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Review

Going in Circles: Integrating Food, Energy and Water Sectors to Enable a Thriving Circular Bioeconomy

by
Dana Cordell
*,
Melita Jazbec
,
Saori Miyake
,
Simon Fane
,
Elsa Dominish
,
Andrea Turner
,
Fiona Berry
and
Laure-Elise Ruoso
Institute for Sustainable Futures, University of Technology Sydney, Sydney, NSW 2204, Australia
*
Author to whom correspondence should be addressed.
Sustainability 2026, 18(12), 6165; https://doi.org/10.3390/su18126165
Submission received: 4 April 2025 / Revised: 12 May 2026 / Accepted: 29 May 2026 / Published: 15 June 2026
(This article belongs to the Special Issue Sustainable Development and Climate, Energy, and Food Security Nexus)
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Abstract

Recirculating organic byproducts like food waste, wastewater and manure efficiently and at scale in a circular bioeconomy will be critical to ensuring future food security, energy security, climate resilience, water security and environmental health. Ultimately, we will not be able to live within the safe operating space of our planetary boundaries if we do not stop our wasteful and inefficient habits. Our food, waste, energy and water sectors are starting to transform towards circularity, driven by a diverse range of drivers, from net zero emissions targets, to food waste policies, and to rising fertiliser prices and geopolitical risks. However, these sectors are often not transforming in a coordinated manner, risking unintended consequences like competition between end-uses, technology lock-in, the prevention of scalability, or failure to achieve key sustainability targets, causing rebound effects. For example, society’s organic waste is being earmarked for the production of bioenergy, sustainable aviation fuels, biomaterials, and biofertilisers; however, it is not clear if there will be a sufficient supply of organic waste to meet these diverse demands. Phosphorus flow analyses indicate that we will need to secure almost all of the nutrients in organic waste as fertiliser raw material to produce food. There are some existing pockets of innovation within sectors related to food waste, water and wastewater, fertilisers and agriculture, and bioenergy. However, many initiatives are being driven by short-term challenges, are not operating at scale, or are not sufficiently integrated across sectors. In this paper, we provide examples of innovations and challenges from around the world, including Italy, Australia, Sri Lanka, the UK, Japan, and Malawi. This paper identifies a pathway to navigate tensions to achieve co-existing sustainability goals, including key enablers and barriers, ranging from overcoming regulatory fragmentation to a lack of capital investments. Creating a truly viable circular economy for organic byproducts requires the integration of policies, markets, technologies and people. This means engaging diverse stakeholders, from local councils and private waste contractors, farmers, and fertiliser companies to energy retailers and wastewater utilities, NGOs, informal collectors, and environmental regulators and policy-makers.

1. Introduction: The Rise of Circular Economy Frameworks and Their Limitations

The rapid rise in the popularity of circular economy (CE) concepts by businesses and policymakers over the past decade can in part be attributed to the promise of creating economic value while addressing key global environmental goals, particularly climate change, biodiversity loss and pollution [1,2]. That is, the circular economy seeks to “decouple value creation and human wellbeing from resource consumption” (p. 11). Shifting from today’s predominantly linear economy to a circular economy of sustainable resource use is based on three key design principles: eliminating waste and pollution, circulating products and materials at their highest value, and regenerating nature [3]. Implementing these principles to address the planetary crisis will be critical; however, CE practice is still in its infancy and will need to overcome some key challenges before it can be effectively implemented at scale.
The CE concept has roots in environmental paradigms such as industrial ecology, cleaner production and eco-design [4]; however, some argue that most definitions today focus too heavily on economic prosperity [5]. Today, there are more than 220 definitions of CE. However, many definitions focus narrowly on recycling, which is problematic for at least two reasons: they overlook the CE waste hierarchy, which prioritises strategies such as avoidance and reduction first [5] (see Figure 1), and they fail to value the social and institutional infrastructure essential to supporting circular value chains (see Section 5). In this paper, we adopt Geissedoerfer’s definition of a CE as “a regenerative system in which resource input and waste, emission and energy leakage are minimised by slowing, closing, and narrowing material and energy loops” (p. 759) [6]. This definition has an explicit focus on “slowing” (using and reusing resources longer or more intensively) and “narrowing” (using resources more efficiently) resource use, alongside closing resource loops (recycling and recovery at end-of-life). Whilst avoidance and efficiency (R0–R2) are at the top of the hierarchy (Figure 1), attention must be paid to avoiding the rebound effect, where greater efficiency in a product coupled with cheaper production can result in increased consumption [7].
Importantly, this framework has been predominantly designed for, and applied to, inorganic materials and products, like metals, plastics and concrete. The framework’s application to food and biomass is still in its infancy. The term “bioeconomy” is growing in popularity. While it focuses on biomass use to substitute fossil fuel sources, it lacks an explicit objective to circularise biomass from organic wastes, for example, rather than, say, growing virgin crops for energy use [9], especially applied to the range of organic byproducts that are generated along the food value chain, like agricultural residues, manure, food waste and wastewater. However, as we argue in this paper, circularising organic byproducts through the food system will be critical to future food security in addition to energy and climate security. Ensuring all people have access to sufficient, safe and nutritious food has been a global priority since the 1960s [10] and is today represented by the UN’s second SDG, Zero Hunger. Yet, alarmingly, today there are more people suffering from hunger and malnutrition than consuming healthy diets [11].
Producing food fundamentally depends on a healthy environment, including access to clean water, land, air and biodiversity. At the same time, the growing impact of food production and consumption on the environment led the UN’s FAO to formally adopt the term “food systems” in 2021 to acknowledge this interplay between food value chains and planetary health [12]. For example, a third of the food produced for human consumption is lost or wasted along the food value chain, causing significant and wide-ranging economic, social and environmental impacts from food insecurity and resource loss to environmental contamination and greenhouse gas (GHG) emissions [13].
Indeed, the food sector is one of the single largest contributors to climate change, estimated at over a third of human-made greenhouse gases [14]. The combined environmental and public health cost of today’s food system now exceeds the economic value of agriculture itself [15]. Academics, the business community, IPCC and NGOs all agree that the business-as-usual “production” paradigm is no longer viable and the food system needs fundamental transformation [13,16]. Shifting towards a circular food system is promoted as one key strategy.
While not yet fully circular, the EU’s Bioeconomy Strategy is perhaps the most comprehensive bio-based blueprint to date, as it provides a high-level vision for a decarbonised economy which covers all sectors and systems that rely on biological resources, including organic waste [17]. The EU’s Bioeconomy Strategy was originally developed to meet five comprehensive goals: ensure food security; sustainable natural resource management; reduce dependence on non-renewable resources; adaptation to climate change; and modernisation and strengthening of the EU’s agriculture and business. However, it does not include ensuring real environmental and social impacts within planetary boundaries, including chemical safety and managing organic byproducts effectively, thereby embedding circularity.
This review paper highlights the limitations of the current CE framework when applied to organic byproducts like food waste and sewage, puts forward a new definition and framework, and identifies how current approaches to CE across four key sectors (food waste, bioenergy, agriculture and wastewater) are fragmented and have a strong need for integration. Finally, we identify a range of barriers and enablers to integration and propose a way forward.

