TREATMENT

WETLANDSRobert H. Kadlec

The University of Michigan, Ann Arborand

Management ServicesChelsea, Michigan

Robert L. KnightCH2M HILL

Gainesville, Florida

LEWIS PUBLISHERSBoca Raton New York London Tokyo

Table of Contents

Section 1 Introduction and Scope

Chapter 1Introduction to Wetlands for Treatment 3

Why Wetlands? 3Historical Perspective 5Organization and Scope of This Book 13Key References Concerning Treatment Wetlands 16

Chapter 2Review of Water Quality Treatment Needs 19

Sources of Pollutants 20Conventional Treatment Technologies 23

Chapter 3Natural Systems For Treatment 31

Upland Natural Treatment Systems 33Onsite Infiltration 35Slow-Rate Land Application 37High-Rate Land Application (Rapid Infiltration) 39Overland Flow Systems 40

Aquatic and Wetland Systems 40Facultative Ponds 41Floating Aquatic Plant Systems 42Wetland Systems 43

Section 2 Wetland Structure and Function

Chapter 4Landform and Occurrence 49

What is a Wetland? 49Distribution of Natural Wetlands 53Constructed Wetlands 55

Habitat Wetlands 56Constructed Treatment Wetlands 58Flood Control Wetlands 60Constructed Aquaculture Wetlands 60

Chapter 5Wetland Soils 63

What Are Wetland Soils? 63Accumulation Rates of Wetland Soils 65Physical Properties of Hydric Soils 67Hydric Soil Chemical Properties 69

Cation Exchange Capacity 69Oxidation and Reduction Reactions 70Hydrogen Ion (pH) 73Phosphorus Dynamics 74

Biological Influences on Hydric Soils 75Microbial Soil Processes 75Wetland Algae and Macrophytes 76Effects of Animals on Wetland Soils 77

Treatment Wetland Soils 78Surface-Flow Wetlands 78Subsurface-Flow Wetlands 79

Chapter 6Wetland Hydrology and Water Quality 81

Wetland Hydrology 81Definition of Hydrologic Terms 82Global Water Mass Balances 87Water Mass Balance Impacts on Pollutant Reductions 98Wetland Water Quality 99

Ambient Concentrations in Natural Wetlands 102Particulate and Dissolved Forms 105Temporal Patterns 105Spatial Patterns 107Variability in Measurements 108

Biogeochemical Cycling 109Global Chemical Budgets 111

Chemical Terminology 116

Chapter 7Wetland Microbial and Plant Communities 119

Wetland Bacteria and Fungi 120Wetland Algae 126Wetland Macrophytes 131

Chapter 8Wetland Wildlife 157

Invertebrates 158Fish .' 165Amphibians and Reptiles 168Birds 171Mammals 176

Section 3 The Effects of Wetlands on Water Quality

Chapter 9Hydraulic and Chemical Design Tools 181

Wetland Evapotranspiration 181Surface-Flow Wetlands 182

Predictive Tools 184Pan Factor Methods 184Energy Balance Methods 185Heat Transfer and Water Convective Mass Transfer 188

Forested Wetlands 192Subsurface-Flow Wetlands 192

Overland Flow in Wetlands 194The Conservation Laws 194Friction Equations 196Friction Equation Coefficients 199

Manning's Coefficients 199The Power Law Model 201

Head Loss Calculations 203The Effects of Rain and ET 206

Subsurface Wetland Hydraulics 207The Geohydrological Background 208

Adaptations for SSF Wetlands 209Bed Friction and Hydraulic Conductivity 209

Correlations for Hydraulic Conductivity 211Measurement of Hydraulic Conductivity 213Soil-Based Systems 215Clogging 215

Surface Water Elevation Profiles 218The Simplest Case 219Rapid Assessment of Profiles 220Flooded Operation 220Dynamic Responses: Rain and ET 222Shadow Zones 223

Vertical Shadow Zones 223Corner Zones 224

Hydraulic Design of SSF Wetlands 225Large Bottom Slopes, Outlet Level Adjustment 225Robust Design Procedure 227Design Criteria 229

Bed Slope 229Loading 229

A Hydraulic Design Example 234Nonideal Flow Patterns 236

Gross Areal Efficiency 236Vertical and Transverse Mixing 238

The Theoretical Background 240Chemical Reaction Calculations 243Models for Wetland Mixing with Reaction 245Data Analysis, The RTD, Design and This Book—IMPORTANT! 247The Tanks-in-Series Model (TIS) 248

