the bulk biosolids are applied.

    1.12 Chapter One

    Figure 1.5 Biosolids land application for agricultural production: (a) sub-surface injection of liquid biosolids; (b) surface application of dewateredbiosolids. (Courtesy of Ag-Chem Equipment Company, Inc.)

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  • If, for any reason, bulk biosolids subject to cumulative limits havebeen applied to the site but the cumulative amount of pollutantsapplied is unknown, no further amount of biosolids can be applied tothe site unless it can meet the more stringent pollutant concentrationlimits (see Sec. 1.2.2).

    In addition to the general requirements, the 40 CFR Part 503 rulerequires that biosolids meet two levels of quality with respect to pol-lutant limits, i.e., pollutant ceiling concentrations and any one of thefollowing: (1) pollutant concentration limits, (2) cumulative loadingrate limits, or (3) annual pollutant loading rate limits. The 40 CFRPart 503 rule also has created two levels of biosolids quality withrespect to pathogen concentrations, i.e., Class A and Class B biosolids.Finally, the 40 CFR Part 503 rule permits two types of approaches formeeting vector attraction reduction, namely, (1) biosolids processing or(2) use of physical barriers. The following sections describe each ofthese requirements and their impact on the suitability of biosolids tobe applied to land.

    1.2.2 Pollutant limits

    A central feature of the biosolids land-application requirements is pol-lutant limits. It should be noted that at the time of this writing, theonly regulated pollutants for land-applied biosolids were heavy met-als. It should be noted that the USEPA recently promulgated a pro-posed limit of 300 parts per trillion (300 ppt) for dioxin in land-appliedbiosolids (dry-mass basis), but this standard has not yet been codifiedinto law [33]. The heavy metal pollutant limits are divided into twotypes: (1) concentration limits (i.e., limits on the concentrations of pol-lutants in biosolids) and (2) loading rate limits (i.e., limits on the rateat which pollutants may be applied to land). Concentration limits arefurther divided into two types: (1) ceiling concentration limits, whichgovern whether a biosolids can be applied to land at all, and (2) pollu-tant concentration limits, which define biosolids that are exemptedfrom meeting pollutant loading rate limits, certain recordkeepingrequirements, etc.

    All land-applied biosolids must meet the ceiling concentration lim-its for heavy metals. The ceiling concentrations are the maximumconcentration limits for nine heavy metals typically found in biosolids(Table 1.3).

    If the concentration limit for any one of the heavy metals exceedsthe level given in Table 1.3, the biosolids cannot be applied to land.The ceiling concentration limits for heavy metals were included in 40CFR Part 503 to encourage industrial pretreatment efforts and toprevent the introduction of heavily contaminated materials into theenvironment.

    Management Practices and Regulatory Requirements 1.13

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  • Depending on the effectiveness of industrial pretreatment programsand wastewater treatment operation, the heavy metal concentrationsin biosolids may be reduced to the pollutant concentration limits (seeTable 1.3). POTWs whose biosolids meet pollutant concentration lim-its are offered two important advantages with regard to biosolids landapplication, namely, (1) there are no limits on the lifetime quantity ofpollutants that can be applied to a site, and (2) the biosolids applica-tion rate depends only on the agronomic rate (see Sec. 1.3.2.1).

    Like concentration limits, loading rate limits are also divided intotwo types: (1) cumulative pollutant loading rates (CPLRs) and (2)annual pollutant loading rates (APLRs) (Table 1.4). Bulk biosolidsthat meet ceiling concentration limits but do not meet pollutant con-centration limits must meet cumulative pollutant loading rates,which specify the total lifetime quantity of pollutants that can beapplied to a site (see Table 1.4). Once the cumulative pollutant load-ing rate has been reached, no more biosolids of this quality may beapplied to a site.

    In contrast to biosolids that are applied in bulk, biosolids that aresold or given away in bags or other containers meeting ceiling limitsbut not meeting pollutant concentration limits must meet APLRs,which specify the total amount of pollutant that can be applied to asite in any one year. The following sections provide additional infor-mation specific to the land application of bulk and bagged biosolids.

