Effects of membrane filter material and pore size on turbidity and hazardous element concentrations in soil batch leaching tests.

Soil batch leaching tests are conducted worldwide to quantify the leaching of hazardous substances from contaminated soil. In the extracts of soil batch leaching tests, some inorganic substances such as arsenic and lead are released both in colloidal and dissolved form. Recent studies have found that soil colloidal particles with small diameters persist in the filtrate even after the extracts are filtered through a membrane filter (MF) with a pore size of 0.45 μm, and they might affect the concentration of arsenic or lead. This study evaluated the effects of 0.45- or 0.4-μm MF materials on filtrate turbidity and leaching concentrations of inorganic hazardous elements during batch leaching tests. Turbidity and arsenic and lead concentrations in the filtrates of the tested soil samples varied greatly depending on the MF material. These findings indicate that the MF material affects the removal rate of colloidal arsenic or lead and therefore affects the results of leaching tests.