Evaluation of Water Treatment Efficiency according to Number of Regeneration of GACs For Efficient Operation of GAC Process

Abstract

This study was conducted to evaluate the effect of increasing the number of regenerated granular activated carbon (GAC) on the adsorption efficiency of DOC and THMs from 2011 to 2016. As increase the number of regeneration times, the apparent density, hardness and I2 number were decreased, and the ash was increased. Average breakthrough period of virgin GAC for DOC (C/C0 = 0.8) was about 8 months and each GAC basin (300 m3) adsorbed about 4,246 kg of DOC. The regenerated GACs reached to breakthrough 7 to 10 months and these GACs have 3,514~4,656 kg/basin adsorption capacity. The average THMs breakthrough (C/C0 = 1.0) period of virgin GAC was about 7 months and each basin adsorbed 60.6 kg of THMs. 1st and 2nd and more regenerated GACs had 44.8 kg/basin, 21.6 kg/basin and 10.8 kg/basin adsorption capacity respectively. To determine the optimum regeneration times, 6th regenerated GAC has almost same degree of adsorbing DOC capacity of virgin GAC that means it is difficult to determine the appropriate regeneration times for DOC, on the other hands for THMs, 2nd regenerated GAC’s adsorption capacity has one thirds of virgin GAC of that and more 4th regenerated GAC has only one sixths of virgin of that, therefore, more two times of regenerated GAC needs to be considered for THMs removal. Key words: Granular Activated Carbon (GAC), Regeneration, Regeneration Times, Trihalomethanes (THMs), Dissolved Organic Carbon (DOC), Breakthrough