When aluminum is in an alkaline state, the aluminum oxide film surrounding aluminum is dissolved and moisture penetrates the exposed aluminum surface, causing corrosion of aluminum. At this time, hydrogen gas is generated and there is a risk of explosion due to the generated hydrogen gas. Aluminum radioactive waste is difficult to permanently dispose of because it does not meet the standards for the acquisition of low- and intermediate-level radioactive waste cave disposal facilities currently managed and operated by the Korea Nuclear Environment Corporation. However, because of this risk, it is necessary to study how to safely treat and dispose aluminum waste. In this study, overseas cases were investigated and analyzed to ensure the safety of aluminum waste disposal, and the current status of aluminum radioactive waste generated during decommissioning of the Korea Research Reactor 1&2 and a treatment plan to secure disposal suitability were presented. The process of removing a little remaining oxygen in molten steel during the reduction of iron oxide in the iron refining process is called deoxidation, and a representative material used for deoxidation is aluminum. In the case of metal melting decontamination, which is one of the decontamination processes of radioactive metal waste, a method of treating aluminum waste by using aluminum as a deoxidizer is proposed.

A large amount of small and medium-sized metal waste is generated during the decommissioning of nuclear power plants (NPPs). Metal waste is mostly contaminated with low-level radioactive, so it needs decontamination for self-disposal and recycling. A large amount of Organic Decontamination Liquid Waste during decontamination will be generated. The generated organic liquid waste is low in concentration, so the decomposition efficiency is low in the decomposition process. A conditioning process is necessary to concentrate at a high concentration. For effective treatment for Organic Decontamination Liquid Waste, the composition of organic liquid waste and conditioning process were analyzed. Organic acids, metal ions, radioactive nuclides, surfactants, etc. are present in the Organic Decontamination Liquid Waste, and suspended solids are sometimes generated by various reactions. According to previous studies, the concentration of organic acids including surfactants obtained results from several tens of ppm to a maximum of 1,000 ppm, so the maximum value of 1,000 ppm was assumed. For the composition and total amount of metal ions, the average value (52.7wt% Fe, 16.3wt% Ni, 15.1wt% Cr, 15.9wt% Mn) of the distribution of metal species removed by the actual decontamination process is applied, and the total amount is 1,000 ppm was assumed. As for the radionuclides, only 60Co and 137Cs, which are expected to be mainly present, were considered, and 60Co was assumed to be 2,000 Bq/g and 137Cs to be 360 Bq/g by referring to the literature. The amounts of suspended solids were assumed to be 500 ppm by referring to the characteristics of the liquid waste generated in the decontamination process of the NPPs. Based on the estimated value, a reaction formula was established and a simulated Organic Decontamination Liquid Waste was prepared. As a result of measurement using an analysis device, the composition of the estimated and simulated Organic Decontamination Liquid Waste had similar values. The conditioning and treatment process largely consists of pretreatment, conditioning, decomposition processes. Organic Decontamination Liquid Waste goes through a pretreatment process to remove impurities with large particles. In the conditioning process, treated water that has passed through the UF/RO membrane system is discharged into the environment. At this time, Concentrated water goes through a decomposition process for processing the Organic Decontamination Liquid Waste, and is discharged to the environment through a secondary RO membrane system. The conditioning process is the low-concentration Organic Decontamination Liquid Waste in the UF membrane system is forming a micelles in an RO membrane system, concentrating it to a high concentration and then go through a recirculation process in the UF membrane system. An experiment was conducted to confirm whether the concentration of surfactants occurred during the conditioning process. As a result of the experiment confirmed that the highly concentrated surfactant formed micelles and was filtered out in the UF membrane system.

