Page 20 - Environmental Control in Petroleum Engineering

Introduction to Environmental Control in the Petroleum Industry §

Nonhydrocarbon aqueous wastes can be treated by a number of
methods, including ion exchange, precipitation, reverse osmosis,
evaporation/distillation, biological processes, neutralization, and solidi-
fication. These processes can remove dissolved solids from water
or encase them in other solids to prevent subsequent leaching follow-
ing disposal.

1.1.6 Waste Disposal Methods

A number of disposal methods are available for petroleum industry
wastes. The method used depends on the type, composition, and
regulatory status of the waste.
The primary disposal method for aqueous wastes is to inject them
into Class II wells. If the quality of wastewater meets or exceeds
regulatory limits, permits to discharge it into surface waters may be
obtained in some areas.
The primary disposal methods for solid wastes are to bury them or
to spread them over the land surface. All free liquids normally must
be removed prior to disposal, either by mechanical separation, evapora-
tion, or the addition of solidifying agents. Land treatment of wastes
may be prohibited if volatile and leachable fractions are present in the
wastes. Disposal can occur either on or off-site. Underground injection
of slurries has also been used for solids disposal in some areas.
1.1.7 Cleanup Methods for Contaminated Sites

The most appropriate cleanup method will depend on the contami-
nant and on the site characteristics. The most common contaminated
sites are those that have spilled hydrocarbons in the soil and those
containing old drilling fluids.
A number of methods can be used to clean up sites. Mobile hydro-
carbons can be removed by drilling wells or digging trenches and
pumping the hydrocarbons to the surface with groundwater for treat-
ment. Volatile hydrocarbons can be removed by injecting air and/or
pulling a vacuum to vaporize those components. The use of heat,
surfactants, and bioremediation to remove subsurface hydrocarbons is
being studied. Dissolved hydrocarbons in water and volatilized hydro-
carbons in air can be removed by filtration or by absorption with