Permeable Reactive Barriers (Proceedings of the International Symposium held at Belfast, Northern Ireland, March 2004). IAHS Publ. 298, 2005, 110-116.

Abstract Performance of barrier materials is important for the long-term success of permeable reactive barriers (PRBs). A number of selected wastes and natural materials were tested in batch experiments for their ability to remove heavy metals from synthetic groundwater. Two potential materials (clinoptilolite and calcified seaweed) were further investigated in column and elution experiments. Results showed that both materials have high metal removal (immobilization) (>95%) efficiencies. However, pore clogging as a consequence of mineral precipitation was recorded in a calcified seaweed column (size fraction 0.1–1.0 mm) after 7 months. Clogging was not observed in clinoptilolite columns. Elution tests showed some subsequent release of Cu, Cd and Zn in clinoptilolite and calcified seaweed columns eluted with acidic solution. Desorption of Cd and Zn was observed in a clinoptilolite column eluted with alkaline solution. No significant release of metals was observed in any of the columns eluted with a neutral pH fluid.

Key words calcified seaweed; clinoptilolite; column experiments; elution experiments; heavy metals; permeable reactive barriers