Lab scale experiments for permeable reactive barriers against contaminated groundwater with ammonium and heavy metals...

Batch tests and column tests were performed to determine the design factors for permeable reactive barriers (PRBs) against the contaminated groundwater by ammonium and heavy metals. Clinoptilolite, one of the natural zeolites having excellent cation exchange capacity (CEC), was chosen as the reactive material. In the batch tests, the reactivity of clinoptilolite to ammonium, lead, and copper was examined by varying the concentration of cations and the particle size of clinoptilolite. One gram of clinoptilolite showed removal efficiencies of more than 80% against those contaminants in all cases except in very high initial concentrations of ammonium (80 ppm) and copper (40 ppm). The effect of particle size of clinoptilolite was not noticeable. In the column tests, permeability was examined using a flexible-wall permeameter by varying particle sizes of clinoptilolite. When the washed clinoptilolite having the diameter of 0.42-0.85 mm was mixed with Jumunjin sands in 20:80 ratio (w/w), the highest permeability of 2 x 10(-3) to 7 x 10(-4)cm/s was achieved. The reactivity and the strength property of the mixed material were investigated using a fixed-wall column, having eight sampling ports on the wall, and the direct shear test, respectively. Clinoptilolite was found to be a suitable material for PRBs against the contaminated groundwater with ammonium and/or heavy metals.