H2S removal is a key step for biogas cleaning because this component can lead to premature corrosion of the equipment and its cleaning has a significant cost. The aim of the present work was to assess the use of sewage sludge derived ash (SSA)-materials for H2S removal from a landfill biogas. SSA and mixtures made with SSA, activated carbon (AC) and sand were tested for H2S removal. The best removal efficiency was obtained with the mixture 80%m SSA and 20%m AC, while SSA alone was not a good adsorbent under tested experimental conditions. The materials characterization helped the adsorption mechanism understanding. Indeed, results highlighted that SSA presence stabilizes the pH on a basic range, favorable for H2S dissociation into HS- then its chemisorption. On the other hand, with the microporosity of AC, the contact surface between H2S and oxygen was sufficiently large for chemisorption kinetics. It also appeared that the mixture with sand and AC adorbs non selectively H2S but also other volatile organic pollutants present in biogas. Contrariwise, with SSA/AC mixtures, H2S seems to be selectively chemisorbed.
Keywords: Adsorption; Biogas; H(2)S removal; Sewage sludge ash.
Copyright © 2021 Elsevier Ltd. All rights reserved.