    1.2.2.1 Land application of bulk biosolids. The 40 CFR Part 503 rulemandates that bulk biosolids cannot be applied to agricultural land,forest land, or a public contact site at a rate greater than the agro-nomic rate. The agronomic rate is defined as the biosolids applicationrate that provides nitrogen (or phosphorus) at a rate that just satisfiesthe crop nutrient requirements. Figure 1.6 is a photograph depicting

    1.14 Chapter One

    TABLE 1.3 Concentration Limits for Biosolids Applied to Land*

    Ceiling concentration limits Pollution concentration limitsHeavy metal (mg/kg) (mg/kg)

    Arsenic 75 41Cadmium 85 39Copper 4300 1500Lead 840 300Mercury 57 17Molybdenum 75 Nickel 420 420Selenium 100 36Zinc 7500 280

    *Adapted from ref. [31].Dry-weight basis.Monthly average concentration.

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  • the land application of biosolids in bulk at a forest site. Bulk biosolidscan be applied to land at a reclamation site at a rate greater than theagronomic rate if authorized by the permitting agency [31].

    In all cases, when bulk biosolids that do not meet pollutant con-centration limits are applied to land, the application rate and site lifemust be determined as part of the overall land-application design.Preparers or appliers of bulk biosolids have the option of using theCPLR values to estimate either (1) a maximum site life based on agiven biosolids application rate or (2) a maximum annual wholesludge application rate (AWSAR) in terms of dry metric tons (dmt)per hectare (or U.S. tons per acre) given a design site life. In mostcases, POTWs will use their existing biosolids land-application rate(i.e., AWSAR) to estimate site life if their biosolids application rate

    Management Practices and Regulatory Requirements 1.15

    TABLE 1.4 Loading Rate Limits for Land-Applied Biosolids*

    Cumulative pollutant loading Annual pollutant loadingPollutant rate limits (kg/ha) rate limits (kg/ha)

    Arsenic 41 2.00Cadmium 39 1.90Copper 1500 75.00Lead 300 15.00Mercury 17 0.85Nickel 420 21.00Selenium 100 5.00Zinc 2800 140.00

    lb/acre = 0.8922 kg/ha.*Taken from refs. [24,31].To qualify as exceptional quality biosolids, none of the heavy metal concentration canexceed the pollutant concentration limits.

    Figure 1.6 Photograph of biosolids being applied to land in bulk at a forest site.

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  • is at or below the agronomic rate. However, the latter approach tobiosolids land-application design is sometimes used in cases where itis necessary for the POTW to adjust the AWSAR downward to extendsite life.

    To estimate site life, an APLR must be estimated for each regulatedpollutant given the existing biosolids land-application rate. The APLRis obtained by multiplying the concentration of each pollutant by theAWSAR, as illustrated by Eq. (1.1).

    APLR biosolids pollutant concentration AWSAR (1.1)

    Once the APLR is estimated, the site life can be obtained by divid-ing the CPLR by the derived APLR [Eq. (1.2)].

    Site life (years) (1.2)

    When site life is calculated for each regulated pollutant, the short-est time duration becomes the design site life for the biosolids land-application program. Example 1.0 illustrates the use of Eqs. (1.1) and(1.2) in estimating site life for a biosolids land-application system.

    Example 1.0 The CPLR for arsenic is 41 kg/ha. If the concentration ofarsenic in the biosolids is 10 mg/kg (dry weight), estimate the site life basedon arsenic if the AWSAR is to be maintained at 15 dmt/ha (15103 kg/ha).

    solution

    Step 1. Estimate the APLR using Eq. (1.1).

    APLR biosolids pollutant concentration AWSAR

    0.15 kgha yr

    kg106 mg

    15 103 kg

    ha yr10 mg

    kg

    kg106 mg

    103 kgha yr

    mgkg

    kgha yr

    CPLR hk

    ag

    APLR hak

    gyr

    kg106 mg

    103 kgha yr

    mgkg

    kgha yr

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  • Step 2. Estimate the site life using Eq. (1.2).

    Site life (years)

    273 years

    NOTE: In the actual biosolids land-application design, similar calculationswould be performed for each of the nine regulated heavy metals. The metalyielding the shortest site life would become the limiting pollutant.

