The season for green polycarbonate bottles will arrive soon in the Northern hemisphere and has never left the warmer countries. It is important to emphasize the need for effective bottle washing. Most of the soiling on a returned bottle is on the outside of the bottle. Even a thin layer of dust can contain algal spores. This means that the tank of the washer will soon become contaminated.
The environment in the washer should be made as inhospitable as possible for the spores. Temperatures should be kept high, around 65 degrees C, but not too high that bottle damage can result (70 degrees C and above), detergent concentrations should be maintained throughout the shift with top-up as required. Use products containing a “real” detergent rather than just water softening components.
Bottle wash products are now available containing biocide, as well as regular detergent components (eg, Liqualin Safeguard) which will help in the fight against algae. Always use a peracetic acid rinse after the wash and a final rinse with ozonated water, if this facility is available. Remember to always dump your wash tank at the end of the shift and flush out the inside with more peracetic acid.
Finally, you need to be ruthless in discarding green bottles that come into your plant for washing.