Page 355 - Materials Chemistry, Second Edition

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326 Waste Management Practices: Municipal, Hazardous, and Industrial

FIGURE 10.20 Landfill runoff ready for treatment.

10.4.22 RESTRICTIONS ON LIQUIDS IN LANDFILLS
As mentioned previously, many older land disposal facilities in the United States had become envi-
ronmental nightmares because of the disposal of toxic wastes, often in liquid form. As a result, the
RCRA regulations require that bulk or noncontainerized liquid wastes not be placed in MSWLFs
unless (40 CFR Part 258.28):

● The waste is household waste.
● The waste is leachate derived from the landfill and the unit is designed with proper lin-
ers and a leachate collection system.
The restriction of free liquids is intended to limit the generation of leachate. Liquid waste refers
to any waste material that is determined to contain free liquids as defined by SW-846 (U.S. EPA,
1986b) Method 9095 — Paint Filter Liquids Test. The paint filter test is performed by placing a 100
mL sample of waste in a conical, 400 µm paint filter. The waste is considered a liquid waste if any
liquid from the waste passes through the filter within 5 min. The apparatus used for performing the
paint filter test is illustrated in Figure 10.21. Due to concerns over cost and practicality, it is impos-
sible to regulate household waste for its content of liquids. Containers holding liquid waste may not
be placed in a landfill unless the waste is a household waste.
If the waste is considered a liquid waste, absorbent materials may be added to render it a ‘solid’
material (i.e., a waste or absorbent mixture that no longer fails the paint filter liquids test). Sludges
are a common waste stream that may contain significant quantities of liquid. Sludge is a mixture of
water and solids that has been produced during water and wastewater treatment in commercial or
industrial operations. Sludge disposal is acceptable provided the sludge is nonhazardous and passes
the paint filter test.

10.4.23 LEACHATE FORMATION
Landfill leachate production and migration are among the most acute concerns for operators of
municipal sanitary landfills. Leachate is the liquid generated by the action of water (rainwater or
infiltrating groundwater) and liquids present within the initial waste percolating through the stored
waste within a landfill cell. As the absorbent components of the waste begin to fail to absorb the
liquids, free leachate forms.