Production of as Adsorbents by Biomass Hydrothermal Carbonization and Iron Precipitation: Pilot Scale Optimization Under the BIOAs Project

The pilot scale optimization of a two-stage process for the synthesis of As adsorbents from olive pomace is presented. In the process, a Fe-hydrochar allowing arsenic to be adsorbed from groundwater is produced by hydrothermal carbonization of olive pomace and subsequent iron precipitation. To evaluate the technical feasibility and the environmental impact of the process, tests were con-ducted by running a pilot plant (production capacity of 27 kg/day) designed and constructed under the European project LIFE BIOAs. In this contribution, the results of the tests performed to optimize pilot plant operation are illustrated. The influence of the main process parameters (iron concentration, iron precipitation pH and temperature) and the impact of adsorbent post-treatment (activation and granulation) are discussed. Finally, a preliminary environmental assessment is presented by quantifying the reduction in the mass of CO2 equivalents that can be attained from a life-cycle perspective by the application of the produced adsorbent as compared to the state of the art arsenic adsorbent.