Wetlands engineered for beauty, wildlife habitat &

Transcription

1 Wetlands engineered for beauty, wildlife habitat & pollution control Alex Horne Ph. D. Professor Emeritus Ecological Engineering Group Dept. Civil & Environmental Engineering University of California, Berkeley

2 Summary:Wetlands Ecological systems designed on the principles p of ECOLOGICAL ENGINEERING Constructed wetlands can: Remove pollutants from large volumes of water Provide beautiful views & wildlife habitat

3 Beautiful wetlands: Hall of Green Wilderness, Yuan Yao 1770

4 Wildlife habitat in wetlands

5 NITRATE mg/l Nitrate removal in large wetlands

6 Constructed Wetlands in China Principles of Ecological Engineering Sustainable energy sources e.g. sunlight on wetlands Provide excellent e water quality at lower cost than alternative Work in cooperation with other treatment methods

7 What are wetlands? 1. Shallow water 2. Hydric (waterlogged) soils 3. Adapted plants (vegetation adapted to grow in anoxic/hydric flooded wetland soils)

8 Shallow water, hydric soil, adapted plants 1 - marsh

9 Shallow water, hydric soil, adapted plants 2 cypress swamp

10 Shallow water, hydric soil, adapted plants 3 Acid Bog

11 Shallow water, hydric soil, adapted plants 4 treatment wetland

12 Reed beds are vital for wetlands

13 Reeds provide renewable energy for waste treatment Professor Horne 3 m

14 Rivers & Lakes not good for waste treatment because they have a small BIOFILM

15 Microbial biofilm is the engine of wetlands pollution treatment Biofilm = Bacteria, attached algae, protozoans, rotifers, nematodes, chironomid id midge larvae & others Function: transformation of chemical compounds Wetlands: transform undesirable chemicals into harmless ones

16 Biofilms & Wetlands Emergent Plants EMERGENT Cattails (Typha) EMERGENT Surface Water Lilies (Nymphaea) SUBMERGENT pond weed (Potomogeton) may be covered with aufwuchs FLOATING Duckweed (Lemna) SCALE SUBMERGED BIOFILMS 1 m 1 m WATER LEVEL OXYGENATED ANOXIC

17 Submerged plants with biofilm WHITE BIOFILM

18 How do treatment wetlands work? Properly designed constructed wetlands can treat nutrients, heavy metals, pesticides, pathogenic bacteria. Methods are: 1. Sedimentation 2. Microbial metabolic destruction or immobilization

19 Use only surface water wetlands Surface water Good wildlife Beautiful SURFACE No standing water, No wildlife Ugly GRAVEL SUB-SURFACE

20 A Californian wetland at work

21 Key to treatment wetlands: Redox in the sediments & peat Redox potential milivolts Transformation Oxidized water NO 3 to N 2 gas +100 Fe +++ to Fe SO4 to S (see Cu ++ ) Cu ++ (toxic) to CuS (inert) -300 CO 2 to CH 4

22 The key to Redox: correct plants Kind of plants used in wetland set the oxygen demand & thus the redox N t ll tl d l t d f Not all wetlands plants are good for pollution removal, wildlife or amenity values

23 Role of University Research What do you mean, you couldn t find any brains!

24 Prof. Horne s research: Typha better than Scirpus

25 China, a Problem: too much waste from humans & pigs

26 Oxidation ponds and wetlands: Concepts

27 Turner Road: example of agricultural wetland: winery waste Oxidation Ponds TREATMENT WETLAND AIPS Pond 4 Storage Pond Influent AIPS Pond 3 AIPS Pond 2 Cattail Wetland Island Aeration Pond Bulrush Wetland AIPS Pond 1 Lawn Flow Patterns Irrigation Water Conveyance Pipes Not to Scale N

28 Turner Road BOD removal performance in AIPS Ponds

29 Turner Road Winery Wetland after 3 years Bulrush (Scirpus) Bulrush (Scirpus) Plants

30 Wetland Polishing of agricultural waste:turner Road Site Safe for rivers

31 Animal waste: wetland performance Unit AIPS inflow AIPS outflow AIPS performance Wetland inflow Wetland outflow Wetland performance BOD 1,000 to 6,000 mg/l 50 to 200 mg/l 91% removal 125 mg/l 33 mg/l 74% removal

