We applied column experiments to investigate the environmental fate and transport of silver nanoparticles(AgNPs) in fully saturated conditions of porous media. These column experiments were performed to emphasize oxidation method with H2O2 concentration and acidic conditions. The mobility of AgNPs was decreased with the increasing ionic strength that the surface charge of AgNPs(zeta potential) was neutralized with the presence of positive ions of Na+. Additionally, it was also affected due to that not only more increased aggregated size of AgNPs and surface charge of quartz sand. The decreased breakthrough curves(BTCs) of bisphenol-A(BPA) and 17α-ethynylestradiol(EE2) were removed approximately 35.3 and 40%. This is due to that endocrine disrupting chemicals(EDCs) were removed with the release of OH․ radicals by the fenton-like mechanisms from acidic and fenton-like reagent presenting. This results considered that higher input AgNPs with acidic conditions is proved to realistic in-situ oxidation method. Overall, it should be emphasized that a set of column experiments employed with adjusting pH and H2O2 concentration in proved to be effective method having potential ability of in-situ degradation for removing organic contaminants such as BPA and EE2.

Recent Engineered nanoparticles were increasingly exposed to environmental system with the wide application and production of nanomaterials, concerns are increasing about their environmental risk to soil and groundwater system. In order to assess the transport behavior of silver nanoparticles (AgNPs), a saturated packed column experiments were examined. Inductively coupled plasma-mass spectrometry and a DLS detector was used for concentration and size measurement of AgNPs. The column experiment results showed that solution chemistry had a considerable temporal deposition of AgNPs on the porous media of solid glass beads. In column experiment, comparable mobility improvement of AgNPs were observed by changing solution chemistry conditions from salts (in both NaCl and CaCl2 solutions) to DI conditions, but in much lower ionic strength (IS) with CaCl2. Additionally, the fitted parameters with two-site kinetic attachment model form the experimental breakthrough curves (BTCs) were associated that the retention rates of the AgNPs aggregates were enhanced with increasing IS under both NaCl and CaCl2 solutions.

Soil column experiments were evaluated effects of silver nanoparticles (i.e., 0, 2.5, 5, and 10 mg/L) on the microbial viability which is strongly associated with the degradation of organic matter, pharmaceutically active compounds(PhACs) and biological oxidation of nitrogenous compounds during river bank filtration. The addition of silver nanoparticles resulted in almost no change in the aqueous matrix. However, the intact cell concentration decreased with addition of silver nanoparticles from 2.5 to 10 mg/L, which accounted for 76% to 82% reduction compared to that of control (silver nanoparticles free surface water). The decrease in adenosine triphosphate was more pronounced; thus, the number and active cells in aqueous phase were concurrently decreased with added silver nanoparticles. Based on the florescence excitation-emission matrix and liquid chromatograph - organic carbon detection analyses, it shows that the removal of protein-like substances was relatively higher than that of humic-like substances, and polysaccharide was substantially reduced. But the extent of those substances removed during soil passage was decreased with the increasing concentration of silver nanoparticles. The attenuation of ionic PhACs ranged from 55% to 80%, depending on the concentration of silver nanoparticles. The attenuation of neutral PhACs ranged between 72% and 77%, which was relatively lower than that observed for the ionic PhACs. The microbial viability was affected by silver nanoparticles, which also resulted in inhibition of nitrifiers.

우리나라에서는 5개 발전사의 10개 화력발전소에서 2013년 기준으로 약 891만 톤의 석탄재가 발생하고 있다. 석탄재는 약 82%가 비산재, 18%는 바닥재로 구성되어있으며, 이 중 비산재는 대부분 레미콘혼화제 및 시멘트 대체원료 등으로 재활용되고 있으나 바닥재는 발전소 내의 매립시설에 보관되어 있는 실정이다. 본 연구에서는 바닥재의 토양으로 재활용 가능성을 평가하고자 하였으며, 석탄재가 함유하고 있는 유해물질을 중심으로 석탄재의 환경영향 가능성 평가를 위해 SP 및 HD석탄재를 각각 단독 또는 토양과 혼합하여 컬럼시험(Percolation test)을 진행하였고, 대조군시험을 위해 비오염토양을 확보하여 동일하게 분석을 수행하였다. 컬럼시험에 사용한 유입수는 해수, 산성강우(pH 4.5), 증류수이며, 유입 유속을 1 mL/min으로 유지하여 운전하였다. 각 컬럼에서 2L씩 최대 15 Fraction의 용출액을 채취하였으며, 채취한 즉시 pH, 온도 및 전기전도도를 측정하였고, 이 외에 생태독성, 중금속 및 이온물질을 분석하여 유해물질 용출 패턴을 확인하였다. 컬럼 용출액 중 pH를 모니터한 결과, SP 석탄재는 8.20~8.78, HD 석탄재는 7.63~8.03 범위를 보였다. 석탄재에 함유되어 있는 다양한 중금속의 용출패턴을 확인한 결과, 전반적으로 유출량에 따른 뚜렷한 감소특성을 보이지 않았다. 철(Fe)은 초기 용출액에서 낮은 농도가 검출되다가 6 Fr 이후부터 높은 농도가 유출되었고, 다시 12 Fr 이후부터 감소하였다. 석탄재를 단독으로 사용한 컬럼에 비해 토양과 혼합한 컬럼의 용출액 중 보론(B) 농도가 낮은 것으로 나타났다. Al, Mn, Ni, Sb, Se 등은 특별한 경향을 보이지 않았으며, 이 외에 분석한 중금속 항목 중에 Cd, Cu, Pb, Zn, Hg, 6가크롬은 용출액에서 모두 불검출 되었다. 용출액을 가지고 물벼룩의 급성독성을 시험하여 유입수에 따라 독성 수준이 다른 것을 확인하였다. 즉, 석탄재 자체의 독성보다는 해수, 담수, 산성강우 등 유입수의 영향을 받는 것으로 보인다. 증류수를 유입한 컬럼 중 SP석탄재는 모두 불검출 되었고, HD석탄재에서는 첫 번째 유출액에서만 1 TU이상의 값이 나오다가 이후 감소되었다. 해수를 흘려준 컬럼에서는 염도의 영향으로 1~2 TU 이상이 5 Fr 까지 유지되었고, 산성강우를 흘려준 SP석탄재와, 토양과 혼합한 HD석탄재 컬럼에서는 10 Fr 까지 1 TU이상을 유지하였으며 최대 8.2 TU의 독성을 나타내었다. 국내에서는 생태독성을 산업폐수 배출허용기준으로 적용하고 있으며, 청정지역과 청정지역 외로 구분하여 각각 1 TU와 2 TU로 규제하고 있다. 미국 델라웨어주와 뉴욕주, 독일의 폐수종말처리장에서도 2 TU로 관리하고 있다. 석탄재중 용출시험 결과 2 Fr 이후부터는 2 TU 이하를 유지하는 것으로 나타났으나, 일부 컬럼의 초기 용출액에서 나타난 독성영향에 대해서는 추가적인 검토가 필요하다.