PRODUCTION OF A BIOFILTER FROM OLIVE MILL SOLID WASTES FOR THE REMOVAL OF HEAVY METALS FROM CONTAMINATED ROAD RUNOFFS

摘要

Biochar is a carbon-enriched and porous material produced from a variety of biomass including lignocelluloses material. The production of biochar from biomass is based on pyrolysis without the presence of oxygen which is a carbonization process in which the content of carbon increases with temperature accompanied by a simultaneous decrease in oxygen and hydrogen contents. Olive oil production is a major agro-industrial sector in the Mediterranean. The process of olive oil production generates large amounts of unexploited olive mill solid wastes (OMSW). The OMSW represent an environmental problem. The aim of our work was to use OMSW as a base material for producing biochar filters for treating runoff or industrial wastewater contaminated especially for removal of heavy metals. OMSW biochar was produced form the dried raw material by pyrolysis at 450, and 550 °C (i.e OMBC made by pyrolysis at 450°C; D. OMBC made by pyrolysis at 550°C). The potential of the produced OMBC to absorb heavy metals was evaluated at different concentration levels and compared to a commerical activated carbon at different pH using a batch and continous process. The pyrolysis process at the different temperatures yielded in average 27.5-34% biochar. The potential of the OMBC to remove different heavy metals showed that the 550 °C produced the best biofilter and there was no need for heigher tempeartures. The results showed that OMBC showed significantly better removal of Pb and Cu at pH= 6.0 compared to commerical activated carbon. The heavy metals Zn, Cd and Ni showed lesser removal efficiency at pH= 6.0, but still better than activated carbon. When the pH was raised to 8.0 the OMBC biochar showed significantly better removal capacity for all heavy metals compared to lower pH. The Se was the least to be absorbed to either matrix even when the pH was raised to 8.0. Using continous process the results correlate well with the batch data, i.e. good absorbance of Pb and Cu. Our results demonstrate that the OMBC is a good matrix to be used as biofilter to remove heavy metals from contaminated industrial wastewater.