A review of wet air oxidation and Thermal Hydrolysis technologies in sludge treatment.
With rapid world population growth and strict environmental regulations, increasingly large volumes of sludge are being produced in today's wastewater treatment plants (WWTP) with limited disposal routes. Sludge treatment has become an essential process in WWTP, representing 50% of operational costs. Sludge destruction and resource recovery technologies are therefore of great ongoing interest. Hydrothermal processing uses unique characteristics of water at elevated temperatures and pressures to deconstruct organic and inorganic components of sludge. It can be broadly categorized into wet oxidation (oxidative) and thermal hydrolysis (non-oxidative). While wet air oxidation (WAO) can be used for the final sludge destruction and also potentially producing industrially useful by-products such as acetic acid, thermal hydrolysis (TH) is mainly used as a pre-treatment method to improve the efficiency of anaerobic digestion. This paper reviews current hydrothermal technologies, roles of wet air oxidation and thermal hydrolysis in sludge treatment, and challenges faced by these technologies.
School of Civil, Environmental and Chemical Engineering, RMIT University, 3001 Melbourne, Australia.
Kevin
K
Hii
Department of Chemical & Material Engineering, Faculty of Engineering, The University of Auckland, Private Bag 92019, Auckland, New Zealand; Scion, 49 Sala Street, Rotorua 3010, New Zealand.
Saeid
S
Baroutian
School of Civil, Environmental and Chemical Engineering, RMIT University, 3001 Melbourne, Australia.
Raj
R
Parthasarathy
Scion, 49 Sala Street, Rotorua 3010, New Zealand.
Daniel J
DJ
Gapes
School of Civil, Environmental and Chemical Engineering, RMIT University, 3001 Melbourne, Australia. Electronic address: nicky.eshtiaghi@rmit.edu.au.
Nicky
N
Eshtiaghi
D056804:Biofuels; D057919:Biological Oxygen Demand Analysis; D006358:Hot Temperature; D006868:Hydrolysis; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D011312:Pressure; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*
D056804:Biofuels; D012722:Sewage
Hydrothermal processing; Sludge treatment; Thermal hydrolysis; Wastewater sludge; Wet air oxidation