EQUILIBRIUM-MODEL FOR BIODEGRADATION AND ADSORPTION OF MIXTURES IN GAC COLUMNS

An equilibrium model for simultaneous biodegradation and adsorption wa s developed and verified with existing data. For simplicity the model was restricted to only two components: one biodegradable and one not. The results from modeling over 300 hypothetical situations identified conditions where biodegradation significantly extends the service life of granular activated carbon (GAG) columns. When the nonbiodegradable chemical controls the service life, the only significant gains in ser vice life occurred when the biodegradable and nonbiodegradable chemica l had similar adsorbabilities. When the biodegradable chemical control s the service life, the service life was 1.2-7 times that with adsorpt ion alone, depending on the relative adsorbability of the two chemical s. The increase in service life can be maximized by ensuring that biod egradation begins as soon as possible after start-up. The model provid es a good screening tool for initial assessments of process feasibilit y, preliminary economic analyses, and planning of detailed experimenta l and computer modeling studies.