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CONTENTS
Volume 11, Number 3, May 2020
 

Abstract
Wastewater treatment plants (WWTPs) have been recognized as one of the significant greenhouse gas (GHG) generators, due to the complex biochemical reaction and huge consumption of energy and materials. Recently, WWTPs have been built underground and they will be confronted with the challenges of mitigating GHG emissions and improving the quality of treated wastewater. Here, we focus on estimating GHG emissions to set up effective management plans for a WWTP built underground. First, we apply the process-based life cycle assessment (LCA) with an inventory database of the underground WWTP for a case study. Then, we identify significant factors affecting GHG emissions during service life using sensitivity analysis and suggest the proper tactics that could properly reduce GHG emissions from the WWTP.

Key Words
greenhouse gas emissions; underground wastewater treatment plant; life cycle assessment

Address
Daeseung Kyung: School of Civil & Environmental Engineering, University of Ulsan 44610, Republic of Korea
Da-Yoon Jung and Seong-Rin Lim: Department of Environmental Engineering, College of Engineering, Kangwon National University,Chuncheon, Gangwon 24341, Republic of Korea

Abstract
Electrodialysis has been applied for treatment of industrial wastewater including metal electroplating. The wastewater from metal plating industries contains high concentrations of inorganics such as copper, nickel, and sodium. The ions in the feed were separated due to the electrical forces in the electrodialysis. The concentrate compartment is exposed to the elevated concentrations of the ions and yielded inorganic precipitations on the cation exchange membranes. The presence of organic matter in the metal plating wastewater affects complex interfacial reactions, which determines characteristics of inorganic scale fouling. The wastewater from a metal plating industry in practice was collected and the inorganic and organic compositions of the wastewater were analyzed. The performance of electrodialysis of the raw wastewater was evaluated and the effects of adjusting pH of the raw water were also measured. The integrated processes with neutralization and electrodialysis showed great removal of heavy metals sufficient to discharge to aquatic ecosystem. The organic matter in the raw water was also reduced by the neutralization, which might enhance removal performance and alleviate organic fouling in the integrated system.

Key Words
electrodialysis; metal plating wastewater; inorganic; organic; neutralization

Address
Department of Civil and Environmental Engineering, Konkuk University 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Korea

Abstract
In this study, electrokinetic remediation equipment was used to remove cesium (Cs) from clay soil and waste solution was treated with sorption process. The influence of electrokinetic process on the removal of Cs was evaluated under the condition of applied electric voltage of 15.0-20.0 V. In addition to monitoring the Cs removal, electrical current and temperature of the electrolyte during experiment were investigated. The removal efficiency of Cs from soil by electrokinetic method was more than 90%. After electrokinetic remediation, Cs was selectively separated from soil waste solution using sorbents. Various adsorption agents such as potassium nickel hexacyanoferrate (KNiHCF), Prussian blue, sodium tetraphenylborate (NaTPB), and zeolite were compared and KNiHCF showed the highest Cs removal efficiency. The Cs adsorption on KNiHCF reached equilibrium in 30 min. The maximum adsorption capacity was 120.4 mg/g at 0.1 g/L of adsorbent dosage. These results demonstrated that our proposed process combined electrokinetic remediation of soil and waste solution treatment with metal ferrocyanide can be a promising technique to decontaminate Cs-contaminated fine soil.

Key Words
electrokinetic remediation; cesium; fine soil; potassium nickel hexacyanoferrate

Address
Decommissioning Technology Research Division, Korea Atomic Energy Research Institute,
989-111 Daedeokdae-ro, Yuseong-gu, Daejeon 305-353, Republic of Korea

