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Journal of Korean Society of Environmental Engineers
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2383-7810 - ISSN (Online) 1225-5025
Published by Korean Society of Environmental Engineers Homepage  [1 journal]
  • Evaluation of Bio-drying Process of Sewage Sludge using Mathematical Model
           of Heat and Mass ...

    • Abstract: Objectives : The effects of temperatures of supplied air and exhaust gas on moisture removal in the bio-drying process of sewage sludge were assessed by simulating the process. We also suggested performance and efficiency indicators for moisture removal in this process and identified their effectivity.Methods : The bio-drying process of sewage sludge was simulated by mathematical modeling of heat and mass balance under different combinations of supplied-air temperatures and control ranges of exhaust gas temperatures. The simulation results were analyzed by using some indicators for assessing the performance and efficiency of moisture removal.Results and Discussion : While BVS (biodegradable volatile solid) degradation was inhibited at a higher supplied-air temperature and a lower control range of exhaust gas temperature, moisture reduction was enhanced at the supplied-air temperature nearer to ambient and the controlled exhaust gas temperature for 45 to 50
      PubDate: Wed, 02 Dec 2020 00:00:01 +010
       
  • Determination and Comparison of Trace Elements in Various Parts of
           Eichhornia crassipes by a ...

    • Abstract: Objective : In this study, we have evaluated trace element concentration of various parts of Eicchornia crassipes, collected from three different lakes in Pune district, India.Methods : The dried segregated parts of Eicchornia crassipes were subjected to microwave digestion, followed by measurement with Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). Optimization and validation of the method was performed for determining the minor and trace element concentrations of Co, I, Ni, Cu, Mn, Zn, Fe in roots, petiole and leaves of the plant. NIST Standard reference material SRM 1547 (Peach leaves) was used for establishing accuracy of the analytical method. Rhodium was used an internal standard for correcting matrix effects.Results and Discussion : A validated ICP-OES and ICP-MS method was established for determining the minor and trace element concentrations of Co, I, Ni, Cu, Mn, Zn, Fe in roots, petiole and leaves of the plant. Levels of all elements were found to be higher in roots, followed by petiole and leaves. Except for Zn and Fe, where concentration in leaves was found to be higher than in petiole. Of all the measured elements, total concentration of Mn was found to be highest (566 mg kg-1), followed by Fe (341 mg kg-1), Zn (40.26 mg kg-1), Cu (28.04 mg kg-1), Ni (9.54 mg kg-1), Co (4.33 mg kg-1) and I (0.94 mg kg-1). A surprising finding was the presence of iodine in the plant, despite its non-marine source.Conclusion : Plant-derived products form an important category in alternative medicine that is often used for treatment of several disorders. Eicchornia crassipes (water hyacinth), considered as the world
      PubDate: Mon, 30 Nov 2020 00:00:01 +010
       
  • Optimum Operating Conditions of Drinking Water Treatment System for
           Fluoride Removal using High ...

    • Abstract: Objectives : Bone char is used in many eastern countries in Africa to remove high levels of fluoride from groundwater. However, due to the low adsorption efficiency of bone char, it is necessary to replace bone char frequently, which cause significant burden to the people in those areas. In this study, we developed a water treatment system to remove high level of fluoride in groundwater using a high efficiency bone char.Methods : In order to make a high efficiency bone char, cow bones were washed, dried and cut into small pieces. Then the bones were burned for 1, 3 and 5 hours at 350, 450 and 550
      PubDate: Mon, 30 Nov 2020 00:00:01 +010
       
  • Sludge Production Characteristics of Sedimentation

    • Abstract: Objectives : In order to prevent eutrophication and algal blooms, Ministry of Environment in Korea reinforced the effluent standards of wastewater treatment facilities. As a result, many advanced wastewater treatment processes have been implemented nationwide. Current conventional treatment systems have usually been facing high operational costs and large sludge production problems. Therefore, it is essential to develop more economic and efficient process to cope with these issues.Methods : The sedimentation and dissolved air flotation (SeDAF) process has been developed, that integrates sedimentation and dissolved air flotation. Several simulation experiments were carried out to verify and optimize the operation conditions of the SeDAF process. Removal efficiencies of each water quality item and sludge mass balance were analyzed intensively in the SeDAF process using the modified jar-test.Results and Discussion : Removal efficiencies of the SeDAF process were higher and more stable than those of sedimentation process. Several
      PubDate: Mon, 30 Nov 2020 00:00:01 +010
       
  • Applicability of Al/P (Aluminium/Phosphorus) Ratio in SeDAF Process for
           Enhanced Phosphorus Removal

    • Abstract: Objectives : To prevent eutrophication and algal blooms, Ministry of Environment in Korea has reinforced the effluent standards of wastewater treatment facilities. In the last 20 years, various advanced wastewater treatment processes have been introduced nationwide. The sedimentation?dissolved air flotation (SeDAF) process has been developed for efficient enhanced phosphorus removal in the previous researches. In the study, several factors were reviewed to examine the operation characteristics of the SeDAF process. In particular, the applicability of aluminium/phosphorus (Al/P) and aluminium/turbidity (Al/T) ratios were investigated intensively.Methods : To derive the appropriate operating conditions for the SeDAF process, several sets of lab-scale tests were carried out. For each operating condition, Al/P (Al/T-P), Al/PO43--P, and Al/T (Al/Turbidity) ratios were analyzed, compared and reviewed respectively.Results and Discussion : Al/P ratio was revealed as the most prominent factor in terms of stability and feasibility of operation, and Al/P values of the SeDAF process could achieve lower values than those of other processes in the previous researches.Conclusions : It could be expected that the coagulant dosage decision using Al/P ratio has many advantages to reduce coagulant dosage and to decrease the amount of sludge production in the SeDAF process.

      PubDate: Mon, 30 Nov 2020 00:00:01 +010
       
  • Safety Management Plan through Offsite Risk Assessment during Tank
           Terminal Construction

    • Abstract: Objectives : In order to conduct the quantitative risk assessment for hazardous chemical storage facilities at the tank terminal in the port area, the entire risk assessment process was performed in according to the guidances of the Korea Ministry of Environment.Methods : The risk of the facility was derived by the worst-case scenario, alternative scenario, and then evaluated by KORA program. The countermeasures of the risk were suggested by the concept of LOPA.Results and Discussion : Focusing on the worst case scenario and alternative scenario among the scenario having effet to offsite, risk can be reduced to satisfy regulation by applying measures of passive, active, and managerial.Conclusions : According to the result of risk assessment on benzene storage tank and tank lorry when port construction, the amount of storage inside the tank has a significant impact on the offsite. It is necessary to organize the risk of benzene, and comprehensive management of tank terminal storage facilities.
      PubDate: Mon, 30 Nov 2020 00:00:01 +010
       
  • Bioremediation of Endosulfan Contaminated Soil by using Microbial
           Consortia in the Field

    • Abstract: Objectives : The use of risky and persistent organochlorine pesticides was prohibited, but is still detected in many agricultural lands. In this study, Phanerochaete chrysosporium Y-2 (KCCM-10725P) and Streptomyces sp. MJM14747 (KACC 81078BP), which were finally selected among various candidate microorganisms, were applied to field soil and estimated the endosulfan removal rate.Methods : The field testing sites were set to an area of 3 m
      PubDate: Mon, 30 Nov 2020 00:00:01 +010
       
  • Analysis of Key Technologies for Industrialized Treatment of Fatty Acid
           High-Salinity Organic ...