Chemical Reactions in TIS 249Tanks-in-Series Model with a Delay 252Plug Flow Modified by Dispersion 254Regression of Numerical Model 254

Chemical Reactions in PFD 255Chemical Reactions in Partially Mixed Wetlands: An Approximation 256

A Mass Balance Design Model 258Rationale .' 258Compartmental Analysis 259

The Water Compartment 260The Static Compartments 262

Lumping 263

Simplifying Situations 265Simplification for the Stationary State 266Averaging Pulse Driven Systems 270

Mass Transfer with Reaction: Biofilm Processes 271Thick Biofilms 271Very Fast Reaction in a Very Thin Film 272Specific Surface Area 273

Temperature Dependence 275Velocity Dependence 275

The Mass Transfer Step 275Surface-Flow Wetlands 275Subsurface-Flow Wetlands 276Closure 277

Wetlands with Water Losses or Gains 277The Plug Flow Case 277

Chapter 10Temperature, Oxygen, and pH 281

Wetland Water Temperatures 281Wetland Temperatures in Spring, Summer, and Fall 283

Surface-Flow Wetlands 283The Balance Point Temperature 283Approach to the Balance Point Temperature 284

Subsurface-Flow Wetlands 287Empirical Observations 287

Wetlands in Winter 288Surface-Flow Wetlands 288

Energy Balance Calculations 290Subsurface-Flow Wetlands 294

Oxygen Transfer to Wetland Waters 296Biochemical Production of Oxygen 297Oxygen Consumption in the Water 299Physical Oxygen Transfer to Water 299Gravel Bed Mass Transfer 301Plant Oxygen Transfer 301

.Oxygen Sag Curves in SF Wetlands 304Prediction of Wetland Effluent Dissolved Oxygen 308

Wetland Hydrogen Ion Concentrations 308Treatment Wetlands ;.T 310

Chapter 11Suspended Solids 315

Solids Measurement 315Paniculate Processes in Surface-Flow Wetlands 316

Component Processes 316Settling of Particulates 316Resuspension 320Resuspension: The Extreme Case of Planar Sediment Beds 322"Filtration" 323Biological Sediment Generation 324Chemical Precipitation and Dissolution Reactions 324

Some Internal Details 324Rate Equations 325Averaging 326Model Verification 327Model Parameters 328Sediment Buildup 328

Data Regression 329Percent Removal 330

Effects of Temperature and Season 331Paniculate Processes in Subsurface-Flow Wetlands 333

Regression Equations 334Clogging 335

Pond-Wetland Combinations 336Design Examples 338

Chapter 12Biochemical Oxygen Demand 341

Measures of Carbon Content 341BOD, COD, and TOC 342Wetland Water Chemistry of Carbon 342

Inorganic Carbon 342Organic Carbon 344

Carbon Processing in Wetland Soils 345Overall Input/Output Correlations 348

Regression Equations 349Surface-How Wetlands 349Subsurface-Flow Wetlands 350Internalization 351

Mass Balance Design Model 351Rationale 351Model Equations 353

Surface-Flow Wetlands 353Subsurface-Flow Wetlands 354Volumetric vs. Areal Models 355

Parameter Values 355BOD Reduction Parameters for SF Wetlands 355BOD5 Reduction in SSF Wetlands 357BOD5 Reduction in Soil-Based SSF Wetlands 358

First-Order Models Without C*: Irreversible Models 360Ponds 363Floating Aquatic Beds 363

Temperature Effects on BOD5 Reduction 363Surface-Flow Wetlands 364Soil-Based Wetlands 365Subsurface-Row Wetlands 365Speculation on Contributing Factors 365

Short-Term Variations in BOD5 Concentrations 366Adaptation Trends 368Stochastic Variability 369

Impact of Variability on Design 369

Chapter 13Nitrogen 373

Nitrogen Forms and Storages in Wetlands 373Inorganic Nitrogen Compounds 373

Ammonia 373Nitrite 374Nitrate 374Gaseous and Atmospheric Forms of Nitrogen 375

Organic Nitrogen Compounds 375Amino Acids 375Urea and Uric Acid 375Pyrimidines and Purines 376

Total Nitrogen 376Wetland Nitrogen Storages 376

Nitrogen Transformations in Wetlands 377Ammonification (Mineralization) 380Nitrification 383