    1.2.2.2 Land application of bagged biosolids. When the biosolids pre-parer cannot control the number of biosolids applications made to asite directly (i.e., when biosolids in bags or other containers are givenaway or sold), APLRs must be met (see Table 1.4). In this case, as longas the annual limits are met, the total pollutant load to the site overtime will not exceed levels identified through the USEPA risk assess-ments as protective of human health and the environment [28].

    For the case of biosolids sold or given away in bags or other con-tainers, only the AWSAR (in dry metric tons/hectare or dry U.S.tons/acre) needs to be determined. To estimate the AWSAR, Eq. (1.3)is used. It should be noted that Eq. (1.3) employs the APLR limitsfound in Table 1.4.

    AWSAR

    (1.3)

    When AWSARs for all nine regulated pollutants are calculated, thelowest AWSAR becomes the limiting application rate for those

    APLR hak

    gyr

    concentration of pollutant biosolids mkg

    g 0.001

    APLR hak

    gyr

    concentration of pollutant in biosolids mkg

    g 10

    k6gmg

    1d0m

    3 ktg

    dry metric tons

    hectare

    41

    hakg

    0h.a15

    kyr

    g

    CPLR hk

    ag

    APLR ha

    k

    gyr

    Management Practices and Regulatory Requirements 1.17

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  • biosolids. Example 1.1 illustrates the use of Eq. (1.3) in estimatingthe biosolids application rate for bagged biosolids that ensures that theAPLRs are not exceeded.

    Example 1.1 The Little County Water Reclamation Facility is consideringselling its biosolids to the general public in 100-pound sacks. What is theAWSAR in dry metric tons per hectare per year if the biosolids have the fol-lowing average heavy metal concentrations?

    Metal Concentration in biosolids (mg/kg)

    Arsenic 20.3Cadmium 52.1Copper 1133.1Lead 723.1Mercury 4.1Nickel 321.7Selenium 27.8Zinc 2241.6

    solution

    Step 1. Calculate the AWSAR for each regulated pollutant using Eq. (1.3)and the APLRs from Table 1.2. For example, for arsenic, the APLRlimit is 2.0 kg/hayr (see Table 1.4). Given this APLR, the AWSARcan be estimated as follows:

    AWSAR

    Step 2. The AWSAR can be calculated for each heavy metal using the sameprocedure. The results are given in the following table:

    Concentration in Metal biosolids (mg/kg) APLR (kg/hayr) AWSAR (metric tons/hayr)

    Arsenic 20.3 2.0 98.5Cadmium 52.1 1.9 36.5Copper 1133.1 75.0 66.2Lead 723.1 15.0 20.7Mercury 4.1 0.9 207.3Nickel 321.7 21.0 65.3Selenium 27.8 5.0 179.9Zinc 2241.6 140.0 62.5

    98.5 dmt

    ha yr

    h2a.0

    kygr

    20.k3gmg 10

    k6gmg

    1d0m

    3 ktg

    APLR hak

    gyr

    concentration of pollutant in biosolids mkg

    g 10

    k6gmg

    1d0m

    3 ktg

    dry metric tons

    ha yr

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  • Step 3. The limiting AWSAR is 20.7 metric tons/hayr, which was estimat-ed for lead. Therefore, the maximum annual biosolids applicationrate for these biosolids is 20.7 metric tons/hayr.

    Biosolids sold or given away in bags or other containers are requiredto have a label attached or a handout sheet provided. The informationrequired on the label or handout sheet includes (1) the name andaddress of the preparer, (2) a statement prohibiting application exceptin accordance with the instructions on the label, and (3) the calculat-ed AWSAR that does not cause the APLR to be exceeded (see Sec.1.2.3.5). Finally, when metal concentrations limit the biosolids loadingrate, the nutrient levels must be monitored to determine if supple-mental fertilization is required. Example 1.2 illustrates the approachfor estimating the level of supplemental fertilization required as aresult of biosolids land application.

