THE NEGATIVE IMPACT OF INDUSTRIAL WASTE
ON PHYSICAL-CHEMICAL TREATMENT
W. Guirguis, Research Manager
J. P. Harris, Chief Engineer
Cleveland Regional Sewer District
Cleveland, Ohio 44114
P. B. Melnyk, Assistant Professor
Case Institute of Technology
Cleveland, Ohio 44106
INTRODUCTION
Physical-Chemical Treatment (PCT) for wastewaters has been investigated extensively
in the past decade as a tertiary step for existing treatment facilities.   Recently, PCT has
been accepted as an alternative process for complete treatment of wastewaters.   In 1973,
ten PCT plants were reported [ 1 ] to be either under design or construction, whereas
three of these are now in operation.   The lower space requirements, ability to absorb
wide variations in both hydraulic and concentration loadings, and insensitivity to toxic
shock loads are advantages which have increased the interest in employing PCT.
The typical flow scheme for a physical-chemical process, as shown in Figure 1, includes:
(a) chemical addition to precipitate soluble wastes and provide nuclei for particle growth;
(b) flocculation to promote particle growth; (c) solids separation; (d) pH adjustment;
(e) activated carbon adsorption to remove soluble organics; and (f) disinfection to destroy
microorganisms.
Chemical recovery and spent activated carbon regeneration may also be included.   To
date, limited experience is available on the application of PCT to combined industrial
municipal wastes.   The majority of data reported are from bench- and pilot-scale systems.
This paper evaluates the performance of PCT on combined wastes, and demonstrates
both its limitations and the need for process modification.
FLOCCULAIOFI
tK'f
AC
CANON
1
Cltp
Figure 1.  Flow scheme of typical physical-chemical treatment.
EXPERIMENTAL PROCEDURES
The data referenced hereafter were obtained from a PC pilot plant in operation since
1974 [2,3).   The hydraulic capacity of this plant is a constant 30 gpm.   The influent
contains wastes from both industrial and municipal sources.   The principal unit operations
include single-stage lime treatment, solids separation, activated carbon adsorption and
ozone disinfection.   These operations are carried on 24 hr/day, 7 days/week.   Samples
are collected hourly, composited, and chemical analyses are carried in accordance with
Standard Methods [4].   A listing of the values of pertinent operating parameters at each
stage is given in Table I.
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