Presentation is loading. Please wait.

Presentation is loading. Please wait.

Herwig Goldemund, Ph.D. Geosyntec Consultants Atlanta Regional Office

Similar presentations

Presentation on theme: "Herwig Goldemund, Ph.D. Geosyntec Consultants Atlanta Regional Office"— Presentation transcript:

1 Herwig Goldemund, Ph.D. Geosyntec Consultants Atlanta Regional Office
The Use of Constructed Wetlands for Treatment of Landfill Leachate and Other Wastewaters Herwig Goldemund, Ph.D. Geosyntec Consultants Atlanta Regional Office

2 Overview Constructed Wetlands Technology Overview
Types of Wastewater Treated Pilot Study Results Leachate Treatment Using Constructed Wetlands Conclusions Q&A

3 Constructed Wetlands Wetlands have a long and successful history in treating a variety of waste streams Vast experience from 40+ years of research and practical applications throughout the world Main treatment mechanisms are microbiological processes mediated by plants

4 Constructed Wetlands Plant uptake plays a minor role
Redox conditions can be manipulated to facilitate certain processes aerobic processes nitrification of ammonia aerobic biodegradation of organics (including many contaminants) precipitation of metals as carbonates, oxides and hydroxides anaerobic processes denitrification of nitrate to N2 reductive dechlorination of chlorinated organics precipitation of metals as sulfides

5 Constructed Wetlands Primary uses Low cost, simple
effluent polishing in advanced treatment systems treating mild leachate from older sites treating contaminated groundwater Low cost, simple Very low maintenance or even self-regulating Environmentally friendly Robust (plants are hardy)

6 Popular Wetland Plant Species
Common Reeds (Phragmites) Bulrush (Scirpus) Cattails (Typha)

7 What Do the Plants Actually Do?
Maintain voids Provide insulation Provide habitat Some uptake

8 Types of Constructed Wetlands
Two main wetland types Surface-flow wetland Subsurface-flow wetlands Two types within subsurface-flow wetlands Horizontal flow Vertical flow

9 Traditional Surface Flow Wetlands
Mimics natural wetland systems / vegetation cultivated in shallow channels Wastewater/leachate flows through at low velocity Potential problems poor winter performance requires significant land area potential for direct contact with wastewater/leachate mosquitoes, odors

10 Horizontal Sub-Surface Flow Wetlands
Sand or gravel medium supports aquatic plants Water level maintained below the sand/gravel Wastewater/leachate flows horizontally Potential limitations insufficient aerobic zones to allow for ammonia reduction plugging of sand media may lead to ‘short circuiting’

11 Vertical Flow Wetlands
Water percolates vertically down through medium Draws oxygen through the medium Allows for increased contact between wastewater/leachate, sand and aerobic bacteria = good nitrification and phosphorus removal Efficient treatment, even in winter System termed “Wetland Biofilter System” (WBS)

12 WBS Overview Commercialized constructed wetland system (installed at over 40 sites in North America) Originally developed by Aqua Treatment Technologies in conjunction with USEPA, Environment Canada, and Ontario Ministry of the Environment (SWAMP) Geosyntec helped refine and adapt system for leachate treatment Vertical Flow Wetland System Small footprint Treatment throughout the year (can change inflow depth) Can be above or below grade (even on top of landfill cap)

13 WBS

14 WBS

15 Types of Wastewaters Treated
Waste streams that can be treated in a biological wastewater treatment plant can be treated in constructed wetlands Agricultural waste streams Liquids from waste lagoons, leachate from composting facilities and greenhouses, winery wastes, slaughterhouse effluent, etc.

16 Types of Wastewaters Treated
Residential Applications Sanitary sewage Contaminated Groundwater Aerobically and anaerobically degradable contaminants Municipal/industrial waste streams Municipal/industrial wastewater Hazardous waste (listed and/or characteristic) should not be treated (permitting issues), even if it is technically treatable Landfill leachate

17 Leachate Composition Organics Nutrients (nitrogen, phosphorus)
Oxygen demand (BOD, COD) Synthetics (volatiles, pesticides) Nutrients (nitrogen, phosphorus) NH3/NH4 most problematic Inorganics Metals Anions (chloride, sulfate, alkalinity) Others Total suspended solids (TSS) Total dissolved solids (TDS)

18 Case Study Pilot Project at Active Landfill Site in Southern Alabama
Site recirculates leachate, trucks excess leachate offsite Goal is to design full-scale system with treated effluent discharged to stormwater pond and subsequently, through NPDES outfall

19 Pilot Study Results

20 Pilot Study Results

21 Pilot Study Results

22 Pilot Study Results

23 Pilot Study Results

24 Pilot Study Results

25 Pilot Study Results

26 Pilot Study Results

27 Pilot Project Conclusions
High treatment efficiencies for ammonia, BOD/COD, iron, TSS, and P Variability in ammonia concentrations likely due to analytical issues Some acclimatization of microbes needed Organic pollutants effectively removed Chloride (and TDS) removal is limited has been expected: conservative ion Arsenic removal about 50-75% Denitrification quite impressive Additional carbon source (e.g., compost) may need to be added Treated effluent appears to meet surface water criteria

28 Overall Conclusions Good success with constructed wetlands treatment of ammonia, BOD, COD, iron, phosphorous, many VOCs, pesticides, TSS, E. coli, and some trace metals Challenges include chloride, TDS, high ammonia concentrations, and effective nitrification of several hundred ppm of nitrate CW costs for leachate treatment 1-3 ¢/gal depending on scale (includes capital cost and O&M over 20-year design life) Compared to 5-15 ¢/gal for offsite trucking Can also help minimize POTW surcharges Costs can be much lower if flow is increased (e.g., contaminated groundwater)

29 Q&A

Download ppt "Herwig Goldemund, Ph.D. Geosyntec Consultants Atlanta Regional Office"

Similar presentations

Ads by Google