2. A Circular Economy Framework for Organic Byproducts from the Food System

Circulating organic byproducts such as agricultural residues, manure, food waste and excreta from the food system efficiently and at scale will be critical to future food security, energy security, climate resilience, water security and environmental health. Yet, existing circular economy concepts and frameworks are underdeveloped for and applicable to such organic byproducts. We therefore develop a framework in this paper. First, we define the circular economy of organic byproducts in the food system as “The cost-effective reduction or recovery of any organic byproduct from the food system that is reprocessed for productive reuse in food, energy, or other sectors of the bioeconomy”, underpinned by four key principles (see Table 1 and Section 2.1, Section 2.2, Section 2.3 and Section 2.4).
In this paper, we focus on that part of the circular bioeconomy where organic byproducts are derived from food system activities. Organic byproducts are bio-based residues that are generated at all stages of the food system, including agricultural residues, manure, fishery waste, food processing, food waste, and wastewater, in addition to other non-food biomass residues like forestry waste, pet poo, algae, and landscaping waste. They may come from urban or rural sources.
Key activities in a thriving circular economy of organic byproducts from the food system are illustrated in Figure 2. That is, the collection of organic byproducts, their treatment and processing, new product development, retail, and end-use back into the food production system. Additional inputs to the system include renewable biomass not sourced from the food system. Outputs from the system include: the generation of non-food products like energy and biomaterials and the generation of residual waste that cannot be avoided. Other key activities (not explicitly depicted in Figure 2) include: storage, transport, trade, management, regulation and financing.

2.1. Principle 1: Prioritise Avoidance of Organic Waste

Avoiding the generation of waste should be prioritised over recycling waste. That is, before investing in circularising resources, there is a need to develop strategies to “slow and narrow” the generation of organic byproducts in the first place, through efficiency and avoidance (R0–R2: Figure 1). While there will always be some residual organic waste (e.g., banana peels or human excreta), the circular economy of organic byproducts seeks to minimise avoidable losses and waste first, such as spoiled food. The definitions of food loss and food waste are further described in Section 3.1.
CE has been applied across many sectors, including, more recently, to organic waste and the food system. However, many of the predominant frameworks are challenging to apply to organic biomass resources, which are biodegradable and do not remain in a steady state. For example, the 10Rs framework by Potting et al. [2] (Figure 1) was developed for products and includes strategies for smarter product use and manufacture (refuse (R0), rethink (R1), reduce (R2)), extending product lifespans (reuse (R3), repair (R4), refurbish (R5), remanufacture (R6), repurpose (R7)) and for the useful application of materials at end-of-life (recycle (R8), recover(R9)). This framework (among others) is more suited to products made from resources such as metals and plastics, as they can retain their properties over many uses, and products can be designed for longer lifespans [19]. For organic biodegradable resources, strategies of refuse, rethink and reduce (R0–R2) are highly applicable (such as food waste avoidance and more efficient use of fertilisers) as well as recycling and recovery (R8–R9) (e.g., composting, anaerobic digestion). However, the majority of strategies focused on extending product lifespans (R3–R7) would not apply. There are some exceptions to this, such as the reuse of food through food rescue and food sharing, or the repurposing of food scraps to feed livestock.

2.2. Principle 2: Prioritise Food Security End-Use

While a key principle of the circular economy is “to circulate products and materials at their highest value” [3], we argue that in the case of organic byproducts, the highest intrinsic value is for food production. This is because any valuable nutrient lost from the food system needs to be intentionally returned to ensure food security in the future. Phosphorus fertiliser in particular is currently sourced from finite and geopolitically risky non-renewable reserves. Ensuring phosphorus security for long-term food security will necessitate the use of phosphorus-rich organic materials to produce renewable fertilisers (see Section 3.3). As such, in an ideal circular economy, organic byproducts occurring across multiple sectors in the food value chain are managed in such a way that the nutrients are returned to the food system, such as agricultural soils. Other end-uses beyond food production include bioenergy, sustainable aviation fuels, biomaterials (like bioplastics and bio-concrete), animal and fish feed, non-agricultural soils and landscaping, nature and nutraceuticals. (Figure 3).

2.3. Principle 3: Clean Feedstocks That Are Fit-for-Purpose

Importantly, the circular economy seeks to prevent pollution and toxins from entering the value chain. In the case of organic byproducts, potential contaminants could include plastics, PFAS and other hazardous chemicals, pathogens, pharmaceuticals, heavy metals and emergent viruses. Organic byproducts that can be used as feedstocks in circular supply chains are diverse in terms of contaminants, physical characteristics, and nutrient and calorific concentrations, for example. Similarly, end-uses are diverse (such as fertilisers, bioenergy, soil conditioning), so treatment processes must be fit for purpose to best match the treated product with the desired end-use (Table 2). Treatment processes can range from biological processes like composting and anaerobic digestion, physical processes like maceration, chemical processes like precipitation and reverse osmosis, to thermal processes like incineration and pyrolysis.

2.4. Principle 4: Design for Target End-Use Markets

Finally, any thriving circular economy requires a functioning end-use market. Yet, this is often overlooked (or less developed) for organic byproduct circular economies, such as dumping free or cheap compost at the farm gate and wondering why farmers are not using it. In some cases, it may be that farmers do not have the machinery to easily spread compost, as they use pelletised fertilisers and associated machinery [20,21]. For example, “R6”, remanufacture, refers technically to the “use of parts of discarded product in a new product with the same function”, which does not directly translate to the circular organic byproducts value chain. We re-interpret this as “redesign” for organic byproducts and product development, e.g., for renewable fertilisers (see Section 3.3). End-uses range from fertilisers (for food, pastures, fibre, landscaping, sports turfs) to bioenergy, aviation and nature (Figure 3). An example of a circular organic byproduct value chain is the bioremediation of wastewater with macro-algae by RegenAquaTM [22], which simultaneously generates “clean” water to discharge into sensitive waterways and creates commercial products for food production, like PlantJuiceTM (a bio stimulant) and animal feed.
There is a significant gap between the framework for circularising organic byproducts (proposed here in Section 2) and what is occurring in practice in relevant sectors. In the following section, we highlight the recent directions that four key sectors are taking to circularise and how their lack of interaction or integration is preventing the realisation of the four principles we outlined in Section 2.1, Section 2.2, Section 2.3 and Section 2.4.

3. Competing End-Uses: Drivers and Activities Across Key Sectors in the Value Chain

Our food, waste, water and energy sectors are starting to transform towards circularity, driven in part by a diverse range of drivers, from net zero emissions targets to food waste policies to rising fertiliser prices. In this section, we outline the different drivers, activities and outcomes of moving towards more circular systems in four key sectors by way of example: (1) food waste, (2) water and wastewater, (3) fertiliser and agriculture, and (4) bioenergy. However, they are often not transforming in a coordinated cross-sector manner, risking unintended consequences.
We chose these four sectors as the first two represent two primary waste streams of organic byproducts generated by the food system (food waste and human excreta), while the second two represent two primary end-use sectors for organic byproducts (fertilisers and bioenergy). Other sectors and products not examined here include: construction (e.g., bio-concrete), consumer products (like bioplastics and nutraceuticals), aviation (e.g., sustainable aviation fuels), fisheries, forestry, landscaping and sports fields.
Progress on managing these specific organic waste types and end-uses varies across countries and regions. Country examples are highlighted across Section 3.1, Section 3.2, Section 3.3 and Section 3.4 and summarised in Table 3.

