HANDBOOK OF

ENVIRONMENTAL ENGINEERING

Volume 3

Biological Treatment

Processes

HANDBOOK OF

ENVIRONMENTAL ENGINEERING

Volume 1: Air and Noise Pollution Control

Volume 2: Solid Waste Processing and Resource Recovery

Volume 3: Biological Treatment Processes

Volume 4: Water Resources and Natural Control Processes

Volume 5: Physicochemical Technologies for Water and

Wastewater Treatment

HANDBOOK OF ENVIRONMENTAL

ENGINEERING

Volume 3 Biological Treatment

Processes Edited by

Lawrence K. Wang

Lenox Institute for Research Inc. Lenox, Massachusetts

and

Norman C. Pereira

Monsanto Company St. Louis, Missouri

The HUMANA Press' Clifton, New Jersey

Library of Congress Catalogjng-in-Publication Data

Main entry under title:

Biological treatment processes. (Handbook of environmental engineering; v. 3) Includes bibliographies and index. I. Sewage-Purificatiol}-Biological treatment-Hand­

books, manuals, etc. I. Wang. Lawrence K. II. Pereira. Noman C. Ill. Series. TD170.H37 vol. 3 [TD755J ISBN-13: 978-1-4612-9176-3 DOl: 10.1007/978-1-4612-4820-0

628 s [628.3'5IJ 85-8226 e-ISBN-13: 978-1-4612-4820-0

© 1986 The HUMANA Press Inc .. Crescent Manor - P.O. Box 2148 . Clifton, Softcover reprint of the Hardcover 1st edition 1986

NJ 07015

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher.

Preface

The past few years have seen the emergence of a growing, widespread desire in this country, and indeed everywhere, that positive actions be taken to restore the quality of our environment, and to protect it from the degrading effects of all forms of pollution-air, noise, solid waste, and water. Since pollution is a direct or indirect consequence of waste, if there is no waste, there can be no pollution, and the seemingly idealistic demand for "zero discharge" can be construed as a demand for zero waste. However, as long as there is waste, we can only attempt to abate the consequent pollution by converting it to a less noxious form. In those instances in which a particular type of pollution has been recognized, three major questions usually arise: (1) How serious is the pollution? (2) Is the technology to abate it available? and (3) Do the costs of abatement justify the degree of abatement achieved? The principal intention of this series of books on environmental engineering is to help the reader formu­late useful answers to the second and third of these questions, i.e., to outline the best currently available engineering solutions, and to examine their costs in the light of the real level of benefits afforded.

The traditional approach of applying tried-and-true solutions to specific pollution problems has been a major factor contributing to the success of environmental engineering, and in large measure has ac­counted for the establishment of a "methodology of pollution control. " However, realizing the already great complexity of current environmental problems, and understanding that, as time goes on, these issues will be­come even more complex and interrelated, render it imperative that intel­ligent planning of pollution abatement systems be undertaken. Prerequi­site to such planning is an understanding of the performance, potential, and limitations of the various methods of pollution abatement available for environmental engineering. In this series of books, we are reviewing at a practical tutorial level a broad spectrum of engineering systems (proc­esses, operations, and methods) currently being utilized, or of potential utility, for such pollution abatement. We believe that the unification of

v

vi PREFACE

the concepts and engineering methodology found in these books is a logi­cal step in the evolution of environmental engineering.

The treatment of the various engineering systems presented will show how an engineering formulation of the subject flows naturally from the fundamental principles and theory of chemistry, physics, and mathe­matics. This emphasis on fundamental science is based on the recognition that engineering practice has of necessity in recent years become more firmly based on scientific principles, rather than depending largely on our empirical accumulation of facts, as was earlier the case. It was not in­tended, though, to neglect empiricism when such data lead quickly to the most economic design; certain engineering systems are not readily ame­nable to fundamental scientific analysis, and in these instances we have resorted to less science in favor of more art and empiricism.

Since an engineer must understand science within a context of appli­cations, we first present the development of the scientific basis of a partic­ular subject, followed by an exposition of the pertinent design concepts and operations, and then by detailed explanations of their applications to environmental quality control or improvement. Throughout, methods of practical design calculation are illustrated by numerical examples. These examples clearly demonstrate how organized, analytical reasoning leads to the most direct and clear solution. Wherever possible, pertinent cost data have been provided.

