Membrane biofouling by chlorine resistant <i>Bacillus</i> spp.: effect of feedwater chlorination on bacteria and membrane biofouling

In this study, bacteria isolated from a lake were characterised for their chlorine resistivity and the effects of chlorination on growth, mortality, protein expression and attachment propensity towards membranes. Biofouling and membrane performance were analysed. All isolated chlorine resistant strains, characterised by 16s rRNA gene sequencing, belonged to the genus <i>Bacillus</i>. Chlorination caused limited effects on bacterial growth and mortality. <i>B. safensis</i> and <i>B. lechinoformis</i> suffered the maximum effects due to chlorination. Live-to-dead ratios immediately after chlorination were above 1.3, with some exceptions. The membrane pure water flux recovery was highly strain dependent. Irreversible membrane fouling was observed with <i>B. aquimaris</i>. Membrane flux decreased substantially during ultrafiltration of water containing chlorine resistant bacteria.