3.1. Food Waste (Waste Management) Sector

The global goals of halving food waste (SDG 12.3) and achieving zero hunger (SDG 2) have driven recent actions to curb food waste globally, including the collection of data on food waste and the associated development of policy and regulations.
On average, a third of the food produced for human consumption is wasted along the supply chain [13]. Of this, the percentage of food lost at the upstream end of the supply chain, after harvesting at the farm, transportation, storage, wholesale and processing, is approximately 13% [31]. A further 19% is wasted at the downstream end of the supply chain, split between retail (12%), food services (28%) and households (60%) [32]. Food loss refers to a decrease in the quantity and quality of food intended for human consumption and occurs “upstream” in the food value chain, caused by inefficiency in agricultural production, harvesting and post-harvesting handling, and the transportation and storage of crops. Food waste refers to the discarding of food appropriate for human consumption “downstream” in the value chain at retail and consumer levels [33].
At a regional level, Sub-Saharan Africa has the highest upstream losses at over 20%, predominantly due to structural inadequacies, causing food to be lost before reaching the retail stage of the supply chain. The lowest upstream losses occur in Europe and North America, with greater access to more modern farming and transportation equipment and practices, at approximately 10% [31]. New collated data with broader geographical coverage now shows that households in the downstream end of the supply chain are major contributors to food waste generation but with average household generation varying by only 7 kg/capita/year between high, upper-middle and lower-middle income groupings (between 81 and 88 kg/capita/year) and insufficient data for low-income countries [32].
Over the past half-century, industrialisation has sought to optimise crop yields, reduce costs and increase global market accessibility. However, such modernisation has lengthened value chains, changed food practices and attitudes [34], and is unintentionally contributing to increased waste generation. In more optimised systems, the byproducts of growing food, such as agricultural residues, are ploughed into the soil or used to generate bioenergy, with digestate nutrients returned to the soil.
Food waste strategies responding to local and international policies should ideally prioritise food waste avoidance. However, in reality, they have tended to favour diversion from landfill through the implementation of large-scale food waste collection, treatment and reuse [35,36]. This tendency to rely on existing well-established large-scale infrastructure, known as “regime dominance”, is often prevalent due to such systems having embedded complex socio-technical natures [37] and substantial sunk investment costs [38]. This has resulted in some tension and a disincentive to reduce food waste generation due to organic waste being seen as a resource for nutrients and energy generation [21]. Some scholars argue that focusing on food waste prevention and management creates a paradox as it fails to address the main drivers for food waste generation: overproduction and overconsumption [39]. As food waste is managed by the waste sector, the waste hierarchy approach has dominated decision-making in waste management implementation plans for several decades [40]. Many local governments have prioritised both avoidance and reuse in parallel. The “Love Food Hate Waste” campaign that commenced in 2007 in the UK is a successful avoidance example, showing a 26% decrease in food waste generation at the household level by 2018 when evaluated [41]. The program has now been widely adopted globally, including in Australia, Canada, the Czech Republic, Hungary, New Zealand, Saudi Arabia, Scotland and Slovakia [42], with similar success stories.
Avoiding food waste has also resulted in the establishment of food banks and food exchange platforms in multiple countries and the prioritisation of animal feed before disposal. However, some stringent food waste standards [43] prevent good food from entering the market for reuse, and regulations restrict inputs to feed to avoid devastating unintended consequences such as the Mad Cow Disease experienced in the UK.
Great efforts are being made in some economies to separate food waste from general waste for organic processing, such as composting and anaerobic digestion. Even where organic waste collection systems have been in place for several years, the challenge, however, remains with large proportions disposed of, with mixed waste sent to landfills or incinerators. This causes perverse impacts on the climate, from GHG emissions to contamination of land and water and loss of nutrients. Each food type in terms of LCA has very different impacts, e.g., wastage of meat has major GHG impacts throughout the value chain [13].
Various governments and jurisdictions are introducing policies to mandate source separation of organic waste (including food waste) to more effectively manage organics (e.g., South Korea [44], California [45] and Sydney [23]—see Table 3), banning food waste disposal in particular sectors to incentivise food donation (e.g., France [46]) and increasing landfill levies (e.g., Catalonia [47]). In Vietnam, the 2030 Greater Hanoi Master Plan included an ambitious goal of 70% organic waste recycling by 2050 [48]. Milan has achieved remarkable separation results with their collection method, in the order of 87% [25] (Table 3).
However, when collection methods are implemented, the whole processing approach and end markets need to be considered to avoid lock-in of solutions and end-products not fit for purpose, including unacceptable levels of contamination such as plastics. Bioplastics, for example, are a small but emerging issue. This includes bio-based plastics as part of the bioeconomy and compostable plastics that, when used appropriately, can help collect and recover food waste. When non-certified compostable plastics are used to collect household food waste, they can end up contaminating green bins, making the green waste unfit for reuse.
Addressing food waste and food loss is highly influenced by the context and requires a complementary mix of solutions [49] of varying scales to help achieve the SDG goals and use food and the unavoidable byproducts more effectively.

3.2. Water and Wastewater Sector

A large proportion of organic byproducts from the food system end up in wastewater, either from human excreta or industrial and commercial wastewaters. However, conventional approaches to managing wastewater, such as physical and chemical treatments, result in the loss of nutrients (and potential energy) through the disposal of effluent and sludge.
Historically, before humans began to converge in dense urban settlements, human excreta were deposited on the soil, making it readily accessible for nutrient take-up [36]. As civilisations evolved and densified, the importance of the removal of human waste for health reasons became apparent [50], while the value of human excreta for agricultural fertiliser was also recognised. Long-practised agricultural irrigation with untreated wastewater and the direct application of “night soil” in many parts of the developed world were gradually replaced with sewage farms using treated wastewater as the volume from densification in human settlements increased.
As cities grew, wastewater treatment plants (WWTPs) evolved to process larger quantities on smaller land footprints and to produce effluent safe for disposal to receiving waters [51]. In cities, human-derived wastewater was combined with industrial wastewaters, creating a complex mix of materials, which, combined with modern household pharmaceuticals, has increased exponentially [52]. By the end of the twentieth century, recognition that water is a finite resource shifted the focus again, in this case toward the reuse of treated effluent in many regions. Throughout these shifts, the interest in reclaiming nutrients and organic matter from wastewaters to fertilise and improve soil characteristics diminished [51] and issues of effluent contamination increased.
The development of integrated water resource management plans in drought-affected regions, such as Australia, Spain, the Middle East, the southern United States and Southern Africa, recognised wastewater as a resource [53] and engineering solutions evolved, focusing mainly on purifying water for reuse and as potable water [54]. However, as the centralised system approach transports wastewater for treatment near discharge, it limits the reuse of water due to logistical and economic issues. A growing number of decentralised systems have been implemented in recent years [54] so that treatment occurs near the point of wastewater generation and reuse and sources of contamination are minimised. However, there is yet to be a paradigm shift away from large centralised systems.
More recently, climate mitigation has been driving managers of WWTPs to reconsider their operations, energy use and role. As a response, WWTPs are being modified from primarily aerobic to anaerobic or combined systems, which allow the generation of energy from biogas and contribute to carbon neutrality. As the co-digestion of a variety of feedstocks (not just sewage) results in enhanced biogas generation, other organics streams such as fats, oils and greases (FOG) and/or food waste are being considered [55]. This cross-sectoral synergy is bringing focus to the nutrient-rich digestate that needs to be returned to the food system.
There are significant benefits of generating bioenergy and shifting the role of WWTPs to that of a circular economy hub for not only wastewater treatment but also the generation of energy, fertilisers and soil conditioners, and other organic byproducts [55]. This is especially the case for those cities that are yet to develop collection and processing of organic waste streams, particularly food waste. The other benefit WWTPs have is their connection to the energy grid and infrastructure, as well as proximity to the generation and use of waste streams in cities [56].
However, issues with contaminants in wastewater remain. A key challenge for the integration of the wastewater sector with food systems is inherited contamination issues due to the mix of organic and inorganic contaminants in both sectors. This includes some 80,000 impurities and chemicals in wastewater from the integration of residential and non-residential streams [57] and contamination with non-organic waste, such as plastics in food systems. Despite this, multiple WWTPs around the globe have been successfully resolving these barriers and are transitioning to a circular economy system [55].

