Food waste mainly refers to perishable domestic waste containing organic matter, including household food waste, restaurant food waste, and other food waste. Household food waste is produced in residents’ daily life. Restaurant food waste comes from food residues and processing wastes generated by enterprises or public institutions. Another food waste is the waste of vegetables, fruits or rotten meat leftover in market contexts.
Food waste in China consists of organic matter, water, and salt and accounts for a relatively high proportion of municipal solid waste. Unfortunately, it rots easily and then spreads an unpleasant smell.
In recent years, local governments in China have successively issued a series of waste classification policies which have effectively promoted the classification of waste at sources and the allocation of facilities resources.
The amount of classified food waste, as well as the demands for food waste treatment technology and facilities, have increased. Due to the expansion of the market, many processing technologies have been established. Nevertheless, the industry lacks relevant evaluation systems and methods, which makes it difficult to objectively evaluate these different food waste treatment technologies.
Therefore, the “China Integrated Waste Management NAMA Support Project” and the School of Environment of Tsinghua University aim at establishing a technical evaluation system of food waste through the analysis of case examples. In general, the idea is to treat and utilize food waste by transforming its components, such as C, N, P, K and other elements, into new resources through the application of appropriate processing.
Recently, China has been successful in issuing a technical route for food waste treatment and resource utilization: Applied methods are anaerobic digestion, supplemented by composting, as well as insect larvae processing. Among the aforementioned methods, anaerobic digestion is the main technology applied in China, accounting for 80% of the planned or constructed projects. Anaerobic digestion can be divided into the dry process and the wet process. Whereas restaurant food waste with high water or oil components is more suitable for the wet process, food waste from households usually only contains low masses of water and oil. In the future, food waste with low water content could be treated with dry anaerobic biochemical technology. The biogas emerging through the fermentation in this process can be reused.
However, in addition to technology selection, the construction and management quality is also related to the operating and environmental performance of the facilities. Existing food waste treatment projects still have some problems, such as low resource utilization rates and secondary pollution. Through scientific evaluation, the sustainable quantification and optimal mode screening of the food waste technology combination system can be realized.