Can you compost meat, dairy, and fish?

June 1, 2022

3 minutes, 4 seconds read

Can you compost meat, dairy, and fish?

Composting is one of the best ways to effectively handle food waste. It combats soil degradation, enriches soil, and reduces methane. Composting uses a natural process called aerobic digestion to break down food waste. It requires the following inputs:

  • Organic waste
  • Microorganisms
  • Water
  • Oxygen

The byproduct is nutrient rich soil that returns carbon from the atmosphere and effectively combats global warming. 

Although composting is one of the best ways to handle food waste, there are limitations to what kind of food waste can be composted. The EPA cautions against composting dairy products, meat scraps, and fish bones.

Meat, dairy, and fish may slow down or even prevent proper composting due to infection vectors and fats and oils.

Problems with composting dairy

Ineffective composting: Dairy products differ from normal organic waste due to the high moisture and fat content. 

Fats and oils slow down composting by creating water-resistant barriers around the waste, displacing water, and reducing air flow. A balance of water and air are required to maintain the optimal conditions. Too much or too little water will slow down the composting process.

Odor production: When dairy products begin to spoil, it creates an unpleasant, rancid odor due to the overgrowth of bacteria. This can attract pests and wildlife which can disrupt the compost pile in search of food.

Problem with composting meat

Sanitation issues: When meat decomposes, it can become infected with bacteria such as E. coli, listeria, or salmonella. If infected meat contaminates a compost pile, there is a risk of the bacteria transferring into surrounding plants. 

Decomposing meat can become infected with E. coli, listeria, and salmonella. This present a health hazard as the vectors may transfer to nearby plants.

Odor production: Rotting meat often gives off a sickly-sweet smell that is caused by bacteria breaking down the tissues. This attracts necrophagic insects, flies, and maggots.

Problems with composting fish bones

Odor production: Fish contain trimethylamine oxide (TMAO) which fill their cells with amino acids and help maintain salt and water balance. When fish begin to decompose, bacteria and enzymes convert TMAO into trimethylamine (TMA), which gives off a strong, fishy smell. This smell is hard to cover up unless the fish waste is mixed with sawdust and buried deeply under a hot compost pile.

Labor intensive: Fish bones will not readily compost unless utilized as a bone meal fertilizer. To create bone meal fertilizer, the fish bone must be dehydrated, grinded into a meal, and spread across the soil. This lengthy process requires heat, time, energy, and labor.

What can you do with meat and dairy products if you can’t compost them?

There is no food recovery for these products which are quick to spoil and cannot reenter the food supply chain. Meat and dairy products are typically thrown into the trash where they end up in the landfill and decompose into methane, a climate super pollutant that directly contributes to global warming.

Meat and dairy products should be used before they spoil or disposed of in a way that will prevent contaminants from entering the environment. Certain waste management solutions can be used in conjunction with composting to achieve zero waste. 

A less environmentally friendly method of disposing of dairy products is to send it down your garbage disposal. This may be a means of disposal of spoiled milk and yogurt, but cannot be utilized for large pieces of cheese. It is also not a viable solution for getting rid of spoiled meat and fish waste bones. Garbage disposals are banned in many jurisdictions, and their analogy, the pulper, used on ships is also viewed negatively.

Biodigesters are a great complement to composting. They utilize a similar aerobic composting process that can easily digest spoiled meat and dairy products. Microorganisms digest waste inside a machine and turn it into water that can be safely discharged into the sewage system.

Contact Power Knot here to learn more about how biodigesters can supplement your composting system.