Development of analytical, phyto- and myco-remediation techniques to manage petroleum-contaminated soils

Practical solutions to soil pollution by the petroleum industry are still to be fully realised. With new, unresolved and recurring cases, remediation options that are readily available, cost effective and environmentally friendly are required. Analytical methods for quick and easy monitoring are also crucial. To find appropriate solutions to petroleum-contaminated soils particularly for the Niger Delta, Nigeria; options, which satisfy the above principles, were investigated. Thus, the aims of this research were to identify readily available and sustainable techniques for remediation of petroleum-contaminated soils; evaluate ways to overcoming associated limitations, thereby enhancing these techniques; and investigate for readily available methods of monitoring the petroleum-contaminated and remediated soils. After a systematic and critical literature review, phyto- and myco-remediation were identified as viable options for this research, their limitations were evaluated. The actual study involved sampling of petroleum contaminated soils, treatment with phyto- and myco-remediation agents and investigation of methods for analysis and monitoring of the soils. Agents used for the remediation (evaluated in terms of reduction in Total Petroleum Hydrocarbons-TPHs in the soil samples) were: 3 species of sunflowers (Helianthus annus-pacino gold, Helianthus sunsation & Helianthus annus-sunny dwarf), the fern-Dryopteris affinis, fermented palm wine (from 2 species of palm trees -Elaeis guineensis & Raffia africana), and oyster mushroom (Pleurotus ostreatus). Supplementing the agents with Tween 80 and the use of alternative substrates and methods for application of P. ostreatus enabled the investigation of possible enhancement of their remediation efficiency. The investigation revealed up to 525 g of TPHs per Kg dry weight of soils. The remediation treatments produced as much as 69% reduction in TPHs by the sunflower species, 70% by fermented palm wine, 74% by D. affinis and 85% by P. ostreatus; with up to 100% enhancement on the addition of Tween-80. It was also found that substrates type and method of application has a significant effect on the remediation efficiency of P. ostreatus. The study further revealed that available nitrate, electrical conductivity, standardised crude oil and the biomarkers dodecane and benzene-1,3-bis(1,1-dimethylethyl) can be used to broadly monitor the concentration of TPHs and remediation progress in soils. This research thus demonstrated that, phyto-and myco-remediation can provide readily available and sustainable techniques for remediation of TPHs in soils. Further studies are required to evaluate the application of these techniques for individual petroleum contaminant components such as the polycyclic aromatic hydrocarbon compounds and Asphaltenes

Investigating the potential of sunflower species, fermented palm wine and Pleurotus ostreatus for treatment of petroleum-contaminated soil

Phyto- and myco-remediation have been identified as sustainable options for treatment of petroleum-contaminated soils. To appraise the benefits thereof, the potentials of 3 sunflower species, 2 palm wine types and P. ostreatus to treat petroleum-contaminated soils was investigated. The study involved sampling of petroleum-contaminated soils and treatment with the phyto- and myco-remediation agents for a period of 90-days. Agents used for the remediation were 3 species of sunflowers (Helianthus annus-pacino gold, Helianthus sunsation & Helianthus annus-sunny dwarf), fermented palm wine (from 2 species of palm trees -Elaeis guineensis & Raffia africana), and oyster mushroom (Pleurotus ostreatus). The study further investigated variation in remediation efficiency among the sunflower and palm wine species, as well as different substrates and conditions for optimal application of P. ostreatus. The results obtained revealed up to 340 g/kg dry weight of Total petroleum hydrocarbons (TPHs) in the soils, with remediation outcomes of up to 69% by the sunflower- Helianthus annus (Pacino gold), 70% by fermented palm wine, and 85% by P. ostreatus. While the remediation efficiency of sunflower species was proportional to biomass, there was no significant difference in remediation efficiency of the palm wines. It was also found that substrates type and method of application has a significant impact on the remediation efficiency of P. ostreatus. The study further revealed available nitrate and electrical conductivity as possible useful indicators of TPHs concentration and remediation progress in soils

Cement stabilisation of crude-oil-contaminated soil

© 2016, Thomas Telford Services Ltd. All rights reserved. Crude-oil-contaminated soils are usually considered unsuitable construction materials for earthworks. This paper presents an experimental investigation of the effects of applying Portland cement on the plasticity, strength and permeability of a crude-oil-contaminated soil in order to ascertain its suitability for use as an earthworks construction material. Series of specific gravity, Atterberg limits, compaction, strength and permeability characteristics were determined for a natural soil, the soil after being artificially contaminated with crude oil and the contaminated soil with varying proportions of added cement. It was found that the geotechnical properties of the soil became less desirable after contamination with crude oil, but the application of cement to the contaminated soil improved its properties by way of cation exchange, agglomeration and cementation. Cement stabilisation of crude-oil-contaminated soil provides a stable supporting structure, as well as a capping layer, that prevents the crude oil from interacting with the construction materials above. Thus, instead of disposing of contaminated soils, creating unnecessary waste and incurring costs, stabilisation with cement – which is practically feasible to undertake on site – makes such soils useful for supporting structural foundations or road pavement structures

Investigating the potential of sunflower species, fermented palm wine and Pleurotus ostreatus for treatment of petroleum-contaminated soil

Phyto- and myco-remediation have been identified as sustainable options for treatment of petroleum-contaminated soils. To appraise the benefits thereof, the potentials of 3 sunflower species, 2 palm wine types and P. ostreatus to treat petroleum-contaminated soils was investigated. The study involved sampling of petroleum-contaminated soils and treatment with the phyto- and myco-remediation agents for a period of 90-days. Agents used for the remediation were 3 species of sunflowers (Helianthus annus-pacino gold, Helianthus sunsation & Helianthus annus-sunny dwarf), fermented palm wine (from 2 species of palm trees -Elaeis guineensis & Raffia africana), and oyster mushroom (Pleurotus ostreatus). The study further investigated variation in remediation efficiency among the sunflower and palm wine species, as well as different substrates and conditions for optimal application of P. ostreatus. The results obtained revealed up to 340 g/kg dry weight of Total petroleum hydrocarbons (TPHs) in the soils, with remediation outcomes of up to 69% by the sunflower- Helianthus annus (Pacino gold), 70% by fermented palm wine, and 85% by P. ostreatus. While the remediation efficiency of sunflower species was proportional to biomass, there was no significant difference in remediation efficiency of the palm wines. It was also found that substrates type and method of application has a significant impact on the remediation efficiency of P. ostreatus. The study further revealed available nitrate and electrical conductivity as possible useful indicators of TPHs concentration and remediation progress in soils. (C) 2019 Elsevier Ltd. All rights reserved