Nitrification Reaction Chemistry 383Results from Other Technologies: Monod Kinetics and Environmental Factors 385

Environmental Factors Affecting Nitrification in Suspended Growth 386Attached Growth Treatment Systems 388Relation to Treatment Wetlands 389

Ponds 389Area-Based, First-Order Ammonia Disappearance Model 390Sequential Ammonium Kinetics 392Solution for the Plug Flow Case 396Data Fits 396Environmental Factors in Operating Wetlands 399

Denitrification 400Chemical Reactions 400Results from Other Technologies: Monod Kinetics and Environmental Factors 402

Monod Kinetics 402First-Order Models 403

Temperature Coefficients from Wetland Data 404Accounting for Nitrate Production 407Nitrogen Fixation 407Nitrogen Assimilation 408

Other Nitrogen Fluxes 410Atmospheric Nitrogen Inputs 410Ammonia Volatilization 411Biomass Decomposition 413Burial of Organic Nitrogen 414Ammonia Adsorption 414

Total Nitrogen Removal Rates in Wetlands 415North American Treatment Wetlands 416Design Factors Affecting Total Nitrogen Removal 417Area-Based, First-Orde^k-C* Model for Total Nitrogen 420

Effects of Season and Temperature 422Other Factors that Affect Total Nitrogen Removal 426

Design Approaches to Remove Nitrogen 427Regulatory Limits and Stochastic Variability 427

Preliminary Estimates of Nitrogen Removal 429Correlative Input/Output Design Approaches 431

Some Historical Perspective 431Regressions for Wetland Nitrogen Removal 434

Mass Balance Design for Nitrogen Removal 436Total Nitrogen 436

Nitrogen Component Transformations—Organic Nitrogen 438Nitrogen Component Transformations—Ammonium Nitrogen 438Nitrogen Component Transformations—Nitrate Nitrogen 440

Chapter 14Phosphorus 443

Process Characterization 443Wetland Water Chemistry of Phosphorus 445Plant Chemistry of Phosphorus 447Biomass: Growth, Death, Decomposition 448Uptake and Storage by Biota 449Physical Processes 451Soil Water Phosphorus Processes 451

Storage Potential: Soils 451Sorption Isotherms 453Rates of Movement of Phosphorus in Soils Without Vegetation 455

Frontal Movement 455Downward Diffusion 456

Phosphorus Releases 456Overall Input-Output Correlations 457

Emergent Marshes 458Forested Wetlands 459Subsurface-Flow Wetlands 460Submerged Aquatic Beds 461Internalization 461General Considerations 461Temperature and Seasonal Dependence 462

The Mass Balance Model with First-Order Areal Uptake 463Verification of the Simplest Model: Some Examples 464Calibration of the First-Order Model: Intersystem Variability 465Emergent Marshes 466Forested Wetlands 467SSF Wetlands 467Calibration of the First-Order Model: Intrasite Variability 467

Temporal Variability 468Variability Due to Ecosystem Structure 468Variability Due to Wetland Configuration 469

Some Potentially Important Site-Specific Factors 469Depth Effects 470Mixing Effects : 470

Landscape Scale 470Plot Scale 471

Temperature Effects 472Seasonal Effects 473

Adaptation Trends 474More Detailed Models 475Stochastic Effects 477

Field Results 477Stochastic-Deterministic Modeling 478

Chapter 15Other Substances 481

Integrative Parameters 483Hardness (Calcium and Magnesium) 483Specific Conductance 483Salinity 484Total Dissolved Solids 484

Chloride 484Other Macronutrients 485

Sodium and Potassium 486Sulfur 487Silicon 490

Trace Metals 490Chemistry, Occurrence, and Significance 491Wetland Removal Performance 491Occurrence and Wetland Treatment 497

Aluminum 497Arsenic 499Cadmium , 499Chromium 501Copper 503Iron 505Lead 508Manganese 508Mercury 510Nickel ". 512Selenium 514Silver 516Zinc 516

Chapter 16Organic Compounds 521

Wetland Projects 521Petroleum Processing 522

Refinery Effluents ! 522Spills and Washing 522Oil Sand Processing Water 523Produced Water 523Research 524