32 Petaluma: compromise design Oxidation pond WETLAND 65 acres Wetland placed after now smaller & powered oxidation area

33 Let s build more new wetlands / htt // / t Treatmentsystems.org

34 NTS: General e Plan

35 Drainage stick model

36 NTS plan & example

37 Taking out the toxicants Toxic heavy metals (e.g. Cu, Zn) are immobilized in the inorganic sediments (as insoluble sulfides) Toxic pesticides are broken down or immobilized in organic sediments (by sorption)

38 Wetlands transform metals & organics Inflow Wetland process of Outflow respiration & growth NO 3 Bacterial transformation to NH 4, N 2 or biomass in biofilm NH 4, DON, PON N 2 lost as gas Cu ++,Zn ++, Bacterially-mediated Much lower amounts Pb ++ (soluble) precipitation in biofilm & peat to CuS, ZnS, PbS - all insoluble Pesticides, PAHs & other organics Bacterially-mediated decomposition & physical sorption Much lower amounts

39 Copper in waste & mines Insoluble metals become soluble if correct bacteria, oxygen & water are present (e.g. leaching of mine tailings) Cu ++ is toxic ~ ug/l in many waters Acid mine waste can exceed 100 mg/l (~ 1,000 x above toxic threshold) Domestic sewage, dairy waste, street runoff ug/l

40 Bonanza mine + tailings, Alaska 94 Ruins of Mine headworks Blue Copper ore Ore tailings pile Leaching copper Cu++ at snowmelt

41 Fate of heavy metals in wetlands

42 Wetlands remove metals quickly Soluble lead in water LEAD 203 Pb Radioisotope experiments Very difficult & dangerous Metals in plankton & wastewater removed in a few days from soluble (bioavailable & toxic) fraction to sediments Other research shows metals end up as insoluble sulfide minerals

43 Successful cases of metals removal in wetlands Source/metal Inflow conc. ug/l Outflow conc. ug/l % removal Mine tailings leachate Cu Acid coal mine runoff Fe 69, Domestic wastewater Cu Domestic wastewater Pb Domestic wastewater Cu 33 <3 >90 simulated wetland

44 Pesticide removal in wetlands Good removal during a storm IN OUT Rainfall A = azinphos-methyl, C = chloropyrifos, E= Endosulfan

45 Explosives removal in wetlands TNT only SORBTION TO BIOFILM PARTIAL DEGREDATION OF TNT HELD BY DOC TNT + STRAW DOC

46 Kind of plant carbon & redox potential research improves performance Straw ln conc. TNT Bulrush Cattail TIME (hrs)

47 How do we work wetlands to removal what we need? Ecological Engineers adjust the redox potential in the wetland biofilm How? Adjust the kind and quantity of carbon & the hydroperiod d to give the correct redox

48 Removal of organics in wetlands Removal of organics by design in wetlands in its infancy. Experimental evidence for removal of a variety of simple & complex organics (TNT, birth control drugs, halogenated organic compounds & pesticides). Simpler compounds decomposed, more complex ones absorbed, partially degraded &/or immobilized on peat.

49 Leaf litter,,peat & sorbtion IRISH PEAT BOG CATTAIL LEAF LITTER & PEAT

50 Surface water treatment wetland + Birds

51 200 ha constructed wetland in Southern California designed by Professor Horne INFLOW ~ mg/l Nitrate-Nt N OUTFLOW ~ 1 mg/l Nitrate-N

52 Beautiful Wetlands

53 Any Questions?

54 Wetlands Extension Course Professor Alex Horne CLASS SONG # 1 THE WETLANDS SONG

55 1. If you ve got shallow water

56 2. Chorus Shallow water Hydric soil Adapted plants

57 3. There s swamps & bogs & marshes

58 4. Wetlands they need water HYDRO- PERIODS The important t thing is to stay hydrated. d

59 5. Wetlands are anoxic

60 6. they ve got that biofilm

61 7. Wetlands they are transformers

62 8. If we want to save our wetlands..

63 9. Shallow water is your guideline...