72    TREATMENT OF STORM RUNOFF BY OIL-WATER
SEPARATION,
FLOTATION, FILTRATION, AND ADSORPTION.
PART A: WASTEWATER TREATMENT
Lawrence K. Wang, Director
Lenox Institute for Research Inc.
Lenox, Massachusetts 01240
William J. Mahoney, Technical Director
Imperial Oil Company Inc.
Morganville, New Jersey 07751
INTRODUCTION
The feasibility of removing soluble arsenic (+ 5) and other conventional pollutants from combined
storm runoff and process wastewater by oil-water separation, dissolved air flotation (DAF) filtration,
and granular activated carbon (GAC) adsorption was fully demonstrated for an oil blending company
in a northeastern state.
The oil separated from the raw combined wastewater by the American Petroleum Institute (API)
oil-water separators was virgin, and was, therefore, skimmed off, dried and reused.
The oil-water separator effluent containing 1.01 mg/L of arsenic, 3 NTU of turbidity, 50 units of
color, 28.5 mg/L of oil and grease (O&G), and 83 mg/L of chemical oxygen demand (COD) was fed
to a DAF clarifier (Supracell) for removal of arsenic by 90.1 %, turbidity by 30%, color by 43 %, O&G
by 43.2% and COD by 32.5%. Either ferric chloride or ferric sulfate was an effective coagulant for
arsenic removal.
The same oil-water separator effluent was also successfully treated by a DAF-filtration clarifier
(Sandfloat). Reductions of arsenic, turbidity, color, O&G, and COD were 90.6%, 93.3%, 98%,
74.7% and 51.8%, respectively.
Although Supracell and Sandfloat both demonstrated to be excellent pretreatment processes, GAC
post-treatment removed 100% of soluble arsenic.
This chapter summarizes and discusses the technical data on combined treatment of storm-run and
process water by the innovative treatment systems.
PRETREATMENT BY PILOT FLOTATION AND FILTRATION SYSTEM
The pilot plant system shown in Figure 1 was set up for this research. The system consisted of a
rapid mixing chamber, a rectangular static hydraulic flocculator (L x W x H = 102 in x 16 in x 10
in = 259.08 cm x 40.64 cm x 25.40 cm), a dissolved air flotation unit (Krofta Supracell Model SPC
3; Diameter = 0.91 m = 3 ft; Depth = 55.88 cm = 22 in), and three sand filters (28 cm of quartz
sand as filter bed). The pilot dissolved air flotation unit (DAF) was the heart of the entire pilot plant
system. The following were the typical pilot plant operational conditions:
Influent:     Combined storm runoff water and process water, pretreated by the existing API oil-
water separators, and spiked with soluble arsenic when necessary
Chemicals: 15 mg/L of sodium aluminate (as A1203), and 15 mg/L of either ferric chloride or
ferric sulfate (as Fe)
Continuous influent flow: 39.62 m3/hr (9 gpm)
Continuous DAF effluent flow: 39.33 m3/hr (8.934 gpm)
Continuous DAF sludge flow: 0.29 m3/hr (0.066 gpm)
Continuous DAF recycle flow: 8.8 m3/hr (2 gpm)
44th Purdue Industrial Waste Conference Proceedings, © 1990 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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