Section 4. CHEMICAL WASTES
TREATABILITY OF DIVERSE WASTE STREAMS IN
THE PACT® ACTIVATED CARBON-BIOLOGICAL PROCESS
Richard W. Soderberg, Engineering Associate
Richard E. Bockrath, Senior Supervisor
E.I. duPont de Nemours & Company, Inc.
Deepwater, New Jersey 08023
INTRODUCTION
Du Pont operates a large diversified organic chemicals manufacturing plant (Chambers Works) at
Deepwater Point in southern New Jersey. Major product groups at this facility are nitrated, chlorinated and/or amminated derivatives of benzenoid chemicals, aliphatic surfactants, Freon® fluoro-
carbons, elastomers, and petroleum additives. A large waste water treatment plant handles aqueous
wastes not only from on-plant processes but also from other Du Pont plants and from outside customers.
This paper discusses means used to screen new aqueous waste candidates to ensure that they do not
represent a threat to human or biomass health and that their organic content can be removed to the
extent necessary to ensure continued compliance with regulatory requirements.
DISCUSSION
During the early 1970's, a 40 mgd treatment plant (WWTP) was constructed at the Deepwater site.
Since the waste water is normally acidic, a primary treatment step uses slaked lime to neutralize it to
pH 7. During neutralization, significant reduction in heavy metals content occurs through precipitation and settling. The clarified primary effluent is then subjected to biological treatment in the presence of powdered activated carbon in conventional aerated tanks. This combined activated carbon-
biological treatment is known as the PACT® process. The PACT technology is now owned by Zim-
pro, Inc., who are making it available under license.
After final clarification, the effluent flows into the Delaware River. Solids are removed from the
process by filtration and are deposited in a secure landfill on the plant site.
During the late 1970's, a waste treatment service was established to handle aqueous wastes from
other Du Pont plants and from outside customers to more fully utilize the WWTP capacity. This business has grown steadily and waste water is received in both tank trucks and railroad tank cars. Modification of existing facilities to handle barges is under consideration.
Screening Tests
Treatment of a large diversity of wastes from both on-site and off-site sources requires a screening
process to characterize each waste before it can be accepted. We must be sure that it represents no
threat to human health and that it will not upset the chemical-physical or biological functioning of the
WWTP.
In deciding what screening should be performed for each waste, consideration is given to its
expected volume and to the process which produced the waste. Minimum screening consists of the
tests shown in Table I. Limits are imposed on the concentration of sulfide and cyanide because acidification of waste containing significant amounts of these ions could result in unacceptable levels of
hydrogen sulfide or hydrogen cyanide in the air. Copper is limited because it is known to be inhibitory
to biological activity at higher concentrations. The next three items are determined both to estimate
treatment cost and to determine the impact on treatment plant capacity. Degree of acidity affects lime
usage, suspended solids have an impact on filtration and landfill capacity, and dissolved organic carbon has an impact on biological treatment capacity and activated carbon requirements.
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