Biochar-based remediation of water and soils contaminated by organic compounds

Abstract

Biochar is a carbonaceous material obtained by pyrolysis of vegetable biomasses. Due to its nature, biochar can be used as soil amendment to increase soil fertility and to mitigate climate change. In addition its particular porous structure and high specific surface area make it a very effective sorbent for organic and inorganic contaminant in soil and water. Therefore, the aim of this thesis was to evaluate the efficiency of poplar and conifer biochars in remediation of i) water and soil contaminated by phenanthrene (Phe) and pentachlorophenol (PCP) and ii) olive mill wastewater (OMW). Biochar from conifer removed more successfully contaminant molecules in Phe and PCP contaminated water solution also when it was confined in dialysis tube. Greater efficiency of conifer biochar was observed also in the treatment of contaminated soil leading to the consequent reduction of soil phytotoxicity. Conversely, biochar from poplar better performed the OMW remediation resulting in the reduction of total phenols (up to 72%) and phytotoxicity. Furthermore, soil amended with treated OMW showed beneficial changes in chemical and biochemical soil properties. The aim of this thesis was also to establish an improved analysis method for black carbon metabolites measurements using ion chromatography in order to have information about the fate of black carbon (biochar) in soil. Black carbon metabolites are ubiquitous in soil like black carbon itself. However, black carbon concentration in soil is no good predictor about fate of black carbon degradation. Rather, physical, chemical and probably also biological soil properties yet to be identified, to control black carbon metabolism in soil.