Industrial composting of organic waste

Learn about industrial composting, the law and managing risks of harm.

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Industrial composting is the commercial production of compost from organic waste material.

Compost results from microorganisms reacting with organic materials under controlled aerobic conditions. Aerobic means with oxygen.

Composting has 3 phases:

  • mesophilic
  • thermophilic (pasteurisation)
  • maturation.
  • In the first phase, mesophilic microorganisms – primarily bacteria – break down easily degradable materials. This produces heat that causes a transition to the second phase.

In the second phase, thermophilic microorganisms – such as spore-forming bacteria, actinobacteria and fungi – break down more complex molecules and compounds in the waste. This includes:

  • proteins
  • carbohydrates
  • lignin – found in plant cell walls.

The high temperature in this phase is what reduces the number of pathogens and plant propagules in the compost.

In the maturation phase, activity decreases as the waste material that feeds the microorganisms decreases. This gradually decreases the temperature of the compost pile.

Industrial composting and the law

The general environmental duty applies to all activities involved with industrial composting. You must eliminate or reduce the risks of harm so far as reasonably practicable. Harm can include odour.

Composting facilities receiving organic waste feedstock must be authorised to receive it and must meet the duties of persons receiving industrial waste.

If your composting activities cause pollution, these duties may apply:

If your composting activities contaminate land or groundwater, these duties may apply:

In addition to the duties, you must get a permission to conduct composting activities. Permissions have conditions that must be followed. Depending upon the amount of material you are composting, you need either:

Our role in industrial composting

We regulate the storage, transport and deposit of industrial waste. This includes organic waste for use in compost processing.

We provide guidance to responsible authorities to help them assess planning permit applications for composting facilities or which involve composting operations.

Impact of industrial composting on health and the environment

Odour from composting operations is one of the most common causes of community pollution reports.

Odour can be generated when organic material breaks down anaerobically. Anaerobic means without oxygen. This can happen when the decomposition of organic material is not controlled – for example, with:

  • stored feedstock that has begun to break down
  • stored leachate that has become anaerobic.

During anaerobic decomposition:

  • pathogens are not as readily reduced
  • chemical compounds are produced.

Some of these chemical compounds are odorous and extremely offensive to humans – for example, hydrogen sulfide, also known as 'rotten egg gas'.

Odour can escape and have impacts beyond the boundary of the premises.

Dust and bioaerosols from composting facilities can impact health. Bioaerosols are particles in the air that come from biological sources such as:

  • fungi
  • viruses
  • bacteria
  • pollen.

Composting can also contaminate groundwater, surface water or land. This happens when water comes into contact with organic matter during the composting operation, and the water seeps or runs off into the local environment. Water that is contaminated with organic matter – leachate – must be managed.

Learn more about how contamination can cause harm.

Manage impacts from composting

Using best practice to design and operate composting facilities can help you:

  • meet your general environmental duty
  • minimise many of the potential impacts.

Use our guidance Designing, constructing and operating composting facilities to support your knowledge and understanding.

For information about managing odour, visit Control odour from your business.

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