In the context of climate change, people have begun to recognize the importance of resource utilization from waste and are shifting from a linear economic model to a circular economic model. In the case of agricultural materials, due to their historically low economic value, farmers have often resorted to in-situ composting, incineration, or landfilling for disposal. According to statistics from the Council of Agriculture, composting and incineration/landfilling account for 80% of the overall waste treatment methods for solid agricultural materials^〔1〕. However, with proper handling, these agricultural materials can be transformed into valuable resources and used in the production of items like biochar, pyroligneous acid, stationery made from pear branchlets, bulrush drinking straws, triangle rush woven products, pineapple leaf fiber fabric, sea wool, and other valuable products. This article will share case studies to introduce various processing models for the resource utilization of agricultural materials.

Yearly Statistics Table of Agricultural Solid Waste：

Agricultural materials are primarily composed of lignin, cellulose, and hemicellulose, and they can be processed and reused through methods such as high-temperature carbonization, fiber drawing, calcination grinding, prototype processing, and others.

 

High-Temperature Carbonization

Crops, in general, are composed of lignin, cellulose, and hemicellulose. Lignin, due to its turtle shell-like chemical structure, serves as an excellent carbon source material^〔2〕. Agricultural materials with high lignin content, when subjected to pyrolysis, can be converted into valuable products in solid, liquid, and gaseous forms. Solid refers to biochar, which, due to its functional groups, high-specific surface area, high porosity, and chemical stability, can be used in applications such as agricultural fertilizers^{〔2、3、4〕}, water purification^〔2〕, and air purification^〔2〕. The liquid phase consists of a mixture of vinegar and tar, composed of 80-90% water and 10-20% organic compounds. The organic compounds include organic acids, phenols, alcohols, aldehydes, esters, and pyrroles, with a pH value of around 2-4, making them suitable for applications like soil ameliorants, agricultural fertilizers, insecticides, and cleaning agents^〔5〕. The gaseous phase is a combustible gas mixture consisting of CO2, CO, CH4, and H2, commonly known as syngas, which can be utilized as a fuel gas^〔2〕.

The Sustainable Materials Library currently includes domestic industry cases such as Guantian Black Gold's Water Caltrop Biochar and DAWOKO’s Biochar：

 

Fiber Drawing

The cauline leaves contain abundant cellulose, often exceeding 50%. This cellulose serves as a valuable natural material^〔6〕. Taking pineapple leaf fibers as an example, after harvesting pineapples, the leaves are typically left behind. Traditionally, farmers would use agricultural machinery to crush and plow these leaves into the soil as fertilizer^〔7〕. However, with the rise of environmental awareness, people have started to recognize the excellent water resistance, abrasion resistance, and softness of pineapple leaf fibers. The length of these fibers is typically around 3-8 mm. By scraping, washing, drying, and twisting the fibers, pineapple leaves can be transformed into yarn suitable for textiles. Applications include making fabrics for bags, shoe uppers, clothing, and other textiles through blending or weaving^〔8、9〕.

The Sustainable Materials Library also features collections of such fabrics, such as pineapple fiber-blended fabrics from Bentex Essential Sustainable Textiles Co., Ltd. and Super Textile Corp：

 

Application of Agricultural Materials through Calcination Grinding

Calcium is one of the most abundant elements in nature, found in natural minerals and living organisms. Common minerals containing calcium include gypsum (calcium sulfate, CaSO4), apatite (calcium phosphate, Ca5(PO4)3(F,Cl,OH)), fluorite (calcium fluoride, CaF2), and more. In living organisms, calcium is often present in the form of calcium carbonate (CaCO3)^〔10〕, found in shells, crustaceans, corals, and avian eggs.
With the growing awareness of environmental protection, people have started to obtain calcium resources from by-products of livestock farming. Take oyster shells and eggshells as examples; traditionally, these biomaterials were often disposed of through random stacking or calcination. To address this issue, research has shown that high-temperature calcination can transform calcium carbonate into calcium oxide. The resulting calcium powder exhibits antimicrobial and porous characteristics. It can be incorporated into synthetic fibers to create antimicrobial fibers or used as an additive in calcium health food supplements^{〔10、11〕}.

The Sustainable Materials Library has compiled products created by domestic businesses in this field. For instance, Creative Tech Textile Co., Ltd utilizes recycled PETSPUN combined with oyster shell powder to produce Seawool, a fabric material. Another example is TAMAGO NO TAKARA BIOTECHNOLOGY CORPORATION, which uses eggshell powder to create a food additive in the form of calcium powder.

 

Prototype Processing

Taiwan is a major producer of fruits, and to ensure stable annual yields, farmers regularly prune fruit trees. The branches and limbs resulting from pruning can amount to several tons each year. Traditionally, farmers disposed of these agricultural materials through burning or haphazard disposal. To address this agricultural waste, in addition to the previously mentioned option of converting it into biochar through high-temperature carbonization, there are also cultural and creative entrepreneurs who selectively choose thicker branches. Through simple processes like turning, grinding, and polishing, these branches can be crafted into pens, stamps, and other items^〔12〕. Some entrepreneurs recognize the sturdy characteristics of certain herbaceous plants and process them into various products. For example, bulrush drinking straws take advantage of the hollow structure, firm texture, and thick walls of the reed. The process involves cleaning, cutting, hollowing, drying, and disinfecting the reeds to create straws^〔13〕. Items like grass hats, grass shoes, and grass mats use the fine, resilient, moisture-absorbing, and fragrant qualities of bulrush. The bulrush is processed through procedures such as splitting, beating, kneading, laying, and weaving to produce bulrush products^〔14〕.

The examples mentioned above are also among the products currently collected by the Sustainable Materials Library. These include the pear-branchlet stationery designed by Pear Designer, the bulrush drinking straws created by WONDERGREENER CO., and the triangle rush weavings produced by Taiwan Tsioh Rushcraft：

Prototype Application of Agricultural Materials

Summary

Agricultural materials are resources provided by nature. In the past, due to their low commercial value, we often disposed of them through methods such as burning, landfilling, or haphazard dumping. However, by delving into their characteristics and utilizing them wisely, these agricultural by-products can be transformed into valuable materials, offering an opportunity to create value in the context of a circular economy.

Remarks

The Plastics Industry Development Center, supported by the Small and Medium Enterprise Department of the Ministry of Economic Affairs, has established the "Sustainable Materials Library", both as a physical library and an online platform. It officially opened to the public in 2021. The library collects materials from seven major categories: plastics, fibers, rubber, metals, minerals, natural materials, and others. Through services such as business matchmaking, material consultation, design, and prototyping, the Center aims to facilitate the development of a circular economy for sustainable materials in Taiwan.

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