    Example 1.2 The Little County Water Reclamation Facility (Example 1.1)has negotiated with a local nursery to deliver several hundred sacks ofbiosolids over the course of the growing season to supply nutrients to orna-mental shrubbery. If the local nursery estimates that the crop nitrogenrequirement is 150 pounds of nitrogen per acre-year, what would be theamount of nitrogen provided by the biosolids relative to the crop nutrientrequirements during the first year? Assume that the nitrogen content of thebiosolids is 1.5 percent and that 30 percent of the nitrogen (dry-mass basis)is available during the first year of application.

    solution

    Step 1. From Example 1.1, the AWSAR was estimated to be 20.7 dmt/hayr.Since the crop nutrient needs are given in pounds per acre-year, theAWSAR in metric tons per hectare-year must be converted to U.S.units.

    Step 2. Since nitrogen is only 1.5 percent of the total biosolids added and,

    of this, only 30 percent is available in the first year, the availablenitrogen from biosolids (pounds of nitrogen per acre-year) is calcu-lated as follows:

    0.3 lb N available

    lb N applied

    0.015 lb N applied

    lb biosolids2000 lb

    ton9.22 tons biosolids

    acre yr83.0 lb nitrogen

    acre yr

    ha2.47 acre

    ton2000 lb

    2.2 lb

    kg1000 kg

    metric tons

    20.7 metric tons

    ha year9.22 tons biosolids

    acre yr

    Management Practices and Regulatory Requirements 1.19

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  • Step 3. Since the biosolids can only supply 83.0 pounds of the required nitro-gen when applied at a AWSAR of 20.7 metric tons per hectare per year,an additional 67 pounds of nitrogen per acre must be added throughsupplemental fertilization during each growing season.

    NOTE: This is only an approximate method for estimating the supplementalnutrient requirements. In most cases, there is both native nitrogen andnitrogen from previous biosolids application available for meeting cropnutrient requirements. To account for these other nitrogen sources in deter-mining supplemental nitrogen requirements, see Chap. 7.

    1.2.3 Management practicesIn addition to heavy metal concentrations and loading limits, the 40 CFRPart 503 rule requires that certain management practices be met whenbiosolids are being applied to land. The only instance where a land appli-er is exempt from management practices is when exceptional-quality(EQ) biosolids are being applied (see Sec. 1.4).

    Management practices were included in the 40 CFR Part 503 rule to(1) constrain risks when actual risks were not evaluated, (2) supportrisk-modeling assumptions, or (3) ensure proper handling of biosolids.A summary of the management practices for land application ofbiosolids is given in Table 1.5. Details on each of the land applicationmanagement practices are provided in the following sections.

    1.2.3.1 Endangered species. The 40 CFR Part 503 rule prohibits theland application of biosolids if they could have a negative impact onendangered or threatened species or their designated critical habitat.Critical habitat is defined as any environment where an endangeredor threatened species lives and grows during its life cycle [24]. It is theresponsibility of the land applier to determine if land application ofbiosolids will adversely affect the endangered species or their criticalhabitat. In addition to seeking advice from the permitting authority,land appliers can contact the U.S. Department of Interiors Fish andWildlife Service (FWS), which publishes an annual list of endangeredand threatened species [24,31].

    1.2.3.2 Application to flooded, frozen, or snow-covered land. Applicationof biosolids to flooded, frozen, or snow-covered land is not prohibitedby the 40 CFR Part 503 rule. However, biosolids applied to such landmust not enter surface waters or wetlands unless specifically autho-rized by a permit issued under Sections 402 or 404 of the CWA. Somecommon runoff controls at biosolids land-application sites includeslope restrictions, buffer zones/filter strips, berms, dikes, silt fences,diversions, siltation basins, and terraces [24,31].

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  • 1.2.3.3 Buffer zonedistance to surface waters. Bulk biosolids may notbe applied within 10 m (i.e., 33 ft) of any surface waters (e.g., inter-mittently flowing streams, creeks, rivers, wetlands, or lakes) of theUnited States unless otherwise specified by the permitting authority[24,31]. Permitting authorities can allow exceptions to this require-ment if the application of biosolids is expected to enhance the localenvironment. For example, biosolids application may be used to reveg-etate a stream bank or otherwise assist in minimizing bank erosion.

