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 the decommissioning process of nuclear power plants, Ni-59, Ni-63 and Fe-55 present in radioactive waste are crucial radionuclides used as fundamental indicators in determining waste treatment methods. However, due to their low-energy emissions, the chemical separation of these two radionuclides is essential compared to others. Therefore, this study aims to evaluate the suitability of various pre-treatment methods for decommissioning waste materials by conducting characteristic assessments at each chemical separation stage. The goal is to find the most optimized pre-treatment method for the analysis of Ni-59, Ni-63 and Fe-55 in decommissioning waste. The comparative evaluation results confirm that the chemical separation procedures for Fe and Ni are very stable in terms of stepwise recovery rates and the removal of interfering radionuclides. However, decommissioning waste materials, which mainly consist of concrete, metals, etc., possess unique properties, and a significant portion may be low-radioactivity waste suitable for on-site disposal. Considering that the chemical behavior and reaction characteristics may vary at each chemical separation stage depending on the matrix properties of the materials, it is considered necessary to apply cascading chemical separation or develop and apply individual chemical separation methods. This should be done by verifying and validating their effectiveness on actual decommissioning waste materials.

The nuclear facilities at Korea Atomic Energy Research Institute (KAERI) have generated a variety of liquid radioactive waste and most of them have low-level radioactive or lower levels. Some of the liquid radioactive waste generated in KAERI is transported to Radioactive Waste Treatment Facility (RWTF) in 20 L container. Liquid radioactive waste transported in a 20 L container is stored in a Sewer Tank after passing through a solid-liquid separation filter. It is then transferred to a very low-level liquid radioactive waste Tank after removing impurities such as sludge through a pre-treatment device. The previous pre-treatment process involved an underwater pump and a cartridge filter device passively, but this presented challenges such as the inconvenience of having to install the underwater pump each time, radiation exposure for workers due to frequent replacement of the cartridge filter, and the generation of large amounts of radioactive waste from the filter. To address these challenges and improve efficiency and safety in radiation work, an automated liquid radioactive waste pre-treatment device was developed. The automated liquid radioactive waste pre-treatment device is a pressure filtration system that utilizes multiple overlapping filter plates and pump pressure to effectively remove impurities such as sludge from liquid radioactive waste. With just the push of a button, the device automatically supplies and processes the waste, reducing radiation hazards and ensuring worker safety. Its modular and mobile design allows for flexible utilization in various locations, enabling efficient pre-treatment of liquid radioactive waste. To evaluate the performance of the newly constructed automated liquid radioactive waste treatment device, samples were taken before and after treatment for 1 hour cycling and analyzed for turbidity. The results showed that the turbidity after treatment was more than about four times lower than before treatment, confirming the excellent performance of the device. Also, it is expected that the treatment efficiency will improve further as the treatment time and number of cycles increase.

Reverse osmosis seawater desalination facilities can extend the cleaning cycle and replacement time of the reverse osmosis membrane by pretreatment process. Selection of pretreatment process depends on water quality. It was attempted in this study to select approriate pretreatment process for the Masan bay, which was high in particles and organic content. For this purpose, performances of pretreatment processes such as filter adsorber (FA), pore controllable fiber (PCF), and ultrafiltration (UF) were compared based on the silt density index (SDI). The SDI value of the filtrate should be less than 3. The study results showed that UF can produce the filtrate quality satisfying the requirement. However, the transmembrane pressure (TMP) of UF increased quickly, reaching 0.6 bar within 4 days. In order to secure stable operation, FA and PCF were combined with UF. The study results showed that combination of PCF and UF was able to extend the filtration duration (more than 2 months) until to reach TMP of 0.6 bar.

The purpose of this study was to analyze the effects of the pre-treatment method on the measurement of probiotic cell counts. The probiotic cell count was not significantly different in the pre-treatment method such as experimenters, diluted solution, medium, and homogenization duration. The mean value of probiotic cell count with capsule was 2.2×1010±9.5×109 CFU/g. This probiotic cell count was converted into 2.8×1010±1.2×1010 CFU/g based on the net weight. The mean value of probiotic cell count without capsules was 4.3×1010±1.8×1010 CFU/g. As a result of this comparison, probiotic cell count showed significant difference with and without capsules. Thus, it is suggested that the probiotic cell count is measured by removing the capsule in capsule probiotics.

In this study, the effect of pre-aging treatment for inhibition of natural aging of Al-4.8Zn-1.3Mg alloy by extrusion process was investigated. Firstly, the as-cast microstructure of Al-4.8Zn-1.3Mg alloy billet and its evolution during homogenization(460℃, 4h + 510℃, 5h) were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness analysis. The as-cast microstructures of Al-4.8Zn-1.3Mg alloy reveal Mg2Zn, Al5Cu, Al3Cu formed between dendrities. After homogenization, MgZn, Al4Cu, Al13Cu phases precipitated into the matrix. In addition, standard deviation of homogenized billet was improved than as-cast billet from 2.62 to 0.99. According to pre-aging(100℃, 1h) Al-4.8Zn-1.3Mg alloy by extrusion process, yield strength and tensile strength deviation improved more than condition by natural aging.

