Management of food organics and garden organics (FOGO) has emerged as a critical policy priority due to methane emissions from landfilled organics in Australia. Here, the responsibility for organics recovery rests with state and local governments, resulting in fragmented implementation, differing regulatory settings, and variable landfill levy designs. This study examines the viability of FOGO systems by drawing on three Queensland regional case studies: Lockyer Valley, Rockhampton, and Bundaberg. The study uses qualitative document analysis and comparative case study methods, supported by systems mapping, to examine interactions between policy, governance, infrastructure, and community factors. Seven key domains were identified as being central to system performance: (1) government waste strategy, (2) waste regulation, (3) political acceptance, (4) collection systems, (5) cost and funding, (6) community acceptance, and (7) compost processing. Examining these components collectively demonstrated that effective FOGO delivery relies on their alignment, with each layer reinforcing or constraining the others. To highlight waste regulation tools, the study compared landfill levies as a central economic and governance instrument in two contrasting Australian jurisdictions. In Queensland, the levy operates primarily as a fiscal tool rather than as a behavioural driver, limiting councils’ ability to invest in new services. By contrast, New South Wales’s mandatory FOGO implementation and a more mature regulatory framework have driven widespread service rollout but have also revealed the complexities of enforcing a universal policy in diverse regional contexts. The paper offers new insights into the financial and governance dynamics shaping regional waste policy, demonstrating how whole-of-system coherence is essential for advancing circular economy transitions in dispersed local contexts.

Societal Impact Statement Agricultural industrialisation has led to levels of nutrients in the environment that are well above safe operating limits, yet fertiliser use is necessary to feed a growing population. The recovery of nutrients from human urine in large, developed cities may offset some of the ecological and economic impacts associated with fertiliser production, as well as lessen environmental impacts associated with wastewater. Achieving a circular economy of nutrients faces several challenges, many of which require transdisciplinary solutions. Here we summarise some of the key challenges and highlight potential solutions at all stages from collection at the source to application to plants. Summary The utilisation of nitrogen (N) and phosphorus (P) in agriculture has surpassed the safe‐operating thresholds for biogeochemical cycles, necessitating the adoption of more efficient nutrient management strategies to restore this balance. The predominant source of N and P supplementation globally stems from the application of synthetic fertilisers. This study explores the potential of nutrient recovery and recycling from human urine as a viable alternative at sub‐global and regional levels. Such an approach could significantly reduce energy consumption associated with fertiliser production and transportation, as well as the demand for precursor materials. Additionally, it would mitigate the risk of eutrophication resulting from the release of excess N and P into the environment via untreated or inadequately treated wastewater. By integrating waste material utilisation within the nexus of social and ecological systems, this strategy may enhance socio‐ecological resilience, particularly in urban areas. Here, economies of scale could facilitate the successful implementation of urine diversion and conversion initiatives, offering a sustainable solution for nutrient management in densely populated regions.

Literature is emerging on Australian household food and garden waste disposal and recycling habits; however, little is known about the feasibility of, and community attitudes to, kerbside organics collection in regional settings. This study provides results on the conversion of food and garden organics to compost in a council-owned small scale, boutique composting system and employed a series of surveys to evaluate household residents' attitudes to the collection and processing of food organic and garden organic material in two regional towns in the Lockyer Valley Regional Council, Queensland. The trial achieved substantial diversion of organic waste from the general waste stream, which was reduced by 31%. Extrapolation showed that implementation of a similar collection system across the entire council region would extend the current landfill life by at least 2 years. The composting system cost less than 200,000 Australian dollars (AUD) to establish and eliminated considerable transport and gate fee costs for commercial composting, which would have exceeded 500,000 AUD for the treatment of the tonnes of food waste collected in the trial. Pre- and post-trial surveys showed residents' willingness to pay increased from 44% to 50% and the range of costs the respondents were willing to pay was between 22.80 and 42.80 AUD. Key to improving residents' attitudes lie in clearly communicating how waste charges are applied and the costs to councils to manage waste. Further recommendations to enhance the overall trial effectiveness include sufficient lead in time for trial preparation, strategic communication and recycling education specifically related to separation of food.

