In the summer months, there is always an increase in numbers of green bottles being returned for washing. Once green bottles enter the washer, this can lead to contamination of all other bottles during the washing process. Unfortunately, the storage of full and empty bottles by the customer is not always ideal, but with a few simple precautions, it is possible to reduce the incidence of green bottles.
Algal spores are everywhere in the environment and they can be carried easily by the wind. With sunlight, warmth and moisture, algae can grow quickly and soon become visible in the bottle. Empty bottles, if stored outside, must be covered with black or dark plastic wrappings and not left outside for more than seven days. Filled bottles should not be left outside for more than 24 hours and never in direct sunlight.
Customers should be advised on best storage places, for example avoiding direct sunlight at windows, and keeping empty bottles away from dusty environments. Regular collections should be made to avoid prolonged exposure of empty bottles.
Checking bottles before washing should be done thoroughly and diligently, badly contaminated bottles should be discarded. Bottles with small amounts of algal contamination should be pre-washed with oxidising products before entering the main washer. Older bottles have more tendency to suffer from algal growth. This is because of the presence of micro-cracks, which create a refuge for spores during the washing process. Micro-cracks are a result of stressing the polycarbonate through transport and too many wash cycles. Older bottles should be discarded and recycled.
Preferably use a wash detergent containing a disinfectant component and ensure that the wash temperature does not fall below 60 degrees C. At the end of the shift, the washer should be thoroughly disinfected with a suitable material such as peracetic acid.