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.

The intensive development of the petrochemical industry globally reflects the necessity of an efficient approach for oily sludge and wastewater. Hence, for the first time, the current study utilized magnetic waxy diesel sludge (MWOPS) to synthesize activated carbon coated with TiO2 particles for the removal of total petroleum hydrocarbons (TPH) and COD from oily petroleum wastewater (OPW). The photocatalyst was characterized using CHNOS, elemental analysis was performed using X-ray fluorescence spectroscopy (XRF), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HR-TEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectrometer (FTIR), Raman, energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), MAP thermo-gravimetric analysis/ differential thermo-gravimetric (TGA–DTG), Brunauer–Emmett–Teller (BET), diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometer (VSM). The optimization of synthesized highly porous AC/Fe3O4/TiO2 photocatalyst was conducted considering the impacts of pH, temperature, photocatalyst dosage, and UVA6W exposure time. The results demonstrated the high capacity of the MWOPS with inherent magnetic potential and desired carbon content for the removal of 91% and 93% of TPH and COD, respectively. The optimum conditions for the OPW treatment were obtained at pH 6.5, photocatalyst dosage of 250 mg, temperature of 35 °C, and UVA6W exposure time of 67.5 min. Moreover, the isotherm/kinetic modeling illustrated simultaneous physisorption and chemisorption on heterogeneous and multilayer surfaces. Notably, the adsorption efficiency of the AC/Fe3O4/TiO2 decreased by 4% after five adsorption/desorption cycles. Accordingly, the application of a well-designed pioneering photocatalyst from the MWOPS provides a cost-effective approach for industry manufacturers for oily wastewater treatment.

The object of this study is to feasibility assesment for co-digestion efficiency of food waste recycling wastewater(FWR) with thermal hydrolysis process dehydration cake (THP Sludge). As a result of THP pre-treatment experimental conditions to 160oC and 30 minutes, the solubility rate(conversion rate of TCOD to SCOD) of the THP sludge increased by 34%. And the bio-methane potential in the THP sludge increased by about 1.42 times from 0.230 to 0.328 m3 CH4/kg VS compared to the non-pre-treatment. The substrates of the co-digestion reactor were FWR and THP sludge at a 1:1 ratio. Whereas, only FWR was used as a substrate in the digestion reactor as a control group. The experimental conditions are 28.5 days of hydraulic retention time(HRT) and 3.5 kg VS/m3-day of organic loading rate(OLR). During the 120 days operation period, the co-digestion reactor was able to operate stably in terms of water quality and methane production, but the FWR digestion reactor deteriorated after 90 days, and methane production decreased to 0.233 m3 CH4/kg VS, which is 67% of normal condition. After 120 days of the experiment, organic loading rate(OLR) of co-digestion reactor was gradually increased to 4.5 kg VS/m3-day and operated for 80 days. Methane production during 80 days was evaluated to be good at the level of 0.349 m3 CH4/kg VS. As a result of evaluating the dehydration efficiency of the sludge before/after 150-180oC THP using a filter press, it was confirmed that the moisture content of the sludge treated before THP at 180oC was 75% and improved by 8% from 83-85% level. Therefore, it is expected that the co-digestion reactor of FWR and THP sludge will ensure stable treatment water quality and increase bio-methane production and reduction effect of dehydration sludge volume.

Abstract Recently, the circular economy aiming at elimination of waste and the continual use of resources has attracted a lot of attentions. In the circular system, the resource recovery uses the recycled wastes as the raw material to manufacture new valuable products. This work focuses on a low-cost process, in which an activated carbon (AC) adsorbent was prepared from waste cation exchange resin by calcination and HNO3 activation hydrothermal method. Surface structure and chemistry of AC were characterized by SEM, XRD, FTIR and Boehm titration. It was found that the acid treatment could increase the number of pores and the content of oxygen-containing functional groups on AC surface. In the adsorption experiment, Methylene blue (MB) was used to assess the adsorption capacity of AC. Experimental results showed that the highest efficiency of MB removal was achieved by AC with modification of 4M HNO3, showing the acidification effect on the adsorption capacity of AC. Adsorption isotherms of Langmuir and Freundlich were employed to fit the experimental data. It was shown that MB adsorption on AC is more consistent with Langmuir model that assumes a homogeneous adsorption. In the adsorption kinetic analysis, the adsorption was found to follow the pseudo-second-order model, indicating that adsorption of MB on acidified AC is dominated by chemical adsorption. The study revealed that the waste ion-exchange resin is a proper precursor of carbon adsorbent for MB dye. This low-cost method would specifically reduce the environmental cost of waste disposal.

