Section Five
WASTE TREATMENT PROCESSES
E. ANAEROBIC BIOLOGICAL PROCESSES
58    ANAEROBIC PRETREATMENT OF A SYNTHETIC
INDUSTRIAL WASTEWATER IN A FLUIDIZED BED
BIOLOGICAL REACTOR
Robert M. Cowan, Research Associate/Assistant Professor
Hari Krishnan, Graduate Research Assistant
C. P. L. Grady Jr., R.A. Bowen Professor and Acting Department Head
Environmental Systems Engineering, Clemson University
L.G. Rich Environmental Research Laboratory
Anderson, South Carolina 29634-0919
INTRODUCTION
Many high strength industrial wastewaters contain significant concentrations of biologically recalcitrant organic compounds in a matrix with high concentrations of readily biodegradable compounds.
When this occurs it can be beneficial to pretreat the waste biologically before another process is used
to remove recalcitrant contaminants because the pretreatment prevents the biodegradable organic
compounds from interfering with the efficacy of the other process. This applies whether the downstream process used is physical, chemical, or biological. Often the concentration of biodegradable
COD in wastewaters of this type is of sufficient magnitude that anaerobic pretreatment is the preferred treatment scheme.
Industrial wastewaters resulting from esterification processes used in the manufacture of polyester
fibers are wastewaters whose composition matches the above description. These wastewaters are of
high strength, typically having total CODs of 29,000 to 45,000 mg/L, with the bulk of the COD being
contributed by acetaldehyde and ethylene glycol, both of which are amenable to anaerobic biological
treatment.1,2 Typically the wastewater also contains significant concentrations of the biorecalcitrant
cyclic ethers 1,4-dioxane and 2-methyl-l,3-dioxolane.3,4 These compounds can be removed from the
wastewater using advanced oxidation processes (AOPs)5 or aerobic biodegradation with a specialized
bacterial culture.6 While it may be possible to treat the wastewater directly with either of these
processes, it is unlikely that either alone would be less expensive than their use in combination with
anaerobic pretreatment. Therefore, this project was undertaken to evaluate the feasibility of using an
anaerobic process for the pretreatment of this type of wastewater.
OBJECTIVES
• Develop an anaerobic culture capable of degrading the major COD constituents of the
wastewater, i.e. acetaldehyde and ethylene glycol.
• Investigate the anaerobic biodegradability and anaerobic toxicity of the wastewater components.
• Determine the maximum loading rate which can be treated in an anaerobic fluidized bed
reactor while achieving a high degree of destruction of the biodegradable organic chemicals present.
• Assess the robustness of the FBBR for response to shock loads of organics and develop a
method for predicting system response to other shock load events.
49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
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