Performance and effectiveness of adsorbents prepared from lignocellulosic agro-industrial residues on the abatement of leachate odor containing ammonia
Teses
This work aimed to prepare different adsorbent materials (bioadsorbent, pyrochar,
hydrochar, and activated carbon), using olive stone and malt bagasse as feedstock and
evaluating its performance and effectiveness in the adsorption of ammonia (NH3),
deriving from composting leachate. A lab-scale adsorption system was assembled for the
adsorption tests. The performance and effectiveness of the adsorbents on NH3 adsorption
were evaluated objectively, by chemical analytical measurement, and subjectively by
olfactometric assessment using the human sense of smell. The materials' preparation was
studied to assess the biomass loss and the carbon released into the liquid phase during the
hydrothermal carbonization process. Besides, resultant adsorbents were characterized to
study their surface chemistry, elemental analysis, and textural properties. Saturated
adsorbents were regenerated using water and subsequently re-used in the adsorption of
NH3 coming from the leachate to assess their adsorption capacities after a sorptiondesorption
cycle. The hydrochar derived from olive stone, prepared by hydrothermal
carbonization assisted by sulfuric acid (H2SO4), was found as the best adsorbent for NH3
removal produced in this work since it has the lowest height of mass transfer zone (0.315
- 0.520 cm) and the highest NH3 adsorption capacity (9.445 - 11.421 mg g-1). The
bioadsorbent prepared only by milling and drying olive stones was also capable of
adsorbing NH3, showing a height of mass transfer zone of 0.484 - 0.565 cm, and an
adsorption capacity of 0.975 - 1.455 mg g-1; besides the advantage of being
environmentally-sound since it requires low energy expenditure, and no chemicals are
used in its preparation. The olfactometric evaluations confirmed that the adsorbents
mentioned above, prepared by olive stone, can reduce odor annoyance of the gases
derived from leachate. Finally, the regeneration process using water delivered adsorbents
capable of being used in one NH3 sorption-desorption cycle, with satisfactory
performance (>70% of the mean NH3 adsorption capacity of its respective first-generation
adsorbents), leading to increasing the materials' resource-use efficiency.
