Design Manual Constructed Wetlands and Aquatic Plant Systems for Municipal Water Treament HYDRIK United States Environmental Protection Agency Wetlands Consultants Office of Research and Development This document has been delivered to you as a EPA/625/1-88/022 service of Hydrik Wetlands Consultants. September 1998 http://www.hydrik.com Notice This document has been reviewed in accordance with the U.S. Environmental Protection Agency’s peer and administrative review policies and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. This document is not intended to be a guidance or support document for a specific regulatory program. Guidance documents are available from EPA and must be consulted to address specific regulatory issues. ii Contents Chapter Page 1 AQUATIC TREATMENT SYSTEMS .................................... 1 1.1 Introduction ................................................... 1 1.1.1 Scope .................................................. 1 1.1.2 Potential Uses of Natural Systems .............................. 1 1.2 Classification .................................................. 2 1.2.1 Natural Wetlands ........................................... 2 1.2.2 Constructed Wetlands ....................................... 3 1.2.3 Aquatic Plant Systems ....................................... 4 1.3 Natural Wetlands ............................................... 4 1.4 Constructed Wetlands ........................................... 4 1.4.1 Free Water Surface Systems (FWS) ............................. 4 1.4.2 Subsurface Flow Systems (SFS) ............................... 5 1.5 Aquatic Plant Systems ........................................... 5 1.5.1 Floating Plant Systems ...................................... 5 1.5.2 Submerged Plant Systems .................................... 6 1.6 References ................................................... 7 2 ENVIRONMENTAL AND PUBLIC HEALTH CONSIDERATIONS ................. 9 2.1 Introduction ................................................... 9 2.2 Nitrogen ..................................................... 9 2.3 Phosphorus ................................................. 10 2.4 Pathogens .................................................. 10 2.4.1 Parasites ............................................... 10 2.4.2 Bacteria ................................................ 10 2.4.3 Viruses ................................................ 11 2.5 Metals ..................................................... 11 2.6 Trace Organics ............................................... 11 2.6 References .................................................. 12 3 DESIGN OF CONSTRUCTED WETLANDS .............................. 15 3.1 Types of Constructed Wetlands ................................... 15 3.1.1 Free Water Surface Systems with Emergent Plants ................. 15 3.1.2 Subsurface Flow Systems with Emergent Plants ................... 15 3.2 Site Selection ................................................ 15 3.2.1 Topography ............................................. 15 3.2.2 Soil Permeability for Free Water Surface Systems .................. 15 3.2.3 Hydrological Factors ....................................... 16 3.2.4 Water Rights Considerations ................................. 16 3.3 Performance Expectations ....................................... 16 3.3.1 BOD5 Removal in FWS Wetlands .............................. 18 3.3.2 BOD5 Removal in SFS Wetlands .............................. 19 III Contents (continued) Chapter Page 4 DESIGN OF AQUATIC PLANT SYSTEMS . 47 Figures Number Page 1-1 Common Aquatic Plants .......................................... 3 3-1 General Design Schemes for Denitrification ........................... 16 3-2 Pilot-Scale Constructed Wetland - Gravel Planted Trench with Brush ....... 18 3-3 Sensitivity of Ce/Co Ratio to Av ................................... 20 3-4 Sensitivity of Ce/Co Ratio to Temperature ............................ 20 3-5 Regression Curve of TKN vs. Detention Time in the Effluent of an Alternating Typa/Open-Water/Gravel System ......................... 23 3-6 Arcata, CA Pilot Marsh System .................................... 28 3-7 Arcata, CA Wastewater Treatment Facilities Flow Diagram ................ 31 3-8 Arcata, CA Intermediate FWS System ............................... 32 3-9 BOD Performance Data for Emmitsburg, MD SFS ...................... 35 3-10 TSS Performance Data for Emmitsburg, MD SFS ....................... 35 3-11 BOD5 Performance Data for Gustine, CA Pilot Marsh System .............. 37 3-12 SS Performance Data for Gustine, CA Pilot Marsh System ................ 37 3-13 Gustine, CA Marsh System Flow Schematic .......................... 40 3-14 Fabius Coal Facility Site Plan ..................................... 