If you are interested in learning more about food sanitization, it would be a good idea to watch this video. Before you start to clean the drain, you should check the integrity of the equipment that you are going to be using. You should take the debris that you see and put it in an appropriate waste container.
You should have the appropriate signage in place as well, so that other people know what you are doing when you are cleaning the drain. Rinse any remaining debris from the covers with low pressure water, and then use the appropriate detergent to clean them further. Then, you can use a long-handled brush to scrub around the area, including the surfaces and the edges of the gully. Then, once everything is done, rinse the cleaning equipment, as well as the covers and the drain itself. Inspect the equipment and clean it all again if this is necessary.
It is important to make sure that you are following whatever protocols apply to the place where you work. Especially if you are dealing with food on a regular basis, you want to make sure that the place is sanitary, so that you do not end up delivering unsanitary food to customers.
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