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ORP profile을 이용한 연속 회분식 반응기(Sequencing Batch Rector)에서 무산소공정 추론
심문용,부경민,임정훈,우혜진,김창원 한국환경과학회 2004 한국환경과학회지 Vol.13 No.3
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 PO₄^(3-)-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.
Poo, Kyung-Min,Son, Eun-Bi,Chang, Jae-Soo,Ren, Xianghao,Choi, Yun-Jung,Chae, Kyu-Jung Elsevier 2018 Journal of environmental management Vol.206 No.-
<P><B>Abstract</B></P> <P>For the purpose of reusing wasted marine macro-algae generated during cultivation, harvesting, processing and selling processes, biochars derived from <I>Saccharina japonica</I> (known as <I>kelp</I>) and <I>Sargassum fusiforme</I> (known as <I>hijikia</I>) were characterized and their removal capacities for Cu, Cd, and Zn in aqueous solution were assessed. Feedstocks, <I>S. japonica, S. fusiforme,</I> and also pinewood sawdust as a control, were pyrolyzed at 250, 400, 500, 600 and 700 °C. In evaluating heavy metal removal capacities, SJB (<I>S. japonica</I> biochar) showed the best performance, with removal efficiencies of more than 98% for the three heavy metals when pyrolyzed at over 400 °C. SFB (<I>S. fusiforme</I> biochar) also showed good potential as an adsorbent, with removal efficiencies for the three heavy metals of more than 86% when pyrolyzed at over 500 °C. On the contrary, the maximum removal efficiencies of PSB (pinewood sawdust biochar) were 81%, 46%, and 47% for Cu, Cd, and Zn, respectively, even at 700 °C, the highest pyrolysis temperature. This demonstrates that marine macro-algae were advantageous in terms of production energy for removing heavy metals even at relatively low pyrolysis temperatures, compared with PSB. The excellent heavy metal adsorption capacities of marine macro-algae biochars were considered due to their higher pH and more oxygen-containing functional groups, although the specific surface areas of SJB and SFB were significantly lower than that of PSB. This research confirmed that the use of marine macro-algae as a heavy metal adsorbent was suitable not only in the removal of heavy metals, but also in terms of resource recycling and energy efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Marine macro-algae wastes were reused as biochar for the pollutant removal. </LI> <LI> Marine macro-algae biochar (MMAB) showed an excellent heavy metal removal performance. </LI> <LI> MMAB exhibits high pH and abundant oxygen-containing functional groups on the surface. </LI> <LI> The yield and efficiency of MMAB were higher than those of conventional woody biochar. </LI> <LI> MMAB can work efficiently even as pyrolyzed at relatively low temperatures (400–500 °C). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Son, Eun-Bi,Poo, Kyung-Min,Chang, Jae-Soo,Chae, Kyu-Jung Elsevier 2018 Science of the Total Environment Vol.615 No.-
<P><B>Abstract</B></P> <P>Despite the excellent sorption ability of biochar for heavy metals, it is difficult to separate and reuse after adsorption when applied to wastewater treatment process. To overcome these drawbacks, we developed an engineered magnetic biochar by pyrolyzing waste marine macro-algae as a feedstock, and we doped iron oxide particles (e.g., magnetite, maghemite) to impart magnetism. The physicochemical characteristics and adsorption properties of the biochar were evaluated. When compared to conventional pinewood sawdust biochar, the waste marine algae-based magnetic biochar exhibited a greater potential to remove heavy metals despite having a lower surface area (0.97m<SUP>2</SUP>/g for kelp magnetic biochar and 63.33m<SUP>2</SUP>/g for hijikia magnetic biochar). Although magnetic biochar could be effectively separated from the solution, however, the magnetization of the biochar partially reduced its heavy metal adsorption efficiency due to the biochar's surface pores becoming plugged with iron oxide particles. Therefore, it is vital to determine the optimum amount of iron doping that maximizes the biochar's separation without sacrificing its heavy metal adsorption efficiency. The optimum concentration of the iron loading solution for the magnetic biochar was determined to be 0.025–0.05mol/L. The magnetic biochar's heavy metal adsorption capability is considerably higher than that of other types of biochar reported previously. Further, it demonstrated a high selectivity for copper, showing two-fold greater removal (69.37mg/g for kelp magnetic biochar and 63.52mg/g for hijikia magnetic biochar) than zinc and cadmium. This high heavy metal removal performance can likely be attributed to the abundant presence of various oxygen-containing functional groups (COOH and OH) on the magnetic biochar, which serve as potential adsorption sites for heavy metals. The unique features of its high heavy metal removal performance and easy separation suggest that the magnetic algae biochar can potentially be applied in diverse areas that require biosorbents for pollutant removal.