Our treatment of pollution-abatement engineering is offered in the belief that the trained engineer should more firmly understand fundamen­tal principles, be more aware of the similarities and/or differences among many of the engineering systems, and exhibit greater flexibility and origi­nality in the definition and innovative solution of environmental pollution problems. In short, the environmental engineer should by conviction and practice be more readily adaptable to change and progress.

Coverage of the unusually broad field of environmental engineering has demanded an expertise that could only be provided through multiple authorship. Each author (or group of authors) was permitted to employ, within reasonable limits, his or her personal style in organizing and pres­enting a particular subject area, and consequently it has been difficult to treat all subject material in a homogeneous manner. Moreover, owing to limitations of space, some of the authors' favored topics could not be treated in great detail, and many less important topics had to be merely mentioned or commented on briefly. In addition, treatment of some well­established operations, such as distillation and solvent extraction, has been totally omitted. All of the authors have provided an excellent list of references at the end of each chapter for the benefit of the interested reader. Each of the chapters is meant to be self-contained, and conse-

PREFACE vii

quently some mild repetition among the various texts was unavoidable. In each case, all errors of omission or repetition are the responsibility of the editors and not the individual authors. With the current trend toward metrication, the question of using a consistent system of units has been a problem. Wherever possible the authors have used the British System (fps), along with the metric equivalent (mks, cgs, or SIU), or vice versa. The authors sincerely hope that this inconsistency of units usage does not prove to be disruptive to the reader.

The series has been organized in five volumes: 1. Air and Noise Pollution Control 2. Solid Waste Processing and Resource Recovery 3. Biological Treatment Processes 4. Water Resources and Natural Control Processes 5. Physicochemical Technologies for Water and Wastewater

Treatment As can be seen from the above titles, no consideration is given to

pollution by type of industry, or to the abatement of specific pollutants. Rather, the above categories are devised from the three basic forms in which pollutants and waste are manifested: gas, solid, and liquid. In addi­tion, noise pollution control is included in Volume 1.

This Engineering Handbook is designed to serve as a basic text, as well as a comprehensive reference book. We hope and expect it will prove of equal high value to advanced undergraduate or graduate stu­dents, to designers of pollution abatement systems, and to research work­ers. The editors welcome comments from all readers. It is our hope that these volumes will not only provide information on the various pollution abatement technologies, but will also serve as a basis for advanced study or specialized investigation of the theory and practice of the individual engineering systems covered.

The editors are pleased to acknowledge the encouragement and sup­port received from their colleagues at the Environmental and Energy Sys­tems Department of Cal span Corporation during the conceptual stages of this endeavor. We wish to thank the contributing authors for their time and effort, and for having borne patiently our numerous queries and com­ments. Finally, we are grateful to our respective families for their pa­tience and understanding during some rather trying times.

LAWRENCE K. WANG Lenox, Massachusetts

NORMAN C. PEREIRA St. Louis, Missouri

Contents

Preface ................................................... v Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. xix

CHAPTER 1

BIOSCIENCE CONCEPTS FOR ENVIRONMENTAL CONTROL...................................... 1

MARY Lou BUNGA Y AND HENRY R. BUNGA Y

I. Introduction.................................... 1 II. The Cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

III. Biochemistry................................... 3 A. Important Compounds. . . . . . . . . . . . . . . . . . . . . . . . 3 B. Photosynthesis............................... 8 C. Chemosynthesis ............................. 9 D. Respiration ................................. 10 E. Nutrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

IV. Microbiology................................... 13 A. Bacteria.................................... 13 B. Algae...................................... 15 C. Protozoa.................................... 15 D. Fungi...................................... 16 E. Viruses..................................... 17 F. Other...................................... 18

V. Ecology....................................... 18 A. Structure of the Ecosystem .................... 18 B. Biogeochemical Cycles. . . .. . .. .. .. . . . . . .. . .. . 19 C. Interspecies Relationships ..................... 20 D. Population Dynamics. . . . . . . . . . . . . . . . . . . . . . . . . 22

ix

X CONTENTS

VI. Physical and Biological Factors in Waste Treatment Ecosystems .................................... 24 A. Chemical Composition of the Medium. . . . . . . . . . . 24 B. Indices of Pollution .......................... 25 C. Flow Rates and Concentration. . . . . . . . . . . . . . . . . . 26 D. Surfaces and Substrata. . . . . . . . . . . . . . . . . . . . . . . . 27 E. Nutrition~ Shifts .... ... ..... ................ 27 F. Biological Interactions. . . . . . . . . . . . . . . . . . . . . . . . 28 G. Ecological Succession ........................ 29

