Food waste belongs to the classification of wet waste, which includes: ingredient waste, leftovers, expired food, melon peels and kernels, flowers and plants, and dregs of traditional Chinese medicine.

And ingredient waste includes: grains and their processed foods (rice, rice, noodles, bread, beans), meat and eggs and their processed foods (chicken, duck, pork, beef, mutton, eggs, animal offal, bacon, luncheon meats, eggshells), aquatic products and their processed foods (fish, fish scales, shrimp, shrimp shells, squid), vegetables (leafy greens, root vegetables, mushrooms), seasonings, sauces etc.

Leftovers: hot pot soup base (solid waste after draining), fish bones, broken bones, tea dregs, coffee grounds, etc.

Fruit peels, rotten leaves, leftovers, meat, etc. included in food waste are included in ingredient waste and leftovers, as food waste is classified as wet waste.

Wet garbage should be collected separately from other kinds of garbage from the time it is generated, and drained as much as possible before putting it out. Among them: wet garbage with packages should be put out after removing the packages, and the packages should be put out in the corresponding recyclables or dry garbage collection containers; containers holding wet garbage, such as plastic bags, should be removed when putting out.

Food waste contains high levels of moisture and organic matter, which can easily spoil and produce a foul odor. After proper handling and processing, it can be transformed into a new resource. The high organic matter content makes it possible to use it as fertilizer and feed after rigorous treatment, as well as to produce biogas for use as a fuel or for power generation, and the oil and grease portion of the waste can be used for the preparation of biofuel.

The garbage formed in the process of meal processing is mainly the leftovers from kitchen processing, such as the stems and leaves cut down from vegetables, the soil entrapped by vegetables, fish scales, and the head and feet feathers of poultry. This type of garbage does not contain leftovers and oil-water separator garbage, oil containing very little, the economic value is not high, generally no one alone to collect this type of garbage, this type of garbage is mostly used for composting, the production of organic fertilizer.

Leftover food, commonly known as slop. This type of waste is mainly leftover meals and soups, etc. The oil raised from it is called slop oil. This type of oil is basically neutral in nature, with a low acid value, and can easily be incorporated into cooking oil. Such pigs that grow up eating swill are called garbage pigs.