    1.2.3.4 Agronomic rates. The agronomic rate is a biosolids land appli-cation rate that will result in the application of nitrogen that justmeets crop or vegetative requirements, thus minimizing the amount ofnitrogen that will pass below the root zone of the crop or vegetation tothe groundwater. The 40 CFR Part 503 rule requires that the rate ofapplication of bulk biosolids be equal to or less than the agronomicrate except in the case of a reclamation site, where a different rate ofapplication may be allowed by the permitting authority. Although thebiosolids preparer is required to supply the biosolids land applier withinformation on the nitrogen content of the biosolids, the land applieris responsible for determining that the biosolids are applied at a ratethat does not exceed the agronomic rate for that site. Procedures forthe design of the agronomic rate differ depending on such factors asthe total and available nitrogen content, nitrogen losses, nitrogen fromsources other than biosolids, and the nutrient requirements for theexpected crop yield. Moreover, in some cases, phosphorus rather than

    Management Practices and Regulatory Requirements 1.21

    TABLE 1.5 40 CFR Part 503 Management Practices for Land-Applied Biosolids*

    Management practice Reason included in the 40 CFR Part 503 rule

    Protection of threatened or Consistency with federal regulation (50 CFR Partsendangered species 17.11 and 17.12)

    Restriction of biosolids land Prevents biosolids from entering surfaceapplication on flooded, frozen, or waters and wetlandssnow-covered ground

    Ten-meter (33-ft) buffer from U.S. Protects waters of the United States: helpswaters ensure risk is no greater than that calculated in

    the biosolids risk assessment, which assumed a10-m buffer zone from surface waters

    Agronomic application rate limit Protects groundwater from nitratecontamination

    Labeling requirements for bagged, Helps ensure that appliers use proper containerized biosolids application rates, which ensure that pollutant

    limits are met

    *Adapted from refs. [24,31].

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  • nitrogen is used for determination of the agronomic rate. For detailson the procedures for estimating the agronomic rate, see Chap. 7.

    1.2.3.5 Labeling requirements for bagged or containerized biosolids.Bagged or containerized biosolids sold or given away must be appliedat a rate equal to or less than the APLR limit (see Table 1.2). To ensurethat biosolids are applied at a rate that does not exceed the APLR lim-it, a label or information sheet must be affixed to the bag or container.At a minimum, the label or information sheet must contain the fol-lowing information:

    The name and address of the person who prepared the biosolids A statement that prohibits application of the biosolids to the land

    except in accordance with the instructions on the label or informa-tion sheet

    A maximum AWSAR that does not cause the APLR to be exceeded Biosolids nitrogen content

    It should be noted that it is the responsibility of the preparer ofbiosolids to calculate the AWSAR for biosolids (see Example 1.1).

    1.2.4 Pathogen levels in biosolidsIn addition to meeting pollutant limits and management practices,land-applied biosolids must meet either the Class A or Class Bpathogen-reduction criteria. The pathogen-reduction criteria for bothclasses of biosolids are given in Table 1.6. These criteria use a combi-nation of technological and microbiological approaches to ensure ade-quate protection of human health and the environment from

    1.22 Chapter One

    TABLE 1.6 Maximum Concentrations of Pathogens Permitted in Biosolids*

    Class A Biosolids

    Salmonella sp. Less than 3 MPN per 4 g total solids (or less than 1 103

    MPN fecal coliforms per gram total solids)

    Enteric viruses Less than 1 MPN per 4 g total solids

    Viable helminth ova Less than 1 MPN per 4 g total solids

    Class B Biosolids

    Fecal coliforms Less than 2 106 colony-forming units (CFUs) per gramtotal solids

    NOTE: These requirements must be met when the biosolids are used or disposed.*Adapted from ref. [34].MPN, most probable number.

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  • pathogens. The objective of the Class A criteria is to reduce thepathogens in biosolids to below detectable levels, whereas Class B cri-teria ensure that pathogen concentrations have been reduced to levelsthat are unlikely to pose a threat to public health and the environ-ment. Both Class A and Class B pathogen-reduction criteria are dis-cussed in greater detail in the following sections.

