The Combined Treatment of Petrochemical
Wastes, Gasification Wastes and Fischer-
Tropsch Synthesis Wastes
P. R. LOEWENSTEIN, Divisional Manager
Coordination and Planning
W. P. DE WAAL, Superintendent
Water and Effluent Area
South Africa Coal, Oil, and Gas Corporation
Sasolburg,
Republic of South Africa
INTRODUCTION
The South African Coal, Oil and Gas Corporation (Sasol) was formed in September 1950 with the object of producing from coal, both gas, and hydrocarbons
ranging from LPG through gasoline and diesel oil to waxes. Production was to be
by Fischer-Tropsch synthesis. The factory was built south of the Vaal River between Vereeniging and the Barrage in order to exploit the extensive low-grade
coal deposits in this area (Figure 1). The first oil from coal was produced in August 1955.
In the early stages of planning it was apparent that large volumes of wastes
would require treatment before discharge to the Vaal River. The problems of waste
treatment were therefore studied and sewers and treatment facilities provided to
meet our special requirements (1).
The effluents from the factory could be grouped into two main types, i. e.
those containing only inorganic salts and those polluted with organic chemicals.
The first group consisted of sludges and brines from the raw water flocculation
plant and softening plant, and blowdown from the cooling water system and boilers. Since these streams require no biological treatment they were routed either
to ash handling or direct to the final effluent dams. For the second group the following sewer systems were provided: 1) a domestic sewer; 2) a "chemical sewer"
to carry synthesis wastes plus dephenolated ammonia stripped gas liquor; 3) an
"oily sewer" t0 carry general refinery drainage other than (2) above; and 4) a
storm water sewer. The first and second are discharged to the effluent purification works; the third to API separators and the fourth to a storm basin into which
the API separators also discharge.
Effluent from the storm basin and final effluent from the purification works
are returned to the factory for the hydraulic handling of power station and gasification ash.   After ash handling, water flows to the final effluent dams.
The Sasol factory, being in the catchment area of the Barrage reservoir from
which the Rand Water Board draws its supplies, was not allowed to discharge any
effluent into the Barrage, but had to provide a pipeline for effluent disposal to the
Vaal River, below the Barrage.
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