title: The effect of acid pretreatment on the anaerobic digestion and dewatering of waste activated sludge.
abstract: Waste activated sludge (WAS) is difficult to degrade in anaerobic digestion systems and pretreatments have been shown to speed up the hydrolysis stage. Here the effects of acid pretreatment (pH 6-1) using HCl on subsequent digestion and dewatering of WAS have been investigated. Optimisation of acid dosing was performed considering digestibility benefits and level of acid required. Pretreatment to pH 2 was concluded to be the most effective. In batch digestion this yielded the same biogas after 13 days as compared to untreated WAS at 21 days digestion. In semi-continuous digestion experiments (12 day hydraulic retention time at 35°C) it resulted in a 14.3% increase in methane yield compared to untreated WAS, also Salmonella was eradicated in the digestate. Dewatering investigations suggested that the acid pretreated WAS required 40% less cationic polymer addition to achieve the same cake solid content. A cost analysis was also carried out.
authors.affiliation: University of Glamorgan, Sustainable Environment Research Centre, Upper Glyntaff, Pontypridd CF37 4AT, Wales, UK. dcdevlin@glam.ac.uk
authors.forename: D C
authors.initials: DC
authors.lastname: Devlin
authors.forename: S R R
authors.initials: SR
authors.lastname: Esteves
authors.forename: R M
authors.initials: RM
authors.lastname: Dinsdale
authors.forename: A J
authors.initials: AJ
authors.lastname: Guwy
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism*; D019149:Bioreactors; D006851:Hydrochloric Acid / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000096:biosynthesis*; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000191:economics / Q000379:methods*
chemical_list: D012722:Sewage; D008697:Methane; D006851:Hydrochloric Acid