    1.2.4.1 Class A biosolids. All biosolids applied to lawns or home gar-dens and all biosolids sold or given away in bags or other containersmust meet Class A pathogen-reduction criteria (see Table 1.6).Biosolids that meet this more stringent level of pathogen control arenot subject to any harvesting or public access restrictions.

    To meet Class A pathogen-reduction criteria (Table 1.6), a POTW canchoose one of six alternatives. These alternatives include (1) use of atime/temperature-based process employed to treat the biosolids whilemeeting the pathogen limit in biosolids based on an indicator organ-ism (fecal coliforms) or Salmonella sp. (see Table 1.6), (2) use of analkali/air-drying stabilization process while also meeting thepathogen-based limit (see Table 1.6), (3) demonstration that the per-formance of a process for reducing enteric viruses and helminth ovameets the bacteria-based pathogen limit (see Table 1.6), (4) testing forpathogens (i.e., fecal coliform bacteria, enteric viruses, and helminthova) at the time biosolids are used or disposed, (5) biosolids treatmentin a process to further reduce pathogens (PFRP), or (6) use a processdeemed equivalent to PFRP by the permitting authority. Each of thesealternatives is summarized in Table 1.7.

    Management Practices and Regulatory Requirements 1.23

    TABLE 1.7 Alternatives Used to Meet Class A Biosolids Pathogen-Reduction Criteria

    Alternative 1: Thermally treated biosolidsAlternative 2: Biosolids treated in high pHhigh-temperature processAlternative 3: Biosolids treated in other processes*Alternative 4: Biosolids treated in unknown processesAlternative 5: Use of processes to further reduce pathogens (PFRPs)Alternative 6: Use of processes equivalent to PFRP

    *This requirement relies on comprehensive monitoring of bacteria, enteric viruses, andviable helminth ova as well as sludge treatment operating conditions. It is assumed that thetreatment process is meeting Class A criteria as long as it is operating under the same condi-tions that successfully reduced the pathogen densities.

    This requirement is similar to alternative 3, except that there is no option to substitutemonitoring of effective operating parameters for microbiological monitoring.

    PFRPs include (1) composting, (2) heat drying, (3) heat treatment, (4) thermophilic aerobicdigestion, (5) beta-ray irradiation, (6) gamma-ray irradiation, and (7) pasteurization.

    Any process that can be demonstrated, through microbiological monitoring, to reduceSalmonella sp., enteric viruses, and viable helminth ova to below detectable levels may beused for PFRP equivalency. This is normally conducted on a site-specific basis by the regula-tory authority.

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  • If a POTW chooses the first alternative, the generated biosolidsmust meet pathogen-reduction criteria (see Table 1.6) using either thefecal coliforms or Salmonella sp. as indicator organisms. The biosolidsmust be shown to contain fewer than 1103 most probable number(MPN) fecal coliforms per gram of total dry solids or less than 3 MPNSalmonella sp. per 4 g of total dry solids at the time the biosolids areused, disposed, or prepared for use or disposal. Additionally, the tem-perature must be maintained at a specified level and for a period oftime based on the type of heating process employed.

    For each of the four types of heating regimes described in the 40CFR Part 503 rule, empirical equations are used to determine the min-imum length of time that biosolids must be subjected to a given tem-perature to achieve Class A pathogen reduction (Table 1.8). Theempirical equations take into consideration (1) the solid-liquid charac-teristics of the biosolids, (2) particle size, and (3) the mechanism bywhich particles are brought into contact with the heat. In addition, thetime-temperature equations account for the fact that the internalstructure of the mixture can inhibit mixing. For example, since lessinformation is available about the operational parameters that couldinfluence pathogen destruction for heating regime C, a safety factor isincorporated in the time-temperature equation used for treatingbiosolids under these conditions. Use of the equations in Table 1.8 isillustrated in Examples 1.3 and 1.4.

    Example 1.3 The Poole County Water Reclamation Facility has installed abiosolids drier that will be operated at 65C (149F). If centrifuged biosolidshaving a solids content of 12 percent are to be discharged to the drier, esti-mate the minimum processing time necessary to achieve class A pathogen-reduction if heating regime A is followed.

    solution Use the time-temperature equation that describes regime A (seeTable 1.8) to estimate the minimum processing time.