3.3. Fertiliser and Agricultural Sector

A key need to circularise organic byproducts in agriculture relates to the security of essential plant nutrients. There is no substitute for phosphorus and nitrogen in food production. Today, these nutrients come from conventional fertilisers sourced from non-renewable mined resources and emissions-intensive natural gas resources in a linear economy. However, just 150 years ago, fertiliser value chains and food systems were still largely circular: local organic resources like manure, human excreta, crushed bones and crop residues were ploughed back into agricultural soils, returning valuable nutrients to grow food for local consumption [58]. The Green Revolution, coupled with urbanisation and the sanitation revolution, changed all of that. The discovery of the Haber–Bosch process in the 1960s literally created nitrogen fertilisers out of thin air, which in turn drove the acceleration of phosphate rock mining to keep up with global phosphate fertiliser demand. The use of manures and human excreta as fertiliser was largely abandoned in favour of what was seen as a cheap and limitless supply of phosphate [59].
In the 1990s, widespread nutrient pollution from fertiliser runoff and wastewater treatment plants began to drive nutrient removal and recovery in Western Europe and North America [60]. However, the environmental technologies and regulatory infrastructure that have emerged have stopped short of facilitating the beneficial reuse of phosphorus and nitrogen in agriculture. For example, nutrient removal from wastewater that meets mandated nutrient limits commonly generates sludge (or biosolids), which is not the most effective or appropriate fertiliser. First, the recovered nutrients are often tightly bonded to aluminium and hence not plant-available. Second, transporting bulky wet material like biosolids over large distances is not cost-effective. Third, sludge formed from mixed wastewater with high industrial wastewaters can contain heavy metals and other contaminants at concentrations inappropriate for food production, and finally, the sludge is often spread on land in a way that meets environmental regulations but not necessarily at nutrient application rates matched to the region’s specific crop production systems [58].
Widespread eutrophication of waterways and toxic algal blooms resulting from inefficient fertiliser use and land practices also drove more efficient use of fertilisers, facilitated through local regulations, farm research, development and extension and industry stewardship. The fertiliser industry’s “4Rs”, for example, encouraged farmers to use fertilisers at the right time, right rate, right place, and right form to reduce inputs, increase productivity and reduce runoff to water [61]. More recently, climate change is driving more efficient use of nitrogen fertilisers, in particular, as Nitrous Oxide emitted from fertiliser production and use is a potent GHG, and this represents up to 5% of total global GHG emissions [62,63]. However, there has been less policy attention on the phosphorus value chain, which remains highly inefficient: around 80% of phosphorus mined for food production is lost in the food system, from mine to field to fork [59].
The 2008 fertiliser price spike triggered new awareness of phosphorus scarcity. The unprecedented 800% phosphate price spike demonstrated that even a short-term disruption to the world’s supply of phosphate could have devastating consequences for the global food system, from Haiti to India [64]. While all farmers need access to phosphorus, just five countries control 83% of the world’s remaining high-grade phosphate rock reserves [65]. Morocco alone controls three-quarters of the global share, some of which is in the occupied region of the Western Sahara. The long-term security of phosphate rock supply is also uncertain: while estimates of the crunch point when demand will outstrip the supply of non-renewable phosphate vary between fifty and a few hundred years [66], there is consensus that cheap fertilisers will become a thing of the past. Remaining phosphate reserves are lower quality (lower P concentration, higher contaminants), harder to physically access (such as under the seabed), more energy-intensive to mine and process, and more costly to produce [67].
The European Commission, EU member states and other stakeholders in Europe have now begun to take action to support a more coherent approach to recovering and reusing nutrients to meet both water quality and food security objectives. For example, the European Sustainable Phosphorus Platform (ESPP) is a multi-stakeholder body that has been influential in creating evidence-based awareness, dialogue via summits, and expert submissions to policy formulation [68]. In 2016 and 2017, Switzerland and Germany, respectively, mandated that 50% of phosphorus from sewage must be beneficially reused in agriculture [69]. In 2021, Sri Lanka took the bold move of banning the importation of chemical fertilisers and shifting fertiliser subsidies to financial incentives to stimulate local organic fertiliser markets. However, this ban has since been removed, in part due to the economic turmoil facing the island state at the time of writing.
However, perhaps the most pressing challenges are in Sub-Saharan Africa. The region still has some of the lowest rates of soil fertility and the highest rates of food insecurity, as well as inefficiency in food production. One in seven farmers globally cannot access fertiliser markets, with farmers in many land-locked African countries paying 2–5 times more than European farmers due to distribution costs like port duties and rail transport [70]. Yet, in many of these countries, like Malawi, there is enough phosphorus theoretically circulating in organic byproducts like human excreta, crop residues and manures [71].
For the most part, there is no coherent governance of phosphorus at national or international levels. Ensuring global phosphorus security will almost certainly require the reuse of all organic byproducts as renewable fertilisers coupled with demand-side interventions that reduce phosphorus losses and increase efficiency on farm and across the whole food value chain, to ensure food security into the future [72].

3.4. Bioenergy

Bioenergy is a renewable energy generated from the conversion of biomass into heat, electricity, biogas and liquid fuels (e.g., bioethanol and biodiesel used in aviation and road transport). Over the past two decades, bioenergy demand has been growing, particularly due to climate change mitigation and net-zero targets, as well as the need to replace fossil-fuel-based products with renewables, income opportunities for rural communities, and a shift to a circular bioeconomy. In 2019, bioenergy met 9% (55EJ) of global energy demand, which is estimated to nearly double by 2030 to 99 EJ and rise to 153 EJ by 2050 under IRENA’s 1.5 °C Scenario [73].
Bioenergy feedstocks range from dedicated energy crops to organic byproducts like sewage, food waste and agricultural residues. Organic byproducts have lower environmental impacts and therefore provide an advantage over land-based dedicated crops for bioenergy generation.
Increasing bioenergy demand (especially biofuels), driven by national targets in the 2000s (e.g., European Union and USA), resulted in concerns in all areas of environmental and social sustainability through the intensification of agricultural practice, the displacement of agricultural production, or/and the expansion of agricultural land into areas with primary forests, savannas, and native grasslands, such as Brazil and Indonesia [74].
The expansion of traditional food and feed crops, e.g., palm oil, rapeseed, maize and sugarcane, for bioenergy production, however, has raised food security concerns. The US’s 2007 ethanol policy contributed to the 2008 global food and fertiliser spikes; phosphate fertiliser prices alone spiked 800% (as noted in Section 3.3) [64]. Rapid growth in the biogas market in Germany, driven by the national Renewable Energy Act (EEG), saw the number of biogas plants in the country increase from 850 to 9632 between 2000 and 2020, with a cumulative installed capacity rising from 50 to 5700 MW/h [75]. However, this raised sustainability questions on feedstock supply, evidenced by the rapid expansion of maize cultivation for biogas production. This resulted in reviews of the legislation to limit the cultivation area of maize and increase the diversity of the feedstock in 2012 and to make major cuts in the subsidies for biogas plants fuelled by energy crops in 2014 [76]. In 2018, the EU also revised the Renewable Energy Directive (EU-RED II) to strengthen sustainability criteria for agricultural feedstocks and GHG emission reduction thresholds. They introduced limits on the use of food and feed crops as bioenergy feedstocks, providing definitions of “wastes”, “residues” and “byproducts” to prioritise organic byproducts over energy crops for biogas and biofuel production [77].
As a result, many studies have estimated bioenergy potentials of different types of organic byproducts from different streams and for different global and local regions [78]. Estimates of agricultural and forestry residue availability in existing studies range from 12–76 EJ/year in 2050, with a mean of 55 EJ/year [79]. However, this is only half of the IRENA’s estimated global bioenergy demand for 2050. A stable and sustainable supply of biomass would be a challenge due to the competing demand for organic byproducts while achieving food security [80]. This could also trigger other sustainability issues, such as excessive removal of agricultural residues from the agricultural lands, which can cause land degradation through soil erosion and a decline in nutrients and soil organic matter [81,82].

