Environmental Engineering Reference
In-Depth Information
grains, which is essential in the growth of the hydrated structure of cement.
Moreover, volatile organic compounds can be expelled from the solid matrix due to
the heat produced during cement hydration. Some approaches can be adopted to
stabilize organic materials, but they must be carefully selected for each type of
waste. The activated carbon and organically-modified clays are examples of sorption
reagents that are employed with the stabilization of cement grout. Relatively recent
studies have proved that the use of hydrogen peroxide (H
2
O
2
) and potassium
permanganate (KMnO
4
) as reactive agents in the flushing fluid can be used to treat
organic contaminants [CLI 97].
Notice that the majority of the processes used in solidification/stabilization
processes were developed for the treatment of ground contaminated with heavy
metals. The common reagents used in this case include cement and other pozzolanic
materials such as lime, fly-ashes and slags. It is only recently that the
immobilization of organic materials has become possible. Table 15.4 lists the kinds
of waste that can be treated by the process of stabilization/solidification. Table 15.5
lists the considerations that should be taken into account when treating grounds
contaminated by organic materials (oil).
General remarks
The method is mainly empirical and requires preliminary studies of treatment on
a case-by-case basis to evaluate the potential success of the chosen reagents with the
grounds and contaminants on the site. Moreover, a follow-up post-execution is
typically required to evaluate the success or the failure of the treatment. In any
event, the successful treatment of waste depends on its physical and chemical
characteristics. Indeed:
− successful treatment can be difficult to achieve with strongly variable waste;
− a high proportion of fines can prevent solidification;
− an elevated level of organic materials can interfere with the treatment;
− the volatilization of organic materials due to the mixture and heat of the
chemical reaction can be a concern;
− the treatment increases the volume and weight of waste, particularly in
treatment with cement grout. The volume and weight can increase up to 100%
[MAR 94]. Since treated waste must be contained, the treatment can significantly
increase the costs of provision by 20-55% [USES 90].
