Anaerobic digestion of thermal pre-treated sludge at different solids concentrations--Computation of mass-energy balance and greenhouse gas emissions.
The effect of thermal pre-treatment on sludge anaerobic digestion (AD) efficiency was studied at different total solids (TS) concentrations (20.0, 30.0 and 40.0 g TS/L) and digestion times (0, 5, 10, 15, 20 and 30 days) for primary, secondary and mixed wastewater sludge. Moreover, sludge pre-treatment, AD and disposal processes were evaluated based on a mass-energy balance and corresponding greenhouse gas (GHG) emissions. Mass balance revealed that the least quantity of digestate was generated by thermal pre-treated secondary sludge at 30.0 g TS/L. The net energy (energy output-energy input) and energy ratio (energy output/energy input) for thermal pre-treated sludge was greater than control in all cases. The reduced GHG emissions of 73.8 × 10(-3) g CO2/g of total dry solids were observed for the thermal pre-treated secondary sludge at 30.0 g TS/L. Thermal pre-treatment of sludge is energetically beneficial and required less retention time compared to control.
INRS Eau, Terre, Environnement, 490, rue de la Couronne, Québec G1K 9A9, Canada.
Sridhar
S
Pilli
INRS Eau, Terre, Environnement, 490, rue de la Couronne, Québec G1K 9A9, Canada.
Tanaji
T
More
INRS Eau, Terre, Environnement, 490, rue de la Couronne, Québec G1K 9A9, Canada.
Song
S
Yan
INRS Eau, Terre, Environnement, 490, rue de la Couronne, Québec G1K 9A9, Canada. Electronic address: tyagi@ete.inrs.ca.
Rajeshwar Dayal
RD
Tyagi
Dept. of Civil Engineering, University of Nebraska-Lincoln, N104 SEC, P. O. Box 886105, Lincoln, 68588-610, USA.
Rao Y
RY
Surampalli
D001421:Bacteria, Anaerobic / Q000378:metabolism*; D019149:Bioreactors; D003246:Conservation of Energy Resources; D017752:Greenhouse Effect; D006358:Hot Temperature; D006801:Humans; D008962:Models, Theoretical; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*
D012722:Sewage
Energy ratio; Mixed sludge; Net energy; Primary sludge; Secondary sludge; Thermal pre-treatment