Organic Polymers for Stabilization/Solidification - Stabilization and Solidification of Hazardous, Radioactive, and Mixed Wastes - page 93

TABLE 5.1
Toxicity Characteristic Leaching Procedure Data for Polyethylene-
Microencapsulated Waste Forms

Toxic Metal Source Term Concentration a
(Microencapsulated Waste Form TCLP Concentration, mg/L) Waste

Loading,
wt% Waste Stream Pb Cr Cd Hg Se As

DOE Mixed Salts 60 3000

(0.07)

3000
(0.10)

3000
(0.37)

DOE Incinerator Ash 60 5000

(0.01)

5000
(0.01)

5000
(0.01)

SRS CIF Blowdown 40 2250

(< 0.05)

500
(0.07)

125
(< 0.05)

250
(< 0.04)

INEEL Carbonate
Salt

50 120

(< 0.14)

INEEL Ion Exchange
Resin

40 1200

(1.6 )

INEEL Sodium-
Bearing Waste

40 218

(< 0.14)

351
(2.4)

246
(0.34)

242
(< 0.0002)

Commercial
Incinerator Ash

50 15

(< 0.15)

Molten Salt Oxidation
Residuals

50 2400

(1.6)

Fernald Silo 1 Sludge 50 (0.712)

Fernald Silo 3 Sludge 60 (0.058) (0.029) (0.002) (0.088) (0.245)

Maximum Allowable
Concentration,
TCLP

5.0 5.0 1.0 0.2 1.0 5.0

Maximum Allowable
Concentration, UTS b

0.75 0.60 0.11 0.025 5.7 5.0

a Total concentration in the undiluted, untreated waste, i.e., source term; the concentration in TCLP
extracts of the polyethylene-microencapsulated waste is given in parentheses below the total concen-
tration.
b EPA is phasing in new Universal Treatment Standards (UTS) with lower allowable concentrations
for toxic metals.

Polyethylene encapsulation shares several advantages with thermosetting resins
including:

• Relatively high waste loadings (typically up to 50 to 70 wt% for dry salt

wastes). Waste loading may be limited by either physical processing
constraints or final waste form performance.

• Relatively low process temperatures minimize generation of secondary

waste through collection in the off-gas system. Polyethylene melts at
120°C and is generally processed at approximately 135 to 140°C.

• Compatibility with a wide range of waste types.