    D

    0.105 day, or 2.51 hours (151 minutes)

    Example 1.4 The Poole County Water Reclamation Facility (see Example1.3) has determined that in order to minimize expenditures on biosolidsstorage facilities, it needs to have a maximum biosolids processing time inthe drier of 15 minutes (0.0104 day). To ensure that Class A biosolids canstill be generated by the system, what is the minimum temperature towhich biosolids must be subjected for the 15-minute period if heatingregime A is followed?

    131,700,000

    100.14 (65)131,700,000

    100.14 T

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  • solution Use the time-temperature equation that describes regime A (seeTable 1.8) to estimate the minimum processing temperature.

    D

    0.0104

    T 72.2C

    When the second alternative is chosen to achieve Class Abiosolids, the generated biosolids must meet the same pathogen con-centration limits as alternative 1 (see Table 1.6). In addition, thePOTW must raise the pH of the biosolids to 12 for 72 hours while thetemperature remains above 52C (125.6F) for at least 12 hours. Atthe end of the 72-hour period, the biosolids must be air-dried to 50percent solids [24].

    If alternative 3 is chosen to achieve Class A biosolids, the generatedbiosolids must meet the same pathogen-reduction criteria as alterna-tive 1 (see Table 1.6). In addition to meeting the pathogen-reduction cri-teria, the effectiveness of a Class A process must be demonstrated.

    131,700,000

    100.14 T

    131,700,000

    100.14 T

    Management Practices and Regulatory Requirements 1.25

    TABLE 1.8 Time-Temperature Requirements for Meeting Class A BiosolidsPathogen-Reduction RequirementsAlternative 1*

    Time-temperatureRegime Applies to Requirement equation

    A Biosolids with 7% Temperature of biosolidsD solids or greater must be 50C (122F) or

    higher for 20 min or longer

    B Biosolids with 7% Temperature of biosolidsD solids or greater in must be 50C (122F) or

    the form of small higher for 50 s or longerparticles and heated by contact with either warmed gases or an immiscible liquid

    C Biosolids with less Biosolids must be heatedD than 7% solids for at least 15 s but less

    than 30 min

    D Biosolids with less Temperature of biosolidsD than 7% solids is 50C (122F) or higher

    with at least 30 min or longer contact time

    *Adapted from ref. [34].D time in days; T temperature in degrees Celsius.

    50,070,000

    100.14 T

    131,700,000

    100.14 T

    131,700,000

    100.14 T

    131,700,000

    100.14 T

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  • Demonstration of a Class A process requires that the biosolids be ana-lyzed for enteric viruses and viable helminth ova before pathogen-reduction treatment. If the concentration of enteric viruses inuntreated biosolids does not exceed 1 plaque-forming unit (PFU) per 4g of total dry solids, and when viable helminth ova do not exceed oneper 4 g of total dry solids after pathogen-reduction treatment, thebiosolids are considered Class A until the next monitoring episode.When one or the other limit is exceeded before biosolids processing, butthe final pathogen criteria are met after processing, then the processparameters and their operational conditions used to achieve sufficientpathogen reduction must be documented. Future biosolids exiting thetreatment process are then considered to be Class A if the documentedoperational conditions are met during biosolids processing.

    When the POTW chooses alternative 4 (i.e., treatment in unknownprocesses) to achieve Class A biosolids, the biosolids must be tested atevery monitoring episode (i.e., when a batch of biosolids is recycled ordisposed or when the batch is being prepared for sale/give away) forthe concentration of either fecal coliform or Salmonella sp. as well asenteric viruses and viable helminth ova. If the fecal coliform concen-tration is less than 1103 MPN per gram of total solids or Salmonellasp. are less than 3 MPN per 4 g of total dry solids and enteric virusesand viable helminth ova are present at less than 1 PFU and one viablehelminth ovum per 4 g of total dry solids, respectively, then thebiosolids meet Class A pathogen-reduction criteria.

    Alternatives 5 and 6 pe