AWWA JAW28841

The objective of this research was to examine the accumulation and adsorption capacity of powdered activated carbon (PAC) in a solids contact slurry recirculating clarifier (SCSRC). If high concentrations of PAC can be achieved in a sludge blanket, then PAC could be an efficient alternative to granular activated carbon for plants requiring only intermittent organics removal. A method to determine the PAC concentration in the clarifier slurry was developed based on a gravimetric analysis approach. It was found that very high concentrations of PAC (>4,000 mg/L) could be accumulated in an SCSRC; the profile of PAC accumulated through the clarifier revealed that the PAC was evenly distributed. Isotherm tests showed that the adsorptive capacity of the PAC-containing slurry for chloroform appeared to decrease somewhat when the residence time of the PAC in the clarifier was longer than 100 h. Includes 16 references, tables, figures.