To facilitate development of sustainable municipal organic processing in Australia, this research assessed feasibility and benefits of integrated composting and anaerobic digestion processing facilities. The paper reports on development of a decision support analytical framework for techno-economic feasibility of four different scenarios based on seven organic processing facility options with reference to a case study scenario in Southeast Queensland, Australia. Under the conditions of the case study entered into the techno-economic decision support framework, the following ideal outcome was recommended: Firstly, development of a new organics processing facility should consider integrated processing and co-location with a high energy consumer industry to maximise product value and economic benefits. Results show 28% improvement in financial returns over the single technology composting facility. Secondly, both new and existing composting facilities would benefit from receiving co-mingled food and garden organics for processing through a biogas facility. Although food made up just 37% of the feedstock, it was the largest source of methane, contributing 74% of the total gas yield. Lastly, facilities would benefit from implementation of biogas upgrading to sell biomethane and carbon dioxide alongside compost. Results revealed biomethane export has potential for a 77% financial gain over a compost facility but biomethane must be valued at retail values and will be more difficult to achieve. The current waste levy imposed by the local authority in the regional case study is key to providing incentive to divert organic waste from landfill, but suitable product pricing would drive further expansion to produce energy products.

Fat-rich wastes can increase viability of food waste anaerobic digestion and divert waste from landfill, but inhibition by long chain fatty acids (LCFAs) is a well-known concern. Inhibition models can estimate the associated risk but their suitability for LCFAs is yet to be clarified. The current work uniquely compared LCFA inhibition model functions using data from rapid 3-day specific methanogenic activity tests with four distinct inocula sampled from full-scale digesters. Oleic acid was tested as model LCFA at 0.25-4 g·L-1. Microbial community composition was analysed by short-read DNA sequencing. LCFA inhibition resilience differed, with a half-inhibition parameter KI50 ranging from 0.3 g·L-1 oleic acid (1 mmolar) for the least resilient inoculum to 1.4 g·L-1 oleic acid (5 mmolar) for the most resilient inoculum. Microbial community differed significantly between the inocula; however, no significant correlations were found between inhibition resilience and key community members, or whole, bacterial, or archaeal communities. The results suggest LCFA is a broad-spectrum inhibitor and inhibition resilience is derived from whole-community redundancy influenced by LCFA pre-exposure. Only an adsorption-style inhibition model gave statistically identifiable parameter values for all tested inocula and simultaneously fit data for an inoculum sampled at two distinct biomass concentrations. The results suggest a general applicability of an adsorption-style LCFA inhibition model and support an adsorption mechanism of LCFA inhibition. Accordingly, an adsorption-style inhibition function is recommended for future use with LCFA. The approach in this study can quantify and manage LCFA inhibition risk at operational facilities to encourage co-digestion of fat-rich wastes and increase digestion viability.

This paper reports on an alternate approach to hospital waste management by technically evaluating onsite steam sterilisation coupled with gasification to treat general and clinical waste. A literature review revealed a dearth of information on compositional breakdown of Australian hospital waste which may limit the application of more circular waste management practices. Three Australian hospital waste profiles were assessed; general and clinical wastes contributed on average 84.8 % and 6.9 % by weight respectively. Australian hospital general waste composition, reported here for the first time, was categorised into its major components with plastic and paper & cardboard representing 74.5 % and 13.4 % respectively. Technical assessment combining waste composition with theoretical values revealed that Australian hospital waste was well suited to processing through gasification and provided significant benefits. Environmental benefits included 95.9 % reduction in landfilling and associated emissions from landfill, transport and incineration, improved landfill lifespan and recycling. National hospital waste production was estimated at 230,717 tonnes per annum for 2019/2020.

This study investigated biochemical methane potential (B0) of manure residues and solid-liquid separation fractions from Australian dairies. This is important for country-specific sector emissions and biogas potential estimates. A range of samples were collected from 12 farms across 4 Australian states, and B0 was measured. A first B0 value for grazing dairy effluent is reported, at 161 LCH4 center dot kgVS-1. The B0 of manure residues from intensive dairies with total mixed ration feeding was not significantly different, at 202 LCH4 center dot kgVS separation decreased B0 with potential fugitive methane losses. Mechanical separation preserved B0, allowing organic matter diversion to reduce fugitive methane emissions. Cleaning method at a dairy significantly influenced residue total solids content, important for solid-liquid separation and selection of anaerobic digestion technology. Overall, B0 for Australian dairy residues was estimated at 76.2 million m3N methane per annum, with a total energy content of 2.8 petajoules center dot annum 1.