42 3-15 Fabius Coal Facility Impoundment 1 Wetlands ......................... 43 4-1 Morphology of the Hyacinth Plant .................................. 50 4-2 Suitable Areas for Hyacinth Systems ................................ 50 4-3 Morphology of and Potential Growth Areas for Duckweed Plants ............ 51 4-4 Evolution of Flow pattern Through San Diego, CA Water Hyacinth Treatment Ponds .............................................. 56 4-5 Evolution of Pond 3 Flow and Aeration System Configurations at San Diego,CA ............................................... 57 4-6 Site Plan for San Diego, CA Aquaculture Pilot Plant ..................... 63 4-7 Schematic Diagram of Primary and Secondary Facilities - San Diego, CA Aquaculture Pilot Plant .......................................... 64 4-8 Schematic of Hyacinth Pond Step-Feed System With Recycle - San Diego, CA 65 4-9 BOD5 Performance Data for San Diego, CA Pond #3 With 200 Percent Recycle 66 4-10 SS Performance Data for San Diego, CA Pond #3 With 200 Percent Recycle ... 66 4-11 lnfluent and Effluent BOD, SS, and DO for Step-Feed Hyacinth Pond - San Diego, CA 4-12 Definition Sketch for the Analysis of a Hyacinth Pond With Step-Feed . 68 and Recycle ................................................. 70 4-13 Analysis of Performance Data for Hyacith Pond 3, San Diego, CA, with Step-Feed and Recycle ........................................ 70 4-14 Hornsby Bend, TX Hyacinth Facility Basin Configuration .................. 72 4-15 Hornsby Bend, TX Hyacinth Facility Pond and Roof Section ............... 72 4-16 Iron Bridge, FL Hyacinth Facility Basin Configuration ..................... 76 vi Contents (continued) Chapter Page 4.5 Performance Expectations ....................................... 56 4.5.1 Design Equations ......................................... 56 4.5.2 Nitrogen Removal ......................................... 56 4.6 Sample Design Problems ........................................ 58 4.6.1 Sample Problem No. 1 ..................................... 58 4.6.2 Sample Problem No. 2 ..................................... 59 4.7CaseStudies ................................................ 61 4.7.1 San Diego, California ....................................... 61 4.7.2 Austin, Texas ............................................ 69 4.7.3 Orlando, Florida .......................................... 74 4.7.4 Summary ............................................... 77 4.8 References .................................................. 78 APPENDIXA ...................................................... 81 APPENDIXB ...................................................... 83 V Tables Number Page 1-1 Functions of Aquatic Plants In Aquatic Treatment Systems ................. 2 1-2 Percent Removal for Several Pollutants from Secondary Effluent in Natural Wetlands ............................................... 4 1-3 Summary of Nutrient Removal from Natural Wetlands ..................... 5 1-4 Summary of Nutrient Removal from Constructed Wetlands ................. 5 1-5 Summary of Wastewater Treatment Performance of Aquatic Plant Systems ..... 6 2-1 Pollutants and Pathways of Concern ................................. 9 2-2 Trace Organic Removal in Pilot-Scale Hyacinth Basins .................. 12 3-1 Removal Mechanisms in Wetlands for the Contaminants in Wastewater ....... 17 3-2 Performance of Pilot-Scale Constructed Wetland Systems ............... 17 3-3 Predicted vs. Actual Ce/Co Values for Constructed Wetlands .............. 19 3-4 Media Characteristics for Subsurface Flow Systems ..................... 21 3-5 Emergent Aquatic Plants for Wastewater Treatment ..................... 26 3-6 City of Arcata, CA Wastewater Discharge Requirements .................. 27 3-7 Arcata, CA Pilot Marsh System Hydraulic Loading Ratios and Detention Times . 29 3-8 Experimental Vegetation and Compartments for Marsh Cells - Arcata, CA ..... 29 3-9 Average Annual BOD5 Concentration (mg/L) Arcata, CA ................ 30 3-10 Arcata, CA Marsh and Wildlife Sanctuary Wastewater Treatment Plant Performance ........................................... 33 3-11 Arcata, CA Marsh and Wildlife Sanctuary Project Expenditures ............. 33 3-12 Performance of the Emmitsburg, MD SFS 35 3-13 Determination of Nitrification Component in BOD5 Test Gustine, CA ....... 38 3-14 BOD5 and SS Removal Efficiencies As a Function of Detention Time - Gustine, CA . 38 3-15 Design Criteria for Constructed Wetland at Gustine, CA . 39 3-16 ............... 41 3-17 Initial Operating Schedule of the Gustine, CA Marsh System .......................... 3-18 Capital Costs for Gustine, CA Marsh Project 41 ............... 45 3-19 Fabius Coal Preparation Facility