Zheng, Meris (2020) A critical analysis of current practices in the treatment of household food waste in Australia: strategic and technical improvements within a Micro Circular Economics (MCE) context. PhD thesis, Victoria University.

Abstract

Food waste (FW), generated from the point of production to the dinner table, represents approximately one third of all the food produced worldwide. It is estimated that more than 95% of household food waste (HFW) goes to landfill and is the major contributor to greenhouse gas (GHG) emissions from such sites, with other environmental impacts such as pollution of groundwater. There are also significant costs involved with the management of FW worldwide. These issues are compounded by increasing urban populations and there is an urgent need to better address the management and disposal/treatment of FW generally - and HFW in particular. In order to achieve this, more research is urgently needed to obtain specific information on the details of HFW management and on the development of appropriate technologies that are consistent with a micro circular economic (MCE) approach. To this end, an extensive review of HFW management and technology worldwide has been conducted. Together with the above information, in collaboration with three local Councils, research has been undertaken with respect to the Melbourne metropolitan area specifically that involves the design and implementation of a strategy to survey residents across three different well-defined dwelling types, in order to obtain detailed information on their household management and disposal of domestic food waste. Thus, an extensive survey has been designed and conducted that separately targets residents of detached houses, semi-detached/low-rise and high-rise dwellings. This survey has revealed differences in HFW management, attitudes and practices, that that depend on dwelling type - and that also provide important general information and data that has informed the subsequent design, construction and testing of a miniaturized anaerobic-digestion (AD) pilot-plant. This information is of both a qualitative and quantitative nature. For example, it is important to know both the nature and the quantity of the food waste generated as well as residents’ attitudes towards disposal and treatment. The designed and constructed pilot plant is meant to serve as a prototype for the on-site treatment of HFW that will produce biogas for domestic consumption. An ultimate goal here is to utilize HFW to supplement a household’s gas supply and at the same time remove the necessity of sending HFW to landfill. Thus the pilot-plant experimental program has collected and analysed replicate temporal data on the effect on biogas (CH4) production of parameters such as household food waste composition and quantity (as informed by the survey) and texture, the nature of the inoculate, operating conditions such as pH and temperature, oxygen infiltration and fatty acid production - as well as design aspects such as the footprint, the number of tanks and the required control equipment. In terms of biogas yield, a multiple tank set-up has been found to be superior to a single tank set-up and an important aspect has been found to be an appropriate mixing of food waste substrate between AD tanks that results in an increased biogas yield. In summary, the combination of an extensive targeted survey of HFW management in the Melbourne metropolitan area, coupled with the design and trialling of a potential household pilot plant for the on-site generation of biogas, has yielded valuable information that will eventually result in a commercially viable product.

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