    • Abstract: Objectives : Wastewater produced by fatty acid production contains high concentration of organic substances and high concentration of salts (mainly sodium sulfate), causing great pollution to water resources and environment. The pollution prevention and control of this type of wastewater are very necessary. The key to treating this type of wastewater is to remove salts and COD to achieve harmless treatment. This is a problem in wastewater management that has plagued the industry for a long time. This paper proposed a technique suitable for fatty acid high salinity organic wastewater.Methods : First, the industrial treatment technology of organic wastewater with high salinity was introduced and analyzed. Combined with the principle of industrial wastewater treatment, the process route for the treatment of fatty acid high salinity organic wastewater was analyzed and selected. In addition, the key technology and process for anaerobic desalination and COD removal were analyzed and selected.Results and Discussion : According to the unique nature of this type of wastewater mainly containing sulphate salts and the feasibility of industrial production, a special technology combination was proposed to treat this wastewater at this stage. Since this wastewater has a B/C ratio of 0.4 to 0.45, it is easier to use biological treatment method. Thus, the conventional treatment method is pretreatment + biological treatment. Biological enhancement and reactor process optimization can be studied for better efficiency.Conclusions : Considering the high COD and sulphate concentration characteristics of fatty acid high-salinity organic wastewater, high-efficiency anaerobic biochemical treatment is mainly considered. Combined with modern high-efficiency anaerobic suspended sludge granule technology, it was concluded that pretreatment + high efficiency IC anaerobic + secondary biological treatment can achieve industrialized treatment of such wastewater in a targeted, low-cost and reliable way. In the later stage, bio-enhancement of the anaerobic process as well as structural and process optimization of the reactor can be carried out to obtain better technical and economic results in production practice.
      PubDate: Mon, 30 Nov 2020 00:00:01 +010
       
  • A Study on Oxidation of Tetramethylammonium Hydroxide (TMAH) using
           UV/Persulfate

    • Abstract: Objective : In order to efficiently remove TMAH from the wastewater generated by the TFT-LCD manufacturing process, the oxidation of TMAH was tested by applying an UV/persulfate. The optimum reaction conditions for high concentration TMAH oxidation were investigated by evaluating and comparing the removal efficiency according to the factors affecting TMAH oxidative degradation.Methods : In this study, TMAH was decomposed by sulfate radical (SO4-?) and hydroxyl radical (OH?) generated from persulfate activated by UV. Factors affecting on the treatment efficiency were try to be optimized by comparing and evaluating the removal efficiency depending on the initial pH, oxidant concentration, and initial TMAH concentration.Results and Discussion : Depending on initial pH (2, 7, 12), persulfate addition (0, 50, 100, 150, 200 mM), initial TMAH concentration (100, 300, 500, 700 mg/L) degradation rates of TMAH were compared. When UV/persulfate was applied, the removal efficiency of TMAH was close to 90% regardless of the initial pH and, at initial pH 12, was the highest with 89%. It was confirmed that the generation pattern of intermediate formed were different depending on the initial pH. When the oxidizing agent was not added, there was little change in TMAH concentration. The removal efficiency was highest when 100 mM persulfate was added. However the efficiency was rather low when 150 mM persulfate was added. When the initial TMAH concentration was 100 mg/L, it was decreased within 150 minutes. As the initial concentration increased, the removal efficiency and reaction rate constant decreased.Conclusions : As a results, during the oxidation of 750 mg/L TMAH by using UV/persulfate, the removal efficiency was highest with initial pH 12 and 100 mM of persulfate addition.

      PubDate: Sat, 31 Oct 2020 00:00:01 +010
       
  • Assessment of Water Quality of Major Tributaries in Seoul using Water
           Quality Index and Cluster ...

    • Abstract: Objectives : 17 water quality measurement networks (WQMNs, tributaries) in Seoul were analyzed by using NSFWQI and cluster analysis to provide basic data for future river water quality management so that citizens could easily and comprehensively understand the water quality information on the rivers in Seoul.Methods : For the past 3 years (2015~2017), in order to estimate WQI, 9 items, DO (% sat), Fecal coliform, pH, BOD, Temperature change (TC), TP, NO3-, Turbidity and Total solids, were selected from among the 19 water quality data measurement items produced monthly from 17 WQMNs in Seoul. WQI was derived and graded using NSFWQI and cluster analysis was performed using Ward Linkage Method, SOM (Self Organizing Map).Results and Discussion : Water quality of most water quality monitoring networks was BOD
      PubDate: Sat, 31 Oct 2020 00:00:01 +010
       
  • Screening of Effective Media for Black Soldier Fly Larvae Used in Food
           Waste Treatment

    • Abstract: Objectives : Black soldier fly larvae (BSFL) are organisms that effectively decompose various types of organic waste including food waste, and food waste treatment using BSFL is attracting attention as a sustainable waste treatment method. However, food waste discharged from Korea has a wide variety of properties, and its high salt concentration limits its treatment by BSFL. Therefore, to increase the efficiency of food waste treatment using BSFL, it is necessary to increase the quality of food waste as a production medium for BSFL. In this study, the ratio of protein and fat was adjusted by adding bean sprouts and wheat brans to food wastes treated at high temperature under vacuum, and whether such medium is suitable for rearing BSFL was investigated.Methods : To improve the medium, the ratio of protein and fat was adjusted to approximately 2:1 by adding bean sprouts and bran residue to food waste. Subsequently, the growth and development rate of BSFL reared on chicken feed, food waste, food waste + bean sprouts, food waste + wheat bran were measured. Also, the decomposition rate of each medium was analyzed.Results and Discussion : The growth rate of BSFL grown on food waste + wheat bran medium was similar to that of BSFL reared on chicken feed. The speed of development at day 7 was also the fastest for BSFL reared with food waste + wheat bran medium and chicken feed. These results suggest that the mixed medium to which wheat bran has been added to food waste has the potential to be used as a commercial medium for BSFL production. The survival rate of BSFL was 89% or higher in all media.Conclusions : When food waste was used alone, BSFL development was poor compared to that in media combined with agricultural by-products such as bean sprouts and wheat bran. Therefore, to use food waste as a rearing medium of BSFL, it is necessary to adjust the ratio of protein and fat by adding various agricultural by-products and reduce salinity. For the improvement of food waste treatment technology using BSFL, mass rearing of useful insects such as BSFL, and promotion of the use of agricultural by-products, additional research is needed to optimize the composition of rearing medium based on food waste.

      PubDate: Sat, 31 Oct 2020 00:00:01 +010
       
  • Enhancement of the Congo Red Adsorption Capacity of Biochars by Surface
           Modification with MgCl2 ...

    • Abstract: Objectives : The physicochemical characteristics of Mg-biochar composites derived from kelp and pine after pretreatment with MgCl2 were analyzed, and their adsorption capacities for an anionic dye, Congo red (CR), were evaluated.Methods : After pretreating 60 g of kelp and pine sawdust in 1 L of 0.1 M MgCl2'6H2O, the raw materials were pyrolyzed at 500
      PubDate: Sat, 31 Oct 2020 00:00:01 +010
       
  • Changes in Soil Properties after Soil Washing of Metal-contaminated Soil
           near the former ...

    • Abstract: Objectives : Changes in soil properties after washing of metal-contaminated soil near the former Janghang Smelter were investigated in this study. Contaminated input soils and remediated output soils were sampled from three different soil washing plants and analyzed for soil physical and chemical properties. Soil quality was evaluated by the soil fertilization guideline suggested by the Korea Rural Development Administration (KRDA). This study revealed the necessity of soil quality management for the remediated soil as an ecosystem member.Methods : Three soil washing plants (1OU, 2OU, 3OU) were commonly divided into the five steps: 1) the particle separation (crushing and grinding etc.)
      PubDate: Sat, 31 Oct 2020 00:00:01 +010
       
  • Current Research Trends and the Need for Localization in Ultrapure Water
           Production Facilities ...

    • Abstract: Objectives : This study aims to summarize the market status, patent applications, and technology trends for the production of ultrapure water in semiconductor industries. In addition, the potential of technological localization of ultrapure water production facility is reviewed in order to incubate domestic core technologies as well as to reduce the technical dependence to the market stake holders.Methods : Through the collection and summary of information from global water institute (GWI), market analyst firms in ultrapure water fields, and the patent analysis for the past 10 years, the technological gap between domestic and market leading in Japan, the United States, and Europe were analyzed. In addition, the research trend related to the core removal processes for the production of ultrapure water was also analyzed.Results and Discussion : As a result of market analysis in the industrial water sector, the capital investment is expected to reach USD 39.9 billion by 2024, with a steady growth of 4.1% per year. The unit processes required for the production of ultrapure water becomes more complex and diversified, and the recent technological advancement has been mainly put on the development of eco-friendly water treatment processes such as electrodeionization (EDI) in order to reduce the chemical usage. In addition, research on the development of new processes for the treatment of hardly degradable trace substances (i.e. urea, THM, IPA, etc.) is actively under investigation. However, the patent analysis revealed that the three Japanese companies occupied 71% of the world
      PubDate: Sat, 31 Oct 2020 00:00:01 +010
       
  • Estimation and Assessment of Total Phosphorus and Trophic State Index
           Estimated from Landsat 8 ...