멤브레인 기반의 MBRWG (Membrane Bioreactor for Waste Gas) 처리기술은 폐가스 흐름에 대한 높은 선택성을 바탕으로 효과적인 생물학적 제거를 수행할 수 있다. MBRWG에는 몇 가지 잠재적 이점이 있는데, 이 중 가장 두드러진 점은 기상과 액상이 멤브레인 양쪽으로 명확히 분리되어 액상 내 생물막의 최적제어가 용이하고 이를 통해 효과적인 생분해와 생물막의 활성화를 도모할 수 있다는 것이다. MBRWG 처리기술은 특히 xylene 같은 소수성 독성 기체 성분 제거에 유리한데 이는 소수성 기체의 물질전달속도, 독성 및 제거율이 생물막 인근의 액상흐름 및 수분제어에 민감하게 변화하기 때문이다. MBRWG 처리에 쓰이는 다양한 멤브레인 중에서 PDMS-중공사막(hollow fiber)이 가장 높은 기체 물질 전달을 제공한다고 보고되었다. Capillary 형태도 중공사막형태에 비해 비표면적은 낮지만 비교적 활발한 연구가 진행되고 있다. 소수성 기체성분 제거 외에도 기존 생물학적 폐가스 처리 장치에서 배출된 잔류 기체 혼합물이나 먼지를 제거하기 위한 후단 공정에서 멤브레인 활용을 고려할 수 있다.

The public relations room of the waste disposal facility is a space that can be visited by a large number of unevaluated personnel. Therefore, it is essential to design against fire, and research on fire and evacuation is essential. In this study, in order to evaluate the safety of the occupants in the event of fire and evacuation based on the life safety standards of occupants, the increase in risk due to heat, visible distance, and toxic gases on a plane 1.8m from the floor, which is the limit of breathing of the evacuee, over time. It was analyzed by location. As a result, the RSET of the P-01 exit was 93.0 seconds and the ASET was 272.6 seconds, the RSET of the P-02 exit was 45.8 seconds, the ASET was 147.7 seconds, the RSET of the P-03 exit was 106 seconds, and the ASET was 182.9 seconds.

Three kinds of STS304-Zr alloys were fabricated by varying the Zr content, and their microstructure and fracture properties were analyzed. Moreover, we performed heat treatment to improve their properties and studied their microstructure and fracture properties. The microstructure of the STS304-Zr alloys before and after the heat treatment process consisted of α-Fe and intermetallics: Zr(Cr, Ni, Fe)2 and Zr6Fe23. The volume fraction of the intermetallics increased with an increasing Zr content. The 11Zr specimen exhibited the lowest hardness and fine dimples and cleavage facets in a fractured surface. The 15Zr specimen had high hardness and fine cleavage facets. The 19Zr specimen had the highest hardness and large cleavage facets. After the heat treatment process, the intermetallics were spheroidized and their volume fraction increased. In addition, the specimens after the heat treatment process, the Laves phase (Zr(Cr, Ni, Fe) 2) decreased, the Zr6Fe23 phase increased and the Ni concentration in the intermetallics decreased. The hardness of all the specimens after the heat treatment process decreased because of the dislocations and residual stresses in α-Fe, and the fine lamellar shaped eutectic microstructures changed into large α-Fe and spheroidized intermetallics. The cleavage facet size increased because of the decomposition of the fine lamellarshaped eutectic microstructures and the increase in spheroidized intermetallics.

General process for waste vinyl pretreatment system is consisted of separating, crushing, washing, drying and recovering impurities. However, there are problems such as wastewater when washing of waste vinyl. In order to solve these problems we have developed new dry type cleaning system. This system consists of five equipment : 1) Hydraulic cutter to cut in 1m size, 2) 1st crusher to cut in 20～30cm size, 3) 2nd crusher to cut in 3～8cm size. 4) Separation to recovering impurities. 5) Thermal fiow dryer to dry.

Acetate, propionate, butyrate are the major soluble volatile fatty acids metabolites of fermented food waste leachates. This work investigate the effects of volatile fatty acid on the growth rate and NH4-N, PO4-P removal efficiency of mixotrophic microalgae Chlorella vulgaris to treat digested food waste leachates. The results showed that acetate, propionate and butyrate were efficiently utilized by Chlorella vulgaris and microalgae growth was higher than control condition. Similar trends were observed upon NH4-N and PO4-P consumption. Volatile fatty acids promoted Chlorella vulgaris growth, and nutrient removal efficiencies were highest when acetate was used, and butyrate and propionate showed second and third. From this work it could be said that using mixotrophic microalgae, in this work Chlorella vulgaris, fermented food waste leachates can be treated with high efficiencies.

