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Circular Bioeconomy and Sustainability

Isıl Aksan Kurnaz1,2, Elif Damla Arisan1,2 and M. Levent Kurnaz2,3

1Gebze Technical University, Institute of Biotechnology, Gebze, Kocaeli, Turkey

2Original BioEconomy Resources Center of Excellence (OBEK), GTEAV, Gebze, Kocaeli, Turkey

3Center for Climate Change and Policies & Department of Physics, Bogazici University, Bebek, Istanbul, Turkey

1.1 Introduction

The UN projections indicate that by the end of the century world population will total 11.2 billion people, and considering some calculations indicate that the Earth's carrying capacity is around 7 billion people, it becomes clear that the resources are becoming increasingly scarce while demand constantly increases. In order to feed, fuel, and heal the world, a different approach is required to maximize the efficiency of resource use and to minimize the waste thereof. The circular economy was formulated as such an approach, whereby production and consumption of materials are optimized. The European Parliament defines circular economy as "a model of production and consumption, which involves sharing, leasing, reusing, repairing, refurbishing and recycling existing materials and products" [1].

The bioeconomy, on the other hand, is defined by the European Commission (EC) as "the production of renewable biological resources and conversion of these resources and waste streams into value added products, such as food, feed, bio-based products and bioenergy" [2]. The societal challenges that drive this need are food security and sustainability of natural resources, and hence the need for reducing our reliance on non-renewable resources but instead increasing use of renewable resources, and of finally the climate change issue that we are all facing.

In order to achieve that, the EC has set a Bioeconomy Strategy and outlined three major action plans:

1. To develop new technologies and processes for the bioeconomy,
2. To develop markets and competitiveness in the bioeconomy, and
3. To push policymakers and stakeholders to cooperate.

The bioeconomy relies on biological resources (such as animals, plants, microorganisms, or organic waste) and involves all production and economic sectors that use biological resources (such as forestry, agriculture, aquaculture, etc., including those in food, feed, bio-based products, and bioenergy). Interestingly, although medical and aromatic plants are heavily used in the pharmaceutical sector, it is not explicitly stated within some definitions of bioeconomy, which is sometimes interpreted as the biopharmaceutical sector not being included in the bioeconomy. However, all sectors involving biological resources in one way or another, and those creating organic waste, has to be considered as an inherent component, and all bioeconomies need to have sustainability and circularity in their focus, not only to make efficient use of resources but also to make sure we protect and enhance biodiversity.

1.2 Overlaps and Differences - Bioeconomy, Circular Economy, Circular Bioeconomy

Linear economies rely on renewable or non-renewable raw materials that enter the production line, where a product is generated and marketed for user consumption, at the end of which there is waste that is thrown away. More recently, a recycle-based system has been established whereby the linear economy has an additional feedback loop, where some aspects of the product that the consumer uses, such as plastic or paper packaging, is recycled back to the production line, thereby to a certain extent reducing the waste that is deposited to the environment or used as landfill (Figure 1.1a and b). However, as neither system regenerates the input material, the challenge of finite and diminishing natural resources remains unresolved.

The circular economy essentially describes an economic system [3] where the business models divert from an "end-of-life" model for production toward a "re-use, refurbish, repurpose, re-cycle and recover" model to achieve sustainable production, reducing negative environmental effects while maximizing economic prosperity and social equalities (Figure 1.1c).

Although there is no worldwide agreed-upon definition, bioeconomy focuses on the sectors that are involved with renewable biological resources, including agricultural and forestry products, fish, animals, and microorganisms, for the food, feed, materials, and energy sectors, and essentially can be linear or circular, and includes only bio-based products and services, usually with the use of biotechnology [3].

The circular bioeconomy is a relatively recent concept and is at the intersection of the circular economy and the bioeconomy, aiming to improve resource efficiency, reducing the demand for fossil fuels, valorization of waste material and such; however, the bioeconomy has unique aspects that are beyond the circular economy, including reutilization of by-products and bio-waste, new production processes that minimize toxicity to humans and environment, protection of biodiversity, healthy bio-based products, etc., which are incorporated into circular bioeconomy [4].

Waste is a central concept in the circular bioeconomy since it provides "sustainable biomass" from which new bio-based products can be generated, in addition to being available for compost production (Figure 1.1d). Another important tenant of the circular bioeconomy is the biorefinery concept, which can be used to generate a single bio-based product or in more recent versions integrated biorefineries can handle multiple co-products from the same biomass through efficient design and innovative conversion technologies. Waste biorefining is different from classical waste management and the recycling concept, in the sense that "waste" of one process may be used as a "resource material" for another process, generating a completely different bio-based product in circular bioeconomies, whereas waste recycling in the classical schemes simply reuse or recycle the waste in some aspect of the same production line [5]. The most common waste materials used in bio-based production include lignocellulosic wastes, mostly from rice or wheat straw or corn stover, followed by municipal solid waste and food wastes. Among these, whey - cheese waste - is a by-product of cheese manufacturing and the worldwide production is estimated at around 200 million tons?year-1, which could be valorized through biotechnology and redirected to the generation of a number of different value-added bio-based products including lactic acid, polylactic acid used in bioplastics, and bio-based fertilizers. This would not only prevent pollution and relieve negative environmental pressure but also create new circular value chains and innovative manufacturing ecosystems [5].

Figure 1.1 The linear economy with and without recycling feedback, circular economy vs circular bioeconomy. (a) The linear economy starts with raw materials that enter the production chain, which is then marketed and consumed, eventually ending in waste materials. (b) The recycle economy with feedback loops is essentially a linear economy where raw material enters the production chain and is marketed; but, after consumption some products will be recycled and entered to the production chain, such as plastic or paper packaging, but eventually ending in waste materials. (c) The circular economy relies on raw materials entering the production circle, but the principle is the sustainable recycling of waste material back to the production chain, which eliminates (as much as possible) waste materials and minimizes raw material requirements. (d) The circular bioeconomy relies on sustainable biomass (including residues and waste) as raw material, which enters the integrated production circle that maximizes multiple bio-based production (e.g. biofuel, biodiesel, biomaterials, food, feed, biopharmaceuticals, etc.) through biorefineries, encourages prolonged and shared use of products so as to minimize over-consumption, and instead of generating recyclable waste material, relies on energy recovery from waste as well as use of waste in composting, thereby renewing and supporting long-term sustainability of biological resources.

Similar to the Circular Economy Action Plan adopted in 2015, which aims to turn Europe's economy into a more sustainable economy, a number of policies and strategy papers indicate that it is possible to boost global competitiveness of countries or regions via promoting sustainable economic growth. Circularity of waste management provides minimal generation of waste and maximizes the recycling and reuse.

Biomass cascading is a relatively recent concept in waste management of the circular economy or bioeconomy, where biomass is exploited for high value-added product generation in succession, where residual biomass left after each production step is utilized for generation of another product (and/or co-product), until all value-added products possible have been exploited and the remaining residue is ultimately used as an energy source (Figure 1.2 shows the cascading...