Comparison of landfarming amendments to improve bioremediation of petroleum hydrocarbons in Niger Delta soils

Abstract

Large scale landfarming experiments, using an extensive range of treatments, were conducted in the Niger-Delta, Nigeria to study the degradation of oil in contaminated soils. In this work the effect of nutrient addition, biosurfactant, Eisenia fetida (earthworm) enzyme extract, bulking and sorption agents and soil neutralization were tested. It was found that these treatments were successful in removing up to 53% of the total petroleum hydrocarbon in the soil within 16 weeks. A comparison between treatments demonstrated that most were no more effective than agricultural fertilizer addition alone. One strategy that did show better performance was a combination of nutrients, biochar and biosurfactant, which was found to remove 23% more Total Petroleum Hydrocarbons (TPH) than fertilizer alone. However, when performance normalized costs were considered, this treatment became less attractive as a remedial option. Based on this same analysis it was concluded that fertilizer only was the most cost effective treatment. As a consequence, it is recommended that fertilizer is used to enhance the landfarming of hydrocarbon contaminated soils in the Niger Delta. The attenuation rates of both bulk TPH and Total Petroleum Hydrocarbon Criteria Working Group (TPHCWG) fractions are also provided. These values represent one of the first large scale and scientifically tested datasets for treatment of contaminated soil in the Niger Delta region. An inverse correlation between attenuation rates and hydrocarbon molecular weight was observed with heavy fractions showing much slower degradation rates than lighter fractions. Despite this difference, the bioremediation process resulted in significant removal of all TPH compounds independent of carbon number.

Metagenomics insight into microbial dynamics in field-scale remediation of crude oil-polluted soil

“…It was observed that the highest reduction in TPH was achieved within the rst 36 days of remediation which is typical of soil undergoing bioremediation. A similar observation has been made by several researchers [12,20]. In this study approximately 72% of the total extractable TPH was removed within the rst 36 days of remediation.…”

“…Manipulating parameters such as nutrients, pH, moisture and oxygen has been demonstrated to reduce the half-life of hydrocarbon removal from contaminated soils [11][12][13]. It has been severally applied both in the Niger Delta and other parts of the world [12,14,15].…”

Factorial Design Study of Total Petroleum Contaminated Soil Treatment Using Land Farming Technique

“…This served mainly as catalyst in microbes' reproduction processes and consequent consumption of the TPH contaminants. Although higher concentration of substrate does not guarantee high TPH degradation, but when suitably combined with other parameters such as turning rate, high pH value and average moisture content; then a better degradation result can be obtained [27]. As fertilizer application on crude oil contaminated site was well systemic and well calculated, TPH degradation result was less than 40%, this was mainly due to the low moisture content and high acidic values of the treated samples.…”

“…In some cases, sawdusts, animal dungs, and straws may supply bacterial with carbon sources in form of fertilizer [26]. Land farming techniques has been practiced in some regions of the world to bioremediate crude oil contamination in soils to minimize the health risk on human and the environment at large [27,28]. It has been used successfully to remove petroleum hydrocarbons at large scale [23,29], and because of its simplicity in implementation, Niger Delta has also employed it.…”

Membrane separation as a pre-treatment process for oily saline water

“…The most commonly used remediation methods are chemical oxidation and enhanced oxidation processes [107][108][109], bioremediation processes [110][111][112], solid-phase processes [113][114][115][116], Bioslurry processes [117], and incinerations [118][119][120][121]. Table 2 provides a comparison between various oily wastewater treatment techniques [10,53].…”