• Membrane and Water Treatment
• /
• 제9권3호
• /
• pp.173-179
• /
• 2018

Microcystin-LR, one of algal toxins induced by the eutrophication of a reservoir, is known to be harmful to human by adversely affecting our liver and brain. Hypochlorous acid is very efficient to remove Microcystin-LR in a clear well. The previous researches showed that CT, pH and temperature affected removal rate in batch tests. It was noted that hydrodynamic properties of clear well could also influence its removal rate. A mathematical model was built using an axial dispersion reactor model and software was used to simulate the removal rate. The model consisted of the second order differential equations including dispersion, convection, Microcystin-LR reaction with chlorine. Kinetic constants were obtained through batch tests with chlorine. They were $0.430{\times}10^{-3}L/mg/sec$ and $0.143{\times}10^{-3}L/mg/sec$ for pH 7.0 and 8.1, respectively. The axial dispersion reactor model was shown to be useful for the numerical model through conservative tracer tests. The numerical model successfully estimated the removal rate of Microcyctin-LR in a clear well. Numerical simulations showed that a small dispersion number, low pH and long hydraulic retention time were critical for higher removal rate with same chlorine dosage. This model could be used to optimize the operation of a clear well during an eutrophication season.

• 상하수도학회지
• /
• 제10권4호
• /
• pp.64-72
• /
• 1996

The effect of $O_3$, $O_3/pH$, and $O_3/H_2O_2$, $O_3/UV$, and $H_2O_2/UV$ advanced oxidation process(AOP) were investigated for the treatment of tetrachloroethylen(PCE) at various condition. The removal efficiency of 10, 20, and 30ppm PCE by ozonation were almost same, only about 60%. And pseudo first-order rate constants, ko for overall oxidation was about 0.097($min^{-1}$). In the $O_3/pH$ AOP experiment for the 20ppm PCE, the removal rate of PCE increased with the increase of pH. However, mineralization rate of PCE at pH 7 was higher than at pH 10. In the $O_3/H_2O_2$ AOP, the removal rate of PCE was the highest at peroxide-to-ozone dosage ratio of about 0.9, which PCE was removed over 99.95%. Despite 42% of PCE was directly photolyzed by the UV irradiation, the removal efficiency of PCE by $O_3/UV$ AOP was only about 70%. In $H_2O_2/UV$ AOP, the removal efficiency of PCE increased to about 98% in proportion to the $H_2O_2$ injection concentration at constant UV intensity of 5W/l.

• 대한환경공학회지
• /
• 제30권12호
• /
• pp.1255-1261
• /
• 2008

생물활성탄(BAC) 재질별 EBCT 및 수온변화에 따른 HAA 5종의 생물분해 특성을 조사한 결과 다음과 같은 결론을 얻을 수 있었다. 본 연구에서 BAC에서 HAA 제거시 EBCT와 수온이 매우 큰 영향을 미치는 것으로 나타났다. EBCT와 수온을 증가시킬 경우 HAA의 제거율이 상승하였으며, 수온이 20$^{\circ}C$ 보다 높을 경우 HAA의 제거능은 EBCT의 영향을 크게 받지 않는 것으로 나타났다. 하지만 수온이 5$\sim$10$^{\circ}C$ 정도로 낮을 경우는 EBCT의 증가가 HAA의 제거율에 큰 영향을 미치는 것으로 나타났다. 활성탄 재질에 따른 BAC에서의 HAA 제거는 석탄계 재질에서의 생물분해능이 가장 높았고, 다음으로 야자계, 목탄계 순으로 조사되었다. HAA 5종에 대한 생물분해 속도상수와 반감기는 수온이 5$^{\circ}C$일 때의 HAA 5종에 대한 생물분해 속도상수(k)와 반감기(t$_{1/2}$)는 0.0373$\sim$0.1175 min$^{-1}$, 반감기는 5.9$\sim$18.58분이었으며, 수온을 10$^{\circ}C$와 20$^{\circ}C$로 증가시켰을 때 5$^{\circ}C$일 때와 반감기를 비교해 보면 1.5$\sim$7.9배로 감소되었다.

