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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Environmental Engineering Research
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Journal DOI :
Korean Society of Environmental Engineering
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Volume & Issues
Volume 16, Issue 4 - Dec 2011
Volume 16, Issue 3 - Sep 2011
Volume 16, Issue 2 - Jun 2011
Volume 16, Issue 1 - Mar 2011
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Degradation of Chlorinated Phenols by Zero Valent Iron and Bimetals of Iron: A Review
Gunawardana, Buddhika ; Singhal, Naresh ; Swedlund, Peter ;
Environmental Engineering Research, volume 16, issue 4, 2011, Pages 187~203
DOI : 10.4491/eer.2011.16.4.187
Chlorophenols (CPs) are widely used industrial chemicals that have been identified as being toxic to both humans and the environment. Zero valent iron (ZVI) and iron based bimetallic systems have the potential to efficiently dechlorinate CPs. This paper reviews the research conducted in this area over the past decade, with emphasis on the processes and mechanisms for the removal of CPs, as well as the characterization and role of the iron oxides formed on the ZVI surface. The removal of dissolved CPs in iron-water systems occurs via dechlorination, sorption and co-precipitation. Although ZVI has been commonly used for the dechlorination of CPs, its long term reactivity is limited due to surface passivation over time. However, iron based bimetallic systems are an effective alternative for overcoming this limitation. Bimetallic systems prepared by physically mixing ZVI and the catalyst or through reductive deposition of a catalyst onto ZVI have been shown to display superior performance over unmodified ZVI. Nonetheless, the efficiency and rate of hydrodechlorination of CPs by bimetals depend on the type of metal combinations used, properties of the metals and characteristics of the target CP. The presence and formation of various iron oxides can affect the reactivities of ZVI and bimetals. Oxides, such as green rust and magnetite, facilitate the dechlorination of CPs by ZVI and bimetals, while oxide films, such as hematite, maghemite, lepidocrocite and goethite, passivate the iron surface and hinder the dechlorination reaction. Key environmental parameters, such as solution pH, presence of dissolved oxygen and dissolved co-contaminants, exert significant impacts on the rate and extent of CP dechlorination by ZVI and bimetals.
Pretreatment in Reverse Osmosis Seawater Desalination: A Short Review
Valavala, Ramesh ; Sohn, Jin-Sik ; Han, Ji-Hee ; Her, Nam-Guk ; Yoon, Yeo-Min ;
Environmental Engineering Research, volume 16, issue 4, 2011, Pages 205~212
DOI : 10.4491/eer.2011.16.4.205
Reverse osmosis (RO) technology has developed over the past 40 years to control a 44% market share in the world desalting production capacity and an 80% share in the total number of desalination plants installed worldwide. The application of conventional and low-pressure membrane pretreatment processes to seawater RO (SWRO) desalination has undergone accelerated development over the past decade. Reliable pretreatment techniques are required for the successful operation of SWRO processes, since a major issue is membrane fouling associated with particulate matter/colloids, organic/inorganic compounds, and biological growth. While conventional pretreatment processes such as coagulation and granular media filtration have been widely used for SWRO, there has been an increased tendency toward the use of ultrafiltration/microfiltration (UF/MF) instead of conventional treatment techniques. The literature shows that both the conventional and the UF/MF membrane pretreatment processes have different advantages and disadvantages. This review suggests that, depending on the feed water quality conditions, the suitable integration of multiple pretreatment processes may be considered valid since this would utilize the benefits of each separate pretreatment.
Nutrient Removal Using Fermented Organic Acids Derived from the Primary Sludge in the Intermittent Aeration Activated Sludge Process
Weon, Seung-Yeon ; Lee, Sang-Il ; Lee, Chan-Won ;
Environmental Engineering Research, volume 16, issue 4, 2011, Pages 213~218
DOI : 10.4491/eer.2011.16.4.213
The two-stage intermittent aeration activated sludge process (IAP) and dynamic-flow intermittent aeration activated sludge process (DFP) were investigated for the nutrient removal of domestic wastewater. Three sets of IAP and one set of DFP were operated. The fermented settled sludge taken from the primary settling tank was added to two IAP and one DFP as an external electron donor, with one IAP, in which an external carbon source was not added, as a control. All the systems were operated at a sludge retention time of 20 days and a hydraulic retention time of 12 hr. A Higher denitrification rate was observed with the fermented settled sludge for the denitrification compared to the process without the addition of the organic source. The result indicates that the fermented acid from the primary domestic sludge has been proved to be an excellent electron donor for denitrification and biological phosphorus removal with IAP and DFP in treating relatively low C/N ratio(Carbon / Nitrogen ratio) wastewater. Phosphate accumulating organisms have a capability of competing with denitrifiers in the presence of volatile organic acids under anoxic conditions.
