Last updated: 13 June 2012

What are biosolids?

Biosolids are a by-product of the wastewater treatment process. Treated appropriately they can be beneficially used.

What are biosolids used for?

Biosolids have high nutrient value and can be used as a soil conditioner on farms. Biosolids can help improve soil quality and crop yields. They can also be reprocessed to produce a compost product.

What crops are grown using biosolids?

Generally dewatered biosolids are applied to large broad-acre farms that grow canola, wheat, oats, barley and pastures. The biosolids are spread and incorporated into the soil prior to sowing. The harvested components of these crops don't come into contact with the soil/biosolids mixture. These crops are also mostly reprocessed eg. into flour.
Composted biosolids are treated to a high level and tested to ensure that they are suitable to be used in the same way as any other composted product.

How is the use of biosolids regulated?

The use of biosolids in NSW is regulated by the Office of Environment and Heritage (formerly the Environment Protection Authority (EPA)). The Environmental Guidelines: Use and Disposal of Biosolids Products (NSW EPA 1997) lists the requirements for biosolids use. The Guidelines stipulate the permissible uses based on the level of treatment. Biosolids treatment processes have been validated to control disease-causing microorganisms (pathogens), and this forms the basis for the Guidelines. The Guidelines include requirements to test biosolids for a range of heavy metal and organic compounds and nutrients; and pathogen and odour control.
The Guidelines were developed with the assistance of a Biosolids Subcommittee, which included representatives from Government Departments (including Health and Agriculture), water utilities (including Sydney Water Corporation) and other related industries. More than 10 years of research were conducted into the application of biosolids in NSW. The Guidelines provide a multi-barrier approach to the management of risks.

What is the international experience with biosolids?

Biosolids are beneficially used in many countries around the world. In the UK, USA and Canada the majority of the biosolids are applied to farms. Some countries use biosolids as a fuel source and others incinerate.
International studies have shown that biosolids, when treated and managed in accordance with guidelines such as we have in NSW, are safe. In 2002 the US National Research Council reviewed that country's experience with biosolids use, current science and the US EPA's biosolids regulation, called the 40CFR Part 503 rule, and concluded that 'There is no documented scientific evidence that the Part 503 rule has failed to protect public health'.

Is the use of biosolids safe?

NSW Health recently convened a panel of experts in microbiology and infectious diseases who considered the use of biosolids in NSW. The panel concluded that the risk to human health was negligible if the treatment and use recommended by the Guidelines is followed.
Biosolids have been applied to soils in NSW for more than 20 years. NSW Health is not aware of any outbreaks of illness in workers or the general public caused by biosolids use.

What precautions should be taken?

When working with biosolids or any soil or potting mix product, appropriate personal protective equipment such as gloves should be used. Exposure to dust can be reduced if required by wetting down the biosolids (if dry) and wearing a P2 mask. Wash your hands after handling biosolids, potting mix or compost, and before eating, drinking or smoking. The NSW Food Authority recommends you wash all fruit and vegetables with cool tap water immediately before eating.
The Guidelines require biosolids producers and re-processors to produce occupational health and safety plans to ensure workers handling biosolids products are adequately protected and informed of risks
Further information.
In NSW call 1300 066 055 to talk to your local Public Health Unit