A break down of organics recycling
By Darren North
Recycling organics through either composting or other controlled alternatives also reduces greenhouse gas production when compared to methane gas outputs from landfill. Organics recycling is a far better option for the environment and its levels of greenhouse gases.
The process of recycling organic materials into a usable product such as compost has been undertaken since organic material first appeared on earth. The production of compost is well established and is a sustainable way of ensuring nutrients are returned to the soil. As long as the raw material is free from contamination (plastics, heavy metals, glass, etc.), composting is a safe and simple way of applying the circular economy principle.
Traditional ‘open windrow’ composting takes place in the open and requires relatively large areas and can generate odours. This type of processing is also very susceptible to contamination and requires a very clean source of organic materials or increased pre-treatments to remove contamination. It has become very challenging to conduct this type of processing near occupied areas due to complaints about odour and the introduction of tighter legislation requires significant controls to be put in place to protect the environment.
The need for compliance with legislation, space restrictions and ability to cope with contaminants has led to several ways of recycling and treating separated organics. In particular, the development and use of In-Vessel Composting, where the composting process is undertaken in an enclosed facility, has become a suitable way of modernising the traditional composting process. This modernisation of the process has also improved the output quality of the compost product, reduced the time required for the process, and assisted with ensuring compliance in terms of the recent legislative requirements around odour and leachate (liquid runoff).
The processing of separately collected organics using either traditional or modern processes continues to produce the best quality materials, but the collection of the organics relies heavily on participants separating the organics correctly and not introducing contamination.
Evidence suggests that significant quantities of organics are still being disposed of in the residual waste bins and the drive to divert these organics from landfill has led to many alternative treatment processes for mixed waste.
Other processes for the treatment of organic waste are derived from the need to avoid composting or to reduce the separation of organics required for composting. These processes and facilities were primarily designed with making the disposal and recovery options less imposing on the waste producer by relying on the treatment process to ‘clean’ the waste, rather than the producer sorting the waste. This processing of organics mixed with general waste has led to concerns around the long-term degradation of land from possible sources of contamination.
Recently, the NSW Environment Protection Authority (EPA) banned the application to land of composted materials derived from waste (red bin) collections services due to long-term contamination fears. This has rendered the original processes of ‘mechanically’ composting the organics in residual (red bin) waste, to becoming a drying exercise to reduce the moisture content and therefore the landfill levy when disposed. In other countries where waste-to-energy is used, the ‘dried’ waste is sent to waste to energy facilities for conversion to power which alleviates the risks of application to land but it also removes the opportunity for key nutrients returning to the soil.