APPENDIX A
Composting versus Garbage Disposals

The battle between using food waste processors (FWPs; garbage disposals or garburators) and composting continues to rage. The most comprehensive study done to date on this topic was funded by InSinkErator and was conducted in Australia. (Australia is the smallest continent and faces a severe water shortage.) This study concluded that home composting (aerobically) was best for the environment but that using a garbage disposal has less of an impact on our ecosystem than disposing of food waste in a landfill. It is this study that we will be citing most in this conversation.1

The study compared home composting (both aerobic and anaerobic), codisposal (municipal waste management systems [MWMS], the mixing of waste and food waste), central compositing (CC; municipal organic composting), and disposals (FWPs).

Aerobic composting. Composting that occurs that provides air circulation. For most efficient composting, turn compost occasionally and keep moist.
Anaerobic composting. Composting that occurs underground or in a tightly enclosed area. This type of composting occurs in landfills and creates methane gas (a greenhouse gas).
Codisposal. Mixing of organic matter (yard debris and food waste) with inorganic matter in municipality landfill.
Centralized composting. Municipality composting.
Eutrophication. Refers to the addition of artificial or natural substances, such as nitrates and phosphates, to the ecosystem. Nitrates and phosphates enter the water system from runoffs from agriculture and development and from pollution created from septic systems and sewers. (See Chapter 5.)

Depending on the efficiency of wastewater treatment plants, excessive amounts of nitrogen and phosphorus from sewers can enter our water system. Phosphorus is linked to algae blooms in lakes, which result in the depletion of oxygen in the water and lead to decreased biodiversity, changes in species' composition and dominance, and toxicity effects.

The study was based on the production of 182 kilograms (wet) of food waste per year for a household of 2.1 persons and incorporated the embodied energy of each item involved (garbage disposal, composting unit, and equipment used in each of the municipal systems: trucks, fossil fuels, wastewater treatment plant). The study also included the life cycle assessment (LCA) of the containers, vehicles, processing facilities, and wastewater treatment plants.

Embodied Energy

To fully define the impact each type of food disposal system has on the environment, the study included the embodied energy of the “container” which aids in the composting of the food waste.

Garbage disposals (garburators) (FWPs)

Require potable water, energy in the kitchen, and processing in the wastewater treatment plant.
The treated water is linked eutrophication in our waterways.
Life span of a FWP is approximately 12 years.
Life span of a wastewater treatment plant is estimated at 35 years.

Home composting unit

Life span of plastic unit is 12 years.

Codisposal landfill
- Food waste in the landfill releases methane (which contributes to global warming). According to the US Environmental Protection Agency (EPA), the release of methane from landfills accounts for 34 percent of all methane emissions in the United States.2 The EPA estimates that approximately 34 million tons of food is added to our landfills yearly.³ This waste accounts for one-quarter of all the fresh water consumption and consumes approximately 300 million barrels of oil yearly.⁴
- Highest-level embodied energy: The study included vehicles that used fossil fuels, although some composting companies are updating their fleets to compressed natural gas (CNG; a fossil fuel that is considered a more environmentally clean alternative to conventional fuels).
- Process
  - Municipal street collection occurs weekly.
  - Waste is transported to a landfill via a transfer station.
  - Waste is deposited and compacted at the landfill.
  - Degradation of organic waste takes place under anaerobic conditions.
Centralized composting
- Medium-level embodied energy: The study incorporated vehicles that used fossil fuels, although some composting companies are updating their fleets to CNG.
- Process:
  - Municipal street collection occurs weekly.
  - Organic waste is transported to a landfill.
  - In some municipalities, organic waste is then transported by a private carrier to a composting facility,

The study concluded that the best option for the disposal of organic waste is under aerobic home composting systems. Using FWPs was the next most efficient method.

This study does not take into effect the current state of the US infrastructure. According to the 2013 Report Card for America's Infrastructure published by the American Society of Civil Engineers, the wastewater treatment plants in the United States currently get a D+ (between a poor and mediocre rating). Many of the nation's 700,000 to 800,000 miles of public sewer mains were installed after World War II and are nearing the end of their useful life. Many of our wastewater treatment facilities are in poor condition and have inadequate capacity. This results in an estimated 900 billion gallons of untreated sewage being dumped into our waterways yearly.⁵

The untreated sewage also includes food waste. It is important to note that waste from the use of FWPs has been found to aid in the progression of algae blooms and the eutrophic process.

In Canada, many cities, including Toronto and Ottawa, have banned FWPs. This leads us to the question: What do they know that we don't?

Embodied Energy

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