Expansion of Shell Chemical Houston Plant's
Waste Treatment Facilities
D. M. WHITNEY, Assistant Manager
Environmental/Utilities Department
Shell Chemical Company
Deer Park, Texas
BACKGROUND
The Houston Shell Chemical Plant is located about 20 miles east of downtown
Houston on a site just south of the Houston Refinery of Shell Oil Company. The
effluent from this plant is discharged into Patricks Bayou, which in turn discharges
into the Houston Ship Channel. This effluent has received primary treatment since
the first unit was brought on stream in December 1940. The primary treatment
facilities presently consist of automatic pH control, two API oil separation basins, an
80-foot primary clarifier, five air flotation units, and primary settling ponds.
The Houston Plant is the largest of all the Shell Chemical Plants. Industrial
chemicals, such as acetone, isopropyl alcohol, glycerine, methyl ethyl ketone, and
ethyl alcohol; EPON resins; and petrochemicals, such as ethylene and butadiene are
produced at this location. The main problem that remained in treating the Shell
Chemical wastewater in 1965 was dissolved organic materials. Since almost all of the
industrial chemicals produced are water soluble, they were not removed by the
ordinary physical means of separation available in primary treatment.
In compliance with the Texas Water Quality Act of 1965, Shell initiated a
program to determine what was necessary in order to provide secondary treatment. A
source survey was undertaken and all discharges into the plant sewer system were
determined and then reduced to the minimum. Approximately 50 percent of the
load was removed by this process. At the same time, a consulting engineering firm
was retained to complete a feasibility study and to design the necessary facilities.
These facilities were completed and brought on stream in January 1969. This
activated sludge unit consisted of two 4.1-million-gallon aeration basins (with
aeration capacity provided by fourteen 75-horsepower Lightning aerators), two
1.7-million-gallon flocculator-clarifiers, and sludge handling facilities (thickener,
centrifuge, and fluid bed incinerator).
Upon start-up, the BOD reduction of the unit was found to be only about 50
percent of design. A program to determine the cause of the problem and to design
the necessary additional facilities was immediately started by Shell Development (the
research and development company of the Shell Companies), the Houston Plant, and
a consultant.
During the period between design of the first unit (1966) and the design of the
second unit, the loading had increased about 70 percent at 90 percent probability. A
933