Food loss and waste (FLW) contains an abundance of nutrient components that can be extracted and converted into valuable bioproducts through biorefining (e.g., pharmaceuticals, cosmetics, nutrients). Australia has identified bioproducts from a FLW feedstock as one avenue through which it can meet its commitment to UN Sustainable Development Goal Target 12.3, aiming to halve food waste by 2030. An industry for bioproducts in Australia is, however, nascent and will require targeted and sustained policy intervention to advance in line with the production targets it has set to meet Target 12.3. The aim of this critical review is threefold. Firstly, it draws on the research literature to identify barriers to advancing a bioproduct industry from FLW. Secondly, it constructs a taxonomy of policies available to overcome these barriers and support industry development. Finally, it applies the taxonomy to established policy settings in Australia (examining both national settings and Queensland state settings) and the European Union (EU), where the industry and associated policy is more mature. Australia has few national policies directly targeting a bioproduct industry. A comparative assessment of policy settings allows this review to identify lessons Australia can draw from the EU experience as it advances its own industry. Findings demonstrate a complex and fragmented policy landscape. Key recommendations from the literature emphasise the need to establish coordinated strategic instruments; target research and development opportunities for optimised, sustainable processes; and implement appropriate incentives to establish a ‘level playing field’, as technology readiness increases. The critical requirement for policy stability and coherence, flags the need to lay groundwork policy in this area as a priority.

Biochar addition in anaerobic digesters is an emerging technique for enhancing high-solids anaerobic digestion. Recycling of biochar can further enhance performance and reduce costs for biochar production; however, mixing biochar with feedstock and separating from digestate is impractical. A more pragmatic method of applying biochar for high-solids digestion could be coupling a leach bed reactor (LBR) with a biochar-packed anaerobic filter (AF) to form a two-phase system. Separating the anaerobic digestion process between reactors can improve process efficiency by enhancing hydrolysis and acidogenesis in the LBR and producing higher quality biogas in the AF. However, two-phase systems can be inefficient if separation of the anaerobic digestion process between reactors - referred to as phase separation - is poor. This article aims to: (i) integrate current knowledge from literature investigating batch LBR-AF systems to improve understanding of the role of different process parameters on phase separation and process efficiency; and (ii) explore the idea of biochar as a filter medium in an LBR-AF system. Feedstocks that rapidly degrade and have ongoing VFA production are particularly suitable for phase separation in LBR-AF systems. Controllable process parameters identified as critical for phase separation and process inhibitor mitigation include co-digestion, recirculation parameters, filter media properties, inoculation method and temperature. The application of biochar in other systems highlights the potential for LBR-AF application. Future research should consider trade-offs between biogas production and digestate quality when optimising LBR-AF performance, and assess economic viability considering the additional expenses of LBR-AF systems.

Soil application of biosolids as an organic fertiliser continues to be a cost-effective way to beneficially utilise its carbon and nutrient contents to maintain soil fertility. However, ongoing concerns over microplastics and persistent organic contaminants means that land-application of biosolids has come under increased scrutiny. To identify a way forward for the ongoing future use of biosolids-derived fertilisers in agriculture, the current work presents a critical review of: (1) contaminants of concern in biosolids and how regulatory approaches can address these to enable on-going beneficial reuse, (2) nutrient contents and bioavailability in biosolids to understand agronomic potential, (3) developments in extractive technologies to preserve and recover nutrients from biosolids before destructive dissipation when the biosolids are thermally processed to deal with persistent contaminants of concern (e.g. microplastics), and (4) use of the recovered nutrients, and the biochar produced by thermal processing, in novel organomineral fertilisers that match specific equipment, crop and soil requirements of broad-acre cropping. Several challenges were identified and recommendations for prioritisation of future research and development are provided to enable safe beneficial reuse of biosolids-derived fertilisers. Opportunities include more efficient technologies to preserve, extract and reuse nutrients from sewage sludge and biosolids, and the production of organomineral fertiliser products with characteristics that enable reliable widespread use across broad-acre agriculture.

Potentiostats are often limited to relatively costly laboratory-based analysis, which limits their access and application by researchers and practitioners, including for mobile in-field systems. This paper presents an alternative low-cost potentiostat design, sufficiently accurate for application with a microbial electrochemical sensor. The design of the device is described, evaluated using simulation and applied to a microbial electrochemical sensor to measure acetate. Incorporated into the design are a micro-controller, local data storage, and a standard industrial communication protocol to provide flexibility and data management. The device was able to produce a potential at +/- 2.5 V relative to an Ag-AgCl reference electrode and to measure current at +/- 2 mA, which was comparable to the performance of laboratory potentiostats on the market. Simulation analysis using fundamental electronic principles, such as Ohm's Law, confirmed that operation of the system was valid and as expected. Further testing using a pseudo-cell showed the device was accurate across a relevant potential range. Results from the initial calibration of the device show less than 1.6 % standard error of the mean. The device was further applied to a microbial electrochemical cell to measure acetate, which confirmed the device was functional for this application and recorded values were consistent with expectations based on the relevant literature.

