Most sorting protocols, including ASTM D 5231, call for labeling each container to indicate which waste category is to be placed in it. When a sorting box is used, however, unlabeled containers have the following advantages:
The sorters are encouraged to establish a customary location for each waste category and sort by location, which is faster than sorting by labels. When sorting is done by location rather than by labels, the containers can be placed closer to the sorters, which further speeds the sorting process. Less time is required to arrange unlabeled containers around the sorting box after the sorted material from the previous sample has been weighed and dumped. Keeping the containers unlabeled increases the flexibility of the sorting operation.
The flexibility gained by not labeling the containers has several aspects. First, different samples require multiple 30-gal containers for different waste categories. Second, many waste categories require a 30-gal container for some samples and only a 5-gal container for others. Third, the need for another empty container arises frequently in an active sorting operation, and grabbing the nearest empty container is quicker than searching for the container with the appropriate label.
Despite the advantages of unlabeled containers, the containers for food waste should be labeled. If individual containers are not designated for food waste, all containers will eventually be coated with food residue. This residue is unpleasant and changes the tare weights of the containers.
The tare weights of the food waste containers should be checked daily. Generally, checking the tare weights of other containers at the beginning of each week of field work is sufficient unless a visible buildup of residue indicates that more frequent checking is required.
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