Cold water bath Coliform tests
At our facility we extrude melted plastic pellets and then cool the material with cold water. For AIB Standards how often would they expect me to test the water for Coliform. I am debating between weekly or monthly.
Is the water recirculated and is it treated?
The tanks are refilled with a soft water line. Other than that the water is untreated. Yes, the water is recirculated between two tanks. The first tank is used in manufacturing to cool down plastic and the other tank has a chiller coil to keep the cool. But the water is only circulated between those two tanks. I don't know what its worth but directly after being cooled down the plastic is sent through hot water (140 degrees Farenheit) to be stretched.
When water is recirculated it should be treated with an antimicrobial such as chlorine, even though you are most likely not getting any loading. Since your net is food contact, it should be between 100-200 ppm. Even though it goes through 140 to stretch think it is most likely not enough to kill the possible bacteria. With an anti-microbial your coliforms tests could be less frequent, but suggest a more intensive frequency at first and after you build some data to show you are not getting hits, then you can reduce the frequency. But then you can demonstrate to an auditor that you have the data to support the less frequent testing.