Thermal treatment in Australia is gaining interest due to legislative changes, waste reduction goals, and the need to address contaminants' risks in biosolids used for agriculture. The resulting biochar product has the potential to be beneficially recycled as a soil amendment. On-farm management practices were reviewed to identify barriers that need to be overcome to increase recycling and examine the role of pyrolysis and gasification in effectively improving the quality and safety of biochar intended for land application. Key findings revealed the following: (1) thermal treatment can effectively eliminate persistent organic pollutants, microplastics, and pathogens, and (2) more than 90% of the total heavy metals content in biosolids may become immobilized when these are converted to biochar, thus reducing their bioavailability following land application. While the reported research on the short-term effects of biosolids-derived biochar suggests promising agronomic results, there is a dearth of information on long-term effects. Other knowledge gaps include the optimization of land application rates, understanding of the rate of breakdown, and the fate of contaminants in soil and water, including heavy metal mobility and redistribution in the environment by processes such as erosion and runoff following land application. An improved understanding of nutrients and contaminants dynamics in soils receiving biosolids-derived biochar is a pre-requisite for their safe use in Australian agriculture, and therefore, it is highlighted as a priority area for future research.

Mechanical solid-liquid separation is an emerging closed-loop technology to recover and recycle carbon, nutrients and water from dilute livestock manure. This closed-loop concept is tested using a modular separation technology (Z-Filter) applied at full-scale for the first time to treat effluent from a pasture-based dairy. Effluent flow rates were 200-400 L min-1 at a total solids (TS) content of 0.52% (pH 7.2). Separation efficiency and composition of the separated solid fraction were determined, and chemically-assisted separation with cationic polymer flocculant with/without hydrated lime was also tested. Without flocculant and lime, 25.9% of TS and 33.4% of volatile solids (VS) ended up in the solid fraction, but total Kjeldahl nitrogen (TKN), phosphorus (P) and potassium recovery was not significant, likely being in poorly separable fine particle or soluble fractions. With a 5% flow-based dosage of flocculant, most of the TS (69%) and VS (85%), and notable amounts of TKN (52-56%) and P (40%) ended up in the solid fraction. Phosphorus recovery was further increased to 91% when both flocculant and hydrated lime was added up to pH 9.2. The solid fraction was stackable with 16-20% TS, making transport more economical to enable further processing and beneficial reuse of nutrients and organic matter. Removal of VS also reduces fugitive methane emissions from uncovered anaerobic effluent ponds. Overall, the results indicated that solid-liquid separation could provide improved environmental management options for dairy farmers with dilute manure effluent to beneficially utilise organic matter and nutrients.

Landfilling organic waste generates greenhouse gases and contributes to climate change. While the management of organic waste has been identified by all tiers of Australian government as paramount to meeting net zero emissions targets, diversion of domestic organic waste from landfill is primarily the responsibility of local government. This review of academic and grey literature considers developments in food organics and garden organics collections in Australia and the implications for regional communities. It reviews source-separated collections and the treatment of organic waste administered by regional local governments and identifies there is a dearth of information in this area. Key knowledge gaps emerging from the study include: (1) There is a disconnect between the various state governments' policies, strategies, and regulation of organics diversion and action on mandating or supporting kerbside collections; (2) there is insufficient funding and subsidy to encourage councils to implement collection systems, and (3) the community has limited understanding of the cost and environmental burden of waste, and subsequently there is no willingness to pay for collection systems. This paper outlines how these issues contribute to individual regional councils deferring kerbside organic waste collection systems and offers recommendations that could enable the achievement of more ideal diversion targets that are relevant to, and affordable for, their local communities.

A key environmental sustainability requirement for the treatment of organic waste via anaerobic digestion (AD) is the prevention of unwanted methane emissions in the production chain whenever possible. Identifying and quantifying these emissions has been frequently investigated, particularly in Europe. However, the challenges of climate change are also becoming vitally important in Australia. This novel study presents the results from emission measurement campaigns carried out at two biogas plants and one landfill site in Australia. An on-site approach consisting of leakage detection and emission quantification by a static chamber method was applied. Twenty-nine leakages were detected predominantly on the digesters (gastight covered anaerobic lagoons) of the biogas plants. Ten emission hot spots were found on the surface cover of a landfill site. Methane emission rates of 9.9 +/- 2.3 kg h-1 (10.5 +/- 2.4% CH4) for biogas plant A, 3.0 +/- 1.9 kg h-1 (8.1 +/- 5.2% CH4) for biogas plant B and 41-211 g h-1 for the two largest emission hot spots from the landfill were measured. Since not every single leakage or hot spot could be quantified separately, the stated overall emission rates had to be extrapolated. Importantly, the emission rates from the landfill should be interpreted carefully due to the limited overall area which could be practicably investigated. Leakages occurred at common components of the covered anaerobic lagoons such as the membrane fixation or concrete walls. Repairing these parts would increase the plant safety and mitigate negative environmental effects.