Abstract
In this study, a biocatalyst composite was prepared by immobilizing oxidoreductases onto Cu-activated zeolite to facilitate biochemical decomposition of 4-chlorophenol (4-CP). 4-CP monooxygenase (CphC-I) was cloned from a 4-CP degrading bacterium, Pseudarthrobacter chlorophenolicus A6, and then overexpressed and purified. Type X zeolite was synthesized from non-magnetic coal fly ash using acetic acid treatment, and its surfaces were coated with copper ions via impregnation (Cu-zeolite). Then, the recombinant oxidative and reductive enzymes were immobilized onto Cu-zeolite. The enzymes were effectively immobilized onto the Cu-zeolite (79% of immobilization yield). The retained catalytic activity of CphC-I after immobilization was 0.3423 U/g-Cu-zeolite, which was 63.3% of the value of free enzymes. The results of this study suggest that copper can be used as an effective enzyme immobilization binder because it provides favorable metal-histidine binding between the enzyme and Cu-zeolite.

Key Words
biocatalyst; 4-chlorophenol; enzyme immobilization; Cu-zeolite; coal fly ash

Address
Muhamad Najmi Bin Zol, Muhammad Firdaus Bin Shuhaim, Jimin Yu, Yejee Lim,
Jae Wan Choe, Sungjun Bae and Han S. Kim: Civil and Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul, Korea
Jae Wan Choe: Civil Engineering, Gwangju University, 277 Hyodeok-ro, Nam-gu, Gwanju, Korea, Korea

Abstract
Electrodialysis (ED) is used in wastewater treatment, during the processing and recovery of beneficial materials, to produce usable water. In this study, sulfate and chlorine ions, which are the anions majorly used for electroplating, were studied as factors affecting the recovery of copper, nickel and water from wastewater by electrodialysis. Although the removal rates of copper and nickel ions were slightly higher with the use of chlorine ions than of sulfate ions, the removal efficiencies were above 99.9% under all experimental conditions. The metal ions of the plating wastewater flowed through the ion exchange membrane of the diluate tank and the concentrate tank while all the water moved together due to electro-osmosis. The migration of water from the diluate tank to the concentrate tank was higher in the presence of a monovalent chloride ion compared to that of a divalent sulfate ion. When sulfate was the anion used, the recoveries of copper and nickel increased by about 25% and 30%, respectively, as compared to the chloride ion. Therefore, when divalent ions such as sulfate are present in the electrodialysis, it is possible to reduce the movement amount of water and highly concentrate the copper and nickel in the plating wastewater.

Key Words
electrodialysis; electroosmosis; metal separation; plating wastewater

Address
Eunjoo Oh, Joohyeong Kim, Jun Hee Ryu, Kyung Jin Min, Hyun-Gon Shin and Ki Young Park

Abstract
Vivianite (Fe32+(PO4)2∙8H2O) and green rust ([Fe42+Fe23+(OH)-12][SO42-·2H2O]2-), ferrous containing minerals, could remove aqueous U(VI) in 5 min. and the efficiencies of green rust were roughly 2 times higher than that of vivianite. The zeta potential measurement results implies that the better performance of green rust might be attributed to the favorable surface charge toward uranyl phosphate species. The removal behaviors of the minerals were well fitted by pseudo-second order kinetic model (R2 > 0.990) indicating the dominant removal process was chemical adsorption. Effects of Ca2+ and CO32- at pH 7 were examined in terms of removal kinetic and capacity. The kinetic constants of aqueous U(VI) were 8 and 13 times lower (0.492 x 10-3 g/(mg∙min); 0.305 x 10-3 g/(mg∙min)) compared to the value in the absence of the ions. The thermodynamic equilibrium calculation showed that the stable uranyl species (uranyl tri-carbonate) were newly formed at the condition. Surface investigation on the reacted mineral with uranyl phosphates species were carried out by XPS. Ferrous iron and U(VI) on the green rust surface were completely oxidized and reduced into Fe(III) and U(IV) after 7 d. It suggests that the ferrous minerals can retard U(VI) migration in phosphate-rich groundwater through the adsorption and subsequent reduction processes.

