Bioremediation of creosote-contaminated soil in South Africa by landfarming

Abstract

Aims: To determine the combined effects of biostimulation and bioaugmentation in the landfarming of a mispah form (lithosol; food and Agriculture Organisation (FAO)) soil contaminated with >310 000 mg kg )1 creosote with a view to developing a bioremediation technology for soils heavily contaminated with creosote. Methods and Results: The excavated soil was mixed with 2500 kg ha )1 dolomitic lime and 2000 kg ha )1 monoammonium phosphate (MAP) before spreading over a treatment bed of shale reinforced with clay. Sewage sludge (500 kg) was ploughed into 450 m 3 of contaminated soil in the second and sixth months of treatment. A further 1000 kg ha )1 MAP was added to the soil at the end of the fifth month. Moisture was maintained at 70% field capacity. Total creosote was determined by the US Environmental Protection Agency (EPA) method 418AE1 and concentrations of selected creosote components were determined by gas chromatography/flame ionisation detection (GC/FID). Total creosote was reduced by more than 90% by the 10th month of landfarming. The rate of reduction in creosote concentration was highest after the addition of sewage sludge. The three-ring PAHs were more slowly removed than naphthalene and the phenolic compounds. The four-and five-ring PAHs, although persist until the end of treatment, were reduced by 76-87% at the end of the experiment. Conclusions: A combination of biostimulation and bioaugmentation during landfarming could enhance the bioremediation of soils heavily contaminated with creosote. Significance and Impact of the Study: The study provides information on the management of a combination of biostimulation and bioaugmentation during landfarming, and contributes to the knowledge and database necessary for the development of a technology for bioremediating creosote-contaminated land.

Bacterial Community Dynamics and Polycyclic Aromatic Hydrocarbon Degradation during Bioremediation of Heavily Creosote-Contaminated Soil

“…Benzo-(a)pyrene and benzo(bϩk)fluoranthene were not significantly degraded (P Ͼ 0.05). The percentages of PAH biodegradation and the kinetics are similar to those reported in other studies (7,12).…”

Managing physicochemical parameters in compost systems to enhance degradation of petroleum wastes from a sludge dam

“…This can also be attributed to the available carbon and nutrients provided by the compost system as well as the initial large population of microorganisms. Compost systems have been reported to enhance the degradation of a number xenobiotic compounds including hydrocarbon compounds (Giles et al, 2001;Atagana, 2003). However the reduction of TPH by compost organisms at the levels used in this experiment is remarkable and worth investigating further.…”

“…Aliquots (0.1 ml) of each of the dilutions 10 -6 to 10 -8 were inoculated onto mineral salts agar (MSA) plates overlaid with 50 µL of oil filter-sterilised through 0.2 µm Millipore filter membrane and incubated for 21-28 days at 28°C and checked daily for bacteria growth to avoid overcrowding of the plates. The enrichment and isolation procedures were adapted from Atagana (2003) and Mashreghi and Marialigeti (2005). Distinct colonies from the MSA plates were inoculated onto nutrient agar plates and incubated for three days at 28°C.…”

“…Most biological methods are economically unsound, as they are prone to prolonged periods of treatment, as such may not be suitable for treating some contaminants (Ward et al, 2003). Heavy hydrocarbon components such as high molecular weight PAHs are generally recalcitrant to most bioremediation treatments (Atagana, 2003) due to their low volatility, hydrophobicity and low water solubility which is largely responsible for their low availability to microbial actions hence their persistence in the environment (Kriipsalu et al, 2008;Cameotra and Makker, 2010;Liu et al, 2011).…”

Co-composting of PAH-contaminated soil with poultry manure

“…These high levels of PAHs provided a good opportunity to study and further understand the potentials of composting in soil bioremediation. Earlier, studies (Atagana 2003(Atagana , 2004 showed that higher molecular weight PAHs remained in the soil at the end of 16 weeks and 11 months of pilot-and full-scale landfarming, respectively. This study intends to exploit the high temperatures prevalent during composting, the high nutrient contents of poultry manure and the heavy microbial load of the compost system in enhancing the biodegradation of high molecular weight PAHs in the soil system under investigation.…”