Food waste that is not composted generally goes directly to a landfill. As landfills fill up and close at an alarming rate, waste disposal and tipping fees to the businesses and institutions generating the waste will continue to climb. Once in the landfill, organic matter may react with other materials and create toxic leachate. Food waste placed in an airtight landfill stops the earth’s natural cycle of decomposition. This cycle plays a crucial role in the health of our environment. More than 72 percent of all materials entering landfills can be diverted through composting. Composting provides a way in which solid wastes, water quality, and agricultural concerns can be joined. An increasing number of communities, businesses, institutions, and individuals are expected to turn to compost to divert materials from landfills and to lower waste management costs. Although waste stream managers view composting primarily as a means to divert materials from disposal facilities, the environmental benefits, including a reduction in water pollution, and the economic benefits to farmers, gardeners, and landscapers can be substantial.
– Reduces solid waste disposal fees.
– Ends wasting large quantities of recyclable raw ingredients.
– Educates consumers on the benefits of food waste composting.
– Helps close the food waste loop by returning it back to agriculture.
– Reduces the need for more landfill space.
Foodservice businesses and institutions have several options depending on feasibility and specific restraints. If the land is available, you may compost the food waste on-site in rows or bins. If minimal space is available or if appearance, odor, and leachate containment are an issue, in-vessel systems or aerated containers are other options that require little attention and labor. Finished compost may be sold for added income or used internally on grounds to beautify landscapes or reduce landscape and soil amendment costs. Finally, the best option may be to export the food waste either to a central compost facility or to a local farmer.
Figure 1 Passive composting, or piling
Passive composting or piling is simply stacking the materials and letting them decompose naturally. This method is simple and low cost but is very slow and may result in objectionable odors.
Figure 2. Aerated static piles
In Aerated static piles, the air is introduced to the stacked pile via perforated pipes and blowers. This method requires no labor to turn compost but is weather sensitive, and can have unreliable pathogen reduction due to imperfect mixing.
Figure 3.4 Windrows
Windrows are long, narrow piles that are turned when required based on temperature and oxygen requirements. This method produces a uniform product and can be remotely located. However, turning the compost can be labor intensive or require expensive equipment. Windrows are typically used for large volumes which can require a lot of space. In addition, windrows can have odor problems and have leachate concerns if exposed to rainfall.
Figure 5. In-vessel system
Simple to use, easy to turn, require minimal labor, are not weather-sensitive, and can be used in urban and public areas. The initial investment can be high.
What must I know to make and monitor food waste compost?
Proper nutrient mix or carbon to nitrogen ratio (C: N) is important for bacteria to process organic material into compost. The optimum ratio to begin composting is 30:1. If the ratio increases decomposition is slowed, if the ratio decreases foul odors and nitrogen loss can occur. Food waste is typically 15:1, fruit waste 35:1, leaves 60:1, bark 100:1, and sawdust 500:1. For example, a recipe using 1 part leaves and 1 part food waste by volume would achieve close to a 30:1 ratio.
The moisture content of 60 percent is optimal for microorganisms to break down the compost. Moisture contents above 70% anaerobic conditions, slow down the process and can create foul odors. Moisture below 50 percent also slows down the decomposition process. The moisture content of fresh food waste is 80 to 90 percent, sawdust is 25 percent, and yard waste is 70 percent. Compost with a proper moisture content will form a clump and will slightly wet your hand when squeezed. If the clump drips water, it is too wet and may require additional aeration or more bulking agent. If the compost falls through your fingers, it is too dry and may need water additions or more food waste.