ADSORPTION OF BIOLOGICALLY INHIBITORY COMPOUNDS AS A PROCESS-CONTROL MECHANISM IN BIOLOGICAL REACTORS

An innovative reactor design that decouples biological removal mechani sms from physical removal mechanisms has demonstrated promise for the treatment of wastewaters containing high concentrations of inhibitory compounds. Inhibition and toxicity prevent treatment of such wastewate rs in conventional biological reactors. The reactor design consists of a high-rate biological reactor with a granular activated carbon (GAC) adsorber inserted into the recycle line of the biological reactor. Pa rtial replacement of GAC from the GAC adsorber provides a mechanism fo r controlling the concentration of inhibitory compounds in the biologi cal reactor. As a process control parameter, GAC replacement can be us ed to maintain the concentration of inhibitory compounds in a range op timal for growth and acclimation. GAC replacement is also varied in re sponse to changes in the influent loading and can be used to provide r apid recovery from shock loadings. Agreement between isotherm studies and experimental data from pilot-scale systems was observed when the a verage GAC particle residence was greater than 3.75 days. Isotherm stu dies may be used to design the GAC adsorber and predict optimal operat ing conditions. The concept of using an adsorption process to optimize biological removal provides an environmentally sound treatment altern ative for many high-strength wastewaters.