    • Abstract: Objectives : Remote sensing of water quality parameters (WQPs) has been widely applied along with the emerging importance of obtaining the spatial pattern of water quality at inland reservoir. This study retrieved the Total Phosphorus (TP) via remote sensing imagery at Daecheong reservoir and used it for acquiring the spatial distribution of Trophic State Index (TSI).Methods : First, stepwise regression for TP was established using the ground-based TP measurement and reflectance of Landsat 8 collocated in space and time. With the developed regression model, we estimated the spatial distribution of TSI and evaluated the severity of eutrophication at Daecheong reservoir.Results and Discussion : The result confirmed that predicted TP yielded reasonable statistics compared against measured TP with R2 of 0.956 and p-value of 0.022. Seasonal variation of TP was highly influenced by the precipitation. Similarly, precipitation also influenced to the spatial pattern of TSI. Before the rainfall event (e.g., August 22 2018) at Daecheong reservoir, TSI metric indicated the oligotrographic stage. However, TSI of Daecheong reservoir after the rainfall (e.g., October 25 2018) indicated the mesotrophic and eutrophic stage.Conclusions : These results confirmed that the retrieval of WQP from remote sensing imagery can serve as a robustness tool to monitor the water quality over the large scale area.

      PubDate: Wed, 30 Sep 2020 00:00:01 +010
       
  • A Study on the Application Characteristics of the Insoluble MMO (Mixed
           Metal Oxide) Electrode ...

    • Abstract: Objective : The zinc electrowinning industry is one of the high energy consumption industries where energy saving is required. In the zinc electrowining process, electrode is a high energy consuming part. In order to reduce energy use in the electrolytic smelting industry, a comparative study was conducted on the current usage of Pb+Ag alloy electrode and insoluble composite metal oxide (MMO) electrode.Methods : In this study, a comparative evaluation of energy consumption was conducted between the generally used Pb+Ag alloy electrode and an insoluble MMO electrode. Aluminum was used as a reducing electrode. The actual on-site zinc electrowinning solution and ZnSO
      PubDate: Wed, 30 Sep 2020 00:00:01 +010
       
  • Improved Affinity of Nanoscale Zero Valent Iron toward Hydrophobic Organic
           Solvent using ...

    • Abstract: Objectives : Levels of organic contaminants in excess of the standard minimum have been detected in many commercial and residential sites, and the severity of soil and groundwater pollution is increasing. In particular, non-aqueous phase liquids (NAPLs) are hydrophobic organic pollutants that do not mix with water and are difficult to remove with existing soil remediation technology. These pollutants slowly dissolve into the groundwater over long periods of time, thus contaminating the groundwater. With the increasing need to remove NAPLs for soil and groundwater remediation, widespread interest has focused on the use of nanoscale zero valent iron (nZVI). However, nZVI has the disadvantage of reduced subsurface mobility. Hence, in the present study, the nZVI surface is modified with poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA), which has both hydrophilic and hydrophobic groups, to improve the mobility and selectivity of nZVI for the removal of NAPL.Methods : The PVP/VA modified nZVI is synthesized through the reaction of FeSO4?7H2O and NaBH4 in the presence of PVP/VA. To confirm the dispersibility of the prepared material, a precipitation experiment is performed using a visible light spectrometer, and the mobility through a sand-filled column is evaluated. In addition, the variation in particle size and characteristics according to the presence of PVP/VA is examined via transmission electron microscopy. The nitrate reduction ability of nZVI with PVP/VA is also evaluated to reveal changes in reactivity depending upon the degree of dispersion. To confirm the selective mobility towards NAPL, trichloroethylene and dodecane are used to evaluate the mobility with and without PVP/VA. Finally, the ratio of nZVI passing through the sponge layer absorbing dodecane is evaluated to determine the selective mobility towards NAPL in the porous medium.Results and Discussion : Although the dispersibility of the PVP/VA-nZVI is not significantly changed, the particle size is significantly decreased. Both the mobility in porous media and the nitrate reduction rate are improved via PVP/VA modification. The affinity for hydrophobic contaminants and the selective migration of PVP/VA-nZVI towards the NAPL layer are also improved. The high affinity for the NAPL was also shown by the column with NAPL layer.Conclusions : Surface-modification with PVP/VA, which has both hydrophilic and hydrophobic ends, enabled the synthesis of nZVI with a smaller and more uniform particle size, thus providing high mobility in porous media and high reactivity towards contaminants. The combined hydrophilicity and hydrophobicity of PVP/VA is shown to increase the affinity of nZVI towards NAPL and, thus, promote its migration to the NAPL layer. Thus, it is anticipated that the efficiency of soil remediation can be improved by promoting the movement of nZVI towards the target NAPL layer.

      PubDate: Wed, 30 Sep 2020 00:00:01 +010
       
  • Effects of Several Physicochemical Factors on the Biodegradation of
           1,4-Dioxane by Microbial ...

    • Abstract: Objective : With the ultimate aim of application for effluent treatment, the relationships between 1,4-dioxane degradation by microbial consortium CDIK-3 and several relevant physicochemical environmental parameters were investigated.Methods : Microbial consortium CDIK-3 enriched from an industrial wastewater sample developed to grow aerobically with 1,4-dioxane as the sole carbon substrate was used to evaluate the degradation of 1,4-dioxane depending on the various environmental parameters and HPLC methodology was used to measure residual 1,4-dioxane in the test consortium.Results and Discussion : The microbial consortium, designated CDIK-3, was originally enriched from industrial wastewater sample. Complete depletion of 1,000 mg/L 1,4-dioxane was achieved in this experiment within 168 h. Effective 1,4-dioxane degradation was observed in slightly alkaline conditions (pH 8) and 30
      PubDate: Mon, 31 Aug 2020 00:00:01 +010
       
  • Proposed Framework of Performance Indicators for Evaluation of Sewerage
           Services: A Case Study ...

    • Abstract: Objectives : The objective of this study was to develop the performance indicators (PIs) framework for the assessment of sewerage services, especially focused on the case of the Seoul Metropolitan Government (SMG).Methods : For the prioritization of each indicator, the Analytic Hierarchy Process (AHP) method was employed to obtain the weights of individual performance ratings, and hence the survey questionnaire asking to make pairwise comparisons between two alternatives at each level was distributed to the experts in field of sewerage services. A total of fifty-six experts responded to the survey, and based on their decision-making, the relative importance of criteria and alternatives were calculated.Results and Discussion : The PI framework developed in this study consists of three hierarchical structures with levels 1 to 3, in which level 1 indicates three goals of the sewerage services, level 2 contains ten performance indicators, and level 3 includes twenty technical performance indicators. Of the framework, especially, the 10 PIs in the level 2 are designed to be open to the public after converting them into the grades. Of level 1, the water environmental soundness showed 62% of the entire weights was found to be the most prioritized objective, followed by the sewer service sustainability (27%) and the customer compliance to policy (11%), respectively. Of 10 PIs in level 2,
      PubDate: Mon, 31 Aug 2020 00:00:01 +010
       
  • Removal of Radioactive Cesium in Secondary Wastewater after Soil-washing
           Process

    • Abstract: Objectives : Secondary wastewater is generated as the soil washing process proceeds to restore contaminated soil near the nuclear power plants (NPPs). In this study, we tried to evaluate the possibility of removing radioactive cesium from secondary wastewater through the adsorption process using illite.Methods : To treat radioactive cesium present in wastewater, as an adsorbent, we used illite collected from Yeongdong, Chungbuk, and weathering illite artificially weathered by high temperature and acid treatment (60
      PubDate: Mon, 31 Aug 2020 00:00:01 +010
       
  • Monitoring of Nitrophenols and Insecticides in the Daecheong Lake, Served
           as Resources of ...

