It was found from our previous studies that adsorption and dissolved air flotation was suitable for the simultaneous removal of suspended solids and dissolved organics in water and wastewater treatments. Adsorption characteristics of natural organic matter were investigated using three different commonly used powdered activated carbons. The molecular weight distribution ranged from 248 to about 36,000 Da with the highest fraction of approximately 850-1000 Da were examined before and after precipitation, OAF and adsorption processes. The experimental results indicated that the presence of natural organic matter was certainly considered in the hybrid process of PAC/OAF.