Bioremediation of hydrocarbons is not difficult. The problem is that bacteria and
fungi have very small stomachs and eat slow. The two components needed for
bioremediation is moisture and nutrients. Moisture should be kept at about 20%
and nitrates at about 20 ppm.
There are plenty of naturally occurring bacteria and fungi in soil to promote
bioremediation. Addition of store bought cultures is not necessary. Often, the
majority of organisms in commercial cultures die when introduced to the
environment because it is foreign to the incubated tanks where they were
developed. Fungi are the main organism doing the remediation, not bacteria.
There are 10,000 times more fungi in soil than bacteria. Little is heard about the
fungi role in bioremediation because fungi are not widely studied, difficult to
culture individually, and there are many species not named. To understand how
aggressive fungi are in bioremediation, look at wood decay in forest due to fungi.
The rotting branches and trunks are due to fungi using them for food. If fungi can
break down wood, they certainly can eat hydrocarbons.
Bioremediation occurs efficiently when the fungi and bacteria (bug) population is
high and thriving. For this to occur they need food, the hydrocarbons, nutrients,
the nitrate, and moisture. The goal is to maximize the bug population and keep
the population high. To do this the nitrate need to be kept at about 20 ppm and
moisture has to be kept at least 20%. When either of these parameters drop, the
bug population drops and the rate of bioremediation decreases. When optimum
conditions return, then the bug populations must regrow in order to have a high
rate of bioremediation. If the nutrients and moisture are constantly bouncing up
and down, bioremediation will be very slow because the bug population does not
maintain a high level.
The bioremediation should be monitored for TPH, nitrates, and moisture every
two weeks or monthly. The material should be mixed by tilling once every month
or two. Depending on the TPH level desired, bioremediation may take 4 mo to
year depending on field conditions. Cooler weather will slow the bioremediation
It is very important that homogeneous, representative samples be taken. The site
should be initially tilled and completely mixed to make as homogeneous as
possible. When sampling, 10 subsamples should randomly be taken and
composited to one sample for testing. It is suggested that the subsamples be
mixed in a plastic bag for the composite before transferring a portion to a 4 oz jar.
The strongest and most representative data would be to take 3 composite
samples, especially on large sites. The data will bounce high and low over time if
representative homogeneous composite samples are not taken