From waste to value: Addressing the relevance of waste recovery to agricultural sector in line with circular economy

The agricultural sector faces various challenges and barriers in transitioning from linear resource consumption to a circular economy. Based on the literature, four key areas of challenges are identified and discussed, conversion technology and research, business model and material flow in the supply chain, analytical tools for the circular economy, and stakeholder involvement. Among the reported studies, anaerobic digestion (AD) is a commonly-used organic waste conversion technology due to its applicability and cost-effectiveness. The success of AD depends on feedstock properties and operating conditions, which impact the quality and quantity of the digestate and biogas produced. Additional processes such as pretreatment, pyrolysis, and hydrothermal liquefaction can enhance biogas production and generate valuable byproducts. However, challenges remain in terms of feedstock composition, high operating temperatures, and the requirement for suitable infrastructure. The business model and material flow in the supply chain demonstrate another set of challenges. Efficient business models are essential for the circular economy in the agricultural sector. Complex circular business models, financial un-certainties, and stakeholders impede effective implementation. The establishment of a sustainable supply chain that ensures the availability of feedstock and byproducts in synchronization with demand is crucial. Suitable infrastructure, management expertise, and continuous training are also of specific importance. Analytical tools play a vital role in feasibility assessment for the circular economy. Life cycle assessment (LCA) is commonly used to quantify environmental impacts, and the related challenges include the limited availability of relevant data and the need to account for feedstock characteristics. Economic evaluation is another useful evaluation tool, but its application to agricultural waste management is limited. Stakeholder involvement, including government, farmers, and consumers, is another key to the success of a circular economy. Governments can incentivize the use of waste-derived products through policies and regulations. Farmers' willingness to adopt circular practices depends on their location, legislative rules, and available incentives. Overcoming these barriers requires collaborative efforts, innovative technologies, and effective communication among stakeholders. The integration of conversion technologies into existing infrastructure, designing sustainable supply chains, and developing appropriate analytical tools are key steps toward a successful agricultural circular economy.