Water sterilisation using different hot gases in a bubble column reactor

Abstract

This study compares the effect of using a range of different hot gases to sterilise water at atmospheric pressure within a hot bubble column evaporator (HBCE) reactor. Water containing bacteria (E.coli ATCC 15597) and viruses (MS2 ATCC 15597-B1) was sterilized with 6 different gases (CO2, N2, O2, Ar, air and combustion gas) at inlet temperatures of 200 °C (for viruses) and 150 °C (for bacteria). The results obtained suggest three different gas dependent sterilisation mechanisms: a thermal inactivation mechanism, based on heat transfer between hot gas bubbles for argon, air and nitrogen; a CO2 specific inactivation mechanism, based on the penetration of CO2 molecules through bacterial membranes and virus capsids; and an oxidation/combustion mechanism that inactivates only E.coli, essentially by direct contact with oxygen or through reactive oxygen species. CO2 gas and combustion gases gave the best inactivation results with viruses and O2 gas was found to be most effective for the destruction of E.coli. Show more