Issues with Arsenic Containing Wastes in Modern Landfills

Transcription

1 Issues with Arsenic Containing Wastes in Modern Landfills Timothy G. Townsend, PhD, PE Department of Environmental Engineering Sciences University of Florida October 3-4, 2006 Boston, Massachusetts Arsenic In Landfills: Protecting Water Quality

2

3

4 Topics Types of landfills Regulations Engineering Controls Chemical environments Toxic chemicals in landfills Concerns for the landfill operator Lessons learned

5 Types of Landfills Hazardous waste landfills Municipal solid waste landfills Other types Construction and demolition debris Industrial waste landfills

6 Hazardous Waste Landfills: RCRA Subtitle C Landfill (40 CFR 264)

7 Typical Subtitle C Liner Double Liner 2 ft drainage material Designed to maintain less than 1ft head on liner HDPE Geomembrane Geonet HDPE Geomembrane 3 ft compacted soil K <= 10-7 cm/sec

8 MSW Landfills: RCRA Subtitle D Landfill (40 CFR 258)

9 Typical Subtitle D Liner Single Composite Liner 2 ft drainage material Designed to maintain less than 1ft head on liner 60 mil HDPE Geomembrane 2 ft compacted soil K <= 10-7 cm/sec

10

11

12

13

14

15

16 Leachate is then sent to Treatment and/or Storage Facility Landfill Leachate Storage Treatment Gravity Drainage Pump Station

17

18 Lined Leachate Lagoon

19 Lined Leachate Lagoon

20 Leachate Storage Tank

21 Leachate Storage/Treatment Tanks

22 Leachate Treatment Plant Brine Evaporation Pond Treatment Plant Leachate Storage Lagoon Aerobic Lagoon Anaerobic Lagoon

23 Aerobic Treatment Lagoon

24 Reverse Osmosis Treatment

25 Leachate Treatment Using Wetlands

26 Leachate Recirculation to Landfill using Spray Irrigation

27 Leachate Storage Recirculation Tank to Landfill using Horizontal Trenches

28 Waste Stabilization in MSW Landfills Preliminary Aerobic Phase Acid Forming Phase Methane Forming Phase Final Aerobic Phase Aerobic Anaerobic Aerobic

29 Waste Stabilization in MSW Landfills Leachate Characteristics ph BOD, VFA Conc Preliminary Aerobic Acid Forming Methane Forming Final Aerobic

30 Cadmium Concentrations in MSW Landfill Leachate 10 3 Cd Concentration, ug/l US 1 FL 2 FL 3

31 Arsenic Concentrations in MSW Landfill Leachate 10 4 As Concentration, ug/l US 1 FL 2 FL 3

32 Other Landfill Types Construction and demolition (C&D) debris landfills Industrial waste landfills

33 C&D Debris Landfill Approximately ½ of states have liner requirements

34 Unlined Landfill for Hurricane Katrina Debris

35

36 Issues Facing Landfill Operators when Accepting Any Waste Is the waste hazardous or otherwise prohibited? Is this waste a bulk liquid? TCLP Paint Filter Test

37 What about wastes that may be legally disposed but do contained toxic trace constituents

38 Lead-Based Paint

39 Mercury Lamps

40 Treated Wood

41 Wood Ash

42 WTE Ash

43 Discarded Electronic Devices

44 Drinking Water Sludge

45 If the waste is not hazardous, and the landfill is lined with the leachate going to a POTW, then why do we care?

46 Potential Problems Posed Impact on leachate quality Impact on gas quality (e.g., Hg) Impact on waste decomposition Long-term operation issues

47 Impact on Waste Decomposition Cumulative methane volume (ml) Blank CCA (1g) + cell CCA (2.5g) + cell CCA 5g CCA 5g + cellulose Cellulose NP Days

48 Implication of Elevated Leachate Concentrations Leachate concentrations can limit leachate management options POTW pretreatment requirements Several sites in Florida encountered problems because of elevated concentrations of arsenic in the leachate

49 Factors to be Considered Leachability Rainfall and amount of leachate Fraction in the landfill

50 A majority of the waste in modern landfills stays dry Important Point

51 Incorrect Perception

52 More Accurate Perception

53 Concerns over Increased Chemical Concentrations Leaching tests such as TCLP can be conducted to assess potential problems Several studies show that TCLP may not be reflective of leaching that will occur in a landfill for some wastes. TCLP does not always under predict leaching.

54 Leaching in MSW LF Leachate Arsenic (mg/l) TCLP Limit Lead (mg/l) TCLP Limit 0 TCLP MSW 0 TCLP MSW CCA-Treated Wood Printed Wire Boards

55 Many Reasons for the Difference ph Leachate chemistry Redox conditions Interactions with waste and other chemicals in leachate Precipitation Sorption

56 Simulated Landfills

57

58

59

60

61

62

63 CCA Lead based paint ACQ

64

65 Cell Phones

66

67 Water distribution system

68 Box Plot of Leachate Lead Concentrations (Leachates with ph less than 7 in cyan, ph greater than 7 in yellow) 1 Pb Concentration (mg/l) Excavated Waste MSW Control 1 MSW Control 2 MSW E-waste 1 MSW E-waste 2 MSW E-waste 3

69 Arsenic vs. Time in C&D Lysimeter Leachate

70 Arsenic Concentration in CCA Lysimeter Leachates from Three C&D Lysimeter Projects 5 4 Arsenic (mg/l) Jang (2000) Dubey (2005) Jambeck (2004) (0.5%CCA) (5%CCA) (10%CCA)

71 Current Situation with CCA-Treated Wood in Florida CCA-treated wood leaches enough arsenic to be characterized as a hazardous waste if not otherwise excluded in the regulations CCA-treated wood is currently allowed to be disposed in unlined C&D debris landfills in Florida The FDEP is developing new rules that would require unlined disposal facilities to identify and remove CCA-treated wood prior to disposal

72 Arsenic Mass Produced, Disposed, and Leached (metric tons) Mass As In-Service (metric tons) Total Produced Amount Disposed Leached During In-Service Use In-Service, before Leach Year Yearly mass of arsenic associated with the production, disposal, and inservice leaching of CCA-treated wood products imported to Florida. Amount of arsenic associated with structures in-service also shown for reference.

73 Cum. Arsenic Mass (metric tons) Cum. Produced Cum. Disposed Cum. Lost During In-Service Use In-Service, After Leach Year Cumulative mass of arsenic associated with CCA-treated wood production, disposal, and in-service leaching. The estimated amounts of arsenic associated with structures in-service also shown for reference.

74