Surfactants 524Food Processing Wastewaters 524

Sugar Refiriing 524Potato Processing 525Milk and Eggs 525

Meat Processing 525Dairying 525

Leachates 526Pulp and Paper Wastewaters 526Pesticides 526

Chlorinated Organics 526Atrazine 527

Phenol 527Naphthoic Acid 530

Chapter 17Pathogens 533

Review of Wastewater Pathogens 533Pathogen Removal Performance 535

Indicator Organisms 535Removal Efficiency 537

Zero-Background Models 540Thek-C* Model 541Removal Efficiency for Viruses 542Variability in Removal 543

Section 4 Wetland Project Planning and Design

Chapter 18Wastewater Source Characterization 547

Municipal Wastewaters 548Industrial Wastewaters 548

Landfill Leachates 548Pulp and Paper Wastewater 551Mine Drainage 551Coal Mine Drainage 552Petroleum Refinery Wastewater 552Electroplating Industries 553Textile Production 553

Agricultural Wastewaters 554Stormwater Runoff 557

Chapter 19Wetland Alternative Analysis 561

Brief Description of Wetland Treatment Alternatives 561Constructed Surface-Flow (SF) Wetlands 562Constructed Subsurface-Flow (SSF) Wetlands 562Natural Wetland Treatment Systems 563Summary of Wetland Treatment Alternatives 564

Technical Constraints 565Assembly of Design1 Data 565

Site Conditions 565Climate 565Geography 567Soils and Geology 569

Groundwater 569Biological Conditions 569

Characterization of the Water to be Treated 570Hows 570Quality 570

Treatment Goals 571Receiving Water Standards 571Interfacing to Reuse or Further Treatment 571

Pretreatment Requirements 572Postwetland Requirements 574

General Wetland Sizing 574Rule of Thumb Approaches 574

Percentage Removal and Reduction 574Detention Time 577Hydraulic Loading Rate 580Pollutant Loading Rate, Pollutant Uptake Rate 580Percentage of the Contributing Watershed 581Design Storm Detention 582

Mass Balance Design Model 584Regulatory Constraints 586

Federal Regulations 586Clean Water Act 586

National Pollutant Discharge Elimination System (NPDES) 587Construction Activities in Natural Wetlands 590

Wetlands Executive Order 11990 591Floodplain Management Executive Order 11988 591National Environmental Policy Act 592Endangered Species Act 592

State Regulations 592Alabama 593Arizona 593Horida 593Maryland 595Mississippi 595South Carolina 595South Dakota 597Texas 597

Treatment Wetland Conceptual Plan 597Site Ranking 597Conceptual Plan 598Alternative Selection 599

Chapter 20Wetland Design: Surface-Flow Wetlands 603

Preliminary Feasibility 603Preliminary Sizing 603Site Characteristics 604Preliminary Economics 606

Capital 606Operating and Maintenance (O&M) Cost 607

Detailed Conceptual Design 607Nonquantified Design Parameters 608Nondesign Parameters 608Maximum Values vs. Averages 608

Final Design and Layout 609Localizing the Design Parameters 609Detailed Area Calculations 610

Wetland Performance Variability 611A Reality Check 612Presumed State of Mixing 615

Conveyance: Aspect Ratios, Head Loss, and Linear Velocity 616Compartmentalization 618Fitting the Project to the Site 620Earthmoving: Dikes, Berms, and Levees 620Hood Protection 623Hydraulic Profile 624Pumping Requirements 625Control Structures 625

Inlets 625Outlets 630

Plants and Planting 633Detailed Economics 634

Capital Costs 634O&M 635Total Present Worth 635

Chapter 21Wetland Design: Subsurface-Flow Wetlands 641

Preliminary Feasibility 641Preliminary Sizing : 641Preliminary Economics 642

Capital Costs 642Operating and Maintenance Costs 642Cost Comparison 642

Detailed Conceptual Design 644Localizing the Design Parameters 644

The Reality Check 645Presumed State of Mixing 645Conveyance: Aspect Ratios and Head Loss 648A Hydraulic Design Example 649Inlet Distribution System 651Basin Configuration 651Bed Media 652Outlet Control System 652Selection of Plants 653

Chapter 22Natural Wetland Systems 657

Site Selection 657Natural Wetland Treatment Area 658

Suitable Natural Wetland Types 660Other Potential Constraints 662

System Configuration ' 663Influent Distribution 663Basin Configuration and Alternate Discharge Locations 664Flow Control Structures 666

