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Leaching

Determination of emission of constituents from waste, soil and building materials

What is a leaching test?
A leaching test is a test during which material is put into contact with a leachat and some constituents of the material are extracted.

What is the purpose of a leaching test?
To determine the release of constituents from materials and with that the potential pollution of the environment with those constituents over a longer time period (up to 100 years).

To get an indication of the mobility of constituents and possible time of release.

To get an indication of the neutralisation capacity of the material.

Leaching tests can be performed on monolitic and granular soil, waste- and building materials.

Types of testing
* Basic Characterisation: To obtain information on the short and long term leaching behaviour and characteristics properties
* Compliance: To determine whether the material complies with specific reference values (After Characterisation)

Column test (Characterisation)
The column test is a dynamic test to determine the leaching (release) from L/S (Liquid/Solid ratio) 0,1 to 10. The total Emission at L/S 10 is the maximum leachable quantity over a period from 60 to 100 years in mg/kgDM.

Diffusion or Tank test (Characterisation)
The Diffusion- or Tank-test is a static test to determine the leaching (release) and stability of monolitic and formgiven (building) materials. The Emission is the maximum leachable quantity over a period from 60 to 100 years in mg/m2.

Compliance (CEN) test EN12547-1 to 4
The compliance test provides information on leaching of granular materials resulting in an Emission in mg/kgDM at L/S 10. (Important: this test has been developed to investigate mainly inorganic constituents. It does not take into account the particular characteristics of non-polar organic constituents nor the consequences of microbiological processes in inorganic degradable wastes).

Maximum availability test (Characterisation)
The maximum availability test gives a general impression off the maximum available quantity of constituents at L/S 100 in mg/kgDM. This test gives the “worst case”. It also gives a figure for the neutralisation capacity.

Legislation that contains leaching
In EU legislation the Landfill Directive (2002) has adapted the EN12457 (Compliance test) and prEN14405 (Column test) as the tests to be used. In almost all cases the EN12457 is used for characterisation.

In the Netherlands all described tests are used for characterisation of mainly building materials and waste.