Thermal treatment, such as combustion, is the most effective way to solve the spatial problem of radioactive waste disposal. Existing incineration technology has the problem of discharging harmful pollutants (CO2 and dioxin, etc.) into the environment. Therefore, it was evaluate the validity of the thermal treatment process that can reduce the volume of dry active waste (DAW) in an eco-friendly. In addition, the stability of the alternative incineration process under development was evaluated by evaluating the emission of harmful pollutants to the environment during the thermal treatment process. We selected 14 samples identical to those discarded by each nuclear power plant (Kori, Saeul, Wolsong, Hanbit, Hanul). And EA (Elemental Analysis) analysis was performed on each sample. As a result, excluded samples containing wastes containing POPs (Persistent Organic Pollutants) such as PCBs (Polychlorinated Biphenyls), which could generate harmful pollutants during thermal treatment, and halogenated organic wastes such as PVC (Polyvinyl Chloride). In addition, the thermal treatment conditions for the four DAWs were derived by Thermogravimetric Analysis/Differential Thermal Analysis (TG/DTA) analysis. At this time, Py-GC/MS analysis was performed at the temperature at which each waste causes thermal decomposition (cotton is 437°C, paper is 562°C, latex glove is 430°C, plastic bag is 485°C). As a result of analyzing the exhaust gas produced during thermal decomposition, about 77.0% of the cotton was Benzoic acid series, the paper was 41.1% Glucopyranose series, and 15.8% hydroxy acetaldehyde. Latex glove was identified to be 45.9% and 19.2% for Limonene and 2-methyl-1, 3-Butadiene, and for plastic bags, Octacosanol and 2-octyl-1-Dodecanol were 38.8% and 15.2%. In addition, it was confirmed that dioxin and harmful heavy metals, which are discussed as environmental risks, were not detected in all samples.

Organic waste generated by small and medium-sized (S&M-sized) metal decontamination in NPP decommissioning. To lower the concentration of these organic substances for a level acceptable at the disposal site, the project of “Development of Treatment Process of Organic Decontamination Liquid Wastes from Decommissioning of Nuclear Power Plants” is being carried out. The conditioning and treatment process of organic liquid waste was designed. Also, the literature was investigated to make simulated organic liquid waste, and the composition of these waste was analyzed and compared. As the decontamination agent, organic acids such as EDTA, oxalic acid, citric acid are used. The sum of the concentrations of these organic materials was set to a maximum value of 1,000 ppm. The major metal ions of the decontamination liquid waste estimated are 59Fe, 51Cr, 54Mn, 63Ni, and the concentrations are respectively 527, 163, 161, 159 ppm. Additional major metal ions are 60Co, 58Co, 137Cs. 58Co is replaced by 60Co because it has the same chemical properties as 60Co. Unlike the HLW, the contamination level of S&M-sized metal in primary system was quite low, so 60Co is set to 2,000 Bq/g. Considering the contribution of fission and gamma ray dose constant, 137Cs was estimated to 360 Bq/g. Also, suspended solids of decontamination liquid waste were set at 500 ppm. Under these assumptions, the simulated organic liquid waste was made, and then organic substances and metal ions were analyzed with TOC analyzer and ICP-OES. The TOC analysis value was expected to 392 ppm in consideration of the equivalent organic quantity. the test result was 302 ppm. Some of organics appears to have been decomposed by acid. The values of metal ions (Fe3+, Cr3+, Mn2+, Ni2+) analyzed by ICP-OES are 139, 4, 152, 158 ppm, respectively. A large amount of Cr3+ and Fe3+ were expected to exist as ions, but they existed in the form of suspended solid. Mn2+ and Ni2+ came out similar to the expected values. The designed conditioning and treatment process is largely divided into pretreatment, conditioning, and decomposition processes. After collecting in the primary liquid waste storage tank, large particulate impurities and suspensions are removed through a pretreatment process. In the conditioning process, treated liquid waste passes through UF/RO membrane system, and pure water is discharged to the environment after monitoring. Concentrated water is decomposed in the electrochemical catalyst decomposition process, then this water secondarily passes through the RO membrane system and then discharged to the environment after monitoring. Through an additional experiment, the conditioning and treatment process will be verified.

