The effect of sodium chloride and sodium bicarbonate derived anolytes, and anolyte-catholyte combination on biofilms

Abstract

Microbial biofilms are problematic in industrial environments where large areas of submerged surfaces are exposed to
relatively high nutrient fluxes, providing niches for the formation of copious surface-associated growth. Biofilms growing in drinking water distribution pipes cause deterioration in the microbiological quality of water contributing to the occurrence of water-borne diseases. Many bacteria are resistant to moderate levels of biocides, with bacteria in biofilms being the most
difficult to control. Electrochemical activation (ECA) technology provides an alternative way of controlling these micro-organisms. The main objective of this study was to evaluate an electrochemically activated solution, anolyte, as an
environmentally safe disinfectant for the control of biofilms. Biofilms were grown using the Pederson device and then exposed to different concentrations of the biocide. Light microscopy and scanning electron microscopy were used to view the effect of treatment on the biofilm structure. Re-growth of the biofilm after treatment with anolyte was detected through
epifluorescence microscopy after DAPI staining of the coupons. Neat (undiluted) and mildly dilute anolyte removed the
biofilm while the more dilute anolyte did not have any effect on the biofilm. Re-growth of the biofilm occurred after
24 h of biofilm treatment with anolyte and anolyte-catholyte combination, showed by the increase in colony forming units.
Re-growth of planktonic bacteria however, occurred only after 72 h of treatment.

Water SA Vol. 32(2) 2006: pp.237-242