FULL-SCALE ANAEROBIC FILTER TREATS HIGH
STRENGTH WASTES
Enrique R. Witt, Research Associate
William J. Humphrey, Development Project Manager
Celanese Chemical Company
Corpus Christi, Texas 78408
Thomas E. Roberts, Supervisor of Environmental Control
Celanese Polymer Specialities Company
Louisville, Kentucky 40299
BACKGROUND
In the early seventies the Celanese Chemical Company Corpus Christi, Texas, Technical
Center began evaluating biological treatment for effluents from its Texas plants.
It soon became apparent that conventional aerobic techniques (activated sludge, lagoons,
etc), although basically applicable, might be difficult to implement. This was due to one or
more features of the various effluents such as high chemical oxygen demand (COD), high
acidity, hydraulic and/or COD surges, occasional presence of heavy metals, etc. Attention
was then turned to anaerobic techniques, and this work culminated in the development of a
modified anaerobic filter, which has been extremely successful for treatment of high-strength
petrochemical effluents in laboratory and pilot units.
Anaerobic filter treatment was also applied to the effluent from a sister Company's plant-
a guar process installation in Vernon, Texas. It was also successful, and led to the construction of a commercial filter, capable of handling the entire wastewater output from the Vernon plant. Design, construction and operation of this unit will be the subject of the second
part of this paper.
Anaerobic treatment has been repeatedly proposed as a superior alternative to aerobic
routes, particularly for high-strength effluents, > 5000 mg/1 COD [ 1, 2, 3, 4, 5, 6]. The
main advantages are: (a) greatly reduced energy requirements-anaerobic treatment can often
be a net energy producer; (b) greatly reduced biomass production-on the order of 10% of
that of activated sludge; (c) freedom from the constraints of F/M control, which becomes a
serious problem above «=10 g/1 COD; (d) much lower sensitivity towards heavy metal poisoning, which can become severe in aerobic systems at as little as s=2 mg/1 heavy metals; and
(e) greatly reduced nutrient requirements. This can become a significant economic factor
for nutrient deficient wastes.
Anaerobic treatment of effluents in the usual digesters or mixed-liquor reactors has the
drawback of poor biomass retention, and except for a few cases, these reactors have failed to
gain acceptance for industrial wastes.
ANAEROBIC FILTER
The problem of biomass retention was solved by Young and McCarty [6] with the invention of the anaerobic filter, but even this device failed to give anaerobic treatment the acceptance it deserves.
Anaerobic filters were applied on a commercial scale by Taylor and Burm for starch effluent [15], and on a more modest scale to a variety of effluents [3,7,8,9,10,11,12,13,14,15]
by other researchers.
RECYCLE ANAEROBIC FILTER
The anaerobic filter of conventional design is not practical for high acidity and/or high
levels of germicides, such as formaldehyde, in plant wastes.  Surges of toxic materials deactivate it, and neutralization of effluent to pH values compatible with methanogenesis is, in
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