Experimental assessment and modelling of nitrate utilisation for primary sludge

Area of Science:

• Environmental science
• Environmental engineering
• Microbiology

Background:

• Wastewater treatment relies on microbial processes.
• Understanding electron acceptor utilization is crucial for optimizing sludge treatment.
• Anoxic conditions are key for certain microbial metabolisms in wastewater.

Purpose of the Study:

• To experimentally investigate the electron acceptor utilization potential of filtered primary sludge under anoxic conditions.
• To assess major kinetic and stoichiometric parameters using model evaluation.
• To compare the performance of ASM1 and ASM3 models in interpreting experimental data.

Main Methods:

• Batch reactor experiments were conducted.
• Nitrate profiles were analyzed.
• Activated Sludge Model 1 (ASM1), modified for endogenous decay, and Activated Sludge Model 3 (ASM3) were used for simulation.
• Kinetic and stoichiometric parameters were evaluated.

Main Results:

• Both ASM1 and ASM3 provided consistent interpretations of the experimental data.
• ASM1 yielded specific values for heterotrophic anoxic growth (mu(H) = 6.1 d(-1), Y(HD) = 0.64 g cell COD/g COD).
• ASM3 characterized the storage mechanism with k(STO) = 13 g COD/(g COD d) and Y(STO) = 0.78 g COD/g COD.

Conclusions:

• The study confirmed consistent data interpretation by both ASM1 and ASM3 models.
• The high k(STO) value obtained suggests a need to re-evaluate the definition of readily biodegradable substrate in ASM3.
• Findings contribute to a better understanding of microbial processes in wastewater treatment under anoxic conditions.