Large amounts of oily wastewater discharged from various industrial operations (petroleum refining, machinery industries and chemical industries) cause serious pollution in the aquatic environment. Although dissolved air flotation (DAF) separating oil pollutants using microbubbles represents current practice, bubble size cannot be selectively controlled, and lots of power is required to generate microbubbles. Therefore, to investigate performance of the DAF process, this study examined the distribution of different sizes of microbubbles resulting from changes in physical shear force via modifying shapes of a slit-nozzle without an additional power supply. Three types of slit-nozzles (different angle, shape and length of the slit-nozzle) were used to analyze the distribution of bubble size. At a slit angle of 60°, shear force was 4.29 times higher than a conventional slit, and particle size distribution (PSD) in the range between 2 and 20 μm more than doubled. Treatment efficiency of synthetic oily wastewater through the coagulation-DAF process achieved 90% removal of COD by injecting FeCl3 and PACl of 250 mg/L and 100 mg/L, respectively, and the same performance resulted using FeCl3 of 200 mg/L and PACl of 80 mg/L employing a slit-nozzle angle of 60°. This study shows that a coagulation-DAF process using a modified slit-nozzle can improve the pre-treatment of oily wastewater.

Capacitive deionization (CDI) process is an emerging process for water desalination. Recently, there has been a major development of architectures in CDI cells using carbon flow electrodes with membrane, called flow-electrode capacitive deionization (FCDI). In FCDI, the advantage is continuous desalination due to the carbon flow electrodes. Numerous research groups dedicated to develop the FCDI process, however, a clear pre-treatment of carbon flow electrodes was not suggested. Study herein, present a clear understanding of effects of pre-treatment of activated carbon based on sonication in the carbon flow electrodes for the basics results with respect to adsorption performance.

Although SWRO treatment shows high performance, a major problem associated with the biological growth of algal blooms (AB) still exists in many areas. This study reviewed the current applications of pretreatment for the removal of AB-forming species in seawater and identified limitations to highlight future research areas. In addition, we evaluated pretreatment techniques such as meshed tube bio-filtration (MTBF) and UV oxidation, with the aim of marine algal cells and marine algal organic matter (AOM) removal, respectively. Vital indicators for ABs quantification, effects of the AB-forming species’ properties (size/shape, cell rigidity and toxicity/mobility) on treatment, and potential problems during AB-forming species removal were also visited.

양파 수확작업은 양파 재배 작업의 전체 노동 투하시간 중 39%, 81.2hr/10a를 소모하며 이 중 줄기절단작업에 20.7hr/10a가 소요된다. 특히 수확작업은 76%가 인력에 의존하고 있다. 이러한 문제를 해결하기 위하여 굴취와 수거작업에 대한 기계화가 연구되고 있으나 줄기절단기계의 경우, 비닐 멀칭상태에서의 원활한 작업이 가능한 장비가 개발되지 않았으며, 농업용 멀칭비닐로 사용하는 저밀도 폴리에틸렌 필름은 양파재배 기간에 비닐이 부식되어 비닐 인장력이 원재료의 90% 수준으로 저하되므로 비닐제거시 찢어짐이 생겨서 비닐수거에 애로사항이 있었다. 따라서 본 연구에서는 국내 환경에서 줄기절단작업 및 비닐회수작업이 원활하게 가능한 양파수확전처리기 개발을 위한 양파 수분함유량에 따른 줄기절단 높이, 칼날형태, 칼날각도, 비닐 인장력, 가이드의 토양내 전진저항시험 등의 기초실험을 실시하였다. 양파줄기의 수분함유량에 따른 줄기절단높이 시험결과, 수분이 많을수록, 줄기절단 높이가 높을수록 절단저항은 낮게 나타났으며 줄기절단저항 시험에서는 칼날 각도 및 기움각에 따른 절단 저항력 시험에서는 칼날 기움각 30°, 칼날각도 20°에서 절단저항력이 가장 낮게 나타나 왕복식 예취칼날이 적절한 것으로 판단되었다. 비닐 인장시험에서는 0.025mm 비닐이 27.99N의 인장력에서도 찢어짐이 거의 없어 양파 재배 시 사용하는 경우 비닐회수 작업이 원활하게 진행될 것으로 판단되며 또한 가이드의 토양 내 전진저항에서 가이드 각도 40°일때 평균저항은 2.26N으로 적정한 것으로 판단되었다.

2012년부터 강화된 총인의 농도를 준수하기 위해서는 응집에 의한 물리화학적 처리가 필수적인 후단공정이 되었으며, 현재 국내 하수처리시설 중 약 60%의 처리시설에서 총인처리시설이 설치되었다. 하지만 총인처리시설 운전에 따른 응집제 사용량이 증가하게 되었고, 이에 따라 약품 비용 및 슬러지 처리비 증가 등의 운영비가 상승하였다. 특히 분리막 공법(MBR)의 경우 막 투과수의 응집액 부족으로 인한 응집효율 저하 및 응집제의 과다 주입으로 인한 처리수질 악화 등의 문제가 발생하는 경우도 있다. 본 연구에서는 MBR 공법내에서 별도의 총인처리시설 필요 없이 생물학적 인제거를 극대화 하는 동시에 응집제 사용량을 최소화하면서 처리수의 인농도를 0.2 mg/L 이하로 유지할 수 있는 방안을 도출하고자 하였다.