Evaluation of bioremediation of oil-polluted soil using the respirometric oxitop® method.

Abstract

Bioremediation includes natural processes to degrade harmful compounds in the
environment. The goal in bioremediation is to stimulate microorganisms with different
additives that will activate them to destroy the contaminants. Respirometry methods have
been used to assess the microbial activity of soil but a few respirational studies have been
performed with surfactants.
The objective of this study was to examine the effects of surfactants and adsorbents on
oil-contaminanted soil respirational activity. The measurement of oxygen consumption is
used to evaluate the enhancement of the bioremediation of polluted soil by surfactants
and adsorbents. Selected surfactants were sodium dodecyl sulfate (SDS), Saponine and
emulsifying agent SR-100. In the present study the respirometric OxiTop® system was
used to measure the oxygen consumption of the soil by adding the different surfactants.
The rates of oxygen consumption were calculated from respiration data.
The measurements of respiration showed that the maximum initial rate of oxygen
consumption of soil was 4.39 mg 02 kg -1 h -1 at the water content of9% (w/w ). SR-100
addition showed the highest initial rate of oxygen consumption - 18.61 mg 02 kg ·1 h -1•
The medium rate of oxygen consumption of the oil contaminated soil for five days was
half of the initial rate. The mixtures of soil and the adsorbents had lower respirational
activity, even when solutions of the surfactants were added. The highest initial rates of
oxygen consumption of soil were 4.24 mg Oi kg -1 h -1 ( Saponine solution was added) and
13.00 mg 02 kg"1 h"1 (SR-100 solution was added) for the hydrophobic and hydrophilic
adrorbents, respectively. For the mixture of soil and adsorbent the longer lag-period for
the activation of oxygen consumption occurred by the adding of surfactants.