VII. Conclusions.................................... 30 Suggested Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 I

CHAPTER 2

TREATMENT BY APPLICATION ONTO LAND . . . . . . . . . . . . 33

DONALD B. AULENBACH AND NICHOLAS L. CLESCERI

I. Introduction.................................... 33 A. Scope...................................... 33 B. Philosophy.................................. 34

II. Types......................................... 36 A. Surface Spreading. . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 B. Slow Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 C. Rapid Infiltration-Percolation .................. 40 D. Vegetative Cover vs Bare Ground. . . . . . . . . . . . . . . 41 E. Final Residence of Liquid. . . . . . . . . . . . . . . . . . . . . 42 F. Chlorination................................. 43

III. Processes...................................... 43 A. Physical.................................... 44 B. Physical-Chemical . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 C. Chemical................................... 48 D. Biological.................................. 49 E. Process Applications. . . . . . . . . . . . . . . . . . . . . . . . . . 54

IV. Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 A. Preliminary Studies. . . . . . . . . . . . . . . . . . . . . . . . . . . 62 B. Application Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 C. Distribution Facilities. . . . . . . . . . . . . . . . . . . . . . . . . 64 D. Monitoring.................................. 65

V. Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 A. Effectiveness................................ 67 B. Applicability................................ 68 C. Cost....................................... 69

CONTENTS xi

D. Ease of Design for Various Conditions. . . . . . . . . . . 71 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

CHAPTER 3

TREATMENT BY SUBSURFACE APPLICATION........... 91

NICHOLAS L. CLESCERI, DONALD B. AULENBACH, AND

JAMES F. ROETZER

I. Introduction.................................... 91 II. Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

A. Pretreatment in a Tank. . . . . . . . . . . . . . . . . . . . . . . . 93 B. Subsurface Disposal. . . . . . . . . . . . . . . . . . . . . . . . . . 96

III. Design........................................ 106 A. General Considerations. . . . . . . . . . . . . . . . . . . . . . . . 106 B. Septic Tank Design .......................... 107 C. Aerobic Tank Design. . . . . . . . . . . . . . . . . . . . . . . . . 108 D. Conventional Tile Field . . . . . . . . . . . . . . . . . . . . . . . 110 E. Aerobic Tile Field ........................... 116 F. Seepage Pit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 G. Institutional and Multiple Dwelling Systems . . . . . . 120 H. Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

IV. State of the Art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 A. Tank Treatment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 B. Effluent Disposal ............................ 124 C. Nutrient Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

V. Conclusions.................................... 126 A. Cost Estimation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 B. Sample Design Problems. . . . . . . . . . . . . . . . . . . . . . 128 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

CHAPTER 4

SUBMERGED AERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

JERRY Y. C. HUANG

I. Introduction.................................... 135 II. Aeration Performance Evaluation. . . . . . . . . . . . . . . . . . . 136

A. Hydraulic Regimes of Performance Evaluation. . . . 137 B. Means of Deoxygenation. . . . . . . . . . . . . . . . . . . . . . 139 C. Oxygen Saturation Concentration. . . . . . . . . . . . . . . 140 D. Data Analysis and Interpretation. . . . . . . . . . . . . . . . 142

xii CONTENTS

III. Submerged Aeration Systems. . . . . . . . . . . . . . . . . . . . . . 147 A. System Components. . . . . . . . . . . . . . . . . . . . . . . . . . 147 B. Major Types of Submerged Aerators. . . . . . . . . . . . 148

IV. Design Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 A. Types of Design Problems. . . . . . . . . . . . . . . . . . . . . 157 B. Case Study Example. . . . . . . . . . . . . . . . . . . . . . . . . . 159 Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

CHAPTER 5

SURFACE AND SPRAY AERATION. . . . . . . . . . . . . . . . . . . . . 169

CHIN-SHU LIU AND SHu-HONG SHIEH

I. Introduction.................................... 169 II. Fundamental Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

A. Equilibrium................................. 170 B. Gas Solubility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 C. Molecular Diffusion. . . . . . . . . . . . . . . . . . . . . . . . . . 172 D. Turbulent Mixing. . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 E. Air-Water Interface. . . . . . . . . . . . . . . . . . . . . . . . . . 176

