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

Abstract

Bioremediation includes natural processes to degrade harmful compounds in theenvironment. The goal in bioremediation is to stimulate microorganisms with differentadditives that will activate them to destroy the contaminants. Respirometry methods havebeen used to assess the microbial activity of soil but a few respirational studies have beenperformed with surfactants.The objective of this study was to examine the effects of surfactants and adsorbents onoil-contaminanted soil respirational activity. The measurement of oxygen consumption isused to evaluate the enhancement of the bioremediation of polluted soil by surfactantsand adsorbents. Selected surfactants were sodium dodecyl sulfate (SDS), Saponine andemulsifying agent SR-100. In the present study the respirometric OxiTop® system wasused 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 oxygenconsumption of soil was 4.39 mg 02 kg -1 h -1 at the water content of9% (w/w ). SR-100addition 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 washalf of the initial rate. The mixtures of soil and the adsorbents had lower respirationalactivity, even when solutions of the surfactants were added. The highest initial rates ofoxygen consumption of soil were 4.24 mg Oi kg -1 h -1 ( Saponine solution was added) and13.00 mg 02 kg"1 h"1 (SR-100 solution was added) for the hydrophobic and hydrophilicadrorbents, respectively. For the mixture of soil and adsorbent the longer lag-period forthe activation of oxygen consumption occurred by the adding of surfactants.