    • Abstract: Objectives:This study aimed to investigate distributions of three nitrophenols (4-nitrophenol, 2,4-dinitrophenol, 2-methyl-4,6-dinitrophenol) and five insecticides (acetamiprid, dinotefuran, thiacloprid, triflumuron, chlorfluazuron) in the Daecheong lake that is primary water resources for the central area in Korea including Daejeon. Furthermore, the effect of land use type and monthly precipitation on the concentration trends of nitrophenols and insecticides were assessed.Methods:River water samples were obtained for once in a month for five months (June to October in 2016) in seven sites of the Daecheong lake. All residues were analyzed by LC-ESI/MSMS after extraction using solid phase extraction cartridge. Method detection limit (MDL) of nitrophenols and insecticides were 0.4-1.2 ng/L and 0.2-5.0 ng/L, respectively. Average recoveries were 93.1% for nitrophenols (2,4,6-Tribromophenol), 68.7% and 41.3% for insecticides (Acetamiprid-d3, Thiacloprid-d4, respectively).Results and Discussion:Detection frequencies (DF) and total concentrations of three nitrophenols were 71.4 to 100%, and not detected (ND) to 487 ng/L, respectively. Among insecticides, DF of neonicotinoids (acetamiprid, dinotefuran, thiacloprid) and benzoylureas (triflumuron, chlorfluazuron) ranged 28.6 to 100%, and 0 to 28.6%. Total concentrations of insecticides were ND to 253 ng/L. Total concentrations of all target compounds showed a significant difference between upstream and downstream, and adjacent lake by Mann-whitney U test. According to raising precipitation, an increasing pattern of three nitrophenols was revealed in tributaries and lakes but not observed three neonicotinoids in three lake sites. In June, dinotefuran was not detected at the Juwon upstream site with a forest land coverage, however the concentrations rapidly increased from July to August, followed by a sharp decrease in September. For the other four sites (Daecheong dam, Munui, Chudong, and Pumgok streams), dinotefuran concentrations increased by over 20 times between July and October.Conclusions:In the Daecheong lake, which is used as a water supply source for over 3,470,000 personnel, three nitrophenol levels indicated 1,000 times lower than US EPA water quality criteria (WQC) unless high detection frequency (up to 70%). Similarly, there is only WQC among insecticides, acetamiprid showed under 1% of those of guideline. These results are acceptable as a drinking water supply source. To assess the correlation between characteristics of potential origin sources by land coverage and pollutant distributions, and relative monthly precipitation, it is indicated to be increased levels along with upstream surrounding with shrubland to downstream and adjacent lake covered with mixed land coverage (i.g. shrub, and human activities such as rice paddy, farm, transportation, and living). Besides, precipitation was higher as much as increasing concentration. It might be assumed that nitrophenols and insecticides spilled as non-target contamination sources with rainfall. Dinotefuran concentrations in Juwon upstream and three-site of lakes were massively increased in summer and autumn season considered as a pesticide spraying season for bug control such as Japanese pine sawyer, fruit moth, lace bug, and mites. These results implicated the possibility of using insecticides in a sanctuary where use of pesticides is prohibited.

      PubDate: Fri, 31 Jul 2020 00:00:01 +010
       
  • Electrochemical Treatment of High Concentration Ammonia using RuO2/Ti
           Anode and TiO2 Nanotube ...

    • Abstract: Objectives:In this study, the treatment potential of ammonia in wastewater generated by S company odor removal process was tested by using electrochemical reactor with RuO2/Ti anode and TiO2 nanotube cathode. The effect of chlorine ion concentration and current density on ammonia oxidation were investigated by comparing the treatment efficiencies.Methods:380 mL of wastewater was electrolyzed for 3 h using 4 anodes and 5 cathodes and pH, NH3-N, NO3--N, and TN were measured and analyzed every 30 minutes.Results and Discussion:As the addition of chlorine ion increases, about 1,700 mg/L of ammonia in the wastewater was found to increase in oxidation reaction rate due to an increase in chlorine based oxidizing agent. An increase in chlorine based oxidizing agent leads to an increase in indirect oxidation. As a result, total nitrogen removal was increased. Ammonia oxidation rate was increased as the current density increased. Nitrate, ammonia oxidation byproduct, was accumulated at a current density from 20 to 40 mA/cm2. At higher than 50 mA/cm2, nitrate was accumulated for a while and then decreased. Total nitrogen removal rate increased as the current density increased. During electrochemical oxidation of ammonia to nitrate, hydroxyl ions were consumed by the reaction. The hydroxyl ion consumed during ammonia oxidation was less than that produced from nitrate reduction.Conclusions:Thus, ammonia in actual wastewater was completely removed using RuO2/Ti anode and TiO2 nanotube cathode and the possibility of reducing nitrate was confirmed. We confirmed the applicability of the two electrodes to the real industry.

      PubDate: Fri, 31 Jul 2020 00:00:01 +010
       
  • A Study on Adsorption of Heavy Metals with Zeolite and FeS Media

    • Abstract: Objectives:Adsorption characteristics in aqueous solution were investigated to effectively remove heavy metals by the crystallization of FeS and reaction kinetics were analyzed to compare with heavy metal adsorption characteristics of zeolite.Methods:The adsorption characteristics of each media were analyzed using Langmuir adsorption isotherm, and the adsorption reaction kinetics of heavy metals (Pb, Cu, Zn) on zeolite and FeS media were analyzed by a pseudo-first or pseudo-second order reaction kinetics.Results and Discussion:The maximum adsorption capacity of zeolite was highest in Pb, and the adsorption preference was in the order of Pb>Cu>Zn. In the case of FeS media, Cu was found to have a higher adsorption capacity than Pb or Zn, and the adsorption preference was observed to be Cu>Pb>Zn. It was found that the adsorption mechanism is based on chemical adsorption (chemisorption) because adsorption of each heavy metal onto zeolite or FeS media is more suitable for pseudo-second order kinetics.Conclusions:It was found that the removal of heavy metals through FeS media has a different pattern from zeolite, and when comparing the adsorption capacity of each media, it was found that FeS media is more effective for Zn or Cu except Pb.

      PubDate: Fri, 31 Jul 2020 00:00:01 +010
       
  • Microbially Powered Electrochemical Systems Coupled with Membrane-based
           Technology for ...

    • Abstract: Objective:Seawater has a potential for managing the intensive potable drinking water demand. The recentconventional desalinating technologies are environmentally unsustainable and energy intensive. Thus, in the quest to find an alternative to the traditional desalination technologies, microbial desalination cells (MDC) have come into limelight. MDCs are considered the promising technologies for treating wastewater while simultaneously producing electricity, which can be utilized for desalinating seawater along with production of some value added products. However, some technical limitations associated with the practical usage of MDCs are pH maintenance at the cathodic side, internal resistance along with membrane fouling and its durability.Methods:These challenges can be dealt by utilizing various integrated configurations.Results and Discussion:Based on the study, the conventional technologies require less operational and maintenance cost but also less environmentally sustainable in comparison to these integrated MDC configurations.Conclusion:This review summarizes the basic working principles of MDCs, its types and factors affecting its performance and also several other applications associated with MDCs. This review also highlights various integrated MDC configurations which can be utilized for reducing the limitations associated to the conventional MDC system.
      PubDate: Fri, 31 Jul 2020 00:00:01 +010
       
  • Removal Characteristics of Toxic Gas on Activated Carbon Fiber Based Paper
           Filter

    • Abstract: Objectives:A paper filter was prepared by pitch based activated carbon fibers to investigate the removal efficiency of toxic gas. Also, changes in pore characteristics and mechanical properties according to the ratio of the adsorbent and the binder were observed to optimize the decrease in specific surface area and micropore, which are the unique characteristics of activated carbon fibers. In addition, it is intended to establish optimized paper filter derived activated carbon fiber manufacturing conditions through evaluation of toxic gas removal characteristics.Methods:The pore characteristics of the activated carbon fiber and prepared paper were analyzed by measuring the BET specific surface area, and SEM analysis was performed on the fine surface shape. Tensile strength and air permeability were performed according to ISO 1924-2 and ASTM D737: 04, respectively. The adsorption performance of the prepared filter was evaluated as a gas removal efficiency using a gas detection tube (GV-110S).Results and Discussion:As the content of the binder increased in the paper manufacturing process, it was confirmed that the specific surface area of ??the prepared filter decreased by up to 39.5% compared to the activated carbon fiber. It is considered that the micropores were closed because the surface of the activated carbon fiber was coated with the excessive addition of the binder. The removal efficiency showed a removal rate of 90% of ammonia, and methyl mercaptan and hydrogen sulfide showed a removal rate of about 60%. This result might be due to the difference in the physical adsorption rate according to the vapor pressure of each material.Conclusions:An activated carbon fiber-based paper filter for removing of toxic gas was prepared. It was confirmed that the mixing ratio of the adsorbent and the binder was an important process parameter for determining moldability and adsorption performance. Finally, optimum condition was selected as weight ratio condition of 8:2.

