In response to the global interest and efforts towards reducing plastic use and promoting resource recycling, there is a growing need to establish methods for recycling discarded fishing gear. In Korea, various technologies are being developed to recycle discarded fishing gear, but significant technical and policy challenges still remain. In particular, biodegradable gill nets require a pre-treatment process to separate biodegradable materials from other substances and to remove salt before recycling. Therefore, this study aims to develop a pre-treatment device for recycling biodegradable gill nets and to evaluate the feasibility of recycling them.

In order to utilize waste wood chip for pavement, a polyurethane resin that is both eco-friendly and suitable for bindingwood chip was developed as the binder, and workability was examined through laboratory experiment for characteristicsof waste wood chip mixture using the polyurethane resin and through test pavement on the field. The new resin was aVOC reduction type free from plasticizer and solvent classified as endocrine-disrupting chemicals and environmentalhazardous substances, and NCO equivalents were set at 8, 9, 10 and 11% by modifying the polyisocyanate-polyol ratio.Laboratory experiment showed that polyurethane resin with NCO equivalent of 9% and 10% had excellent characteristicsas binder for waste wood chip. In the field experiment applying waste wood chip and polyurethane resin in the massratio of 1:0.8, tensile strength of the pavement system was about 30% higher than that using polyurethane resin currentlybeing sold, and permeability coefficient and elasticity thereof were the same as that using the resin currently being sold.Also, examination of compaction methods for waste wood chip pavement system showed that non-heating hand rollerand compactor had the problem of the “waste wood chip - resin mixture” sticking to the roller during the compaction but that heating hand roller had excellent workability and could achieve good planation surface relatively easily.

The physical properties of sidewalk pavement material made by combining rectangular chips with urethane resin were reviewed through both an indoor test and an on-site test. To obtain the chips, forest tree by-products were crushed and then passed through a 10mm sieve. The materials that remained in the 2.36 mm sieve are the above mentioned chips. For the indoor test, the mixing ratios of urethane resin to chips, by mass, were set as 30%, 40%, 50%, 75% and 100%, respectively. Then, the mixture obtained by mixing with forced mixing type mixer was formed in an iron mold. Tests for tensile strength, elasticity and permeability coefficient were performed 7 days after forming. For the on-site test, the cross-section of the sidewalk pavement material consisted of sand filter layer, crushed stone subbase, permeable concrete base and surface layer of the forest tree chip mixture. For the surface layer, the mass ratios of urethane resin to the forest tree chip were determined to be 40%, 60% and 80%, respectively. The physical property test like the one performed in the indoor test and the skid resistance test was performed over 7 days after the completion of trial construction. According to the result of the tests, the tensile strength, GB/SB coefficients and permeability coefficient were 0.1 to 0.7MPa, 15 to 43% and 0.3 to 0.5mm/sec, respectively, depending on the mixing ratio. In addition, the skid resistance coefficient was 75BPN with the mass ratio of the urethane resin to the forest tree chips of 80%. Furthermore, it was found through the on-site test that a pavement surface with excellent surface smoothness could be obtained through the application of a construction method using an electric heat roller. It was also confirmed that the mixing ratio of urethane resin to forest trees chips needed to be 60% or more.