PROCESS OF BIOREMEDIATION
The white rot fungus is not naturally found in the soil and does not work well by itself with the native microflora of nonsterile soils, to help the fungus. Wood chips are commonly used as both a support and growth media for the fungi. Firstly, for the bioremediation of soil using white rot fungus to take place, the bio treatment processes used in laboratories and treatment plants must be adapted to the field, and engineers use the principles developed in the laboratory to design systems that will work in the field (Naresh Magan, 2010). However, cleaning up of contaminated soil may be challenging due to the complex mixture of pollutants present in the soil. The first step in remediating soil is to characterize the site, identify the contaminants found, and the various environmental factors that will promote the growth of fungus.
Ex situ Treatment of soil
As mentioned above, ex situ treatment is a process that involves the removal of polluted material from its site to be treated outside the contaminated site. Considering the fungal remediation of soils as a bio augmentation process since the white rot fungus is not native to soils, therefore, the bioremediation of contaminated soil may involve excavation of the soil and construction of a lined treatment cell. A substrate inoculated with the fungus is easily mixed with the contaminated soil when it has been excavated, and the presence of a liner prevents the migration of the contaminants. It is easy to prove that the site is clean when the soil is excavated. The moisture content of the soil must be maintained at an optimal level for growth. To accomplish this, a carefully engineered soil mound is constructed containing a network of perforated pipe for forcing air through the soil. A second network of pipes is provided for water delivery to add moisture to the soil. The mound is usually constructed on a pad and under-drained to collect runoff. The fungi grow until the growth substrates are fully consumed, degrading the hazardous compounds in a period of 4 to 12 weeks depending on soil conditions and initial contaminant concentration. This process is expensive compared to in situ treatment.
In situ treatment of soil
The in situ treatment is applied when the excavation is impossible, thus, the treatment may be conducted without disturbing the contaminated site by using a recirculating injection well system. This treatment is most effective and less expensive than excavating the soils before treatment. The experiment included both the P. chrysosporium and Phanerochaete sordida because they exhibit the best growth potential in soil containing wood preserving wastes. The study was conducted under optimum growth conditions with temperatures greater than 80°F and soil moisture content greater than 30%. Initial findings show that levels of PCP and PAHs found in the leachate and in the air samples were insignificant, indicating low leachability and low potential of air borne contaminant transport as the result of fungal activities.
PROCESS OF BIOREMEDIATION