Bioremediation In Waste Management

An important part of remediation is to assess the site of contamination, the risks associated with contaminant, the degree of treatment required and the method to be employed.

Bioremediation is a waste management technique which utilizes naturally occurring organisms to break down hazardous substances into less toxic or non-toxic compounds at a contaminated site. There are many bioremediation methods used to treat soil contaminated with organic compounds such as such as In situ, prepared bed/On site and bioreactors (Wilson and Jones, 1993). There are two main groups of bioremediation in situ and ex situ bioremediation. In situ bioremediation is cleaning up a contaminated site on the spot while ex situ bioremediation is taking the contaminated

The waste material is applied to the soil as a slurry and the area is managed by fertilization, irrigation and lime addition to maintain optimal conditions for nutrient content, moisture and pH (Wilson and Jones, 1993). The area is tilled to improve aeration and to ensure that the degradation and immobilisation of contaminants within the upper and lower soil layers occurs (Wilson and Jones, 1993). The microorganisms that are used during this process are most often indigenous to the soil but specifically adapted microorganism can be applied to the area to improve the process. The major disadvantage of this system is the movement of contaminants from the treatment

Each PAH compounds has a unique set of physical and chemical properties. PAHs stability comes from the aromatic ring arrangement, linear being the most unstable and angular being the most stable (Blumer, 1976). PAHs are relatively insoluble is water, their solubility decreases as the number of fused rings increases (Sims and Overcash, 1983), so they mainly associate with organic matter (Means et al., 1980). The volatility of PAHs also decreases as the number of fused rings increases (Wilson and Jones, 1993).Soil structure, organic matter content and particle size affects the degradation process (Manilal and Alexander, 1991). The environmental factor that affect the rate of PAH degradation are temperature, pH and aeration. The presence of contaminants which are toxic to microorganisms such as metals and cyanides also hinder degradation (Wilson and Jones, 1993). The soil removal and decomposition processes that determine the fate of PAHs are volatilisation, abiotic losses and biodegradation (Sims et al.,