• KSBB Journal
• /
• 제19권2호
• /
• pp.143-147
• /
• 2004

휘발성 황화합물 중 생물학적으로 가장 난분해성으로 알려 져 있는 DMS에 대한 분해능이 우수한 신균주를 분리. 동정 하여 Gordonia sihwaniensis PKL-1로 명명하였다. 이 균주는 D DMS 초기농도가 35 mg/L 이상일 때에도 우수한 분해능을 보였고, 회분식 배양에서 최대 비분해속도 $\upsilon_{max}$ 없는 0.0016 mg/(mg-protein).hr이 었고, 최적 의 온도와 pH는 각각 $25^{\circ}C$ 와 pH는 7이였다.

• Advances in environmental research
• /
• 제5권1호
• /
• pp.37-50
• /
• 2016

The main objective of this study is to evaluate adsorptive removal of Methylene Blue (MB) dye from aqueous solution using pumice powder. The effects of pH, adsorption time, agitation speed, adsorbent dose, and dye concentrations on dye adsorption were investigated. Process kinetics and isotherm model constants were determined accordingly. The results showed that adsorbent dose, dye concentration and agitation speed are the important parameters on dye adsorption and the removal of MB did not significantly change by varying pH. A total adsorption process time of 60 min was observed to be sufficient to effectively remove 50 mg/L MB concentration. The MB adsorption data obeyed both pseudo first order and second order kinetic models. Adsorption of MB by pumice fitted well both Langmiur and Freundlich isotherms ($R^2{\geq}0.9700$), except for 150 rpm agitation speed that system fitted only Langmiur isotherm. The results of this study emphasize that pumice powder can be used as a low cost and effective adsorbent for dye removal.

• 한국물환경학회지
• /
• 제27권2호
• /
• pp.141-146
• /
• 2011

Loess, a natural clay, was evaluated as an adsorbent for the decolorization of Acid Orange II, an azo and reactive dye, from aqueous solution. Adsorption studies were performed at $30^{\circ}C$ and the effect of reaction time, loess dosage, initial concentration, loess particle size, pH, agitation rate were investigated to determine the optimum operation conditions. The removal efficiencies of color were measured to evaluate the effectiveness of loess. From this study, it was found that optimal reaction time was 10 min. Color removal efficiencies of Acid Orange II were increased as higher loess dosage, initial concentration and agitation rate. However, color removal efficiencies decreased when pH is high and loess particle becomes large. Adsorption of Acid Orange II fitted to the pseudo-second-order rate kinetics more than first-order rate kinetics. Langmuir and Freundlich adsorption isotherm constants and correlation coefficients were calculated and compared. It was concluded that the adsorption data of Acid Orange II onto loess fitted to the Freundlich model more than Langmuir model.

• 한국환경보건학회지
• /
• 제23권4호
• /
• pp.127-132
• /
• 1997

The characteristics of the ozone treatments of phenol were studied in a laboratory scale wastewater treatment system. The ozone treatment of wastewater was carried out in a batch-type reactor. The initial pH of wastewater(7-10), volumetric flow rate(1-2l/min) and ozone concentration(20~30 mg/l) of aerating gas were considereal as experimental variables in the ozone treatment. Phenol was decomposed easily by the ozone in a batch treatment, where the rate determining step was the COD removal that is decomposition of intermediates formed by the ozonation of phenol. Phenol decomposition and COD removal could be expressed by the first order reaction for the phenol concentration and COD, respectively. Rate constants of phenol decomposition and COD removal increased with the initial pH, volumetric flow rate and ozone concentration of aeration gas. Under the present experimental condition, their relationships could be given by for the phenol decomposition $k'=4.46\times 10^{-9}[pH]_o ^{3.94}[O_3]^{1.42}Q_{O3}^{1.57}$ for the COD removal $k=2.46\times 10^{-10}[pH]_o ^{5.19}[O_3]^{1.15}Q_{O3}^{1.19}$