4. Need for Cross-Sector Integration

Creating circular organic value chains can have a wide range of benefits across sectors. It can avoid pollution, reduce the depletion of finite valuable resources, generate renewable energy, contribute to food and water security, improve public health and create local employment opportunities. While some steps towards the circularity of organics are evident in the food, water and wastewater, agriculture and energy sectors (outlined in Section 3 above), many of the potential benefits remain untapped, with many organic byproduct streams unutilised, undervalued, or double-counted.
Further, the lack of coordination between sectors has resulted in competition between end-uses. The classic example is the competition between food versus fuel in first-generation biofuels (Section 3.4). Other examples include lithium-ion batteries and other green technologies competing for the phosphorus used as fertiliser to grow food [83]. In the absence of any policies or deliberate prioritisation, the end-uses of greatest value are likely to be prioritised by default, such as sustainable aviation fuels or high-value green technologies. However, we argue here that food security is the highest sustainability priority. Otherwise, there is a risk of depleting the food system of critical and non-substitutable nutrients like phosphorus over time. This could jeopardise our fundamental ability to feed humanity into the future. After food production has been prioritised, decision-making on other potential end-uses of organic byproducts, such as bioenergy, forestry and landscaping, bioplastics and other biomaterials, might vary with location.
Figure 4 indicates how a diverse range of drivers are stimulating policy and industry responses, which, in turn, are informing the disparate spread of circular economy activities. Lack of a coordinated approach across the food waste, wastewater, agricultural and bioenergy sectors means it is unclear if sustainability outcomes can ultimately be achieved. Critically, without a “systems view” that considers how all key sectors and benefits are indeed inextricably linked, not only is there an emerging potential risk to the food system, but there will also be a key gap in achieving the range of other sustainability outcomes from circular organic value chains. In the subsequent Section 5, we identify some of the actions that can bridge this (e.g., the transition pathways).

5. Barriers and Enablers to Integration and Transformation

Transformation towards sustainability—including circularity—requires coordinated actions by key stakeholders to transition not just technological innovation but governance, markets, knowledge and engagement pathways [84]. Integration across these five transition pathways is also key. That is, creating a truly viable circular economy for organic byproducts requires the integration of policies, markets, technologies and people. This means engaging diverse stakeholders up and down the circular value chain, from local councils and private waste contractors, to farmers and fertiliser companies, and to energy retailers and wastewater utilities, NGOs, informal collectors, and environmental regulators and policy-makers. We argue that the absence of integration as a cross-cutting theme is a key barrier preventing the viability of the circular economy of organic byproducts at scale. In this section, we identify key integration barriers and enablers as a way forward, ranging from overcoming regulatory fragmentation to a lack of capital investments.

5.1. Integration Barriers

5.1.1. Governance Integration Barriers

The governance of organic byproducts often suffers from institutional fragmentation, which hinders the development of comprehensive and coherent circular economy policies and activities. Indeed, a recent OECD survey found that two-thirds of surveyed cities and regions felt that a lack of holistic vision (due in part to poor coordination or leadership) is a key policy obstacle to transitioning from a linear to a circular economy [85]. In some cases, this can lead to organic byproducts being framed in a reductive and restrictive way, preventing innovative and circular use. For example, Australia’s NSW EPA-regulated “Orders and Exemptions” [86] for the re-use of waste focuses predominantly on minimising risks for human health and safety, as per the EPA’s mandate. While ensuring that products are safe for human health and safety is essential, the stringent requirements (such as bespoke health assessments for each specific waste and technical process) can be piecemeal and tedious and are not conducive to innovation that might be seeking positive impacts on other sustainability outcomes, such as biodiversity, job creation or food security. Another example is phosphorus-related regulations in the United Kingdom. Those regulations were largely developed to singularly prevent water pollution from phosphorus discharges, without considering how the nutrient could be recovered in a form that would enable its use as an agricultural fertiliser [84].
The division of responsibilities between different institutions for the management of organic byproducts can also lead to fragmented or partial policies that only focus on certain types of byproducts. For example, Australia’s NSW state government’s waste strategy [86] only considers biogas feedstocks from municipal solid waste and landfill gas, excluding the potential use of byproducts from agriculture (termed “primary industries”) [86]. This is because organic byproducts from agriculture are managed by the NSW Department of Primary Industries and Regional Development, while municipal solid waste and landfills are managed by the NSW EPA, which falls under the NSW Department of Climate Change, Energy, the Environment and Water, the agency that put together the waste strategy.
In addition to institutional fragmentation, the dominance of the private waste management sector in the discourse on organic byproduct management has led to regime dominance in some areas, which can prevent the adoption of other, more efficient and circular recycling and collection techniques, as they can be seen as challenging the incumbent system [40].

5.1.2. Market Integration Barriers

The development of mature markets for circular organic byproducts is hampered by a poor enabling environment and the disconnection between supply chain stakeholders in many regions. Indeed, it is often outside the remit or interest of waste managers to think about the potential end-use applications of the organic byproducts they generate. For example, the recovery and processing of food waste by private contractors or councils is often not linked up-front to a target end-use market (e.g., generating fertilisers for horticulture, or bioenergy for transport), resulting in products that might not be fit for purpose as desired feedstock by a potential end-user. Similar gaps between resource recovery from waste and market demand for end-uses have been observed in the wastewater sector in different parts of the world, for example in Malawi and the UK, due to a lack of reliable supply chain of raw materials at scale (e.g., wastewater, urine or faeces) to meet the fertiliser sector’s needs [84]; in Australia, due to farmers not being consulted and not having appropriate machinery to spread the compost offered at the farm gate; or insufficient market demand for struvite recovered from wastewater in Europe [87].
Further, the nature of contracts between supply chain stakeholders can also prevent the implementation of circular value chains. For example, in Australia, local councils enter long-term contracts with food waste processors. While this may enable the creation of secure commercial relationships, this can lead to technology lock-in, delaying the adoption of more innovative approaches, particularly in the context of rapid changes [40].
Finally, circular value chains are competing with established linear systems [88]. The logistics and infrastructure necessary to establish circularity are often not in place and may not be economically viable, or the capital may be unavailable (in comparison to existing linear systems) without additional financial and regulatory incentives. Yet, uncertainty and financial risk (or perceived financial risk) can make investments and loans more challenging [85,89].

