CHARACTERIZATION OF CHEMICAL AND PHYSICAL PROPERTIES OF BIOCHAR FOR ENERGY PURPOSES AND ENVIRONMENTAL RESTORATION

Biochar production processes as well as its various applications provide numerous benefits to both environment and economy (Lehmann et al., 2006; Basu, 2010). However, understanding the physicochemical structure of this valuable product has to be improved in order to be able to obtain the aforementioned benefits and to avoid environmental costs. In this study, chicken or poultry manure (PM) was chosen as feedstock for biochar preparation. This biomass is traditionally used by farmers as an effective organic fertilizer (Chan et al., 2008). Indeed, it is considered a valuable source for readily available plant nutrients, such as N, P, K and other micronutrients (Huang et al., 2011). Notwithstanding the advantages of PM for increasing soil fertility, there are food safety and environmental concerns about its application in agricultural sites in its unmodified form (Wilkinson et al., 2003; Chan et al., 2008). In fact, the misuse of chicken manure as fertilizer may result in serious environmental problems (Gay et al., 2003), such as human and animal health risks, odors, and leaching of nitrates 4 and other pollutants into groundwater (Fan et al., 2000). For this reason, conversion of chicken manure to char has been proposed as an attractive methodology to reduce PM volume and weight, and its stink (Shinogi and Kanri, 2003; Popov et al., 2004). Some studies have already examined PM biochar characteristics (Uchimiya et al., 2010). Further studies must be performed to evaluate the possibility to use poultry manure chars either as soil amendments or for remediation purposes in order to avoid environmental damages. As already stressed, char characteristics and properties are greatly affected by pyrolysis process and its parameters (mainly process temperature and residence time). These factors are particularly important in determining the nature of the final product and, consequently, its potential value in terms of carbon sequestration, agronomic performance and/or environmental remediation. The project has two main objectives. Firstly, it aims to report about the changes occurring in the chemical properties and in the physical structure of biochars produced from poultry manure when it is obtained at different pyrolysis temperatures and heating times, and how these changes can influence its agronomic or remediation potential. This topic is discussed in Chapters 3 and 4. The second objective of the project is to investigate the potential of three different kinds of biochars, produced from poultry manure, conifer and poplar wood residues, as adsorbents for inorganic contaminants (i.e., heavy metals) for wastewater treatment. In chapter 5, biochar adsorption qualities are evaluated using kinetic (pseudo-first order, pseudo-second-order), equilibrium and isotherms (Langmuir, Freundlich, Toth and RedlichPeterson) models, used to fit experimental data.