GAC Adsorption of Dissolved Organic Matters for CSOs Treatment and Bioregeneration of Spent-GAC Using Denitrification

Abstract

The capability of a laboratory-scale reactor packed with granular activated carbon (GAC) was evaluated in the removal process of organic matter dissolved in Combined Sewer Overflows (CSOs). First, the capacity of adsorption was recorded by six types of organic matter passing through the GAC reactor. Second, the breakthrough period was investigated when the CODcr adsorption ratio fell below 30% by varying the input intensity of CODcr into the GAC reactor from high, medium, to low. Lastly, the possibility of regenerating GAC through the denitrification process was examined. As a result, GAC adsorption capacity was ranked in order of sewage > sodium acetate > methanol > LB broth ≒ Glucose. Uniquely, glucose, being easily removed in the biological wastewater treatment process, had a low GAC adsorption capacity in this process. Thus, GAC showed the best adsorption for sewage among tested organic matters. Secondly, the breakthrough periods of the GAC adsorption reactor were 21, 28, and 32 days under high, medium, and low CODcr conditions, respectively. Lastly, the organic matter adsorbed in the GAC micro-pore was reused as an external organic carbon source to denitrifying bacteria in CSOs. However, the re-adsorption capacity was not at a satisfactory level which needs further research.