      PubDate: Tue, 30 Jun 2020 00:00:01 +010
       
  • Application of Enhanced BAC Process for Improving Drinking Water Treatment
           Efficiency

    • Abstract: Objectives:In this study, we compared the properties of the attached biofilm with the ability to remove biodegradable dissolved organic carbon (BDOC) in the conventional BAC (biologically activated carbon) process and the enhanced BAC process with phosphorus and hydrogen peroxide added. The enhanced BAC process was designed to increase the operational efficiency of the old O3/BAC process by evaluating the applicability of large-scale water treatment facilities located downstream of the Nakdong River.Methods:The granular activated carbon which was used for 2 years in the O3/BAC process in the water treatment plant located downstream of the Nakdong River was used in this experiment. During the experiment period, the ozone dosage was fixed at 1 mg'O3/mg'DOC. Four acrylic columns with an inner diameter of 20 cm and a height of 250 cm were prepared. Empty bed contact time (EBCT) was fixed at 20 minutes and backwash was performed once a week. The four BAC columns are conventional BAC (control-BAC), enhanced BAC with hydrogen peroxide (H2O2+BAC), enhanced BAC with phosphorus (PO4-P+BAC), and enhanced BAC with phosphorus and hydrogen peroxide together (PO4-P+H2O2+BAC). In the case of enhanced BAC with PO4-P added, PO4-P was added with a concentration of 0.010 mg/L in the influent, and in BAC with H2O2, H2O2 was added with a concentration of 1 mg/L to the influent.Results and Discussion:As a result of evaluating the recovery ability of the damaged biofilm, there was no difference in the biomass recovery rate in the H2O2+BAC compared to the control-BAC, but the biomass was rapidly recovered in the PO4-P+BAC. Considered the biomass and activity of the attached biofilm after the ability to remove organic substances reached a steady state, the biomass and activity in the entire filter layer of the PO4-P+BAC increased by 20 to 86% and 7 to 14%, respectively, compared to the control-BAC. In the H2O2+BAC, only the activity increased by 3~11% and In the PO4-P+H2O2+BAC, biomass and activity were high, about 27 to 87% and 8 to 20%, respectively. In the H2O2+BAC, the BDOC removal rate was higher than the control-BAC by 20%, and in the PO4-P+BAC, the BDOC removal rate increased by more than 100%. Detached total cell counts (TCC) in the control-BAC effluent was 41.7
      PubDate: Tue, 30 Jun 2020 00:00:01 +010
       
  • Comparison of Cation Anion Dye Removal Characteristics between Kelp-based
           Magnetic Biochar and ...

    • Abstract: Objectives:This study investigates the adsorption capacity of magnetic biochar (KB-Fe) derived from kelp for two dyes, Congo red (CR) and crystal violet (CV), which have different charge characteristics. The adsorption capacities were compared to magnetic biochar (PB-Fe) derived from pine.Methods:Pristine biochars (KB, PB) were produced through the pyrolysis of kelp and pine sawdust at 500
      PubDate: Tue, 30 Jun 2020 00:00:01 +010
       
  • Effect of Cell Density on the Removal of Microcystis by Coagulation

    • Abstract: Objectives:This study evaluated the removal of Microcystis by coagulation in raw waters with three different cell densities.Methods:Raw waters were prepared at three different cell densities (target cell densities of 10,000, 100,000, and 1,000,000 cell/mL; actual cell densities of 9,950, 102,000, and 991,000 cell/mL) by adding Microcystis into surface water from Nakdong river. Jar-tests were conducted with PACL, alum, illite, and loess at dosages of 0-150 mg/L.Results and Discussion:Regardless of coagulant types, the removal rates of Microcystis increased as the coagulant dosages increased. PACl and alum exhibited higher removal rates than illite and loess; PACl was the best coagulant to remove Microcystis. Removal of chlorophyll-a was highest when PACl added at 20.4 mg/L, and no significant increase in removal rate was observed with higher dosages of PACl. However, removal rates of chlorophyll-a by illite and loess gradually increased as the dosages increased.Conclusions:With the coagulants tested in this study, removal rates of Microcystis increased as the coagulant dosages increased. Removal rates of Microcystis increased as the cell densities increased probably because Microcystis acted as particles which could enhance the coagulation efficiency.

      PubDate: Tue, 30 Jun 2020 00:00:01 +010
       
  • Development of Methodology for Vulnerability Assessment of Chemical
           Accident in Terrestrial ...

    • Abstract: Objective:With rapid industrial development, human and the environment are frequently exposed to various chemicals. In particular, there is a possibility that terrestrial ecosystems as well as humans are exposed to a large amount of highly toxic chemicals due to accidents occurring frequently in Korea and abroad. If a large amount of chemicals enter the terrestrial ecosystem due to an accident such as a chemical leakage, the terrestrial ecosystem around the accident site may be affected and these chemicals may impair not only a living organisms, but also the function of terrestrial environment, the habitat of the organisms. The aim of this study is to develop methodology for vulnerability assessment of chemical accident in terrestrial ecosystem.Method:First, we selected 41 forest tree species and 41 shrubs among woody plants according to the domestic distribution and establish various vulnerability indicators that can be evaluated according to the exposure and recovery categories.Results and Discussion:As a result of vulnerability scoring for 41 forest tree species and 41 shrubs, most vulnerable species were Daphniphyllum macropodum, Lindera obtusiloba, Juniperus rigida, Diospyros lotus, and Eucommia ulmoides in forest trees and Zanthoxylum piperitum, Cephalotaxus koreana, Forsythia koreana, Cycas revoluta, and Lespedeza maximowiczii in shrubs.Conclusions:This study quantified the vulnerability of trees to chemical accidents by adding them and assigning them according to their characteristics. We expect that the risk of chemicals caused by chemical accidents occurring in these days and the exposure of chemicals to the environment can be assessed in terms of ecological perspective using the assessment of vulnerability of terrestrial ecosystems proposed in this study.
      PubDate: Sun, 31 May 2020 00:00:01 +010
       
  • Evaluation of Dissolved Organic Matter Removal Characteristics in GAC
           Adsorption Process in ...

