BIO-PHYSICOCHEMICAL ADSORPTION SYSTEMS FOR
WASTEWATER TREATMENT: PREDICTIVE MODELING
FOR DESIGN AND OPERATION
Wei-chi Ying, Research Engineer
Amoco Oil Company
Naperville, Illinois 60540
Walter J. Weber, Jr., Professor
The University of Michigan
Ann Arbor, Michigan 48109
INTRODUCTION
Traditional biological treatment processes are frequently not capable of meeting
today's stringent water quality discharge requirements.    Physicochemical systems can
be designed to accomplish higher treatment levels, but are usually energy and operating
cost intensive.   These considerations, while important for municipal applications, are of
particular significance for industrial wastewater treatment, reclamation and reuse.
Because the energy use and operating costs associated with physicochemical processes
are generally proportional to waste load, current wisdom commonly dictates the use of
biological and physicochemical processes in series.   Biological treatment, with lower
energy requirements and operating costs, minimizes the waste load applied to subsequent physicochemical treatment processes.   However, the use of treatment systems in
series entails capital costs, material requirements, and land areas narly double those for
conventional biological systems.
An alternative treatment scheme involving an integrated biological-adsorption process
has been proposed by Weber et al. [ 1 ], and subsequently elaborated upon by Weber
and Ying [2].   The process utilizes an expanded, or partially fluidized, bed of granular
activated carbon with fixed-film biological growth on the surface of the carbon.   Adsorption on activated carbon is the most widely applicable and cost effective physico-
chemical process for many treatment, reclamation, and reuse applications.   Carbon is
particularly effective in removing trace amounts of halogenated organic compounds and
other potentially toxic and/or carcinogenic materials of concern.   Major operating costs
and energy utilization associated with this process relate to thermal regeneration of the
carbon.   The process described by Weber et al. provides simultaneous adsorption of
non-biodegradable contaminants and oxidation of biodegradable contaminants in a
single reactor, obviating dual treatment systems.    The expected results for many waste
treatment applications are lower capital costs for a single reactor system, less frequent
regeneration of the carbon, and, therefore, reduced energy requirements and operating
expenditures.
Experimental results presented in this paper further demonstrate the advantages of
the integrated biological-physicochemical treatment (IBPCT) scheme.   Criteria and
procedures for process modeling and design of IBPCT systems are detailed, and the
application of biological-adsorption models is illustrated.
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