Methods of Food Waste RecyclingThere are two main categories of food waste recycling: home composting & commercial composting.
Home CompostingHome composting systems are typically limited to food waste and yard trimmings. Forms of home composting include:
VermiCompost: This method of composting involves the use of worms (i.e. red worms) and other insects to create a mixture of decomposed food waste and worm castings. Worm castings or worm manure are the byproduct of the breakdown of the organic matter by the worms and these casting are nutrient rich and act as fertilizer for soil.
Bokashi Composting: This method of accelerated composting involves the fermentation of food waste using a bran inoculated with micro-organisms. The microbes break down the food waste and once fully fermented, food waste can be buried in soil where it completes the biodegradation process and fertilizes the soil.
Open Pile / Backyard Composting: This method of composting involves an open air pile of organic matter which is turned to ensure the proper distribution of heat, moisture, and oxygen. The appropriate mixture of wet and dry materials must also be added to ensure that the compost pile does not smell. This method of composting is typically limited to produce, as meats and animal products can attract vermin.
Commercial CompostingCommercial composting environments can accept food waste, yard trimmings, animal waste, food packaging supplies, and most organic materials. Forms of commercial composting include:
Windrow Composting: Windrow composting is the process of producing compost by piling organic matter into long rows or semi circle shaped piles. These piles are then turned by large machinery to maintain even levels of heat, moisture, and oxygen content. Piles will typically range from 4-8 feet in height and 14-16 feet in length.
Aerated Static Pile (ASP) Composting: ASP composting involves the production of compost in piles which have air pulled and pushed through them. Piles are not turned and may be open or enclosed. Enclosed piles are covered by heavy duty plastic bags or tarps. Aerated static piles are typically used by facilities processing large amounts of wet organic materials.
In-vessel Composting: In-vessel composting produces compost through the use of enclosed "reactors" that closely monitor temperature and oxygen levels during the biodegradation of organic materials. Compost production happens rapidly, taking as little as a few weeks, but materials often require curing for weeks after. In-vessel composting requires larger capital costs than Windrow or ASP, but requires less land and labor.
Anaerobic Digestion: Anaerobic digesters decompose organic materials in the absense of oxygen. CO2 and methane are produced at a roughly 1:1 level and methane is captured and used as an energy source and fuel. Once gas generation is complete, the organic matter is aerobically cured and can be used as compost. Capital costs for anaerobic digesters are substantially more than aerobic food recycling methods.