It can seem to take only a few days for fresh groceries to begin to wilt, brown, or show signs of mold. In cases where food goes uneaten, the trip to the garbage can be even quicker. While you may consider the garbage to be the end of life for that spoiled or half-eaten food, the truth is that this is just the beginning of a new phase for organic materials.
Unfortunately, the typical process of disposing of food and other organic waste begins a journey that emits damaging levels of greenhouse gases. By understanding the end-of-life processes – and the byproducts they create – organizations can take more sustainable steps to dispose of food waste.
How the food waste problem starts
The food waste problem begins well before food preparation, but becomes most noticeable in these areas.
When half-eaten foods are returned to the kitchen, or ingredients have passed their “best if used by” date, they are typically sent to the garbage. There, alongside types of nonorganic waste, food begins its decomposition process.
As food spoils, it grows microbes that include bacteria, mold, and yeast, which work to break down food. During this process, both food and microbes release chemicals that create the pungent odor associated with most kitchen waste bins. Those chemicals include carbon dioxide, nitrogen, hydrogen sulfide, and methane.
In addition to being unpleasant for kitchen staff, these more intense odors attract rodents and pests able to digest spoiling food that would make humans sick.
The problem with landfill transport
Kitchens may aim to solve the problem of spoiling food by taking the trash out more frequently, despite being a labor-intensive hassle for staff. More frequent pickups can also help alleviate odors in outdoor bins. However, each garbage pickup also consumes fossil fuels and generates emissions that are damaging to the environment.
As the South Carolina Department of Health and Environmental Control points out, it can be difficult to find a suitable site on which to locate a landfill. As a result of this challenge, and the overall expense of building and operating these sites, landfills are becoming larger today. This allows them to accept waste that comes from further away. With hundreds of trucks crossing longer distances to reach the landfill every day, there are significant emissions generated during the journey from your kitchen to the landfill.
End-of-life food waste issues
For food waste, the real problem begins in the landfill, although not right away. At first, the decomposition of waste in the landfill may be little different from the process that takes place in compost piles. During the early stages of landfill decomposition, nitrogen is among the most common byproducts. Soon, carbon dioxide enters the mix.
As the U.S. Environmental Protection Agency explains, it is within the first year that “anaerobic conditions are established.” As waste piles up, less oxygen is able to reach decomposing organic materials. It is in this oxygen-free environment that significant quantities of methane are first generated. During what the Centers for Disease Control and Prevention’s Agency for Toxic Substances and Disease Registry (ATSDR) refers to as Phase 4 of the bacterial decomposition process, organic waste is emitting 45% to 50% carbon dioxide and 50% to 55% methane. The organization notes that methane makes up between 45% and 60% of landfill gas by volume.
This is problematic because one tonne of methane — the second most abundant greenhouse gas after carbon dioxide — has a global warming potential that is 84 to 87 times greater than CO2 over a 20-year period.
According to ATSDR, Phase 4 decomposition continues at a stable rate for approximately 20 years but may last in excess of 50 years. Part of this lengthy emission process is due to the fact that it takes food longer to decompose in an anaerobic process. For example, the lettuce that may wilt in your fridge within a week may take 25 years to break down in a landfill.
How food waste biodigesters eliminate this problem
Many organizations aim to mitigate these environmental problems by composting food waste. When there is space available to do this compositing onsite, this can be a good alternative to landfill disposal. However, regulations in some areas are creating an industry of off-site composting solutions that still create emissions during the transportation of this waste.
An onsite biodigester provides another alternative to landfills. This sealed equipment is installed directly in the food prep area, eliminating plastic bags and the labor of taking out garbage, any risk of odors, and the emissions generated by frequent waste pickups. Within the equipment, naturally occurring microbes are introduced to break down organic waste in an aerobic process, preventing methane emissions. The gray water that results from this process can be used in onsite irrigation or disposed of down the drain.
Because biodigesters are simple to install and operate, they increase organizations’ success in adopting environmentally friendly waste disposal practices. To learn more about the environmental impact of biodigesters, we invite you to visit our Center of Sustainability.