III. Theories of Gas Transfer. . . . . . . . . . . . . . . . . . . . . . . . . 176 A. Mass Transfer Equation. . . . . . . . . . . . . . . . . . . . . . . 176 B. Two-Film Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 C. Penetration Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 D. Film-Penetration Model. . . . . . . . . . . . . . . . . . . . . . . 182 E. Surface Renewal-Damped Eddy Diffusion Model. . 182 F. Turbulent Diffusion Model. . . . . . . . . . . . . . . . . . . . 183 G. Other Models .... . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 H. Comparison of Gas Transfer Coefficients. . . . . . . . . 184 I. Gas-Liquid Relation. . . . . . . . . . . . . . . . . . . . . . . . . . 185

IV. Aeration Equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 A. Significance of the Aeration Equation. . . . . . . . . . . . 186 B. Influencing Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . 188 C. Natural Reaeration . . . . . . . . . . . . . . . . . . . . . . . . . . . 190

V. Surface Aeration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 A. Introduction................................. 197 B. Types of Surface Aerators. . . . . . . . . . . . . . . . . . . . . 198 C. Techniques for Surface Aerator Performance Test. . 199 D. Surface Aerator Design. . . . . . . . . . . . . . . . . . . . . . . 205 E. Artificial Instream Aeration. . . . . . . . . . . . . . . . . . . . 206

CONTENTS xiii

VI. Spray Aeration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 A. Introduction................................. 210 B. Types of Spray Aerators '" . . . . . . . . . . . . . . . . . . . 211 C. Spray Aeration Applications . . . . . . . . . . . . . . . . . . . 215 D. Spray Aerator Design. . . . . . . . . . . . . . . . . . . . . . . . . 218 Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

CHAPTER 6

ACTIVATED SLUDGE PROCESSES. . . . . . . . . . . . . . . . . . . . . 229

CALVIN P. C. POON, LAWRENCE K. WANG, AND

Mu HAO SUNG WANG

I. Concepts and Physical Behavior . . . . . . . . . . . . . . . . . . . 229 A. Definition of Process. . . . . . . . . . . . . . . . . . . . . . . . . 229 B. Principles of Biological Oxidation. . . . . . . . . . . . . . . 231 C. Energy Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 D. Synthesis and Respiration .. . . . . . . . . . . . . . . . . . . . 240

II. System Variables and Control. . . . . . . . . . . . . . . . . . . . . 242 A. Kinetics of Sludge Growth and Substrate Removal. 242 B. Process Variables, Interactions, and Their

Significance in Process Operation and Performance 251 C. Aeration Requirements. . . . . . . . . . . . . . . . . . . . . . . . 254 D. Temperature Effect. . . . . . . . . . . . . . . . . . . . . . . . . . . 258

III. System Modifications and Design Criteria . . . . . . . . . . . 259 A. The Conventional Activated Sludge Process ...... 259 B. Step Aeration Process. . . . . . . . . . . . . . . . . . . . . . . . . 261 C. Complete Mix Process . . . . . . . . . . . . . . . . . . . . . . . . 262 D. Extended Aeration Process. . . . . . . . . . . . . . . . . . . . . 262 E. Contact Stabilization Process. . . . . . . . . . . . . . . . . . . 263 F. Kraus Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 G. Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 H. Other Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

IV. Computer Aid in Process Design and Operation. . . . . . . 270 A. Prediction of Performance. . . . . . . . . . . . . . . . . . . . . 271 B. Computer Program for Process Design. . . . . . . . . . . 275 C. Computer Aid in Process Operation . . . . . . . . . . . . . 275

V. Practice and Problems in Process Control. . . . . . . . . . . . 277 A. Wasting Sludge, Feedback, and Feed Forward

Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277

xiv CONTENTS

B. Bulking of Sludge and Rising of Sludge ......... 282 VI. Capital and Operating Cost. . . . . . . . . . . . . . . . . . . . . . . . 284

A. Traditional Cost Estimates. . . . . . . . . . . . . . . . . . . . . 285 B. Worksheet for Cost Estimates . . . . . . . . . . . . . . . . . . 286 C. Improvements of Cost Estimation Techniques . . . . . 288

VII. Latest Process Development. . . . . . . . . . . . . . . . . . . . . . . 290 A. Step Sludge Process. . . . . . . . . . . . . . . . . . . . . . . . . . 290 B. High Rate Adsorption-Biooxidation Process. . . . . . 291 C. The Oxygenated Activated Sludge Process. . . . . . . . 293 Appendixes ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 A. Notation.................................... 299 B. Definition of Terms, CASSO Program. . . . . . . . . . . 300 C. Sample Worksheet for Cost Estimates ........... 301 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297

