Influence of Activated Carbon and Other Additives on Bioremediation Rate and Characteristics of Petroleum-Contaminated Soils

Abstract

The main objective of this research was to study remediation of petroleum-contaminated soils after treating with granular activated carbon (AC) in combination with diatomite and a biopreparation (BP). Bioremediation rate and properties of petroleum-contaminated soils were used to explore associated mechanisms. Experiments were conducted under microfield conditions with three types of soils surficially contaminated with crude oil followed by weathering. Soil samples were amended with BP and two doses of AC (in combination or separately) or with diatomite alone (D) and mixed with AC (ACD). Natural attenuation decreased the concentration of total petroleum hydrocarbons (TPH) in the soils (initially 28–29 g kg−1) by 50% at 2 and 72% at 13 months. More efficient reduction of TPH (by 81% at 2 and 85% at 13 months) was achieved during the same period via in situ bioremediation by activating indigenous petroleum degraders, whereas the impact of BP alone was negligible. Soil amendment with the ACD mixture produced the best results; TPH content was reduced by 90% at 2 and 92% at 13 months, and soil phytotoxicity was low during most of the incubation period. Results demonstrated the potential of ACD as an adsorbent for accelerated bioremediation of petroleum-contaminated soils. Addition of the ACD mixture creates better conditions for degrading microorganisms and plant growth due to reversible adsorption of toxic petroleum components and metabolites, an increase in soil water-holding capacity, and total porosity, as well as a liming effect, increased plant resistance to abiotic stress in the presence of ACD, and better availability of compounds adsorbed to AC in the presence of diatomite.