An approach for substrate mapping between ASM and ADM1 for sludge digestion.

Area of Science:

• Environmental Engineering
• Biotechnology
• Biochemical Engineering

Background:

• Municipal activated sludge hydrolysis is critical for anaerobic digestion efficiency.
• Understanding hydrolysis kinetics is essential for optimizing sludge treatment processes.

Purpose of the Study:

• To kinetically model the hydrolysis stage of municipal activated sludge.
• To identify and characterize different degradable organic fractions within the sludge.
• To correlate anaerobic hydrolysis kinetics with aerobic biomass composition.

Main Methods:

• Anaerobic batch tests were conducted to measure methane production rate (MPR).
• MPR curves were analyzed to determine kinetic parameters for different sludge fractions.
• Simultaneous batch aerobic respirometric tests were performed to assess biomass composition.

Main Results:

• Two distinct degradable organic fractions (XS1 and XS2) were identified in municipal sludge.
• XS1 (55% of COD) degraded via first-order kinetics; XS2 (21% of COD) followed Contois-type kinetics.
• Aerobic tests revealed 53% heterotrophic biomass (XH-Aerobe) and 20% slowly biodegradable COD (XS), correlating with anaerobic fractions.

Conclusions:

• The study successfully modeled municipal activated sludge hydrolysis, identifying two key kinetic fractions.
• A strong correlation was found between anaerobic substrate fractions and aerobic biomass components.
• XS1 likely represents anaerobic decay of XH-Aerobe, while XS2 may be hydrolysis of XS.