Biochar for Effective Cleaning of Contaminated Dumpsite Soil: A Sustainable and Cost-Effective Remediation Technique for Developing Nations

Abstract

Several studies have reported that open municipal dumpsites in developing countries are acting as a major source for a wide variety of pollutants. In developing nations, many dumpsites are located in the urban centers or even within the residential boundaries. Contaminants released during incomplete combustion of municipal solid waste have profound adverse impact on human health and the environment. Hence there is an urgent need to identify a low-cost technique to decontaminate such heavily polluted sites. In this chapter, we have reviewed several papers and discussed how different types of engineered biochars can be effectively used to adsorb contaminants from dumpsite soil. Biochars are basically carbon-rich solids treated by high-temperature pyrolysis. Biochars are obtained by heating biomass in presence of less oxygen or in anaerobic conditon. Properly pyrolysed mixtures of organic and cellulosic wastes are capable of adsorbing a wide variety of organic contaminants from wastewater, sludge and soil prior to the release or disposal in engineered landfills. Biochar produced from waste organic material such as coconut shells, sugarcane bagasse and straw has been reported with high adsorption capacity. Because locally produced waste organic material can be utilized for production of these low-cost adsorbents, they are especially attractive for remediation and treatment systems in developing countries. Pyrolytic temperature is believed to be the most important factor affecting the sorption capacity of biochar, followed by grinding to increase the surface area. Holding and adsorption capacity of the biochar for treating contaminants in soil could be a limiting factor of these materials. Some studies have shown that less than 5–7% (m/m) mixing of biochar and soil resulted in higher water retention capacity leading to increased potential for biodegradation. We therefore suggest that improved low-cost processing methods should be investigated so that biochar can be exploited as an adsorptive medium for remediating and treating contaminated soils in these regions.