Active biomass estimation based on ASM1 and on-line OUR measurements for partial nitrification processes in...

Area of Science:

• Environmental Engineering
• Biotechnology
• Wastewater Treatment

Background:

• Stable nitrite accumulation in partial nitrification is challenged by nitrite-oxidizing bacteria (NOB) growth.
• Estimating active biomass online can optimize process control for enhanced nitrite accumulation.

Purpose of the Study:

• To develop and validate an active biomass estimator using ASM1 and online oxygen uptake rate (OUR-E) measurements.
• To compare the performance of the OUR-E estimator against an off-line N-species concentration estimator (Nsp-E).

Main Methods:

• Implementation of an active biomass estimator based on ASM1 and OUR-E in a sequencing batch reactor.
• Operation under two distinct scenarios: unfavorable (SRT=40d, pH=7.6, DO=2mg/L) and favorable (SRT=10d, pH=8.5, DO=2mg/L) for partial nitrification.
• Validation using an off-line N-species concentration estimator (Nsp-E).

Main Results:

• The OUR-E estimator accurately predicted a significant reduction in the NOB active fraction (from 10.3% to 1.6%) during a shift in operating conditions.
• Nitrite accumulation exceeded 80% following the operational change.
• The OUR-E method demonstrated superior prediction quality compared to the Nsp-E method, as indicated by Theil's coefficient of inequality.

Conclusions:

• The proposed OUR-E method is effective for online estimation of active biomass in partial nitrification processes.
• This approach enhances process control for achieving stable and high nitrite accumulation in wastewater treatment.
• OUR-E offers a more reliable prediction of biomass dynamics than off-line N-species measurements.