Search

The mud generated from oil and natural gas drilling, presents a considerable ecological problem. There are still insufficient remedies for the removal and minimization of these very stable emulsions. Existing technologies that are in use, more or less successfully, treat about 20% of generated waste drilling mud, while the rest is temporarily deposited in so-called mud pits. This study investigated in situ bioremediation of a mud pit. The bioremediation technology used in this case was based on the use of naturally occurring microorganisms, isolated from the contaminated site, which were capable of using the contaminating substances as nutrients. The bioremediation was stimulated through repeated inoculation with a zymogenous microbial consortium, along with mixing, watering and biostimulation. Application of these bioremediation techniques reduced the concentration of total petroleum hydrocarbons from 32.2 to 1.5 g kg−1 (95% degradation) during six months of treatment. [ABSTRACT FROM AUTHOR]

This paper describes experiments with standard humic acids (HA-S) and humic acids (HA) isolated from soil that was contaminated with mazut and treated with a consortium of microorganisms for the process of bioremediation (HA-E). Both acids inhibited the toxicity of ferric chloride and increased the growth of a zymogenous microbial consortia compared with controls. Electron paramagnetic resonance spectroscopy showed that HA-S and HA-E exhibit high anti-oxidative activity involving free radical scavenging and iron sequestration. HA additionally promote microbial consortium growth by providing protection from oxidative stress. [ABSTRACT FROM AUTHOR]

Abstract: Mazut (heavy residual fuel oil)-polluted soil was exposed to bioremediation in an ex situ field-scale (600m3) study. Re-inoculation was performed periodically with biomasses of microbial consortia isolated from the mazut-contaminated soil. Biostimulation was conducted by adding nutritional elements (N, P and K). The biopile (depth 0.4m) was comprised of mechanically mixed polluted soil with softwood sawdust and crude river sand. Aeration was improved by systematic mixing. The biopile was protected from direct external influences by a polyethylene cover. Part (10m3) of the material prepared for bioremediation was set aside uninoculated, and maintained as an untreated control pile (CP). Biostimulation and re-inoculation with zymogenous microorganisms increased the number of hydrocarbon degraders after 50d by more than 20 times in the treated soil. During the 5months, the total petroleum hydrocarbon (TPH) content of the contaminated soil was reduced to 6% of the initial value, from 5.2 to 0.3gkg−1 dry matter, while TPH reduced to only 90% of the initial value in the CP. After 150d there were 96%, 97% and 83% reductions for the aliphatic, aromatic, and nitrogen–sulphur–oxygen and asphaltene fractions, respectively. The isoprenoids, pristane and phytane, were more than 55% biodegraded, which indicated that they are not suitable biomarkers for following bioremediation. According to the available data, this is the first field-scale study of the bioremediation of mazut and mazut sediment-polluted soil, and the efficiency achieved was far above that described in the literature to date for heavy fuel oil. [Copyright &y& Elsevier]