Application of biological activated carbon (BAC) in drinking water treatment

Abstract

Biological filtration represents an important process step for the production of high quality drinking water. Bacteria attached to the filter media as biofilm use biodegradable organic matter (BOM) present in the filter influent as a source of carbon and energy. The decrease of BOM levels through biofiltration is important with respect to the prevention of bacterial growth and related problems in the distribution system. The research presented in this thesis examined the applicability of biological activated carbon filtration using the water from the Ömerli Reservoir. The experimental results showed that, the choice of filter material is crucial in BAC systems. The ability of GAC to better adsorb and retain organic compounds increases their chance of being biodegraded by bacteria. Biological activity extended the service life of GAC columns. Thermally activated carbons adsorbed NOM better than chemically activated carbon. Likewise, this better adsorption resulted in higher biodegradation. DOC biodegradation was high and was related to the low specific ultraviolet absorption (SUVA) values in raw water. In the case of low SUVA values, ozonation may not be necessary to increase biodegradability of water. High nitrification efficiencies were observed in BAC columns filled with chemically and steam activated carbons. In-situ and membrane hybridization results indicated that Nitrosomonas species were the dominant ammonia oxidizing bacteria and Nitrospira-related species were the prevailing nitrite oxidizing bacteria. The results suggest that the real-time PCR analysis, the amoA/16S rRNA ratio, is an alternative method to understand nitrifying bacterial population and activity in BAC columns.|Keywords: Biological Activated Carbon (BAC), Granular Activated Carbon (GAC), Ozonation, Biodegradation, Drinking Water