Currently, about 95% of inedible food waste in Victoria goes straight to landfill. As one of the largest emitters of methane, landfill directly contributes to climate change. The efficient diversion of food waste from landfill through composting can therefore help abate global emissions. Large scale, and high density, cites (such as New York, Portland, San Francisco, and Vancouver) have proven the success of using offsite composting to divert food waste from landfill. What is unknown however is how different systems for onsite composting compare with offsite composting in reducing greenhouse gas emissions, producing quality compost for growing food, and encouraging people’s engagement in the compost process.
Therefore an Australian Cooperative Research Centre (CRC) for Low Carbon Living study is currently being undertaken by Swinburne University of Technology, Melbourne, and the University of South Australia, Adelaide. The project pilots various models for composting household and commercial food waste, for the purposes of growing food. In particular, it compares different models of on-site composting (such as worm farms and ‘in-vessel’ 24 hour composters) and off-site composting (kerbside collection) in different urban settings (offices, multistorey apartment buildings, suburban houses, cafes and commercial kitchens, among others). The study investigates three domains: which systems are most effective in reducing greenhouse gas emissions, which produces the better compost product, and which are the most successful in engaging people in composting processes.
The research challenge
The achievements of large, high density cities (such as Portland, San Francisco and Vancouver) prove the success of offsite composting for diverting food waste from landfill. What is not known, however, is how different systems for onsite composting compare with offsite composting in terms of GHG reductions, compost quality and people’s engagement and satisfaction with how their food waste is dealt with. As cities throughout Australia
Project outcomes will include reports, publications, handbooks, and presentations at major national and international conferences. The information will be made available to the pubilc through this webpage and the project facebook page and instagram account. In addition project outcomes will also include:
Strategies for best practice food separation and composting solutions appropriate to different types of site leading to a decrease in the volume of waste to landfill
Data on greenhouse gas reductions from composting food waste for food production
A comprehensive location-relevant resource for choosing amongst models of producing compost for food production from food waste
An integrated decision tool to inform future low-carbon design of precincts (August 2018)
A practical handbook of food separation and composting solutions fordifferent types of urban form, based on the research findings (August2018)
A national symposium tailored to waste management andsustainability areas of government and business (September 2018).
An engaging website tracking progress of the research
A short film on the various composting solutions (November 2017)
consider alternatives to landfilling food waste, the need for this information becomes more critical. The onsite composting pilots range across different types of urban precinct and use either in-vessel composters or Hungry Bin Worm farms. The models of onsite and offsite composting will be compared in three different work domains looking at:
Which results in the better compost product?
The project (The Microbial Ecology of Urban Organic Waste Treatment (Compost)) will study the microbial ecology of various composting materials from household, through community to council/city level. Lab and pilot-scale solid waste bioreactors (e.g. Closed Loop’s Cloey; Hungry Bins; Osca) will be set up and the feed, bioreactor contents and final product will be chemically (including gas volume and composition determination during processing) and biologically analysed. Modern molecular ecological methods including high throughput DNA sequencing, metabolomics and bioinformatics will be used to understand the indigenous microbes and bioprocesses involved in organic waste composting. A critical element of the research will be to determine the incidence and types of health related bacteria in compost and, if present, to develop mitigation strategies for these organisms from finished compost. The nutritive value of the final product will also be ascertained.
Which results in the better compost product?
The UNISA team will focus on two aspects of the project. One involves the specific modelling of the uptake of carbon by the soil via various composting routes. The other is the use of Input-Output analysis to estimate the whole of economy effects of diverting food waste through composting. This will give the total carbon benefits, not just the uptake in soils. A specific critical research challenge is to actually marry up the predicted effects of the different compost methods in reduction of GHG with actual results from on ground trials, and learn from any discrepancies in order to improve implementation of the preferred method. The modelling aspect of the research will quantify the benefits of the two forms of onsite composting, worm farms and in-vessel system, versus transporting the food waste away and then transporting compost back.
Which is more successful in terms of people’s engagement?
The sociological component examines the social dimensions of engagement with food separation, composting and compost use. Case study methodologies will be employed at each pilot site, including observations of systems, interviews and focus groups with those required to separate their food waste, those directly involved in composting and end users of the compost product. A quantitative survey will be undertaken of residences provided with a combined food and green waste bin for kerbside collection. Research pilots will be also be compared with similar existing sites where food waste is separated and collected for off site composting by a commercial waste operator.
Models to be piloted in the research project.
Central to this research project is the real world piloting of models of onsite and offsite composting of food waste in different types of precincts. The proof of concept built into the project will, in combination with the GHG modeling and case study methodology, provide a clear pathway for utilization of the research outcomes by other councils, the construction industry and businesses producing food waste.