CHAPTER 7

WASTE STABILIZATION PONDS AND LAGOONS......... 305

CALVIN P. C. POON, LAWRENCE K. WANG, AND Mu HAO SUNG WANG

I. Concept and Physical Behavior . . . . . . . . . . . . . . . . . . . . 305 A. Pond Ecology and Process Reactions. . . . . . . . . . . . 306 B. Biology of Stabilization Ponds ................. 313 C. Classification of Stabilization Ponds . . . . . . . . . . . . . 317

II. System Variables and Control. . . . . . . . . . . . . . . . . . . . . 319 A. Kinetics of Substrate Removal. . . . . . . . . . . . . . . . . . 319 B. Oxygen Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323 C. Temperature Effect. . . . . . . . . . . . . . . . . . . . . . . . . . . 327 D. Detention Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328

III. Design Criteria .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 A. Design Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . 329 B. Inlet Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 C. Outlet Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 D. Transfer Pipes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 E. Berm Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 F. Bottom Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . 333

IV. Practice and Problems in Process Control. . . . . . . . . . . . 333 A. Staging of Ponds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 B. Pond Recirculation . . . . . . . . . . . . . . . . . . . . . . . . . . . 334

CONTENTS XV

C. Pond Mixing and Aeration. . . . . . . . . . . . . . . . . . . . . 335 D. Odor Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337 E. Algal Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338 F. Insect Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

V. Capital and Operation Costs. . . . . . . . . . . . . . . . . . . . . . . 341 VI. Latest Process Developments. . . . . . . . . . . . . . . . . . . . . . 343

A. Nutrient Removal and Controlled Eutrophication. . . 343 B. Integrated Pond System. . . . . . . . . . . . . . . . . . . . . . . 348

VII. Examples of Process Design ...................... 349 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357

CHAPTER 8

TRICKLING FILTERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

LAWRENCE K. WANG, Mu HAO SUNG WANG, AND

CAL YIN P. C. POON

I. Introduction.................................... 361 A. Process Description of Attached Growth Systems. . 361 B. Historical Development and Applicability of

Attached Growth Systems . . . . . . . . . . . . . . . . . . . . . 364 C. Microbiology and Ecology. . . . . . . . . . . . . . . . . . . . . 367

II. Theories and Mechanisms. . . . . . . . . . . . . . . . . . . . . . . . . 369 A. Transfer of Oxygen in Slime Layer and

Liquid Film. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369 B. Transfer of Substrate in Liquid Film and Slime

Layer. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . 370 III. Types of Trickling Filters. . . . . . . . . . . . . . . . . . . . . . . . . 373

A. General Description. . . . . . . . . . . . . . . . . . . . . . . . . . 373 B. Low-Rate, High-Rate, and Super-Rate Filters. . . . . 373 C. Single- and Multi-Stage Trickling Filter Plants . . . . 380

IV. Performance Models and Design Procedures ....... . . 382 A. National Research Council Models. . . . . . . . . . . . . . 382 B. Velz Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384 C. Upper Mississippi River-Great Lakes Board

Model.. . ........... ........... ...... .... .. 385 D. Howland Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 385 E. Eckenfelder Models . . . . . . . . . . . . . . . . . . . . . . . . . . 386 F. Galler and Gotaas Model. . . . . . . . . . . . . . . . . . . . . . 387 G. Biofilm Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388

xvi CONTENTS

H. U.S. Army Design Formulas. . . . . . . . . . . . . . . . . . . 388 I. U.S. Environmental Protection Agency Model. . . . 389

V. Design and Construction Considerations . . . . . . . . . . . . . 390 VI. Process Control Considerations . . . . . . . . . . . . . . . . . . . . 393

VII. Energy Considerations ........................... 396 VIII. Application, Performance, and Reliability ........... 396

IX. Limitations and Environmental Impact . . . . . . . . . . . . . . 397 X. Design Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397

Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423

CHAPTER 9

ROTATING BIOLOGICAL CONTACTORS . . . . . . . . . . . . . . . . 427

Mu HAO SUNG WANG, LAWRENCE K. WANG, AND

CALVIN P. C. POON

I. Introduction.................................... 427 II. Factors Affecting Performance and Design. . . . . . . . . . . 428

