85    BIOLOGICAL DEGRADATION OF ORGANIC CHEMICALS
IN OCPSF WASTEWATERS
Meint Olthof, General Manager
Donald G. Olmstead, Project Manager
Killam Associates
Warrendale, Pennsylvania 15086
INTRODUCTION
The promulgation of the Organic Chemicals and Plastics and Synthetic Fibers (OCPSF) Category
Effluent Limitations Guidelines on November 5, 1987, has generated a considerable demand by the
regulated community for practical, economical solutions to their compliance needs. The discharge
limits are stringent, and the problem is complex.
Typically the OCPSF regulated streams are high strength variable composition wastewaters generated by batch processes. Wastewater composition varies from day to day and month to month, as
production schedules change and new product lines evolve. The target effluent compounds have
varied as a result of litigation. Table I depicts the discharge limits as promulgated in 1987, with
subsequent revisions annotated.
Waste minimization procedures, and recovery technologies can greatly improve effluent quality. In
most cases however, some form of end-of-pipe treatment is required.
This paper presents the results of biological treatability studies conducted successfully on a pilot
and a laboratory scale for three OCPSF clients.
DESCRIPTION OF BIOLOGICAL TREATMENT
Biological treatment utilizes acclimated, conditioned bacteria to oxidize or reduce organic compounds. The former process occurs under aerobic conditions, and the latter occurs under anaerobic
conditions. Either process can be operated in a fixed film (bacteria attached to media) or a suspended
growth mode.
The studies outlined herein emphasized suspended growth biological treatment. Activated sludge
and sequencing batch reactor (SBR) systems were tested. Both utilize aeration and mixing to oxygenate and suspend bacteria in aerated basins which receive wastewater flows. Bacteria are prevented
from washing out of the system by a clarification step. Clarification is accomplished in the same basin
in the SBR process, and in an external tank in the activated sludge process.
APPROACH
Studies were conducted in the laboratory, and/or on a pilot scale. For studies in which piloting
could not be conducted, historical operating data, future products and production projections, and
available at-source monitoring data were used to determine some "worst case" wastewater compositions. These compositions were simulated by spiking raw wastewater. Usually spikes addressed only
the regulated compounds or compounds envisioned to be refractory or toxic.
Loadings for each reactor were maintained on the basis of the Food to Mass ratio (F/M). For the
studies outlined herein, F/M is the ratio of the daily mass loading of chemical oxygen demand (COD),
to the bacterial mass in the reactor, as measured by the mixed liquor volatile suspended solids
(MLVSS).
The studies conducted for the three facilities usually emphasized variations on two approaches:
high rate activated sludge or SBR treatment (F/M of 0.4 to 0.6) followed by granular activated carbon
polishing; and low rate activated sludge or SBR treatment (F/M of 0.2 to 0.3) without granular
activated carbon polishing.
47th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea. Michigan 48118.
Printed in U.S.A.
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