    • Abstract: Objectives:In this study, we used liquid chromatograph-organic carbon detector-organic nitrogen detector (LC-OCD-OND) to evaluate adsorption and breakthrough characteristics of NOM fractions (biopolymers (BP), humic substances (HS), building blocks (BB) and low molecular weight organic substances (LMW-O)) according to the various characteristics of the different materials of granular activated carbons (GACs).Methods:Breakthrough characteristics, adsorption capacity and partition coefficients were evaluated by NOM fractions (BP, HS, BB, and LMW-O) using a lab-scale GAC adsorption column filled with coal-, coconut- and wood-based GAC. The GAC column test was operated with 10 minutes empty bed contact time (EBCT). The pore characteristics of each GAC were evaluated using an automated gas sorption analyzer (Autosorb iQ3, Quantachrome, USA) and the concentrations of NOM fractions in the influent and effluent were analyzed using chromatography LC-OCD-OND (Model 8, DOC-Labor, Germany).Results and Discussion:NOM adsorption capacity was evaluated for different materials of laboratory scale GAC adsorption column test. To study the adsorption behavior of individual NOM fractions according to the operation time, NOM was fractionated into BP, HS, BB and LMW-O by LC-OCD-OND, and the individual NOM fractions were quantified. Higher MW like BP was not adsorbed to GAC, in contrast, HS, BB, and LMW-O were well removed during the initial operation period, the concentrations in the effluent gradually increased as increase the operation period until reaching to the pseudo steady-state. Poor removal of BP in GAC adsorption may be a result of blocking the pores with large MW BP and hinder the access to the pores. However, in the case of HS, BB, and LMW-O, as the molecular size decreased, these organic matters easily access to the pores inside of GAC. It was confirmed through the partition coefficient that the adsorption capacity of these NOM fractions increased in proportion to the MW. In addition, in order to achieve a high NOM removal efficiency in the GAC adsorption process, not only the specific surface area, pore volume, and pore width of the GAC must be large, but also the pHzpc must be higher than the neutral pH level.Conclusions:In order to achieve a high NOM removal efficiency in the GAC adsorption process, not only the specific surface area, pore volume, and pore width of the GAC must be large, but also the pHzpc must be higher than the neutral pH level. In addition, in the NOM fractions, BP were not adsorbed to GAC, while the adsorption capacity of the remaining NOM fractions increased as the MW of the NOM fractions decreased. LMW-O was the most adsorbed, followed by BB, HS and BP. BP and HS play an important role in the membrane fouling that are introduced a lot into domestic and foreign water treatment plants. This study showed that the BP was not removed by the adsorption mechanism of the GAC process. In addition, HS was adsorbed and removed at the beginning of the operation, but the adsorption capacity of HS decreased rapidly as the operation period increased compared to other NOM fractions. Therefore, the GAC adsorption process is not expected to be an effective pre-treatment technology for reducing membrane foulants. Previous studies showed that the yields of DBPs (?mol?DBP/?mol?C) in the high MW humic and low MW non-humic fractions are similar. Therefore, it is suggested that the GAC adsorption process is more effective for DBP precursor control in water containing a larger percentage of LMW NOM.

      PubDate: Sun, 31 May 2020 00:00:01 +010
       
  • Key Operating Parameters Affecting Partial Nitritation Efficiency in the
           Nitritation Reactor ...

    • Abstract: Objectives:The purpose of this study was to investigate key operating parameters for partial nitritation in the nitritation reactor packed with PVA (polyvinyl alcohol)/alginate carrier.Methods:Partial nitritation was conducted in a 2 L reactor packed with PVA/alginate carrier of 30%. Dissolved oxygen (DO) concentration was considered as the main operating parameters. Raw reject water was used as the influent, and the ammonium concentration of the influent was adjusted with dilution at the beginning of operation. The DO concentration in the reactor was maintained at 3~4 mg O2/L. The activity test of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was conducted periodically. The effect of the operating parameters applied in this study was verified through analysis of microbial community.Results and Discussion:The stable performance for partial nitritation was achieved at operation time of 17 days. Thereafter, the reject water containing 683.6
      PubDate: Sun, 31 May 2020 00:00:01 +010
       
  • Effect of Internal Recycle Ratio on Nitrogen Removal Efficiency in a
           Three-stage ANAMMOX ...

    • Abstract: Objectives:In order to improve the stability of the ANAMMOX process, a three-stage ANAMMOX process combined with denitritation/nitritation process was operated, and effect of internal recycle ratio on the nitrogen removal efficiency was investigated.Methods:For the treatment of supernatant from anaerobic digester, a three-stage ANAMMOX process which combined as anoxic/oxic reactor and subsequent ANAMMOX reactor was installed. The reactor was designed with a working volume of 2.5 m3. The internal recycle ratio was considered as the main operating parameter, and the performance of nitrogen removal in the ANAMMOX process was evaluated.Results and Discussion:As the internal recycle ratio was increased from 0 to 1.5Q, reduction of the nitrogen load increased to 23.5
      PubDate: Sun, 31 May 2020 00:00:01 +010
       
  • Adsorption of Heavy Metals in an Aqueous Solution Using Starfish (Asterina
           Pectinifera) Biochar

    • Abstract: Objectives:Heavy metals caused by industrialization have affected human society for several decades. Because of their toxicity for humans, lots of heavy metal treatments have been developed. However, many of those treatments have economic considerations and environmental disadvantages. This work explored an experimental assessment of adsorption of heavy metals using starfish (SF) biochar through quantitative and qualitative characterization and batch-tests.Methods:Biochar (NACSF) was produced at 300
      PubDate: Sun, 31 May 2020 00:00:01 +010
       
  • A Study on the Improvement of Nitrogen & Phosphorus Removal of a
           Sequence Batch Reactor ...

    • Abstract: Objectives:The purpose of this study is to increase the denitrification and phosphorus removals by the oxygen control of the anaerobic or anoxic period using the circulation of the supernants through the settled sludge and multi-step addition of raw wastewater during the operation of the internal circulation sequence batch reactor (ICSBR).Methods:The internal circulation pipe at the bottom of SBR is installed to circulate the supernatant into the settled sludge layer to create anoxic condition of non-aeration period instead of a stirrer in a SBR. And it is attempted to develope the SBR that properly uses the organic materials of the raw wastewater as a carbon source by the feeding the raw wastewater at a suitable time of the reaction period.Results and Discussion:Dissolved oxygen (DO) concentration of the reactor decreases more rapidly with an internal circulation to which the uniform pressure division method is applied, increasing the efficiency of about 40%. As the multi-step addition of raw wastewater proceeds, the nitrogen concentration of effluent is lowered and the C/N (Carbon/Nitrogen) ratio is higher, the nitrogen removal rate is higher.Conclusions:Circulating the supernatant to the bottom through settle sludge was effected to properly control the dissolved oxygen in the reaction tank, thereby improving the denitrification efficiency by about 68%. Even the higher the C/N ratio at the step addition can be expected the higher the nitrogen removal, it is noteworthy that the optimum feeding ratio of the multi-step addition may be different depending on the C/N ratio.
      PubDate: Sun, 31 May 2020 00:00:01 +010
       
  • Occurrence and Behavior of Residual Pharmaceuticals in the Nakdong River
           Basin

    • Abstract: Objectives:This study was conducted to evaluate the detection characteristics of Nakdong River basin (wastewater treatment plant (WWTP) effluents, tributaries and main streams) by selecting 18 kinds of pharmaceuticals which were detected frequently. It was intended to be used as basic data for advanced treatment of WWTP and securing safe water source.Methods:The selected 18 pharmaceuticals investigated in this study were acetaminophen, atenolol, carbamazepine, caffeine, diclofenac, iopromide, lincomycin, metoprolol, primidone, propranolol, sulfachloropyridazine, sulfamethazine, sulfamethoxazole, tetracycline, trimethoprim, chlorotetracycline, oxytetracycline and sulfathiazole. The residual pharmaceuticals was analyzed LC-MS/MS equipped with on-line solid phase extraction (SPE) system and the limit of quantifications (LOQ) of 18 residual pharmaceuticals were 1~5 ng/L. Sampling points were 27 from the upstream to the downstream, including mainstream, tributary, and WWTP effluents. Sampling was conducted four times in Feb., Jun., Aug. and Nov. 2018.Results and Discussion:The most frequently detected residual pharmaceutical in all WWTP effluents, tributaries and mainstream sites was caffeine, followed by carbamazepine, lincomycin, sulfamethoxazole and iopromide. In addition, iopromide was detected as the highest mean concentration of 44.9~985.4 ng/L followed by caffeine (63.2~337.1 ng/L) and carbamazepine (13.8~145.0 ng/L), sulfamethoxazole (12.3~114.8 ng/L) and diclofenac (3.1~144.1 ng/L). In particular, the proportion ratio of caffeine gradually decreased as going to the downstream, whereas iopromide gradually increased. However, the concentrations of caffeine in the sampling sites of the downstream were higher than those of the upstream sites. The total concentrations of detected residual pharmaceuticals gradually increased from the upstream to the middle stream, showed the highest detected concentration at the Goryeong area in the middle stream of the Nakdong River, and then gradually decreased due to the dilution effect. Residual pharmaceuticals in the Nakdong River basin, which could not be completely removed from the WWTPs, entered into the water system and contaminated source water of the downstream. This process is a typical contaminant pattern of the source water by the emerging micropollutants.Conclusions:The most frequently detected residual pharmaceutical in all WWTP effluents, tributaries and mainstream sites was caffeine, followed by carbamazepine, lincomycin, sulfamethoxazole and iopromide. In addition, iopromide was detected as 44.9~985.4 ng/L, showing the highest mean concentration at the sampling points, and caffeine (63.2~337.1 ng/L) and carbamazepine (13.8~145.0 ng/L), sulfamethoxazole (12.3~114.8 ng/L) and diclofenac (3.1~144.1 ng/L) in order. The total concentrations of detected residual pharmaceuticals gradually increased from the upstream to the middle stream, showed the highest concentration at the Goryeong area in the middle stream of the Nakdong River basin, and then gradually decreased due to the dilution effect.