A. Microorganisms and Environmental Factors. . . . . . . 428 B. Media Selection and Arrangement. . . . . . . . . . . . . . . 430 C. Loadings and Hydraulic Parameters . . . . . . . . . . . . . 430

III. Performance Models and Design Procedures ......... 431 A. US Environmental Protection Agency Model. . . . . . 431 B. Modified US Environmental Protection Agency

Model ...................... " . " ... . .. . .. . 432 C. Manufacturer's Design Procedures . . . . . . . . . . . . . . 432

IV. Process Control Considerations . . . . . . . . . . . . . . . . . . . . 435 V. Application, Performance, and Reliability ........... 436

VI. Limitations and Environmental Impact. . . . . . . . . . . . . . 437 VII. Design Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447 Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448

CHAPTER 10

ANAEROBIC SLUDGE DIGESTION. . . . . . . . . . . . . . . . . . . . . 449

DAVID A. LONG

I. Introduction.................................... 449 II. Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450

A. Nature of Organic Wastes. . . . . . . . . . . . . . . . . . . . . 450

CONTENTS xvii

B. Biochemistry and Microbiology of the Anaerobic Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451

C. Reactor Configurations. . . . . . . . . . . . . . . . . . . . . . . . 453 D. Organic Loading Parameters. . . . . . . . . . . . . . . . . . . 455 E. Time and Temperature Relationships . . . . . . . . . . . . 456 F. Nutrient Requirements. . . . . . . . . . . . . . . . . . . . . . . . 458 G. Gas Production and Utilization . . . . . . . . . . . . . . . . . 459

III. Design Practice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 460 A. Anaerobic Treatability Studies. . . . . . . . . . . . . . . . . . 460 B. Anaerobic Reactor Design and Sizing. . . . . . . . . . . . 463 C. Tank Construction and System Components ...... 465 D. System Equipment and Appurtenances. . . . . . . . . . . 468 E. Gas Utilization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480 F. Sludge Pumping and Piping Considerations. . . . . . . 481

IV. Management of Digestion. . . . . . . . . . . . . . . . . . . . . . . . . 482 A. Control of Sludge Feed . . . . . . . . . . . . . . . . . . . . . . . 482 B. Withdrawal of Sludge and Supernatant. . . . . . . . . . . 482 C. Maintenance of Reactor Stability. . . . . . . . . . . . . . . . 483 D. Digester Performance Criteria. . . . . . . . . . . . . . . . . . 483

V. Capital and Operating Costs. . . . . . . . . . . . . . . . . . . . . . . 484 A. General.................................... 484 B. Items Included in Cost Estimates ............... 484

VI. Design Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 486 A. Example Using Standards Design. . . . . . . . . . . . . . . 486 B. Example Using Solids Loading Factor. . . . . . . . . . . 488 C. Example Using Modified Anaerobic Contact. . . . . . 491 Nomenclature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 493 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494

Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 495

Contributors

DONALD B. AULENBACH • Department of Chemical and Environmental Engineering. Rensselaer Polytechnic Institute. Troy. New York.

HENRY R. BUNGAY • Department of Chemical and Environmental Engi­neering. Rensselaer Polytechnic Institute. Troy. New York.

MARY LOU BUNGA Y • Rensselaer Polytechnic Institute. Troy. New York.

NICHOLAS L. CLESCERI • Department of Chemical and Environmental Engineering. Rensselaer Polytechnic Institute. Troy. New York.

JERRY Y. C. HUANG· Department of Civil Engineering. University of Wisconsin at Milwaukee. Milwaukee. Wisconsin.

CHIN-SHU LIU • New York State Department of Environmental Conserva­tion. Albany. New York.

DAVID LONG • Department of Civil Engineering. Pennsylvania State Univer­sity. University Park. Pennsylvania.

NORMAN C. PEREIRA· Monsanto Company. St. Louis, Missouri.

CALVIN P. C. POON • Department of Civil and Environmental Engineering. University of Rhode Island. Kingston. Rhode Island.

JAMES F. ROETZER • Envirosphere Company. Two World Trade Center. New York. New York.

SHU-HONG SHIEH • Charles J. Kupper. Inc.. Piscataway. New Jersey.

LAWRENCE K. WANG· Lenox Institute for Research Inc .. Lenox. Massachusetts.

MU HAO SUNG WANG· New York State Department of Environmental Con­servation. Albany. New York.

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