Green Remediation. Restoration Alternatives. Harry R. Compton Environmental Engineer U.S. EPA - ERT Chuck Henry University of Washington

Transcription

1 Green Remediation Restoration Alternatives Harry R. Compton Environmental Engineer U.S. EPA - ERT Chuck Henry University of Washington U

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3 EPA s OSWER Priorities Revitalization Recycling One Clean-up Program

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6 Mine Sites Lack of vegetation is a result of: Low fertility Poor soil physical properties Acidity Metal toxicities Salts

7 Goals of Remediation Reduce bioavailability of contaminant in place Rebuild soil or build new soil Restore soil function Sustain plant growth Sustain soil fertility Establish native plant ecosystem

8 Residuals as Soil Amendments Why use wastes? Alternative to conventional remedial technologies lower costs recycling wastes for a better use Can be economical large scale solutions Use application expertise from generators

9 Residences Biosolids Primary Treatment Secondary Treatment Tertiary Treatment raw waterwater primary effluent secondary effluent Settling Biological Settling Chemical Flocculation Settling/ Filtering tertiary effluent Commercial/ Industrial Biosolids Waste Residuals Biosolids treatment/ Treatment/ stabilization Stabilization

10 Biosolids Produced by all municipalities Use regulated under 40 CFR % of biosolids are now land applied Cost - "subsidized" by municipality

11 Primary and secondary pulp & paper sludge Primary settled solids - High C:N ratio Secondary settled solids - Lower C:N ratio Adhesive properties Readily available in some parts of the country

12 Other waste products Ash secondary nutrients liming potential residual carbon Sugar beet lime Manure lumber industry, land clearing debris

13 Compost Stable soil like material Pathogen and odor free

14 Steps in design Site history Soil sampling and analysis Identify site problems Contaminants Soil physical conditions Climate Inventory of available materials Identify appropriate mixtures

15 Three examples of restoration of metal contaminated sites Bunker Hill, Idaho Contaminated wetland Leadville, Colorado River-deposited tailings Tar Creek, Oklahoma Yard soils Mine tailings

16 Bunker Hill - wetland restoration Lead 30,000 mg kg -1 Zinc 15,000 mg kg -1 Cadmium 100 mg kg -1

17 Goal: Wildlife Protection from Acute Pb Poisoning

18 Waterfowl: Use Lateral Lakes wetlands as feeding, nesting area Dive for roots and tubers 20% of diet is sediment Acute Pb poisoning 100 sq mile area is Pb enriched

19 Compost Wood ash Cap

20 Scientific basis of treatments Barrier to contaminated sediments Preferred rooting Limit - access to tailings Create a functional wetland Reducing conditions Reduction of sulfur Formation of galena Galena Reduces Pb availability Further reduces ecosystem threat

21 Scientific basis of treatments Biosolids - compost add: nutrients organic matter = wetland muck Microbial food source Wood ash/waste lime add: ph adjustment Mineral soil Wood waste/other C-rich residuals: limits N availability Road building

22 Biosolids compost 15 cm deep treatment of a mixture of: Wood waste Wood ash

23 County Road Applied by dozer Wood waste road build Straw bales and oil boom for filtration Applied by throw-spreader Applied by blower Excavated CIA Road West Page Swamp Lightly vegetated Heavily vegetated

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27 Coeur d Alene Wetlands

28 Change in Lead Speciation Fourier transform magnitude 4 Pb-S bonding 3 PbS standard #22: compost+ash+high SO 4 2 #18: compost+ash+low SO 4 #15: compost + ash 1 Pb-O bonding #9: control (sediment only) 0 PbO standard Radial Distance (Å) Fig. 1. Radial structure functions (RSFs) derived from Fourier transformation of lead L III -EXAFS data (w=3) for contaminated sediment subjected to various treatments. The Pb-S bonding apparent for all sediment samples indicates a dominance of Pb-sulfide.

29 Ecosystem Implications- Wetland - Plant lead (mg kg -1 ) Control Amended Control Amended Arrowhead Cattail

30 Ecosystem Implications Other metals Cattail Arrowhead Control Amended Control Amended Cadmium Zinc

31 Ecosystem Implications SEM/AVS (Simultaneously Extracted Metals/ Acid Volatile Sulfides ) Treatment SEM/AVS Control 43 Compost 18 Compost + Low S 8 Compost + High S 3

32 Upper Arkansas River Alluvium Remediation Leadville, CO

33 Historic mine tailings washed down and accumulated in deposits up to and exceeding 2 Deposits are toxic to riparian vegetation Contaminated soils, barren of vegetation, are highly susceptible to continued erosion by the river

34 Risks Re entrainment of tailings Risk to river ecosystem Stabilized tailings Potential risk to upland ecosystem

35 Soil System Pyritic tailings Highly acidic Fluctuating water table Often insufficient rainfall Reduced metals oxidize Are wicked to soil surface Salt crust

36 Biosolids/Lime amendment Increase subsoil and surface ph Increased organic matter at surface reduce wicking effect Precipitate metals currently in solution on oxides in biosolids Increased microbial activityincrease potential for reduction and sulfide precipitation Two mechanisms to reduce metal availability

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39 Filling vehicle Application

40 Leadville, CO

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42 Ecological Assessment Mark Sprenger, US EPA ERT Leadville, CO Similar results from Jasper County Similar results from Palmerton, PA

43 Microbial Function CO 2 -C Ratio NO 3 /NH 4 Respiration Tailings 4.7 ± Upstream Control Biosolids amended tailings 16.9 ± ±

44 Earthworm Survival Tailings Biosolids amended tailings Upstream control Survival 0% 89± 3 96 Biomass mg 6.8

45 Earthworms Worm Cd Control - Treated 18.1±3.5 Upstream 12.1 ±0.6

46 Number of Species Poaceae Rosaceae Asteraceae Ranunculaceae Scrophulariaceae Fabaceae Campanulaceae Onagraceae Cistaceae Polygalaceae Boraginaceae Brassicaceae Gentianaceae 0 UUC CVA MB/ME

47 Small Mammals (whole body dry weight) Species Location Cadmium Lead Zinc Shrew B.brevicauda Upstream control 0.68 ± ± ± 9.2 Contaminated vegetated 2.35± ± ±8.5 Biosolids amended Mouse Z. princeps Upstream control ± ± 29 Biosolids amended 0.55± ± ±8.5

48 Re-entrainment Study Fathead Minnow % Survival Control Treated Tailings Untreated Tailings

49 Tar Yard soils Creek, OK Mine wastes

50 Yard Soils- Plant Response Control DAP 5% Compost Biosolids

51 Plant Zn Control DAP Biosolids Compost

52 Plant Cd Control DAP Biosolids Compost

53 PBET Pb Control DAP Compost

54 PBET Pb Control Compost Compost + DAP Compost + DAP +Al Compost +Al

55 Concerns using residuals Not a commodity No fixed price or infrastructure Generators not used to process Perception that they contain toxic levels of contaminants

56 However - Body of research Show potential to absorb metals Basic and Applied

57 Hettiarachchi et al. Objectives Evaluate adsorption capacity of biosolids amended soil Results Observed excess adsorption factor of Fe/Mn oxides and organic matter

58 Joplin, MO In Vivo Feeding Reduction in Bioavailability % P 10% Compost

59 Metals in Biosolids Regulatory limit Cadmium 39 mg kg Lead 300 mg kg Copper 1500 mg kg Zinc 2800 mg kg National Means Cadmium 7 mg kg Lead 134 mg kg Copper 741 mg kg Zinc 1202 mg kg (1990 National Sewage Sludge Survey)

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