Bacterial metabolisms influence the behavior of uranium (U) in deep geological repository (DGR) system because bacteria are ubiquitous in the natural environment. Nevertheless, most studies for the U(VI) bioreduction have focused on a few model bacterium, such as Shewanella putrefaciens, Desulfovibrio desulfuricans, and Geobacter sulfurreducens. In this study, the potential of aqueous U(VI) ((U(VI)aq) reduction by indigenous bacteria was examined under anaerobic conditions with addition of 20 mM sodium acetate for 24 weeks. Three different indigenous bacterial communities obtained from granitic groundwater at depths of 44–60 m (S1), 92–116 m (S2), and 234–244 m (S3) were applied for U(VI)aq reduction experiments. The S2 groundwater contained the highest U concentration of 885.4 μg/L among three groundwater samples, where U mainly existed in the form of Ca2UO2(CO3)3(aq). The S2 groundwater amended 20 mM of sodium acetate was used for the U(VI)aq bioreduction experiment. Variations in the U(VI)aq concentration and redox potential were monitored for 24 weeks to compare U(VI)aq removal efficiency in response to indigenous bacteria. The U(VI)aq removal efficiencies varied among three indigenous bacteria: 57.8% (S3), 43.1% (S2), and 37.7% (S1). The presence of the thermodynamically stable uranyl carbonate complex resulted in the incomplete U(VI)aq removal. Significant shifts in indigenous bacterial communities were observed through highthroughput 16S rRNA gene sequencing analysis. Two SRB species, Thermodesulfovibrio yellowstonii and Desulfatirhabdium butyrativorans, were dominant in the S3 sample after the anaerobic reaction, which enhanced the bioreduction of U(VI)aq. The precipitates produced by bacterial activity were determined to be U(IV)-silicate nanoparticles by a transmission electron microscope (TEM)-energy dispersive spectroscope (EDS) analysis. These results demonstrated that considerable U immobilization is possible by stimulating the activity of indigenous bacteria in the DGR environment.

The United States’ Inflation Reduction Act (IRA) introduces new eligibility requirements for existing USD 7,500 tax-credit provided to electric vehicles. The new requirements condition the credit upon North American final assembly and North American-sourced materials and components. As tensions flare between the US and China, these new local content requirements reflect the US’s effort to establish a supply chain for electric vehicles that circumvents China. The blow, however, is felt elsewhere, namely by South Korean auto makers whose electric vehicle models are no longer eligible for the significant tax-credit necessary to compete in the American market. As South Korea considers submitting a complaint to relevant international bodies, this paper dissects the IRA’s relevant provisions and analyzes the applicability of international trade law rules of the WTO and the Korea-US Free Trade Agreement to the new local content requirements of the IRA.

탄소전극과 이온교환막을 결합한 막결합 축전식 탈염(MCDI) 셀을 이용하여 환원전위가 다른 Na+과 Cu2+ 이온 혼합용액에서 Cu2+ 이온의 제거 특성을 연구 하였다. MCDI 셀에 일정한 전류밀도(1.5 mA/cm2)를 공급하면서 탈염을 실시한 결과 Cu2+ 이온은 일정한 제거속도를 유지하였지만 Na+ 이온의 제거량은 시간에 따라 감소하였다. 이는 Cu2+ 이온은 전착반응에 의해, Na+ 이온은 전기흡착 반응에 의해 제거되기 때문인 것으로 판단된다. Cu2+ 이온의 당량비가 0.14, 0.38, 0.50인 혼합용액을 탈염한 결과 제거된 이온 중 Cu2+ 이온의 당량비는 각 각 0.27, 0.60, 0.79로 나타났다. 이를 통해 Cu2+ 이온의 전착반응에 의해 혼합용 액에서 Cu2+ 이온의 제거율을 증가시킬 수 있음을 알 수 있었다.

