A study on the denitrification of reverse osmosis(RO) concentrated wastewater from sewage reuse treatment plant in P city was conducted using waste desulfurization agent obtained from desulfurization process. Sulfur-based autotrophic denitrifying carrier comprises the predetermined amount of waste iron sulfide (FeS, Fe2S3), mine drainage sludge and elemental sulfur showing mesoporisity with 9.9 nm (99 Å) of average pore size. Sulfur denitrifying bacteria and sulfur reducing bacteria were implanted into the pores of sulfur denitrifying carrier. Nitrate was not affected by empty bed contact time (EBCT). It is probably due to larger reducing capacity of the carrier than the concentration of nitrate in RO concentrated wastewater. Total nitrogen (T-N) removal efficiency exhibited about 90% after 4 days. Sulfate ion was surprisingly decreased with sulfur autotropic process due to the reduction of sulfate ion to HS- and S2- by sulfur reducing bacteria. Sulfide and hydrogen sulfide ions were then taken by Fe(OH)3, main component of mine drainage sludge, releasing OH-. Alkalinity was therefore maintained between 7.5 and 8.5 in pH by the released OH-. Also, it had the effect of suppressing the production of H2S, which causes bad odor.

In domestic nuclear power plants, drums of concentrated radioactive waste solidified with paraffin that do not meet radioactive waste disposal standards are stored temporarily. In this paper, the design of a machine that separates these paraffin drums into paraffin and concentrated waste using heating vaporization and pressure difference is described. The separation process is as follows. First, the paraffin solid is indirectly heated by heating the outside of the drum. The paraffin solid is partially melted to increase the fluidity and is easily detached from the drum. The detached solid is transferred to the melting tank, and further heated in the melting tank. When the temperature is sufficiently high, paraffin is melted and becomes a mixture of liquid paraffin and concentrated waste homogeneously. The mixed solution is transferred to a paraffin recovery vessel and further heated. The vaporization point of paraffin is 370°C under atmospheric pressure, and becomes lower depending on the pressure decreasing in the vessel. The vaporization point of the paraffin is a relatively low value compared to the radioactive elements in the concentrated waste, and therefore only paraffin would be vaporized. A paraffin transfer pipe is installed on the upper part of the paraffin recovery vessel, and is connected to another tank called the paraffin capture vessel. The pressure of the paraffin capture vessel is reduced (i.e. vacuum condition), only gaseous paraffin is transferred to the paraffin capture vessel by the pressure difference. When the paraffin capture vessel is cooled below the vaporization point of the paraffin, the paraffin is liquefied or solidified, and only the paraffin is recovered. Based on the above process, the solidified paraffin could be separated into pure paraffin and concentrated waste. However, if a radioactive element with a lower vaporization point than paraffin exists in the concentrated waste, it may be mixed with paraffin and separated together. Therefore, it is necessary to measure the radioactivity or radiation dose rate for the separated paraffin, and to verify that it is sufficiently low. If necessary, additional separation process may be considered for removing radioisotopes from the paraffin.

가압경수로 원전의 농축폐액건조설비에서 발생된 농축폐액 건조물을 유리화 하는 방안이 연구되어 왔다. 중저준위 방사성폐기물을 유리화할 경우 최종 생성물은 내구성이 우수하고 현저한 부피저감 효과의 장점을 가지고 있다. 붕산농축폐액에 대한 유리화 타당성 연구는 분말시료의 전처리 방법 개발, 유리조성 프로그램을 이용한 유리개발 및 실증시험으로 수행되었다. 분말시료에 대한 전처리 방안으로는 유리화설비에 투입하기 전에 고형성을 갖도록 펠렛화하는 것이다. 농축폐액 성분중 Na와 B의 함량 분포는 유리속에 용융되는 정도와 설비로부터의 폐기물 배출·처리에 영향을 주기 때문에 이를 고려하여 유리조성이 개발되어야 한다. 실증시험에서는 폐기물 투입률, 배기체 특성 및 최종 생성물인 유리고화체의 특성이 검토되었다. 본 연구는 붕산농축폐액에 대한 유리고화체의 물리화학적 특성을 검토하고 유리화 타당성을 확인하는데 목적이 있다.