5.1.3. Technology Integration Barriers

The management of organic byproducts relies, in part, on the development and use of adequate technologies to process organic waste. However, for those technologies to work optimally, the collection and treatment of organic wastes need to be fit for purpose. This is currently not always the case. For example, anaerobic digestion systems cannot process lignocellulosic materials. In Australia and several other countries, food organics and garden organics (FOGO) are increasingly being collected together from households. This poses problems at the processing stage, as garden organics, which contain lignocellulosic materials, are not suited for anaerobic digestion, while food organics are [56].
The practice of collecting food organics and garden organics together also introduces contaminants into the system. Although sophisticated technological solutions could address these contaminants, they are costly. Pre-processing garden organics so they can be digested in an anaerobic digester is also costly. These technological barriers demonstrate that technological solutions are critical for establishing a successful circular economy for organic byproducts. For example, they can influence markets by limiting the ability to produce high-quality, specification-compliant products, and they are also essential for compensating for poor source separation, which otherwise requires more intensive stakeholder engagement.
It is clear that technology plays an important role in the management of organic byproducts, but relying on them to compensate for weaknesses elsewhere in the system (e.g., poor waste segregation in the household) can lead to negative outcomes, especially as complex technology is still in its infancy. In the Australian state of NSW, the organic waste from general waste bins (red bins) at the household level is recovered by tumbling the red bins to separate the organic waste from the rest. The organic matter recovered through this process was initially used to amend soils. However, it was then demonstrated that this organic material contained plastics and other chemical and physical contaminants. As a result, this practice was revoked in 2018 [90]. This shows that an over-reliance on technologies or a techno-bias can still lead to inadequate practices. Additionally, it may also divert us from focusing our efforts on avoidance and efficiency measures that are higher up the hierarchy of circular economy practices, which can be less technology-intensive but may lead to better outcomes.
Finally, a significant and concentrated amount of organic byproducts is generated in cities, but it is likely to be used in rural areas. This poses logistical problems, as organic byproducts need to be transported from where they are generated to where they are used, which may be hundreds to thousands of kilometres apart. Transporting some bulky urban organic byproducts like food waste or urine long distances may have negative environmental impacts [91] and not be economically viable, with trucks transporting organic byproducts in one direction and returning empty, as health risks prevent the use of reverse logistics. Pre-treatment, like dewatering, precipitation or concentration of organic byproducts, may therefore be necessary prior to long-distance transportation to end-use markets.

5.1.4. Knowledge Integration Barriers

The baseline understanding of the circular economy and its benefits more broadly—let alone specifically applied to organic byproducts—is currently low amongst the public, businesses and policy-makers [85]. Yet, developing a holistic understanding of the impacts and benefits of different actions related to organic byproducts will be necessary to develop effective policies at all levels of government and encourage industry and citizens (individually and collectively) to adopt circular practices. Further, some sectors or departments may take a health and safety approach to the management of organic byproducts (due to their remit or lack of awareness), while others may uniquely focus on the development of technological solutions.
A lack of scientific knowledge and evidence, coupled with narrow framings of the issue, can lead to inadequate policies and practices. For example, greenhouse emissions accounting in the food system is fragmented across the four different IPCC sectors (industry, energy, land use and waste) [14]. This means, for example, that emissions from fertiliser production are captured under “industry”, fertiliser use is captured under “land use”, while food waste is captured under “waste”. This obscures the total emissions reduction benefits of organic waste recovery, food waste avoidance and other circular initiatives. Lastly, it is challenging for consumers and other stakeholders (like procurement departments) to make informed decisions when the full lifecycle assessment of a circular product is rarely available [92].

5.1.5. Engagement Integration Barriers

The lack of engagement between stakeholders involved in the value chain of organic byproducts, from households and wastewater service providers to agribusinesses and regulators, can lead to poorly designed policies and outcomes. As demonstrated in Section 5.1.1, responsibilities for the management of organic byproducts are typically split between different government departments. The lack of engagement between those organisations can lead to the development of partial policies (e.g., Australia’s state NSW Waste and Sustainable Materials Strategy 2041 [93]). Similarly, a lack of communication between industry and government stakeholders across the value chain can lead to missed opportunities for circularity, as illustrated in Section 5.1.2, where waste managers are not always able to identify and plan for the potential end-uses for recovered organic byproducts, and could only do so by engaging with retailers. Finally, households play a critical role in the management of organic byproducts. Indeed, source segregation at the household level is necessary to facilitate the recovery of organic byproducts. For example, Sri Lanka trialled load-based pricing for mixed household waste to incentivise households to source-separate organic waste at home [91]. In Australia, source segregation is hampered by a lack of consistency in the way local governments communicate about source segregation as well as an absence of incentives—financial or otherwise—to encourage it. This leads to an over-reliance on segregation at the post-processing stage, which is more costly [56].

5.2. A Way Forward Towards Implementing Circularity: Cross-Sector Actions

In order to overcome the current fragmentation and siloed practices within sectors and work towards shared sustainability goals in a coordinated way, there are important considerations within and across sectors that need to explicitly account for implications for upstream and downstream sectors in the value chain. That is, there is a need to scale up awareness, alignment, commitment and action plans [38].
Cross-learning among and between institutional and industry stakeholders in the value chain could broaden the framing of organic byproducts and avoid partial or myopic takes on the issue. More comprehensive and effective financial and regulatory incentives could encourage the development of markets for organic byproducts. For example, public–private investments could be used to minimise risks related to procurements. Waste collection and processing stakeholders need to consider the impacts of their collection practices on the value chain, such as whether the raw materials collected can be effectively processed into renewable products for end-users like farmers. Further research is needed to support evidence-based policy-making and engagement with circular organic stakeholders (e.g., farmers, households), as was demonstrated in Sri Lanka. Interdisciplinary topics could range from testing the agronomic performance and health and safety implications of different organic byproducts in agriculture and other end-uses, to market analysis of end-use options, and to household attitudes and behaviours regarding waste segregation.
Finally, guiding policies are urgently needed to inform the prioritisation of end-uses for organic byproducts. It is currently unclear whose responsibility this is, and in the absence of such coordination, the end-uses of organic byproducts are largely governed by the market by default and thus likely to be used by the sectors of greatest value, e.g., this could be sustainable aviation fuels, rather than sectors of greatest importance to society, such as food security.
The framework developed in this paper can be applied in both public policy settings and sector strategies by:
  • Identifying a designated department or body to oversee the circular strategy development and coordinate across other departments and sectors.
  • Investing in critical research and development to fill key country-specific knowledge gaps, such as volumes of key organic byproducts, the identification of potential end-use markets, and the quantification of benefits (e.g., reduced GHG emissions, biodiversity, employment, etc).
  • Prioritising country-specific and evidence-based circular practices, which take into account: (a) the largest volumes of organic byproducts and/or (b) those wastes with the greatest environmental or public health impacts, and (c) the end-uses of greatest public good (e.g., food security, energy security).
  • Streamlining regulations so that they encourage rather than hinder circular practices, whilst minimising environmental and health risks.
  • Supporting and stimulating the implementation of circular technologies through incentives, tax subsidies, green loans or other means.