우리나라는 국토환경의 제한과 매년 증가되는 폐기물로 인한 대책으로 미처리폐기물의 매립제로화를 추진하고 있다. 특히 자원순환촉진법 제정을 통해 2035년까지 이용 가능한 폐기물의 직매립을 금지하여 매립비율을 1 % 이하로 목표하였다. 2015 국내 전체 폐기물의 매립처리량은 38,308 톤/일이며 이중 사업장배출시설계폐기물의 매립처리량은 23,577 톤/일로 약 62 %를 차지하고 있다. 사업장배출시설계폐기물인 유기성, 무기성오니류의 매립처리량은 8,926 톤/일로 매립제로화를 달성하기 위하여 재활용과 감량화가 필요하다. 본 연구에서는 유･무기성오니류를 배출사업장 업종별로 구분하여 에너지회수로서 재활용 활성화 방안 등과 같은 간접적인 측면과 열적감량을 통한 감량과 같은 직접적인 측면을 통한 매립억제 가능량에 대해 고찰하였다. 유기성오니류의 경우 수분 전처리를 통한 감량화 및 에너지회수로 매립비율 감소효과가 오니류 매립처리량의 40 %의 감소가 예상되며, 무기성오니류에 대하여 추가적으로 직접적인 반입기준을 강열감량 5 ~ 10 % 적용을 한다면 오니류 매립처리량의 73 % 매립처리량 감소가 가능할 것으로 추산된다.

토양 하부 및 지하수에 생존하고 있는 미생물들이 지하수의 산화/환원전위 변화에 관여하는 사실을 알아보기 위해 미생물들을 주입한 수용액의 시간별 Eh 변화량을 측정하였다. 황산염환원 미생물이 주입된 경우 수용액의 Eh값이 5일 만에 -120 mV에서 -500 mV까지 떨어졌으며, 실험 결과 디설프리칸스 세균이 불가리스 세균보다 수용액을 환원하는 능력이 상대적으로 좋았다. 철환원 미생물인 스와넬라 세균의 경우 Eh값이 황산염환원 세균보다 조금 높은 -400 mV를 보여 주었다. 금속환원미생물에 의해 수용액의 Eh값이 떨어지는 동안 용존 황산염 혹은 산화철이 환원되고 맥키나와이트(FeS)라는 황화광물이 형성되기 시작하였다. 이러한 실험 결과를 바탕으로 일반 지하수의 산화/환원전위는 그 지하수에 생존하고 있는 지하미생물들의 대사 활동에 많은 영향을 받고 있다는 사실과 극환원된 지하수 및 생기원 황화광물들이 풍부한 지하 환경은 산화 핵종들이 환원된 형태로 침전되어 핵종 이동이 억제될 가능성이 높은 곳으로 판단된다.

The SBR(Sequencing Batch Reactor) process is ideally suited to treat high loading wastewater due to its high dilution rate. SBR operates by a cycle of periods consisting of filling, reacting, settling, decanting and idling. The react phases such as aeration or non-aeration, organic oxidation, nitrification, denitrification and other biological reactions can be achieved in a reactor. Although the whole reactions can be achieved in a SBR with time distributing, it is hard to manage the SBR as a normal condition without recognizing a present state. The present state can be observed with nutrient sensors such as NH4+-N, NO2--N, NO3--N and PO43--P. However, there is still a disadvantage to use the nutrient sensors because of their high expense and inconvenience to manage. Therefore, it is very useful to use common on-line sensors such as DO, ORP and pH, which are less expensive and more convient. Moreover, the present states and unexpected changes of SBR might be predicted by using of them. This study was conducted to get basic materials for making an inference of SBR process from ORP(oxidation reduction potential) of synthetic wastewater. The profiles of ORP, DO, and pH were under normal nitrification and denitrification were obtained to compare abnormal condition. And also, nitrite and nitrate accumulation were investigated during reaction of SBR. The bending point on ORP profile was not entirely in the low COD/NOx ratio condition. In this case, NOx was not entirely removed, and minimum ORP value was presented over -300mV. Under suitable COD/NOx ratio which complete denitrification was achieved, ORP bending point was observed and minimum ORP value was under -300mV. Under high COD/NOx ratio, ORP bending point was not detected at the first subcycle because of the fast denitrification and minimum ORP value was under -300mV at the time.