title: Acetic acid recovery from a hybrid biological-hydrothermal treatment process of sewage sludge - a pilot plant study.
abstract: A two-stage process consisting of anaerobic fermentation followed by sub-critical wet oxidation was used to generate acetic acid from sewage sludge at pilot scale. Volatile fatty acids, dominated by propionic acid, were produced over 4-6 days in the 2,000 L fermentation reactor, which also achieved 31% solids reduction. Approximately 96% of the carbon was retained in solution over the fermentation stage. Using a 200 L wet oxidation reactor operating in batch mode, the second stage achieved 98% volatile suspended solids (VSS) destruction and 67% total chemical oxygen demand (tCOD) destruction. Acetic acid produced in this stage was recalcitrant to further degradation and was retained in solution. The gross yield from VSS was 16% for acetic acid and 21% for volatile fatty acids across the process, higher than reported yields for wet oxidation alone. The pilot plant results showed that 72% of the incoming phosphorus was retained in the solids, 94% of the nitrogen became concentrated in solution and 41% of the carbon was converted to a soluble state, in a more degradable form. Acetic acid produced from the process has the potential to be used to offset ethanol requirements in biological nutrient removal plants.
authors.affiliation: Sustainable Design, Scion, Private Bag 3020, Rotorua 3046, New Zealand E-mail: john.andrews@scionresearch.com.
authors.forename: J
authors.initials: J
authors.lastname: Andrews
authors.affiliation: Sustainable Design, Scion, Private Bag 3020, Rotorua 3046, New Zealand E-mail: john.andrews@scionresearch.com.
authors.forename: P
authors.initials: P
authors.lastname: Dare
authors.affiliation: Sustainable Design, Scion, Private Bag 3020, Rotorua 3046, New Zealand E-mail: john.andrews@scionresearch.com.
authors.forename: G
authors.initials: G
authors.lastname: Estcourt
authors.affiliation: Sustainable Design, Scion, Private Bag 3020, Rotorua 3046, New Zealand E-mail: john.andrews@scionresearch.com.
authors.forename: D
authors.initials: D
authors.lastname: Gapes
authors.affiliation: Sustainable Design, Scion, Private Bag 3020, Rotorua 3046, New Zealand E-mail: john.andrews@scionresearch.com.
authors.forename: R
authors.initials: R
authors.lastname: Lei
authors.affiliation: Sustainable Design, Scion, Private Bag 3020, Rotorua 3046, New Zealand E-mail: john.andrews@scionresearch.com.
authors.forename: B
authors.initials: B
authors.lastname: McDonald
authors.affiliation: Sustainable Design, Scion, Private Bag 3020, Rotorua 3046, New Zealand E-mail: john.andrews@scionresearch.com.
authors.forename: N
authors.initials: N
authors.lastname: Wijaya
mesh_terms: D019342:Acetic Acid / Q000378:metabolism*; D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D002244:Carbon / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005285:Fermentation; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000378:metabolism; D010865:Pilot Projects; D011422:Propionates / Q000378:metabolism; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D005232:Fatty Acids, Volatile; D011422:Propionates; D012722:Sewage; D010758:Phosphorus; D002244:Carbon; C029658:propionic acid; D009584:Nitrogen; D019342:Acetic Acid