On-farm, intensive feeding and processing in Australian red meat, dairy and pork industries produce substantial quantities of organic waste (similar to 79 GL.annum(-1) liquid waste plus similar to 2 megatonnes.annum(-1) solid waste) and waste management is a major cost (similar to 180 million Australian dollars.annum(-1) for red meat plus dairy processing). Anaerobic digestion can instead extract value from organic waste as biogas energy and biofertiliser to reduce operational costs and environmental impacts, and to improve industry profitability. Understanding key information gaps is a fundamental step towards fully realizing profitable opportunities for anaerobic digestion. This is addressed here via a critical evaluation of available information on Australian agro-industries (specifically dairy, pork and red meat), their waste availability, biogas energy potential, and potential anaerobic digestion approaches. The analysis revealed varying extents of information, but good biogas energy potential (similar to 13.8 PJ.annum(-1)) to meet a significant energy demand (similar to 18 PJ.annum(-1)). Waste management within respective agro-industries influenced waste amounts and characteristics, which affected anaerobic digestion options. Anaerobic co-digestion, involving aggregated digestion of two or more waste types within or across industries, can provide further opportunities by boosting biogas production and harnessing spare digestion capacity. Overall, cross-industry collaboration, policy support and technology development could help harness the significant opportunities for aggregated biogas production in Australian agro-industries. (C) 2021 The Author(s). Published by Elsevier Ltd.

A laboratory experiment that was conducted to gain an understanding of heavy metals dynamics in soils amended with biosolids (treated sewage sludge) and biochar produced from biosolids. The findings of this study, albeit limited in scope, go some way to inform the development of a scientific-based framework that supports practical and cost-effective management of biochar intended for land application. The risk of heavy metals (Zn, Cu, Cr) leaching in two soils of contrasting mineralogy and physico-chemical properties (Yellow Chromosol and Red Ferrosol) was quantified in a laboratory setup using leaching columns. Application of biosolids and biochar to soil increased pH of the leachate solution, and it increased with the rate of biosolids or biochar applied to soil. Differences in pH of leachate between biosolids and biochar-treated soil were not significant. Zinc (Zn) recovered in leachate was higher in the Red Ferrosol than the Yellow Chromosol, but total Zn recovered after six leaching events was less than 20 mg kg-1 , and there was no clear effect of rate. There was a little more Zn recovered in leachate from biochar- compared with biosolids-treated soil. Copper (Cu) recovered in leachate was higher in the Red Ferrosol than the Yellow Chromosol, but no Cu was recovered after the fourth leaching event, and in both soils Cu in leachate increased with the application rate. The amount of Cu recovered in leachate from biochar-treated soil was about one-third the amount recovered from biosolids-treated soil. Chromium (Cr) recovered in leachate was similar in both soils and recoveries were fairly consistent between-leaching events. In both soils, Cr recovered in leachate increased with the application rate. Total Cr recovered in leachate from biochar-treated soil was about eight times lower than from biosolids-treated soil. There is a need to extend the work reported here and to consider other soil types (e.g., Vertisols) that may respond differently from the physico-chemical and hydrological perspectives, and to capture the dynamics of other heavy metals as well as phosphorus, which were not part of this study. Based on the results of this work, there appears to be potential for future use of biochar in these two Queensland soils.

The livestock sector is a fundamental part of the modern global economy and provides food, clothing, furnishings, and various other products. So as to ensure its resilience to changes in consumer expectations, cost of production, and environmental sustainability, the sector must shift to a circular economy model. Current strategies to recover value from wastes and low-value co-products from livestock industries yield limited value; hence, new technologies are required to upgrade wastes and co-products, and generate high-value products that can feed into the livestock value chain. Anaerobic digestion can convert high organic-content waste to biogas for energy and a stable nutrient-rich digestate that can be used as fertiliser. Microbial technologies can transform wastes to produce nutritionally advanced feeds. New materials from waste can also be produced for livestock industry-specific applications. While aiming to add commercial value, the successful implementation of these technologies will also address the environmental and productivity issues that are increasingly valued by producers and consumers.