Chapter 23Ancillary Benefits of Wetland Treatment Systems 669

Primary Production and Food Chain Support 670Wildlife Management 671Human Uses 672Design for Ancillary Benefits 673

Wetland Siting 674Cell Size and Configuration 674Water How and Depth Control 675Vegetation Planting 675Wildlife Stocking 676Inflow Pretreatment 676Human Access 676

Section 5 Wetland Treatment System Establishment, Operation, and Maintenance

Chapter 24Wetland Treatment System Establishment 681

Wetland Construction 681Site Preparation 681Wetland Landform and Berms 683Gravel/Sand Media Placement 684Piping and Water Control Structures 684

Vegetation Establishment 685Plant Propagules and Sources 686

Bare-Root Seedlings 686Seeds 686Field-Harvested Plants 688Potted Seedlings 690

Plant Establishment 690Climatic Factors 690Soil Preparation 691Soil Moisture 691Plant Density 692

Plant Inspection and Maintenance 693Troubleshooting 695

Water Stress (Levels Too Low) 696Flood Stress (Levels Too High) 696Macronutrient Stress (Nitrogen, Phosphorus, and Potassium) 696Micronutrient Stress 697Dissolved Oxygen Stress (Physical Factors) 697Dissolved Oxygen Stress (Chemical Factors) 697

Rooting Problems 697Pathogens/Herbivory 698Weather/Physical 699

Chapter 25Treatment Wetland Operation and Maintenance 701

Monitoring and Control 701Constituent Loading 703Water Level and Flow Control 704Discharge Site Rotation 705Vegetation Management 706Control of Nuisance Conditions in Treatment Wetlands 707

Potential Nuisances to Society 707Mosquitoes and Biting Insects 707Dangerous Reptiles 710Pathogen Transmission 710Odors 711

Potential Environmental Problems 711Excess Subsidies 711Environmental Toxins 712

Section 6 Wetland Data Case Histories

Chapter 26Wetland Treatment System Inventory 717

North American Wetland Treatment Systems 718Wetland Types 718Geographical Distribution 718Wetland System Costs 724Loading Rates 727Wetland Performance 727

European Wetland Treatment Systems 731Danish Database 735Great Britain 736

Chapter 27Treatment Wetland Case Histories 739

Surface-How Constructed Treatment Wetlands 739Incline Village, Nevada 739

Background 739System Description 740Operation and Maintenance 740Performance 742Ancillary Benefits 742Lessons for Wetlands in Arid Regions 744

West Jackson County, Mississippi 744Background and System Description 744System Design 746Operation and Performance 748Ammonia Treatment Potential 752System Biology 752

Mandan, North Dakota 753Background 753System Description 754Water Quality Performance 756Ancillary Benefits 758

The Des Plaines River Wetlands Project 758Introduction and System Description 758Hydrology 759Water Quality 760Vegetation 763Animals 763Awards 764References 764

Vermontville, Michigan 764Introduction and System Description 764Permits 766Hydrology 766Water Quality 767

Compliance Monitoring 767Research Results 768

Vegetation 769Wildlife 770Operation and Maintenance Activities 770Costs 770

Subsurface-How Constructed Treatment Wetlands 771Richmond, New South Wales, Australia 771

General Conditions of Operation 771Hydraulics 772Water Quality 775

Biochemical Oxygen Demand 775Total Suspended Solids 775Nitrogen Compounds 775Phosphorus 776Pathogens 776

Vegetation 776Benton, Kentucky 777

General Conditions of Operation 778Hydraulics 779Water Quality 779

Biochemical Oxygen Demand 779Total Suspended Solids 779Nitrogen Compounds 779Phosphorus 781Pathogens 781

Mosquitoes 781Vegetation 781

Natural Treatment Wetland Case Histories 783Carolina Bays, South Carolina 783

Background 783Permitting 784System Description and Operation 785

System Performance 787Biological Changes 792Biological Criteria 796Ancillary Benefits 796Awards 798

Reedy Creek, Horida 798Background 798System Description 800Permitting 801System Performance 801Biological Conditions 806

Houghton Lake, Michigan 810Introduction and Project Description 810History '. 812Hydrology 813Permits 813Water Quality of the Wetland Interior 815Soils and Sediments 817Vegetation 817Public Use 819Animals 819Awards 820Literature 820

Appendix 823Glossary 827References 839Index 881