Anaerobic Filter — Kinetics and Application
JAMES A. MUELLER, Associate Professor
Environmental Engineering and Science
Manhattan College
Bronx, New York 10471
JOHN L. MANCINI, President
Hydroscience, Inc.
West Wood, New Jersey 07675
INTRODUCTION
The anaerobic filter is basically a column or tower filled with rock or synthetic media
operated in the upflow mode. Recent research on this process indicates it is a viable system
for pretreatment of high strength industrial wastes. This paper presents the results of a
research effort conducted to obtain a useful kinetic model of the system and to push the
system experimentally to the limits of its capability.
LITERATURE REVIEW
A summary of anaerobic filter investigations conducted to date with their significance
is given in Table I. In 1968, Young and McCarty (1, 2) conducted the initial research on the
filter and presented the following equation to predict soluble ultimate BOD removal
efficiency (%E).
%E= 100(1 -     L8  ) (1)
t
where, t * hydraulic detention time based on initial void volume. They also developed a
mathematical model incorporating biological growth, solids transport, diffusional
resistance of the biofilm and non-steady state solids buildup. The model was useful in
describing the various process mechanisms but too complex for analysis or design.
Following Young and McCarty's work, a number of studies were conducted to
determine the applicability of the process to various types of industrial waste. Successful
operation was obtained for all the wastes studied except for the petrochemical wastes, the
latter due either to the toxicity of the raw waste, high H2S concentrations, or low pH
produced in the filter.
Figure 1 presents a plot of the COD removals obtained by all investigators against
hydraulic detention time. The design equation presented by Young and McCarty for
soluble ultimate BOD is seen to represent the upper bound of the highly scattered data. The
lower removals obtained for many of the studies is due either to the nature of the specific
industrial wastes or to high solids carryover. From two studies, data on sludge age versus
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