Oxygen transfer performance of a supersaturated oxygen aeration system (SDOX) evaluated at high biomass concentrations

Sang Yeob Kim, Hector A. Garcia, Carlos M. Lopez-Vazquez, Chris Milligan, Aridai Herrera, Marin Matosic, Josip Curko, Damir Brdjanovic

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)


Oxygen transfer in wastewater treatment is significantly influenced by the mixed liquor suspended solids (MLSS). The effect is more pronounced at MLSS concentrations higher than 20 g L−1 when supplying air by conventional diffused aeration systems. The oxygen transfer performance of a supersaturated oxygenation technology (i.e., the supersaturated dissolved oxygen (SDOX) system) was evaluated in clean water and in activated sludge with MLSS concentrations from 4 to 40 g L−1 as a promising technology for uncapping such limitation. The evaluation was carried out at the laboratory facilities of the faculty of food technology and biotechnology at the University of Zagreb. The sludge was collected from a full-scale conventional activated sludge (CAS) wastewater treatment plant (WWTP) operated at a solid retention time (SRT) of approximately 5 days. The evaluation was carried out using a laboratory-scale setup consisting of a bench-scale SDOX system (2.75 L) supplying pure oxygen to a 5 L biological reactor. The SDOX exhibited oxygen mass transfer rate coefficient (KLa) values (2.6 h−1) in clean water lower than for fine bubble diffusers (11 h−1). However, higher oxygen transfer rate (OTR) values and alpha factors (mass transfer ratio of process-water to clean-water) as a function of the MLSS concentration were observed. A standard oxygen transfer efficiency (SOTE) of approximately 100 % in clean water was reported. The SDOX technology can be presented as a promising alternative for supplying dissolved oxygen (DO) into mixed liquor solutions; particularly, at the high MLSS concentrations required by high-loaded membrane bioreactor (HL-MBR) systems and aerobic digesters.

Original languageEnglish
Pages (from-to)171-181
JournalProcess Safety and Environmental Protection
Publication statusPublished - 2020


  • Activated sludge
  • Conventional diffused aeration
  • High-loaded membrane bioreactor
  • Mixed liquor suspended solids
  • Oxygen transfer
  • SDOX


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