Waste water treatment by micro air and ozone bubbles

Lau Hao Wen, Patththil Madhav Menon, Ng Kim Choon

Research output: Contribution to journalArticlepeer-review


In this study, a novel physical separation method using a flotation system that employs micron sized air and ozone bubbles is designed and tested to replace conventional dissolved air flotation (DAF) or clarification of water by settling. The bubbles produced are fine and turn the water milky white. Micro air bubbles remove fine coagulated but suspended particles from the waste water, achieving a separation efficiency of up to 99% of oil and grease and suspended solids. The removal of fine suspended particles from the water reduced Total Suspended Solids (TSS), Bio-Oxygen demand (BOD) and Chemical-Oxygen Demand (COD) levels in the water, requiring less chemicals in downstream processes. The water was subsequently treated using high concentration and micron sized ozone. Test results show that both micro air flotation and ozone treatment have achieved high reduction of oil and grease, TSS, BOD and COD. The water is then filtered using a micro-filtration membrane, and the water fouls the membrane. The waste water was replaced with PUB tap water, and micro air and ozone bubbles are backwashed separately through the membrane. Significant increase in the permeate flow is observed, implying that the micro air and ozone bubbles are effective for fouling removal.

Original languageEnglish (US)
Pages (from-to)368-371
Number of pages4
JournalInternational Review of Mechanical Engineering
Issue number3
StatePublished - 2009
Externally publishedYes


  • Micro air bubbles
  • Micro ozone bubbles
  • Microfiltration
  • Waste water treatment

ASJC Scopus subject areas

  • Materials Science (miscellaneous)
  • Automotive Engineering
  • Agricultural and Biological Sciences (miscellaneous)
  • General Engineering
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


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