title: Performance of a biogas upgrading process based on alkali absorption with regeneration using air pollution control residues.
abstract: This work analyzes the performance of an innovative biogas upgrading method, Alkali absorption with Regeneration (AwR) that employs industrial residues and allows to permanently store the separated CO2. This process consists in a first stage in which CO2 is removed from the biogas by means of chemical absorption with KOH or NaOH solutions followed by a second stage in which the spent absorption solution is contacted with waste incineration Air Pollution Control (APC) residues. The latter reaction leads to the regeneration of the alkali reagent in the solution and to the precipitation of calcium carbonate and hence allows to reuse the regenerated solution in the absorption process and to permanently store the separated CO2 in solid form. In addition, the final solid product is characterized by an improved environmental behavior compared to the untreated residues. In this paper the results obtained by AwR tests carried out in purposely designed demonstrative units installed in a landfill site are presented and discussed with the aim of verifying the feasibility of this process at pilot-scale and of identifying the conditions that allow to achieve all of the goals targeted by the proposed treatment. Specifically, the CO2 removal efficiency achieved in the absorption stage, the yield of alkali regeneration and CO2 uptake resulting for the regeneration stage, as well as the leaching behavior of the solid product are analyzed as a function of the type and concentration of the alkali reagent employed for the absorption reaction.
authors.affiliation: Laboratory of Environmental Engineering, Department of Civil Engineering and Computer Science Engineering, University of Rome "Tor Vergata", Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: Renato
authors.initials: R
authors.lastname: Baciocchi
authors.forename: Ennio
authors.initials: E
authors.lastname: Carnevale
authors.forename: Giulia
authors.initials: G
authors.lastname: Costa
authors.forename: Renato
authors.initials: R
authors.lastname: Gavasci
authors.forename: Lidia
authors.initials: L
authors.lastname: Lombardi
authors.forename: Tommaso
authors.initials: T
authors.lastname: Olivieri
authors.forename: Laura
authors.initials: L
authors.lastname: Zanchi
authors.forename: Daniela
authors.initials: D
authors.lastname: Zingaretti
mesh_terms: D000327:Adsorption; D056804:Biofuels; D002119:Calcium Carbonate / Q000138:chemical synthesis*; D002245:Carbon Dioxide / Q000302:isolation & purification*; D006878:Hydroxides / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry*
chemical_list: D056804:Biofuels; D006878:Hydroxides; D017680:Potassium Compounds; D002245:Carbon Dioxide; D012972:Sodium Hydroxide; D002119:Calcium Carbonate; C029943:potassium hydroxide
keywords: Air Pollution Control (APC) residues; Alkali absorption; Biogas upgrading; CO(2) capture and storage; Carbonation; Leaching