Key Words
uranium; vivianite; green rust; phosphate complexes; adsorption; remediation

Address
Decommissioning Technology Research Division, KAERI, Daejeon 34057, Korea

Abstract
An electrochemical oxidation process was applied to remove cyanide (CN-) from real plating wastewater. CN- removal efficiencies were investigated under various operating factors: current density and electrolyte concentration. Electrolyte concentration positively affected the removal of both CN- and Chemical Oxygen Demand (COD). As the electrolyte concentration increased from 302 to 2,077 mg Cl-/L, removal efficiency of CN- and COD increased from 49.07% to 98.30% and from 23.53% to 49.50%, respectively, at 10 mA/cm2. Current density affected the removal efficiency in a different way. As current density increased at a fixed electrolyte concentration, CN- removal efficiency increased while COD removal efficiency decreased, this is probably due to lowered current efficiency caused by water electrolysis.

Key Words
electrochemical oxidation; cyanide; current density; electrolyte

Address
Xin Zhao, Minsik Jang and Jae Woo Lee: Department of Environmental Engineering, college of Science and Technology, Korea University, Republic of Korea
Jin Woo Cho: Department of Environmental, Energy & Geoinformatics, college of Engineering, Sejong University, Republic of Korea

Abstract
Here magnetic iron oxide particles (MIOPs) were synthesized under atmospheric air and which size was controlled by regulating the flow rate of alkali addition and used for efficient removal of bovine serum albumin (BSA) from water. The MIOPs were characterized using field-emission scanning electron microscopy (FE-SEM), Fourier transformation-Infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The results revealed a successful preparation of the MIOPs. The removal efficiency for BSA using MIOPs was found to be about 100% at lower concentrations (≥ 10 mg/L). The maximum adsorption of 64.7 mg/g for BSA was achieved as per the Langmuir adsorption model. In addition, microfiltration membrane for removal of BSA as model protein organic foulant is also studied. The effect of various MIOPs adsorbent sizes of 210, 680 and 1130 nm on the absorption capacity of BSA was investigated. Water permeability of the BSA integrated with the smallest size MIOPs membrane was increased by approximately 22% compared by the neat BSA membrane during dead-end filtration. Furthermore, the presence of small size MIOPs were also effective in increasing the permeate flux.

Key Words
magnetic iron oxide particles; organic fouling; membrane bioreactor; organic fouling

Address
Department of Environment and Energy, Sejong University, Seoul 05006, Korea

Abstract
Industrialization and modern developments have led to an influx of toxic heavy metals into the aquatic environment, and the accumulation of heavy metals has serious adverse effects on humans. Among the various heavy metal treatment methods, adsorption is very useful and frequently used. Plastic materials, such as polypropylene and polyethylene, have been widely used as filter media due to their mechanical and chemical stability. However, the surface of plastic material is inert and therefore the adsorption capability of heavy metals is very limited. In this study, granular media and fiber media composed of polypropylene and polyethylene are used, and the surface modification was conducted in order to increase adsorption capability toward heavy metals. Oxygen plasma generated hydroxyl groups on the surface of the media to activate the surface, and then acrylic acid was synthesized on the surface. The grafted carboxyl group was confirmed by FT-IR and SEM. Heavy metal adsorption capability of pristine and surface modified adsorbents was also evaluated. Overall, heavy metal adsorption capability was increased by surface modification due to electrostatic interaction between the carboxyl groups and heavy metal ions. Fibrous PP/PE showed lower improvement compared to granular PP media because pore blockage occurred by the surface modification step, thereby inhibiting mass transfer.

Key Words
Polypropylene, polyethylene, oxygen plasma, acrylic acid, heavy metals

Address
Jeongmin Hong,Yuhoon Hwang: Department of Environmental Engineering, Seoul National University of Science and Technology, Seoul 01811, Korea
Seungwoo Lee: Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 01811, Korea
Dongah Ko: Innovation Centre Denmark, Seoul 04637, Korea
Eunmi Kwon: ECOSTAR Co., Ltd., Gyeonggi-do 16295, Korea


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