Dynamic α-factor models for fine-bubble- and surface aeration – impact of settleability and implications on N2O emission

Yuge Qiu, Vince Bakos, Nyle Stewart-Campbell, Benedek Plosz

Research output: Contribution to journalArticlepeer-review

Abstract

In water resource recovery facilities (WRRF), aeration efficiency and N2O greenhouse gas emission are affected by the variability of the α-factor. Dynamic calibration of α using sensor data represents a significant knowledge gap this contribution aims to address. To assess factors influencing oxygen and N2O gas mass-transfer, a continuous flow laboratory-scale reactor system was operated to encourage the proliferation of filamentous bacteria. Gas mass-transfer was assessed using fine-bubble and surface aeration. Significant impacts of solid settling velocity on the α-factor – relative to that by MLSS concentration – is obtained. The feasibility of using solid settling velocity and concentration, as α-factor predictors, is tested. The theoretical approach of using relative diffusivity to dissolved oxygen – as an effective predictor of N2O liquid–gas mass-transfer stripping – is experimentally validated, for the first time. Plant-wide WRRF simulations show that surface aeration is inferior to fine-bubble aeration in terms of greenhouse gas emission and treated water quality.

Original languageEnglish
Article number150650
Number of pages9
JournalChemical Engineering Journal
Volume488
Early online date26 Mar 2024
DOIs
Publication statusPublished - 15 May 2024

Data Availability Statement

Data will be made available on request.

Keywords

  • Alpha-factor modelling
  • Filamentous bulking
  • Gas mass transfer in activated sludge reactors
  • Laboratory-scale experiments
  • WRRF simulations

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)
  • Industrial and Manufacturing Engineering
  • Environmental Chemistry

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