      PubDate: Thu, 30 Apr 2020 00:00:01 +010
       
  • Material Flow Analysis of Trichloroethylene in Korea

    • Abstract: Objectives:According to the material flow analysis, the domestic flow of trichloroethylene with the highest emission among carcinogens in group 1 was determined. The purpose of this study is to provide basic data for efficient chemical management and establish measures to reduce emissions.Methods:In this study, the material flow analysis of trichloroethylene was analyzed in Korea in 2014. The material flow chart was presented using STAN 2.6 software. The flow of trichloroethylene by region and industry was analyzed to identify the characteristics of each flow, and the emission reduction method was presented.Results and Discussion:Trichloroethylene was used up to 79.8% in the Seoul metropolitan area, 45.6% in the manufacturing of other machinery and equipment, and 29.4% in the manufacturing of fabricated metal products except machinery and furniture. Trichloroethylene was emitted 42.0% in the manufacturing of rubber and plastics products and 26.8% in the manufacturing of primary metals. The analysis of emissions by company size resulted in 3.9% of total emissions from large companies, 61.6% from mid-sized companies, and 34.5% from small-sized companies. Trichloroethylene was used in various industries and regions, with higher emissions compared to its use.Conclusions:Trichloroethylene has been emitted in large quantities relative to its usage. The study found that the management of chemicals in small businesses was insufficient. This result of the material flow analysis is used as basic data to reduce emissions of chemicals. The result of the study helps to recognize the risk of chemicals and suggest alternative materials, introduce inter-company information and expert exchange system, introduce a total amount of carcinogens emission system, implement duties in the emission reduction plan, and consider emission reduction incentives. In addition, measures to improve risk are proposed to establish risk-based database.

      PubDate: Thu, 30 Apr 2020 00:00:01 +010
       
  • A Study on River Representation for Water Impaired Analysis of Measurement
           Data at TPLMs

    • Abstract: Objectives:This study assessed the applicability of the total pollutant load management (TPLM) data on the analysis of impaired waterbody and pollutant source characterization. To achieve the study objective, the TPLM data collected in the downstream of Yeongcheon-Dam within the Geumho A unit-basin, Nakdong River basin for 6 years (2013-2018) were used to analyze the accountability for precipitation conditions, seasons, and flow rates. Methods:The study area is the downstram of Yeongcheon Dam within the Geumho A unit-basin, Nakdong River basin. The TPLM data used in this study were obtained from the two monitoring stations in the mainstream of Geumho River (i.e., Jahocheon and Geumho A station) and the three tributary streams (i.e., Gochoncheon, Sillyeongcheon, and Bugancheon). Precipitation conditions were classified into rainy (>10 mm/day) and non-rainy days (
      PubDate: Thu, 30 Apr 2020 00:00:01 +010
       
  • Effect of Oxidant Addition on Water Quality and Microfiltration
           Performance during Water Reclamation

    • Abstract: Objective:This study investigated the effects of ozone, chlorine dioxide, and chlorine pretreatment on water quality and microfiltration characteristics in the water reclamation facility.Methods:Ozone (0.5-2.5 mg/L), chlorine dioxide (1-5 mg/L) and chlorine (1-5 mg/L) were injected as an pre-oxidizing agent, and membrane fouling and surface damage during microfiltration (PVDF) were assessed. Results and Discussion:The hydrophobic substances were decomposed as the dosages of ozone and chlorine injected increased. However, chlorine dioxide could not effectively decompose hydrophobic organic matters in the range of 1-5 mg/L. In the case of pretreatment with chlorine, the microfiltration operation time was longer than in the case of pretreatment with ozone and chlorine dioxide. As the concentration of chlorine injection increased, the membrane filtration time before backwash gradually increased. Regardless of the type and concentration of the oxidizing agent, the membrane damage rate by the oxidizing agent was less than 1% within 28 days, and no surface damage was observed. Conclusions:Chlorine was considered to be the most efficient pre-oxidizer for microfiltration process with a PVDF membrane to reuse biologically treated wastewater in the wastewater treatment plant.
      PubDate: Thu, 30 Apr 2020 00:00:01 +010
       
  • Effect of Soil Washing Using Oxalic Acid on Arsenic Speciation and
           Bioaccessibility in Soils

    • Abstract: Objectives : Soil washing process has been widely applied for remediation of contaminated soil with arsenic and heavy metals in Korea. The application of soil washing could change physical and chemical properties of soils and metal speciation in soil, which could affect the risk to the environment and human health. Thus, it is necessary to evaluate metal and arsenic speciation and their mobility in soil after soil remediation in order to evaluate effectiveness of soil remediation process and manage soil quality effectively. The purpose of this study is to evaluate the risk of arsenic in soil after remediation of arsenic contaminated soil via soil washing.Methods : Arsenic contaminated soil collected at the abandoned mine site was washing with oxalic acid. The arsenic contaminated soil was divided into 2,000-500 'm, 500-250 'm, 250-150 'm, 150-75 'm, 75-38 'm, < 38 'm particle size fractions. After soil washing for each soil particle size fraction, arsenic speciation via sequential extraction and bioaccessibility in the soils were evaluated. Results and Discussion : Generally, arsenic and metal concentrations were higher in the soil fractions with smaller particle sizes. But high arsenic concentration was observed at the large particle size fractions (>250 'm), which might be due to the presence of mineral phases containing arsenic such as arsenolite or pyrite in the large particle size fraction soils. Sequential extraction showed that arsenic in mine soils was majorly present as associated with amorphous oxides. After soil washing with oxalic acid, arsenic in soils associated with amorphous oxides was greatly decreased, whereas the arsenic fraction associated sulfide and organic matter was increased. Soil washing decreased the bioaccessible arsenic concentration (mg/kg) in soil, but increased the bioaccessibility (%) depending on the soil characteristics. Conclusions : Soil washing changed arsenic species in soils, which affected mobility and risk of arsenic in soil.
      PubDate: Thu, 30 Apr 2020 00:00:01 +010
       
  • Development of Air Supply Control Technology in Sidestream MLE Process by
           Measuring Conductivity

    • Abstract: Objectives : This study aimed to achieve improved process performance and energy saving by developing a technology to control the air supply of an aerobic basin by measuring the conductivity in the anoxic basin.Methods : To verify whether conductivity can be used as an operation indicator of biological treatment, the correlation analysis between water quality factor and conductivity of each process was conducted by dividing into summer (methanol input), winter and autumn periods. An empirical formula was presented by briefly arranging the required air quantity formula, and a quick reference was prepared by putting air supply in the conductivity range sequentially. The performance evaluation was judged based on the removal efficiency of ammonia nitrogen and total inorganic nitrogen, SNR and SDNR, the change of air supply, the stability of the process against inflow change.Results and Discussion : The seasonal correlation coefficients of conductivity and water quality items were calculated in the order of ammonia nitrogen, total inorganic nitrogen, DOC, and phosphate in the range of 0.5267 ~ 0.9115. It was found that the conductivity could be used as an operation indicator of the biological treatment process with a correlation coefficient of 0.5 or more. The regression equations for the conductivity and ammonia nitrogen are secured by season, so it is possible to estimate the ammonia nitrogen through the conductivity. At the end of the aerobic basin DO was 3.4 mg/L, the nitrogen treatment efficiency in winter was the best. The aerobic basin DO can be controlled by the air supply, and it can be seen that it is possible to control the air supply and improve the nitrogen treatment efficiency by directly measuring the conductivity having a high correlation with nitrogen. An empirical formula for estimating the required air volume through conductivity and inflow is presented. A' and (B' + X') are 0.0589 (m3-air/h)/(m3/h)/(
      PubDate: Tue, 31 Mar 2020 00:00:01 +010
       
