Green Engineering. Harry R. Compton Environmental Engineer U.S. EPA - ERT

Transcription

1 Green Engineering Harry R. Compton Environmental Engineer U.S. EPA - ERT

2 Mine Sites Lack of vegetation result of: Fertility Soil physical properties Acidity Metal toxicities Salts

3 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

4 Why use wastes? Different wastes can be used to remedy a number of factors that may potentially contribute to a soil s inability to support a vegetative cover. -- ph -- soil fertility -- soil physical properties, and -- potentially toxic concentrations of trace metals By combining different materials together, and applying to the soils in-place, soil problems can be corrected. -- lower costs -- recycling wastes

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

6 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

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

8 Metals in Biosolids Regulatory limit (pollutant concentration limits) Cadmium 39 mg kg Lead 300 mg kg Copper 1500 mg kg Zinc 2800 mg kg National Means (1990 national sewage sludge survey) Cadmium 7 mg kg Lead 134 mg kg Copper 741 mg kg Zinc 1202 mg kg

9 Scientific basis of treatments Biosolids/compost add: * nutrients * organic matter * metal complexing ability Wood ash/waste lime add: * ph adjustment * adhesive properties * nutrients Wood waste/other C-rich residuals: * limits N availability * adds bulk * physical soil benefits

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

11 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

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

13

14 Coeur d Alene Wetlands

15 Wetland - Plant lead (mg kg -1 ) South North Control Amended Control Amended

16 Other metals Cattail Arrowhead Control Amended Control Amended

17 Pb 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.

18 Upper Arkansas River Alluvium Remediation Leadville, CO

19

20

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

22 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

23

24

25 Filling vehicle Application

26 Leadville, CO

27

28

29

30

31

32

33

34 Re-entrainment Study Fathead Minnow % Survival = References = Amended Areas = Unamended Areas

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

36 Joplin, MO - In Vivo Feeding Reduction in Bioavailability

37 Leadville, CO

38

39

40

41