Page 199 - Environmental Control in Petroleum Engineering

Waste Treatment Methods 185

6.1.5 Neutralization

Many aqueous wastes in the petroleum industry are either acidic
or alkaline. These wastes often must be treated to neutralize their
reactivity before reuse or disposal. In many cases, the simplest treat-
ment method is to mix these types of wastes for mutual neutralization.
Because mixing may result in an exothermic reaction, it must be done
with care to minimize any safety hazards.

6.2 TREATMENT OF SOLIDS

During drilling and production activities, a substantial volume of
contaminated cuttings, soil, and produced solids are generated. The
most common treatment method is to separate the solids from any
contaminating water and/or hydrocarbons.
A variety of treatment methods are available to clean contaminated
solids and are reviewed below. The effectiveness of different treatment
methods depends on the solid type and size, as well as the initial
contamination level and targeted final contamination level. Prepro-
cessing techniques, including materials handling, can also impact the
effectiveness of a treatment method. Preliminary tests of a particular
method on a representative sample are recommended.

6.2.1 Removal of Water

A variety of methods are available to remove water from solids,
including evaporation and filtration. One of the most common applica-
tions of dewatering technology is treating reserves pits containing drill
cuttings and water-based drilling muds.

Evaporation

The simplest way to dewater solid wastes in arid climates is to put
them in open pits or on concrete pads and allow the free water to
evaporate. Evaporation is a common way to remove water from
reserves pits following drilling, although changes in regulations may
now require a more rapid dewatering than evaporation allows. Pro-
duced water can also be disposed of by evaporation, as long as the
volumes are relatively low (Mutch, 1990).