Chemical osmosis in natural clayey materials

Abstract

Semipenneable properties of clayey natural materials can have a significant impact on a range of geological and geochemical processes on laboratory and field scale. The importance of chemical osmosis in semipenneable natural clays for transport of contaminants was first discussed in the Netherlands in relation to the environmental aspects of contaminated harbour sludge depots. One of the main depots, De Sluiter near the Port of Rotterdam, is constructed in a salt water aquifer without a bottom liner. The clayey harbour sludge itself acts as a layer oflow hydraulic conductivity, restricting advective transport of contaminants. However, the construction also enables the sludge layer to act as a semipenneable membrane. The main objective of this study was to develop and apply instrumentation for the direct measurement of the semipenneability of materials like contaminated harbour sludge and other clayey materials under unconsolidated conditions.