• Environmental Engineering Research
• /
• 제20권1호
• /
• pp.89-97
• /
• 2015

Remediation of wastewater contaminated with metal(II)-complexed species (Cu(II)-NTA (NTA: nitrilotriacetic acid), Cu(II)-EDTA (EDTA: ethylenediamine tetraacetic acid) and Cd(II)-EDTA is attempted using the potential applicability of ferrate(VI). Kinetics of pollutant degradation is obtained with the removal of ferrate(VI) studied at wide range of pH (8.0-10.0) and the concentration of metal(II)-complexed species (0.3 to 15.0 mmol/L) employing a constant dose of ferrate(VI) i.e., 1.0 mmol/L. Pseudo-first-order and pseudo-second-order rate constants were obtained in the reduction of ferrate(VI) which was then employed to obtain the overall rate constants of the pollutant degradation. The mineralization of NTA and EDTA was obtained with the change in TOC (total organic carbon) values collected by the ferrate(VI) treated pollutant samples. Decrease in pH and molar pollutant concentrations was greatly favored the percent mineralization of NTA or EDTA by the ferrate(VI) treatment. The treated pollutant samples were filtered and subjected for AAS (atomic absorption spectrophotometric) analysis to assess the simultaneous removal of copper and cadmium from aqueous solutions at the studied pH as well at the elevated pH 12.0. Results show that an enhanced removal of cadmium or copper was achieved at pH 12.0. Overall, ferrate(VI) possesses multifunctional application in wastewater treatment as it oxidizes the degradable impurities and removes metallic impurities by coagulation process.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
• /
• pp.68-71
• /
• 2004

Effects of surfactants and natural organic matter (NOM) on the sorption and reduction of tetrachloroethylene (PCE) and chromate with iron were examined in this study. PCE and chromate reduction by iron depended on the ionic type of the surfactants in this study. The apparent reaction rate constants of PCE with Triton X-100 and hexadecyltrimethyl ammonium (HDTMA) at one half and two times of the critical micelle concentration (CMC) were relatively higher than without surfactants because of the enhanced PCE partitioning and surface concentration. In the presence of sodium dodecyl benzene sulfonate (SDDBS) at 2000 mg/L and NOM at 50 mg/L, the apparent reaction rate constants of PCE increased, but TCE production decreased. The enhanced removal rate of PCE was not due to the dechlorination, and the sorption was dominant iron with SDDBS and NOM. The apparent reaction rate constants of chromate by iron with Triton X-100 and NOM were 1.4-3.1 times lower than without surfactants while that with HDTMA was two times higher than without HDTMA, When the sorbed HDTMA molecules form admicelles, negatively-charged chromate has an affinity for the positively-charged HDTMA head group.

• 대한환경공학회지
• /
• 제34권3호
• /
• pp.195-203
• /
• 2012

재질별 생물활성탄(BAC) 및 안트라사이트 biofilter에서 EBCT 및 수온변화에 따른 인공사향물질(SMCs) 3종의 생물분해 특성을 조사한 결과 다음과 같은 결론을 얻을 수 있었다. 생물활성탄(BAC) 공정에서 인공사향물질 3종의 제거는 EBCT와 수온에 따라 큰 영향을 받으며, EBCT와 수온이 증가할수록 제거능이 증가하였다. 물질에 따른 제거능은 MK가 가장 높았고 다음으로 HHCB, AHTN 순이었다. 또한, 활성탄 재질에 따른 생물활성탄(BAC) 및 안트라사이트 biofilter에서의 인공사향물질 3종의 제거는 석탄계 재질의 BAC에서 생물분해능이 가장 높았고, 다음으로 목탄계, 야자계, 안트라사이트 순으로 조사되었다. 인공사향물질 3종에 대한 생물분해 속도상수($K_{biodeg}$)와 반감기($t_{1/2}$)는 수온이 $5{\sim}25^{\circ}C$일 때 0.0082~0.4452 $min^{-1}$와 1.56~84.51 min이었으며, 수온이 $15^{\circ}C$와 $25^{\circ}C$로 증가시켰을 때 $5^{\circ}C$에서의 반감기보다 3.1~9.3배 감소되었다.