6. Conclusions

The circular economy of organic byproducts is in its infancy and is far less defined than that for plastics, metals and other materials. Circular initiatives are emerging within different sectors, including bioenergy, agriculture, food waste and water sectors. However, there is a strong need to stimulate, support and connect these circular value chains, to ensure a sustained, thriving, scaled-up, cost-effective and inclusive circular bioeconomy. The first step needs to be a shared understanding of what defines the circular economy for organic byproducts, as products distinct from materials like metals and plastics. Embedding principles of avoidance first, food security-centric end-uses and creating clean feedstocks that are designed for targeted end-use markets will be key. Overcoming integration barriers to coordinating and connecting sectors will also be essential, including seeking co-benefits to harmonise multiple drivers such as net zero, food security and energy security to avoid perverse outcomes.

Author Contributions

D.C.: Conceptualization, Methodology, Writing—Original Draft, Writing—Review and Editing, Visualization, Supervision, Project Administration; M.J.: Conceptualization, Methodology, Writing—Original Draft, Writing—Review and Editing, Visualization, Data Curation; S.M.: Conceptualization, Data Curation, Writing—Original Draft; S.F.: Conceptualization, Methodology, Writing—Original Draft; E.D.: Conceptualization, Methodology, Writing—Original Draft, Writing—Review and Editing; A.T.: Conceptualization, Writing—Original Draft; F.B.: Conceptualization, Writing—Original Draft; L.-E.R.: Writing—Original Draft, Writing—Review and Editing. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

No new data were created or analysed in this study. Data sharing is not applicable to this article.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Framework of 10Rs for prioritising circular economy strategies from greatest to least circularity. Source: [8] adapted from [2].
Figure 1. Framework of 10Rs for prioritising circular economy strategies from greatest to least circularity. Source: [8] adapted from [2].
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Figure 2. Key activities in a thriving circular economy of organic byproducts from the food system. Source: Authors (adapted to organic byproducts from the generic circular economy framework of the European Parliament [18]).
Figure 2. Key activities in a thriving circular economy of organic byproducts from the food system. Source: Authors (adapted to organic byproducts from the generic circular economy framework of the European Parliament [18]).
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Figure 3. Sources of organic byproducts from food and non-food sources and diverse societal end-uses across agriculture, energy, landscaping, nature, and consumer materials. Note that flows are indicative and not to scale. Source: Authors.
Figure 3. Sources of organic byproducts from food and non-food sources and diverse societal end-uses across agriculture, energy, landscaping, nature, and consumer materials. Note that flows are indicative and not to scale. Source: Authors.
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Figure 4. Multiple benefits of circularising organic byproducts: diverse drivers (1), policy and industry responses (2), circular economy activities (3) and sustainability outcomes (4). Note: examples are indicative, not exhaustive. Source: Authors.
Figure 4. Multiple benefits of circularising organic byproducts: diverse drivers (1), policy and industry responses (2), circular economy activities (3) and sustainability outcomes (4). Note: examples are indicative, not exhaustive. Source: Authors.
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Table 1. Definition and principles of a circular economy of organic byproducts. Source: Authors.
Table 1. Definition and principles of a circular economy of organic byproducts. Source: Authors.
Circular Economy of Organic Byproducts
Definition:
The cost-effective reduction or recovery of any organic byproduct from the food system that is reprocessed for productive reuse in food, energy, or other sectors of the bioeconomy.
Principles:
Principle 1: Prioritise the avoidance of organic waste generation before recycling.
Principle 2: Prioritise food production first as the end-use.
Principle 3: Seek to create clean feedstocks that are fit for purpose.
Principle 4: Design recovery systems to suit targeted end-uses.
Table 2. Fit for purpose: Matrix of raw materials, treatment processes and products: (a) Diverse sources of raw material inputs (organic byproducts from the food system) (light green); (b) multiple treatment and processing technologies (dark green); and (c) output products that can be used directly or as intermediate feedstocks to produce end-products like fertiliser, soil conditioner and/or energy (grey), dash indicates that this treatment pathway is not likely, question mark indicates that treatment outputs are not known (Source: Authors).
Table 2. Fit for purpose: Matrix of raw materials, treatment processes and products: (a) Diverse sources of raw material inputs (organic byproducts from the food system) (light green); (b) multiple treatment and processing technologies (dark green); and (c) output products that can be used directly or as intermediate feedstocks to produce end-products like fertiliser, soil conditioner and/or energy (grey), dash indicates that this treatment pathway is not likely, question mark indicates that treatment outputs are not known (Source: Authors).
ORGANIC BYPRODUCTS
(RAW MATERIALS)		TREATMENT PROCESS
Aerobic
(Compost-
ing Vermi-culture)		Anaerobic DigestionWastewater TreatmentDehydration Dewatering EvaporationMaceration Mulching, ChippingPrecipit-ationIncinerationPyrolysisCombined TreatmentNo Treatement (Direct Application)
Agricultural residues
(crop residues, pulp)		composted soil/mulchdigestate, liquor (+biogas)–residue cakeraw mulch–ash (+heat)biochar crop residues ploughed back into fields
Animal manure
(cow, poultry, etc.)		compostdigestate, liquor (+biogas)slurry, biosolidscake, pellets–sturvite
(via dairy waste)		ash (+heat)– manure, slurry
Animal wastes
(blood, bone, carcass, other abattoir)		–digestate, liquor (+biogas)slurry, biosolids–organic fertiliser, soil conditioner?–ash (+heat)–Blood and bone (via rendering)–
Farm yard waste
(farm yared manure, bedding, straw)		compostdigestate, liquor (+biogas)––soil conditioner–ash (+heat)biochar –
Human excreta
(urine, faeces, mixed)		compostdigestate, liquor (+biogas)effluent, biosolids, liquid injected slurrysludge cake (via wwtp)–struvite (via wwtp)ash (+heat)?e.g., lime-treated biosolids (from wwtp)–
Greywater – households
(sink, shower, laundry, etc)		–digestate, liquor (+biogas)effluent, sludge, grease––––– –
Liquid industrial wastes
(e.g., fats, oils, grease)		–digestate, liquor (+biogas)effluent, sludge, grease?–?––e.g.,liquid injection (from polymer separation)
Food waste
(mixed household, C&I, liquid or solid, individual food processors – cofffee beans, etc)		compost, soil conditionerdigestate, liquor (+biogas)biosolidscakeslury
(direct injection)		–ash (+heat)biochare.g., soil conditioner (from rapid food waste decompo-ser)injected liquid (e.g., ice cream)
Green waste
(household garden, public or private landscaping, forestry)		composted soil/mulchdigestate, liquor (+biogas)––raw mulch, chips–ash (+heat)biochar
Fish and seafood wastecompostdigestate, liquor (+biogas) fish silage (via acid ferment-ation) fishmeal and oils via renderinganimal feed
Other
(e.g., pet poo)		compostdigestate, liquor (+biogas)slurry, biosolidscake, pellets––ash (+heat)– –
Table 3. Progress on circular economy initiatives related to organic byproducts in different countries and regions.
Table 3. Progress on circular economy initiatives related to organic byproducts in different countries and regions.
Country/RegionCircular Policy or InitiativeOrganic Wastes
Addressed		Progress
NSW
(Australia)		Law:
Mandate Food Organics and Garden
Organics (FOGO)
recycling (2025).

