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Biochars to improve the quality of soils contaminated with heavy metals

Grant number: 16/19368-6
Support type:Regular Research Grants
Duration: February 01, 2017 - January 31, 2019
Field of knowledge:Agronomical Sciences - Agronomy - Soil Science
Principal Investigator:Cleide Aparecida de Abreu
Grantee:Cleide Aparecida de Abreu
Home Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas , SP, Brazil
Assoc. researchers:Adriana Parada Dias da Silveira ; Aline Renee Coscione ; Cristiano Alberto de Andrade ; Eiko Eurya Kuramae ; Isabella Clerici de Maria ; Jorge Paz-Ferreiro ; Leônidas Carrijo Azevedo Melo

Abstract

Techniques of soil restoration of contaminated areas with heavy metals are usually expensive and sometimes difficult to apply in large field areas. Recently, soils treated with biochars have shown positive results on soil chemical, physical and biological characteristics. However, the extent of biochar contribution to soil recovery depends on the biomass origin, the biomass burning conditions and the soil characteristics. Therefore, it is necessary to have biochar as an easily available, ecologically friendly and low-cost product to be considered a feasible technique to restore or remediate areas contaminated with heavy metals. For that, it is important to choose the adequate biomass, which does not have any efficient final destination or any agronomic value, but is largely produced, such as the waste of coffee grounds and the fine coal. Therefore, the present research proposal main objective is to evaluate the efficiency of biochars from industrial waste originated from the soluble coffee production (coffee grounds), from coffee parchment removal from dry coffee beans, and from fine coals, on the recovery of soils contaminated with heavy metals, as an alternative technique to recover and increase soil quality. Biomass originated from coffee industry will be submitted to pyrolysis at 700oC followed by chemical, physical and image analyses (MEV). In the first experiment, each biochar sample will be analyzed for the maximum capacity of zinc (Zn) adsorption and desorption (the major contaminant). The treatments will consist of soil samples (0-20 cm depth) from Zn-rich area (absolute control, without pH adjustment and without biochar addition); soil plus 5% (m/m) of biochar from coffee grounds; soil plus 5% (m/m) of biochar from coffee parchment; soil plus 5% (m/m) of fine coal. Nevertheless, if pH increase occurs due to alkalinity of the biochar from coffee biomass, two more treatments will be added to the experiment, without biochar and with pH adjustment. The treated soil samples will be incubated for 90 days. In different time periods, samples will be analyzed for chemical determinations (pH, organic matter (OM), P, K, Ca, Mg, CEC, Al, Fe, Mn, Cu, Zn, Cd, Ni, and Pb); microbiological analysis (microbial biomass carbon, basal respiration, metabolic quotient, microbial quotient, dehydrogenase activity, ²-glycosidase activity, protease); and physical analysis (particle size classification and water retention curve). Furthermore, the index of soil quality (ISQ) will be calculated considering the absolute control (contaminated soil without biochar and without pH correction) as a parameter for soil quality improvement comparison; that is, the contribution of biochar for soil restoration or remediation will be evaluated by comparison with the absolute control. The two biochars showing the best performances will be tested in the presence of plants, under greenhouse conditions, in order to assess the plant nutrients and heavy metals contents, the concentration of heavy metals in the soil solution (heavy metal availability); total heavy metal concentrations in the soil; and microbial diversity. (AU)