How does composting reduces green house gas emissions

Have You Ever Wondered Where Your Household Waste Goes?

Have you thought about the impact of disposing of waste into landfills or feeding it to piggeries? These practices are common among bulk food waste generators, such as industrial canteens, apartment complexes, and food processing industries. However, their environmental implications are significant.

Let’s examine how traditional methods of organic waste disposal compare in terms of greenhouse gas (GHG) emissions, and their subsequent effects on soil, climate, and humanity.

GHG Emissions from 1 Ton of Food Waste Using Various Disposal/Treatment Methods:

1. Landfilling

  • Food waste in landfills undergoes a slow decay process over 10–12 years.
  • According to Clean Development Mechanism (CDM) guidelines, 1 ton of food waste sent to a landfill annually (365 tons total) generates 2,650 tons of GHG over a decade.
  • Landfilling food waste leads to long-term global warming impacts due to sustained GHG emissions.

2. Feeding Piggeries

  • Food waste, rich in calories and nitrogen, is often used as pig feed.
  • A single pig consumes 1.8 tons of food in its 9-month lifespan and produces 3.5 tons of GHG.
  • Feeding 1 ton of food waste can sustain 320 pigs daily, which collectively emit an estimated 970 tons of GHG in just 9 months.

3. Anaerobic Digestion (AD)/Bio-Methanation

  • AD processes require sophisticated setups for over 20 tons of food waste per day and constant monitoring of bio-chemical parameters.
  • The biogas produced (200 cubic feet per ton of waste) is composed of 50% methane and 50% CO2, which must be utilized onsite. Transporting biogas is inefficient, consuming 70% of the energy equivalent during bottling.
  • AD produces 3 tons of nitrogen-rich sludge per ton of waste, requiring costly composting to make it soil-friendly.
  • While AD generates renewable energy, its scalability and cost-effectiveness remain challenges.

4. Aerobic Composting

  • Composting emits approximately 550 kg of CO2 per ton of food waste, including emissions from added dry carbon materials.
  • These emissions are biogenic, forming part of the natural carbon cycle, as the carbon originates from plants through photosynthesis.
  • Aerobic composting minimizes methane emissions and produces compost that enriches soil fertility and enhances carbon sequestration.

Carbon Sequestration Potential of Compost

Composting offers a unique advantage: it aids in reversing climate change through carbon sequestration.

  • Compost increases beneficial microbes in the soil, such as mycorrhiza, which uses CO2 to produce glomalin, a stable carbon compound that integrates into the soil without reverting to CO2.
  • Applying compost to soil can sequester up to 2 metric tons of CO2 per hectare annually, providing a powerful tool against climate change.

Why Aerobic Composting is Superior

Unlike other waste management processes, aerobic composting not only reduces methane emissions but also yields compost that regenerates soil and enhances its capacity to store carbon. By integrating compost into the natural carbon cycle, it offers both immediate and long-term environmental benefits unmatched by alternative methods.