A new solvent-free procedure for the recovery of lipids from urban sewage sludge was designed and investigated. Sedimented sewage sludge was first centrifuged, acidified and treated with hydrogen peroxide, heated to 353 K and centrifuged again by releasing the lipid fraction. Such a strategy was initially tested on a lab scale using different acids, namely HCOOH and HCl, and the effect of H2O2 addition was evaluated in terms of recoverability of lipids, as well as on the total solids (TS) content of the residual sludge. This procedure was then investigated on a pilot scale, by processing two cubic meters per hour of sedimented sewage sludge. The recovery yield of lipids essentially depended on the starting composition of sewage sludge, raising value of 70% for sludge containing 22–25%TS of grease. Besides the highly pure lipid fraction (FFA content 90–92%), two main side streams were also generated: an aqueous acidic current and a solid cake, which were analysed and the relevant biomethane potential determined (BMP). In all the cases, the Buswell’s equation well fitted the final value of biomethane produced and the relevant kinetic production confirmed that inhibitory species were never generated during the extraction process. These experimental findings make the proposed procedure a new sustainable way to process urban sewage sludge by recovering resources of high value.
A New Sustainable Solvent-Free Procedure for the Recovery of Grease from Urban Sewage Sludge
di Bitonto L.;Locaputo V.;Gallipoli A.;Braguglia C. M.;Pastore C.
2024
Abstract
A new solvent-free procedure for the recovery of lipids from urban sewage sludge was designed and investigated. Sedimented sewage sludge was first centrifuged, acidified and treated with hydrogen peroxide, heated to 353 K and centrifuged again by releasing the lipid fraction. Such a strategy was initially tested on a lab scale using different acids, namely HCOOH and HCl, and the effect of H2O2 addition was evaluated in terms of recoverability of lipids, as well as on the total solids (TS) content of the residual sludge. This procedure was then investigated on a pilot scale, by processing two cubic meters per hour of sedimented sewage sludge. The recovery yield of lipids essentially depended on the starting composition of sewage sludge, raising value of 70% for sludge containing 22–25%TS of grease. Besides the highly pure lipid fraction (FFA content 90–92%), two main side streams were also generated: an aqueous acidic current and a solid cake, which were analysed and the relevant biomethane potential determined (BMP). In all the cases, the Buswell’s equation well fitted the final value of biomethane produced and the relevant kinetic production confirmed that inhibitory species were never generated during the extraction process. These experimental findings make the proposed procedure a new sustainable way to process urban sewage sludge by recovering resources of high value.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