Modified coagulants were investigated for the removal of phosphorus from secondary effluent of wastewater treatment. The modified coagulants were prepared by mixing alkali earth metal ions such as calcium and magnesium. The basicity of a coagulant influenced on the removal of phosphorus, and coagulants with basicity of 5.9% showed a better removal of total phosphorus than that of 38.5%. Also, coagulants with alkali earth metals enhanced the performance of coagulation by 10% and resulted in 67.1% for total phosphorus removal. Moreover, the removal of suspended solids and chemical oxygen demand was improved using coagulants with low basicity and earth metal ions. Results of this study demonstrated that the use of coagulants with low basicity, and calcium and magnesium ions is recommended to improve wastewater effluent quality.

Response surface methodology (RSM) based on a Box-Behnken Design (BBD) was applied to optimize the thermal-alkaline pre-treatment operating conditions for anaerobic digestion of flotation scum in food waste leachate. Three independent variables such as thermal temperature, NaOH concentration and reaction time were evaluated. The maximum methane production of 369.2 mL CH4/g VS was estimated under the optimum conditions at 62.0°C, 10.1% NaOH and 35.4 min reaction time. A confirmation test of the predicted optimum conditions verified the validity of the BBD with RSM. The analysis of variance indicated that methane production was more sensitive to both NaOH concentration and thermal temperature than reaction time. Thermal-alkaline pretreatment enhanced the improvement of 40% in methane production compared to the control experiment due to the effective hydrolysis and/or solubilization of organic matters. The fractions with molecular weight cut-off of scum in food waste leachate were conducted before and after pre-treatment to estimate the behaviors of organic matters. The experiment results found that thermal-alkaline pre-treatment could reduce the organic matters more than 10kD with increase the organic matters less than 1kD.

Membrane backwashing waste shows seasonally different characteristics and it has bad settleability differently from general backwashing waste in water treatment plant. When chemicals was injected to membrane backwashing waste, the settleability was better than chemicals was not injected. However, when settled lower sludge was not discharged, flowing sludge continuously was concentrated over a certain surface and floatation penomena occurred according to flowing velocity. When the lower sludge was discharged continuously in the thickener to prevent floatation penomena of turbidity materials, the depth of sludge surface was the least and the settleability increased.

Dehydration is a crucial part in the plastic recycling process. Without proper dehydration, a high quality recycled product cannot be produced. This study developed a continuous-type dehydrator using centrifugal force to improve the dehydrating performance and recycling throughput. The designed structure makes it capable to perform a continuous feeding and dehydrating of crushed plastic waste simultaneously. It consists of revolving drum, feed screw, insert screw, differential speed regulator and other components. Several tests were conducted to determine optimal process parameters to achieve results. Field tests using prototypes verified that the dehydrator with the proposed structure has an efficient and excellent performance

Fundamental experiences have been studied for development of pre-treatment process of Sn by-prod-ucts such as solders. Dry and wet separation/recovery processes were considered by the differences of physicalproperties. The by-products, which are analyzed by solder metal and oxides. The metal and oxide were simplyseparated by dry ball-milling process for 12 hours, after that recovery metal powder might be reusable as lead orlead-free solders. In terms of wet separation process, samples were dissolved in HNO3+H2O2 and the precipita-tion were analyzed by SnO2. Overall efficiency of recovery might be increasing via developing simple pre-treat-ment process.

The hydrofoil-tip mixer can be used to create the desired material by mixing the two materials in various industries, especially in the waste water and sewage water treatment. The purpose of this study is to clarify flow characteristics induced by 3 types impellers in a mixing tank by CFD. In this study, flat plate, hydrofoil and hydrofoil-tip type impellers are used and the rotating speeds of impellers are 25, 35, 45 rpm. The results in present study show that hydrofoil-tip type is the most proper impeller for mixing in the waster water treatment tank and reducing required power of rotating impeller. This results can be used for the design of the mixing tank in the waste water treatment system.

수침목재유물은 해저, 호저, 저습지등에서 발견되며 물속에서 외부로 아무런 조치 없이 나오게 되면 수축과 변형을 일으키게 된다. 따라서 보존처리는 목재내부의 물을 화학약품과 치환하고 강도와 치수의 안정화를 이루는 것이다. 이중 EDTA와 PEG는 수침목재유물 보존처리에 가장 많이 사용되는 약품중 하나이다. EDTA는 발굴출토된 목재의 흑화현상의 원인인 타닌산제2철에서 Fe-EDTA의 형태로 흑화현상을 제거한다. 보존처리 후 발생하는 폐 EDTA 용액으로부터 HCl을 첨가하여 Fe-EDTA에서 Fe3+를 분리해 내고 강산성에서 EDTA가 석출되는 원리를 이용하여 EDTA의 침전물을 획득하여 재활용하였다. PEG는 수침목재유물의 강화처리에 사용되며 목재 내에서 추출되는 착색유기물에 의해 용액의 색이 검은색으로 변화하게 되며, 폐 PEG 용액을 H2O2를 이용한 산화작용으로 용액 내에 존재하는 착색유기물을 분해하고 색을 되돌려 재활용하였다.