Petroleum sludge is a residue extracted mostly from petroleum storage. Contaminants from petroleum sludge may exist in the soil for long periods and be transmitted to plants and tissues of living organisms within the soil ecosystem. The aim of this study was to investigate sustainable technology for enhancing bioremediation of soil contaminated with petroleum sludge. The study involved planting of Bamboo (Phyllostachys pubescens) and Papyrus (Papyrus cyperus) plants in contaminated soil. Parts of the plant (roots, stem and leaves) were examined for their effectiveness of absorption and bioaccumulation of three heavy metals (lead, copper and chromium). The plants were harvested after every three months of growing for a period of one year. Presence of heavy metal in the soil and the harvested plant parts were analyzed by Atomic Absorption Spectrophotometry method. After growing the plants in the contaminated soil for 12 months, it was found that highest amounts of chromium (86.86%) were reduced by Bamboo plant while copper (83.33%) was the highest reduced metal by Papyrus plant. Heavy metal analysis on the plant parts depicted that Bamboo is an effective plant in accumulation of heavy metals in petroleum contaminated soil over a long period of time. Conversely, Papyrus accumulates heavy metals over a short period of time even in presences of extra amounts of water in the soil. It was further noted that both Bamboo and Papyrus accumulate copper and lead more in the roots than in leaves, however, chromium is most accumulated in leaves.
Abstract This study sought to use the stress–strain relationship of interlocking stabilized soil block (ISSB) masonry to model its behaviour and develop empirical formulae to aid in predicting its compressive strength. A finite element (FE) analysis adopting the Rankine failure criterion was performed using Abaqus software to simulate the deformability behaviour of the wall which was validated through experimental tests. The compressive strength, modulus of elasticity and density of ISSB defined in the FE model were determined by performing laboratory tests on laterite soil blocks stabilized with pozzolanic cement, hydrated lime and rice husk ash. Conversely, the predictive empirical formulae for the compressive strength of the ISSB masonry was developed by performing statistical multiple regression analysis. In addition to the mechanical properties of masonry, the FE simulation results indicated that the deformability behaviour of ISSB masonry is influenced by the type of stabilizer used on the target material. This dictated the stress distribution and vertical displacement on the masonry. A diagonally stepped failure mode was experienced in more brittle masonry while cone failure mode was observed in less brittle masonry assemblage.
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