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Magnetic biochar derived from marine macro-algae was made for heavy metal adsorption. </LI> <LI> Physicochemical properties and isotherms were characterized using various techniques. </LI> <LI> Iron-loaded condition was optimized for Cd, Cu, and Zn removal and magnetic separation simultaneously. </LI> <LI> Magnetic macro-algae biochar had high selectivity for Cu with plentiful O-containing groups. </LI> <LI> Adsorption and recovery ability showed an opposite tendency as iron doping increased. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Cho, Wan-Cheol,Poo, Kyung-Min,Mohamed, Hend Omar,Kim, Tae-Nam,Kim, Yul-Seong,Hwang, Moon Hyun,Jung, Do-Won,Chae, Kyu-Jung Elsevier 2018 CHEMOSPHERE - Vol.206 No.-
<P><B>Abstract</B></P> <P>Volatile organic compounds (VOCs) are highly toxic contaminants commonly dissolved in industrial wastewater. Therefore, treatment of VOC-containing wastewater requires a robust and rapid reaction because liquid VOCs can become volatile secondary pollutants. In this study, electro-oxidation with catalytic composite dimensionally stable anodes (DSAs)—a promising process for degrading organic pollutants—was applied to remove various VOCs (chloroform, benzene, toluene, and trichloroethylene). Excellent treatment efficiency of VOCs was demonstrated. To evaluate the VOC removal rate of each DSA, a titanium plate, a frequently used substratum, was coated with four different highly electrocatalytic composite materials (platinum group metals), Ir, IrPt, IrRu, and IrPd. Ir was used as a base catalyst to maintain the electrochemical stability of the anode. Current density and electrolyte concentration were evaluated over various ranges (20–45 mA/cm<SUP>2</SUP> and 0.01–0.15 mol/L as NaCl, respectively) to determine the optimum operating condition. Results indicated that chloroform was the most refractory VOC tested due to its robust chemical bond strength. Moreover, the optimum current density and electrolyte concentration were 25 mA/cm<SUP>2</SUP> and 0.05 M, respectively, representing the most cost-effective condition. Four DSAs were examined (Ir/Ti, IrPt/Ti, IrRu/Ti, and IrPd/Ti). The IrPd/Ti anode was the most suitable for treatment of VOCs presenting the highest chloroform removal performance of 78.8%, energy consumption of 0.38 kWh per unit mass (g) of oxidized chloroform, and the least volatilized fraction of 4.4%. IrPd/Ti was the most suitable anode material for VOC treatment because of its unique structure, high wettability, and high surface area.</P> <P><B>Highlights</B></P> <P> <UL> <LI> DSAs composite electrodes were investigated for electro-oxidation of VOCs. </LI> <LI> Both of VOCs' oxidization and volatilization were evaluated to maximum treatment. </LI> <LI> Energy consumption was calculated as a key-factor for electro-oxidation. </LI> <LI> IrPd/Ti achieved the highest removal efficiency compared to other electrodes. </LI> <LI> Current density and electrolyte concentration were adapted for proper operation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Son, Eun-Bi,Poo, Kyung-Min,Mohamed, Hend Omar,Choi, Yun-Jeong,Cho, Wan-Cheol,Chae, Kyu-Jung Elsevier 2018 Bioresource Technology Vol.259 No.-
<P><B>Abstract</B></P> <P>Chitosan modified magnetic kelp biochar (Chi-KB<SUB>m</SUB>) was successfully synthesized for efficient removal of heavy metals (Cu<SUP>2+</SUP>) from wastewater. Interestingly, the characterization results indicated that Chi-KB<SUB>m</SUB> showed 6 times higher surface area (6.17 m<SUP>2</SUP>/g) than the pristine magnetic kelp biochar KB<SUB>m</SUB> (0.97 m<SUP>2</SUP>/g). In addition, new functional groups, such as NH and CN group, have been created on the surface of biochar as a result of chitosan modification process, which in turns led to improve the Cu<SUP>2+</SUP> adsorption capacity. The effect of pH and chitosan loading on heavy metal adsorption, and competition reaction of different metal ions adsorption were also investigated. Chi-KB<SUB>m</SUB> exhibited a separation efficiency of more than 99.8%, which allows to recovery and reusability of the adsorbent material and heavy metals simultaneously. Overall, this study highlighted the Chi-KB<SUB>m</SUB> is a promise adsorbent for heavy metal removal without sacrificing of the separation ability using magnetism.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Chi-KB<SUB>m</SUB> was synthesized using simple, effective and cost less procedures. </LI> <LI> Chi-KB<SUB>m</SUB> achieved excellent Cu<SUP>2+</SUP> removal from aqueous solution compared to KB<SUB>m</SUB>. </LI> <LI> Nitrogen groups played a critical role to enhance Cu<SUP>2+</SUP> removal efficiency. </LI> <LI> Chi-KB<SUB>m</SUB> exhibited more than 99.8% separation efficiency with external magnet. </LI> <LI> Chi-KB<SUB>m</SUB> is an effective heavy metals adsorbent with easy magnetic separation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>