COMPATIBILITY OF SEMICONDUCTOR INDUSTRY WASTEWATER
WITH MUNICIPAL ACTIVATED SLUDGE SYSTEMS
Don F. Kincannon, Professor
Bioenvironmental and Water Resources Engineering
School of Civil Engineering
Oklahoma State University
Stillwater, Oklahoma 74078
Ayoub Esfandi, Project Engineer
Industrial Waste Section
County Sanitation Districts of Los Angeles County
Whittier, California 90607
T. S. Manickam, Assistant Professor
Department of Civil Engineering
University of Delaware
Newark, Delaware 19711
The pretreatment program within the U.S. Environmental Protection Agency is formulated in regulation 40 CFR 403. This regulation requires that the Effluent Guidelines Division establish categorical pretreatment standards. When EPA establishes a guideline for
an industry, that industry is broken down by process products which are referred to as subcategories. Therefore, segregation of the wastewater and treatment of the wastewater for
each individual process is assumed. When the permit is put together for a direct discharge, a
building block approach is used to construct a permit which accounts for all the different
processes within the facility. In setting discharge limitations, it is important to know the
compatibility of a particular industrial wastewater with a wastewater treatment facility.
The objective of this study was to determine the compatibility of the semiconductor subcategory of electrical products industrial wastewaters with biological wastewater treatment
processes.
Two industries were selected by Effluent Guidelines Division for field pilot plant studies.
The field studies were a joint effort between the Bioenvironmental and Water Resources
Engineering Group, School of Civil Engineering, Oklahoma State University and the Robert
S. Kerr Environmental Research Laboratory.
MATERIALS AND METHODS
The general experimental plan specified field pilot plant studies be conducted at two
semiconductor manufacturing plants. The activated sludge pilot plants were to be operated
for four weeks at each industrial site.
A flow diagram of the activated sludge pilot plant is shown in Figure 1. The control and
test until were identical for Industry A. The pdot plants were both used as test units at
Industry B and the control consisted of a 3 liter bench scale internal recycle reactor. The
pdot plants consisted of a 140-gallon covered steel aeration tank and a 46-gallon clarifier.
The wastewater fed to the pilot plant control consisted of Sego (a diet drink), ammonium
chloride, phosphoric acid, tap water, and various percentages of industrial plant effluent.
The wastewater from Industry B contained an acid wastewater. This acid wastewater was fed
untreated to one pilot plant and pretreated with ferric chloride and lime before being fed
to the other pilot plant. The flow rates used for the various pdot plants are shown in Table I.
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