Separation of Radium from Contaminant Sand Filters in a Ground Water Treatment Plant by Organic Acid Solutions

摘要

Sand filters are used as a filter bed in many ground water treatment plants to remove the physical contaminants and oxidation products from ground water. A build-up of radioactivity may take place on the granules, where iron and manganese oxides are deposited and form thin films around surfaces of sand filters. The oxides of iron and manganese play an important role in adsorbing radium from ground water. The disposal of those granules makes a significant problem. A batch technique was used to remove radium from sand filters. This can be accomplished by adopting dissolution process using different organic acids such as formic acid, Acetic acid, Benzoic acid, Succinic acid, Oxalic acid, Phthalic acid, and Adipic acid. The effect of acidity, temperature, contact time and liquid/solid ratio and shaking speed was thoroughly investigated as factors which affect the treatment process. The data obtained are discussed on the basis of the experimental results. It was found that oxalic acid was the best for radium removal from sand filters. The effectiveness of these acids on radium removal was as follows: oxalic acid > formic acid > succinic acid > phthalic acid > acetic acid > adipic acid. The maximum removal obtained was 69.9% at 1M H{sub}2C{sub}2O{sub}4 at 50°C for 120 min contact time.