Driver:
Landfill cost, space limitations and organic waste GHG emissions.		Food waste,
garden waste		In 2025, the Australian state of NSW mandated food organics and garden organics (FOGO) recycling to reduce food waste and stop food waste from going to landfill. By mid 2030, local councils in NSW will be required to provide all households with a FOGO waste collection service. By mid 2026, large food businesses (such as supermarkets and hospitality services) will also be required to have a source-separated food organics (FO) waste collection service. An AU$81 million FOGO Fund will support council infrastructure (and education). While the new law is focused primarily on diverting 1 million tonnes of organic waste from landfill, it is anticipated that it will be processed into compost for landscaping, sports fields and agriculture [23].
Sri LankaLaw:
Ban fertiliser
imports (2021).

Drivers:
Health concerns with fertiliser and pesticide use (chronic kidney disease of unknown aetiology); stimulating organic farming and domestic market for organic fertilisers.		Crop residues (e.g., paddy straw),
manure,
municipal waste compost		Following almost a decade of a cross-ministry strategy to create a “Toxin-Free Nation” due to concerns around the link between agro-chemicals and chronic kidney disease, Sri Lanka’s president banned the importation of synthetic chemicals (including fertilisers) in 2021. The intention was to stimulate the domestic organic fertiliser market and support organic agriculture more generally. Sri Lanka was the first country to transform to 100% organic farming. However, the ambitious and well-meaning ban did not have a transition plan to ensure that domestic organic fertiliser production could meet demand. The significant fertiliser shortages that ensued led to serious crop failures (including rice, considered a staple for national food security). This was set against a backdrop of severe economic turmoil in the country. The ban was eventually reversed in the same year. However, this demonstrates the need for a carefully planned transition, co-developed with key stakeholders and backed by research [24].
Milan
(Italy)		Policy:
Food Policy for Sustainability (2015).

Driver:
Creating a sustainable food system for Milan.		Urban and peri-urban food wasteMilan has achieved remarkable separation results with their collection method, in the order of 87% (with less than 5% contamination).
Milan has held control of their food system since the Middle Ages and includes today a big peri-urban food supply managed by a public agricultural park, university systems of knowledge, and other actors with a holistic and multilevel governance approach. Milan Food Policy is a revolutionary initiative defining 5 priorities for the city: ensuring healthy food and water for all citizens; promoting sustainability of the food system; promoting food education; fighting against food waste; and supporting scientific research in the agri-food sector. The governance model with horizontal (local) and vertical (metropolitan and regional) integration goes beyond silos mentality and is considered the reason for Milan’s success. Proper management and separation of food waste at the source is a key element of the policy. This is enabled with a door-to-door system, with dedicated space in each building that works well and is user-friendly, reaching 100% of all users in the boundaries (households, local businesses and open markets). The high participation results from user friendliness (compostable bags, frequent collection and ongoing communication). The communication channels consist of both digital and traditional avenues and are delivered in 10 different languages and via a dedicated app [25,26].
EU
Bioeconomy Strategy		Policy:
A Strategic Framework for a Competitive and Sustainable EU Bioeconomy (2025).

Drivers:
Reduce reliance on imported fossil-based products; contribute to climate and environmental goals; drive economic growth and strengthen rural and coastal communities; support industry in shifting to circular production models.		Renewable biological resources (agricultural crops and residues, forestry byproducts, animal manure, food waste,
municipal waste, used cooking oils, algae, marine waste)		The European Commission first launched its Bioenergy Strategy in 2012, designed to harness renewable biological resources—from agriculture, forestry, fisheries, and biotechnology—to produce food, energy, materials, and ecosystem services. The strategy was reviewed and updated in 2018 and 2022, shifting the focus towards industrial deployment, market scale-up, competitiveness and resilience. The most recent strategy, the Strategic Framework for a Competitive and Sustainable EU Bioeconomy (2024–2029), was launched in November 2025 and advances the EU’s bioeconomy policy into a fully integrated industrial agenda. Building on previous updates, it focuses on industrial deployment, scaling up biotechnologies, and stimulating green growth. It highlights that Europe’s bioeconomy is valued at €2.7 trillion and 17.1 million jobs in 2023, representing nearly 8% of EU employment. The strategy charts a path to build a sustainable and nature-positive bioeconomy by: (1) scaling innovation and investments; (2) building new lead markets for bio-based materials and technologies; (3) ensuring sustainable biomass supply across value chains; and (4) harnessing global opportunities [17].
JapanLaw:
Food Recycling Law (2001, amendment in 2007).
Food Loss Reduction Promotion Act (2019).

Drivers:
Low food self-sufficiency ratio in Japan, reducing discarded food waste, promoting recycling into animal feed and fertiliser.		Food waste from businesses in the food industry (e.g., manufacturers, processors, food wholesalers, retailers, restaurants, cafes, hotels)Recycling of household waste has been widely practised across all municipalities in Japan for decades (e.g., cans, bottles, metals, paper). However, the separated collection of organic waste from households has not progressed to the same level as other materials, as many municipalities incinerate organic waste as combustible waste.
The Food Recycling Law, enacted in 2001, targets food-related business sectors only. Entities generating over 100 tonnes of food waste annually must submit annual reports to the relevant ministries and develop and implement plans to reduce waste and recycle unavoidable residues into feed, compost, biogas, or for heat recovery. If efforts are insufficient, authorities may issue guidance, orders, or public announcements and impose fines for non-compliance.
In addition, the Food Loss Reduction Promotion Act, issued in 2019, focuses on reducing waste from both businesses and households by turning it into resources such as animal feed or fertiliser and promoting redistribution. The act sets goals to halve food loss by 2030 compared to 2000 levels through stakeholder cooperation and clearer responsibilities for businesses. Specifically, it aims to reduce food loss and waste from businesses by 60% and from households by 50% by FY2030, compared to FY2000 levels [27,28,29,30].
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Cordell, D.; Jazbec, M.; Miyake, S.; Fane, S.; Dominish, E.; Turner, A.; Berry, F.; Ruoso, L.-E. Going in Circles: Integrating Food, Energy and Water Sectors to Enable a Thriving Circular Bioeconomy. Sustainability 2026, 18, 6165. https://doi.org/10.3390/su18126165

AMA Style

Cordell D, Jazbec M, Miyake S, Fane S, Dominish E, Turner A, Berry F, Ruoso L-E. Going in Circles: Integrating Food, Energy and Water Sectors to Enable a Thriving Circular Bioeconomy. Sustainability. 2026; 18(12):6165. https://doi.org/10.3390/su18126165

Chicago/Turabian Style

Cordell, Dana, Melita Jazbec, Saori Miyake, Simon Fane, Elsa Dominish, Andrea Turner, Fiona Berry, and Laure-Elise Ruoso. 2026. "Going in Circles: Integrating Food, Energy and Water Sectors to Enable a Thriving Circular Bioeconomy" Sustainability 18, no. 12: 6165. https://doi.org/10.3390/su18126165

APA Style

Cordell, D., Jazbec, M., Miyake, S., Fane, S., Dominish, E., Turner, A., Berry, F., & Ruoso, L.-E. (2026). Going in Circles: Integrating Food, Energy and Water Sectors to Enable a Thriving Circular Bioeconomy. Sustainability, 18(12), 6165. https://doi.org/10.3390/su18126165

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