Liquid scintillation cocktail is liquid waste, which consists of an organic solvent, scintillator, surfactant, and radionuclide. Large volumes of liquid scintillation waste are generated each year, and both the organic compound and radionuclide content can negatively affect on the health and the environment. Therefore, the liquid scintillation waste should be treated in an appropriate way. In this study, to facilitate the treatment of liquid scintillation waste, the sulfate-radical advanced oxidation process (SR-AOP) was performed for the mineralization of liquid scintillator waste. In SR-AOP, highly reactive sulfate radicals, which react more selectively and efficiently with organic compounds, are produced in situ by cleaving the peroxide bond in the persulfate molecule. For the experiment, 100 times diluted ULTIMA GOLD-LLT (initial TOC=699,800 ppm) was used as a liquid scintillation waste. The TOC removal efficiency of liquid scintillation waste by the OXONE (potassium peroxymonosulfate, PMS, 2KHSO5+KHSO4+K2SO4) and sodium persulfate (PS) with varying dosages (4–12 mM) was tested, and the effects of Co2+ and Cu2+ catalysts were compared at a range of pHs (3, 7, and 9). The experimental results demonstrated that 91% TOC removal of ULTIMA GOLD-LLT could be achieved for SR-AOP at initial pH=9, Co2+=1.2 mM (catalyst), PMS=4.8 mM (oxidant) for 60 min reaction. Compared to traditional Fenton AOP which is effective only at low pH, PMS based SR-AOP with Co2+ catalyst is effective at wide range of pHs and less dependent on the treatment efficiency of the operational pH. Therefore, it can be useful for the mineralization of liquid scintillation waste which is difficult to treat with a general treatment method due to the mixture of various organic compounds.

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.

해양환경관리공단은 MARPOL 73/78에 따른 해양환경 보전을 위하여 1998년 정부로부터 전국 13개 주요 항만에 위치한 선박폐수 처리시설을 위탁받아 운영해왔다. 이 시설은 선박폐수를 처리함에 있어 단순히 해양환경관리법에서 정한 유분농도(n-H 광유류) 15ppm을 충족할 수 있도록 설계되어 운영되어 왔다. 그러나 선박폐수에는 n-H 광유류 뿐만 아니라 유기물에 의한 악취와 각종 불순물이 함유되어 있기 때문에 이들이 처리되지 않고 그대로 해양에 배출됨으로써 해양오염은 물론 주변 인가 등으로부터 민원의 대상이 되었다. 이에 따라 공단은 지난 2007년 선박폐수 처리공정 개선 작업을 시행하여 새로운 수처리 약품을 개발하여 적용하고, 오존을 이용하여 기존의 공정을 3~4 단계 줄이면서도 배출수의 유분농도 뿐만 아니라 콜로이드물질, ABS, 인, 질소 등 난분해성 유기물질과 미생물 분해에 의한 악취를 효과적이고 혁신적으로 저감 시킬 수 있는 새로운 공정을 개발하여 현장에 적용시켰다. 새로운 공정은 각종 오염물질과 악취를 획기적으로 제거할 뿐만 아니라 공정의 단순화를 통해 시설 유지비 10% 이상 절감 등 13개 선박폐수 처리시설 운영비를 매년 1억6천만원 이상 줄일 수 있는 획기적인 공정으로 방법특허를 출원하였다.

반응성 페놀수지 폐액을 처리하기 위해 중공사막 모듈을 이용한 투과증발 막 탈수공정을 연구하였다. 이 공정의 거동을 예측하기 위한 모사모델을 확립하였고 여기에 사용되는 중요 기본 파라메타들을 평판형 막을 사용하여 직접 구하여 사용함으로써 공정모사의 정확성을 얻을 수가 있었다. 이들을 모사치와 중공사 투과증발 막으로 부터 직접 측정한 각 투과특성들을 비교한 결과 서로 잘 일치함을 보여 본 모사모델의 타당성을 입증하였다. 사용된 중공사막은 중공사 안쪽에 활성층이 도포되어 있으며 공급액은 중공사 내부로 공급하였다. 공급액의 막내에서의 흐름속도에 따라 온도분포가 결정되며 이에 따라 막 투과특성이 달라짐을 모사결과로부터 얻을 수가 있었다. 공급액 온도증가는 막을 통한 탈수 투과 속도를 증가시킬 뿐 아니라 반응속도 증가로 인하여 물 생성속도도 증가시킴으로써 공급액 저장조 내의 수분 함량은 이들 상반된 공정들에 의해 결정이 됨을 보였다. 투과압력이 공급액 증기압보다 훨씬 작은 범위에서 증가할 경우 투과추진력인 공급액과 투과부의 투과물 활성도비 감소가 크지 않아 투과특성을 약간 저하시킨다. 그러나 투과압력이 공급액의 증기압에 접근할 경우 활성도비 감소가 현저하게 일어나 투과특성저하가 급격히 일어난다.