Influence of Surfactants on Bacterial Adhesion to Metal Oxide-Coated Surfaces
Choi, Nag-Choul ; Park, Seong-Jik ; Lee, Chang-Gu ; Park, Jeong-Ann ; Kim, Song-Bae ;
Environmental Engineering Research, volume 16, issue 4, 2011, Pages 219~225
DOI : 10.4491/eer.2011.16.4.219
The objective of this study was to investigate the bacterial adhesion to iron (hydr)oxide-coated sand (IHCS) and aluminum oxidecoated sand (AOCS) in the presence of Tween 20 (nonionic surfactant) and lipopeptide biosurfactant (anionic surfactant) through column experiments. Results show that in the presence of Tween 20, bacterial adhesion to the coated sands was slightly decreased compared to the condition of deionized water; the mass recovery (Mr) increased from 0.491 to 0.550 in IHCS and from 0.279 to 0.380 in AOCS. The bacterial adhesion to the coated sands was greatly reduced in lipopeptide biosurfactant; Mr increased to 0.980 in IHCS and to 0.797 in AOCS. Results indicate that the impact of lipopeptide biosurfactant on bacterial adhesion to metal oxide-coated sands was significantly greater than that of Tween 20. Our results differed from those of the previous report, showing that Tween 20 was the most effective while the biosurfactant was the least effective in the reduction of bacterial adhesion to porous media. This discrepancy could be ascribed to the different surface charges of porous media used in the experiments. This study indicates that lipopeptide biosurfactant can play an important role in enhancing the bacterial transport in geochemically heterogeneous porous media.
A Study on Boron Removal by Mineral Cluster Coagulant for Seawater Desalination Application
Vu, Hanh Hong ; Cho, Bong-Yeon ;
Environmental Engineering Research, volume 16, issue 4, 2011, Pages 227~230
DOI : 10.4491/eer.2011.16.4.227
Seawater desalination technology is a complicated and expensive process. Besides salt removal from seawater, thesignificant problem that needs to be solved is boron removal. Boron removal is difficult so it is a considerable challenge for the desalination process. The main technology of this process is reverse osmosis (RO). RO can remove salt and boron more effectively than other technologies. In a conventional seawater desalination process, coagulant is utilized for pre-treatment but it is difficult to remove boron through this stage. In this study, a coagulant called Mineral Cluster was examined for boron removal. Therefore, Mineral Cluster can be considered a potential coagulant for boron removal in seawater desalination technology.
Nitrogen Removal Comparison in Porous Ceramic Media Packed-Bed Reactors by a Consecutive Nitrification and Denitrification Process
Han, Gee-Bong ; Woo, Mi-Hee ;
Environmental Engineering Research, volume 16, issue 4, 2011, Pages 231~236
DOI : 10.4491/eer.2011.16.4.231
Biological nitrogen removal, using a continuous flow packed-bed reactor (CPBR) in a consecutive nitrification and denitrification process, was evaluated. An apparent decline in the nitrification efficiency coincided with the steady increase in
-N load. Sustained nitrification efficiency was found to be higher at longer empty bed contact times (EBCTs). The relationship between the rate of alkalinity consumption and
-N utilization ratio followed zero-order reaction kinetics. The heterotrophic denitrification rate at a carbon-tonitrogen (C/N) ratio of >4 was found to be >74%. This rate was higher by a factor of 8.5 or 8.9 for
-N/volatile solids (VS)/day or
ceramic media/day, respectively, relative to the rates measured at a C/N ratio of 1.1. Autotrophic denitrification efficiencies were 80-90%. It corresponds to an average denitrification rate of 0.96 kg
ceramic media/day and a relevant average denitrification rate of 0.28 g
-N/g VS/day, were also obtained. Results presented here also constitute the usability of an innovative porous sulfur ceramic media. This enhanced the dissolution rate of elemental sulfur via a higher contact surface area.
Pilot Study Analysis of Three Different Processes in Drinking Water Treatment
Kim, Dae-Ho ; Lee, Byoung-Ho ;
Environmental Engineering Research, volume 16, issue 4, 2011, Pages 237~242
DOI : 10.4491/eer.2011.16.4.237
In this study, three pilot-scale plants with the capacity 30
/day were designed and set up to treat reservoir water for the production of drinking water. Three treatment processes were compared in the pilot testing: process 1 (coagulation- flocculation- sedimentationsand filtration- ozone- BAC); process 2 (coagulation- flocculation- sedimentation- microfiltration-ozone- BAC); and process 3 (coagulation- flocculation- sedimentation- sand filtration- GAC). The quality of water has been evaluated on the basis of selected parameters such as turbidity, color, consumption of
, dissolved organic carbon (DOC), trihalomethane formation potential (THMFP), geosmin and 2-MIB. A detailed assessment of performance was carried out during a five months operation. Process 2 was found to have better removal efficiency of DOC, THMFP, geosmin and 2-MIB than process 1 and process 3 under identical conditions, although the removal rate of color was found to be the same in the three cases.
Disinfection of Wastewater by UV Irradiation: Influence of Hydrodynamics on the Performance of the Disinfection
Brahmi, Mounaouer ; Hassen, Abdennaceur ;
Environmental Engineering Research, volume 16, issue 4, 2011, Pages 243~252
DOI : 10.4491/eer.2011.16.4.243
Several mathematical relationships have been developed to describe bacterial responses to UV irradiation. Pseudomonas aeruginosa was taken as a bacterial model. The results obtained showed that the kinetics of disinfection is far to be as uniform. In fact, application of the model of Chick-Watson in its original form or modification, taking into account the speed change during the disinfection process, has not significantly improved results. The application of both models of Collins-Selleck and Hom constitute a major opportunity to simulate goodly the kinetics of UV disinfection. The results obtained showed that despite the major advantage held by applying the Hom model in this process of disinfection and for all strains studied, the model of Collins-Selleck gave the best results for the description of the UV inactivation process. The design of reactors, operating in continuous disinfection system, requires taking into account the hydrodynamic behaviour of water in the reactor. Knowing that a reduction of 4-log is necessary in the case of wastewater reuse for irrigation, a model integrating the expression of disinfection kinetics and the hydrodynamics through the UV irradiation room was proposed. The results highlight the interest to develop reactors in series working as four perfectly mixed reactors.