폐액증발기 농축폐액의 폴리머고화를 위하여 붕산 함유 건조분말에 액상규산나트륨을 과립화제로 활용하여 점적 형태로 분사하고 평균 2~4mm 크기의 과립을 제조하는 농축폐액 과립화 설비를 제작하였다. 또한 폐수지 폴리머 고형화에 대해 미국 원자력규제위원회(NRC)의 인증을 받은 신규 고화기술을 과립화된 농축폐액에 성공적으로 적용하였다. 상기 고화설비는 기계적인 혼합 대신 중력을 이용한 in-situ 고화처리 방식으로 폐기물의 추가적인 부피증가가 없고 폐기물 적재량을 최대화할 수 있다. 생산된 폴리머 고화체의 성능평가를 위해 화재시험, 압축강도시험, 침출 및 침수시험, 방사선조사시험, 열순환시험을 표준시험법에 따라 수행하였다.

수은의 전과정 관리를 통한 환경배출 저감을 위한 미나마타 협약이 2017년 8월에 발효되면서 비준 절차를 진행하고 있는 우리나라 또한 수은을 함유한 제품 또는 폐기물을 친환경적으로 보관 및 폐기해야 한다. 우리나라는 의도적 사용을 위해 원소상 수은을 수입해 왔으나, 수은첨가제품 및 정광 불순물 등 비의도적으로 수은이 유입되어 왔다. 이렇게 비의도적으로 유입된 수은의 69%가 고농도 수은함유폐기물의 형태로 지정폐기물로 구분되어 지정폐기물 유입시설로 유입되고 있는 것으로 추정되고 있다. 그러나 수은함유 폐기물 매립시설 주변대기 중 수은 농도가 우려됨에 따라 수은함유 폐기물의 친환경적인 매립 관리기준과 함께 고수은함유폐기물의 회수 및 처리에 대한 관심이 높아지고 있다. 특히 수은은 대기로의 휘발량이 큰 금속으로 알려져 있으며, 수은함유 폐기물 매립지에서 원소상 수은의 형태로 전환되어 환경 중으로 재유입될 가능성이 있다. 국외의 경우 고농도 수은함유 폐기물의 회수 및 처리에 대한 기준을 두고 있으나 국내에서는 아직 수은 회수에 대한 법적 근거가 마련되어 있지 않은 상황이다. 본 연구에서는 국내 업체에서 발생하고 있는 고농도 수은함유폐기물(비철금속 발생 슬러지)을 대상으로 시간별 온도별에 따른 대상 폐기물 내 수은 함유량 및 용출량 실측을 통해 고농도 수은함유 슬러지 중 최대 비산율 및 온도별 속도상수를 구하고자 하였다. 이를 통해 고농도 수은함유 폐기물의 환경 중 수은 배출 저감 방향을 제시함으로 향후 수은함유 폐기물의 적정 관리기준 설정에 기초자료로 활용될 것으로 판단된다.

In previous research team had reported that the durability of carbonation is improved by filling voids due to the saponification reaction of oil and concrete. The purpose of this study was to have experimental investigation the effect of mock-up experiment on the carbonation resistance of the waste concrete admixture.

In previous research team had reported that the durability of carbonation is improved by filling voids due to the saponification reaction of oil and concrete. The purpose of this study was to have experimental investigation the effect of mock-up experiment on the carbonation resistance of the waste concrete admixture.

This study provides a result of thermal mercury reduction for inventing a mercury recovery technology from the sludgewhich contains high concentration of mercury. Physical, chemical and thermal properties of the sludge were analyzed andmercury degradation at elevated temperatures was investigated to find out the optimum temperature range for thermalrecovery of mercury from the sludge generated from an industrial facility, which contained high concentration of mercury.The study was carried out in the temperature range of up to 650oC from 200oC, and 500~710µm particle size of wastesludge samples were selected from such industries. As primary thermal tests the sludge was heated up to observe weightdegradation at a continuous weight measurable thermogravimetric analyzer and a muffle furnace and the degradationcurves from both devices were found to be well matched. Mercury conversion to gaseous form was investigated fromthe analyzed data of mercury concentrations sampled every 25oC from a muffle furnace. Cold vapor atomic absorptionspectroscopy (CVAAS) Hg analyzer was used for the analysis of mercury content in solid and liquid samples. Most ofmercury was degraded and released as gas phase at the temperature range from 300oC to 550oC, which could be theoptimum temperature of mercury recovery by thermal method for the sludge containing high concentration of mercury.Based on these thermal mercury reduction studies, degradation kinetics study of mercury was conducted to provide thereaction kinetics data for further reactor design to recover mercury using a thermal method.