Analysis of GAC samples for chlorine or dechlorination half value length

The aim of this project was to analyse 3 Granular Activated Carbon (GAC) samples using standard method DIN 19603 (May 1969, ‘chlorine or dechlorination half-value length’) which is used to assess GAC performance for removal of chlorine in industrial applications for production of soft drinks and bottled waters.

For this project WatStech Ltd. used a lab scale column system which incorporated both back washing and forward rinse facilities. In order to determine the dechlorination value of a GAC, four different bed depths for each GAC were investigated to provide an acceptable number of data points. The basic scope of this method is to determine the height of carbon necessary to reduce inlet free chlorine concentrations of approximately 5 mg/l by 50% in a column at a specific velocity.

The submitted samples all had similar dechlorination half lengths which were just less than twice that of a virgin carbon used as a reference material.