  • A Study on the Effects of Model Structure and Demand Allocation on Water
           Network Modeling

    • Abstract: Objectives:In order to reduce the uncertainty of the pipe network modeling, the model structure was basically included all distribution pipes and several models were proposed according to the location of the water meters.Methods:For models verification, first, a steady state simulation of each model was made by constructing a model including all water supply pipes (All-meters Model), which are the bases of 3 simplified models, and considering the location of all water meters. The network analysis was performed by dividing into the steady state and the extended period simulation.Results and Discussion:From the results of models comparison,
      PubDate: Tue, 31 Mar 2020 00:00:01 +010
       
  • A Study on the Verification of Inlet Structural Improvement of Side Stream
           Typed Low Pressure ...

    • Abstract: Objectives:The purposes of this study are to suggest a method to distribute the flow rate into the overall vessel vertically and evenly by improving the inlet hydraulic structure of the side stream type low pressure membrane module.Methods:For those, particle image velocimetry (PIV) technique was used to measure the evenness of flow rate distribution in both of the existing full scale single baffled inlet structure and the improved membrane module inlet structure (double baffled).Results and Discussion:As a result, it was confirmed that the flow distribution of the double baffled inlet structure is improved in comparison to that of the existing single baffled inlet structure. In the case of double baffled inlet structure, the instantaneous velocity distributions of 3, 4, and 5 seconds showed a velocity distribution close to the mean velocity of 0.03 m/s in the entire flow field. Also, a maximum velocity of 0.06 m/s was about 60% less than that of the single baffled inlet structure case (0.13 m/s). Conclusion:When the horizontal flow was observed, it decreased by about 300%. Those were 0.008 m/s for the double baffled inlet structure and 0.027 m/s for the single baffled, respectively.

      PubDate: Tue, 31 Mar 2020 00:00:01 +010
       
  • Pollution Intensity Assessment of Sediments Obtained Near Ieodo Ocean
           Research Station Using ...

    • Abstract: Objectives:The purpose of this study was to evaluate the heavy metal contamination level by analyzing heavy metals in sediments near Ieodo ocean research station located in southwestern Jeju Island. Methods:Sixteen sediments samples were collected from Ieodo ocean research station, and two and three sediment samples were collected from the southwestern region and between Ieodo and Jeju Island. These samples were used for heavy metal content analysis according to the marine pollution process test method, and contamination level of sediments was calculated using the measured heavy metal concentration. Results and Discussion:All heavy metals except Ni were evaluated as non-contamination level, and Ni was found to have high pollution level. According to the US Environmental Protection Agency guideline, samples 6, 9, 15, and 22 were classified as severe contamination, and according to the geoaccumulation index, samples 15 and 22 were classified as slightly contaminated for Ni. When classified by the Enrichment factor value, Ni contamination was categorized as moderately severe enrichment for samples 15 and 22. Using the potential ecological risk factor value, the ecological risks of the heavy metals in all samples were classified as low risk. The mean PEL quotient value for all six heavy metals in samples was a maximum of 0.60, indicating a 21% probability of toxicity for heavy metals in all samples.Conclusions:It was confirmed that there was no contamination by Cd, Cr, Cu, Pb, and Zn, but contamination by Ni was found to be a serious level. Compared with previous studies, the concentration of Ni in the Ieodo was found to be high, which may be due to the inflow of ocean research station or the Yangzu river runoff in China.
      PubDate: Tue, 31 Mar 2020 00:00:01 +010
       
  • A Study on the Rational Requirement Area Estimation of Municipal Sewage
           Treatment Facilities ...

    • Abstract: Objectives:In this study, a adjusted sewage & wastewater treatment capacity-required area estimation methodology was proposed through various data analysis for the required area of domestic sewage & wastewater treatment, the occupancy ratio of each sub-facility, and the treatment processing method. In addition, the reduction rate of the required area according to the application of the adjustment methodology presented in this study was evaluated quantitatively by comparing the actual area with the expected area.Methods:Statistical analysis was performed by collecting 654 data of more than 500 m3/day of treatment capacity in domestic sewage & wastewater treatment facilities. The 33 sewage & wastewater treatment facilities constructed by the LH sample groups were divided into functional areas and analyzed for occupancy rates by each facility.Results and Discussion:A capacity-required area regression model was developed for the collected each samples. As a result, the distributions of the regression model were divided into two clusters according to the analysis sample differences. It was analyzed that the estimated required area using the local government sample group was estimated to be relatively higher than the LH sample group. In this study, a adjusted capacity-required area model based on regression model derived from LH sample was proposed by considering green site ratio and treatment processing methods in sewage & wastewater treatment plant. The results are as follows: A = 15.638
      PubDate: Tue, 31 Mar 2020 00:00:01 +010
       
  • A Study on Membrane Filtration Characteristics of Methanogenic Mixed
           Liquor in Two Phase ...

    • Abstract: Objectives:An experimental study was conducted to investigate the membrane filtration characteristics of mixed liquor in methanogenic reactor to extend solid retention time (SRT) in food waste anaerobic digestion system.Methods:On the basis of the particle size distribution (0.5~700 'm) of the methanogenic mixed liquor, three grade membranes (MF, UF, NF) were tested in a stirred cell filtration and a plate type module. Furthermore foulants of membrane, especially UF, was investigated by SEM-EDS, FTIR, SEC.Results and Discussion:As a result UF membrane was selected for stable filtration of the liquor in terms of flux (2.51 L/m2'h'bar) and the flux recovery (100%) as well as filtration resistance (Total 7.15.E+13 m-1). Average flux was 18 L/m2'h'bar for the selected UF membrane in cross flow filtration using a flat plate module. The filtration results showed that membrane fouling was caused by gel and cake layer formed on the membrane surface and 90% of the initial flux could be recovered by physical washing. It was identified that major fouling causing materials were byproducts of carbohydrate and protein decomposition, and small amount of inorganic substance detected on the membrane surface were salt and struvite like materials.Conclusions:Based on the membrane filtration characteristics analyzed from the study, the UF membrane coupled anaerobic digestion is feasible to be applied as a novel food waste treatment system for SRT extension of the methanogenic reactor.
      PubDate: Tue, 31 Mar 2020 00:00:01 +010
       
  • Bioethanol Production Using Microalgae

    • Abstract: Objectives:Bioethanol is known as an important energy source that comes from plants, uses existing energy infrastructure without additional investment, and emits a low concentration of pollutants during combustion as eco-friendly renewable energy. Microalgae is reported as an effective material for producing bioethanol because of rapid biomass growth and relatively easy pretreatment steps. The objectives of this study are 1) to introduce general information of bioethanol production, 2) to show various processes for bioethanol production from microalgae, and 3) to provide an economic perspective of bioethanol. Methods:Recent published peer-reviewed papers were collected and analyzed. The contents follow the order: 1) introduction, 2) general information about microalgae for bioethanol production, 3) bioethanol producing processes, 4) economic feasibility, and 5) conclusion.Results and Discussion:The selection of the microalgae species and growing method are important to obtain high yield bioethanol. Physical, chemical, biological pretreatment was introduced. Also, comparison of the bioethanol producing processes was provided. Conclusions:Bioethanol production from microalgae is a promising energy source because microalgae have lots of advantages as effective biomass such as rapid growth, high polysaccharide contents, and easy preparing step for bioethanol production. However, it has some limitations that need to overcome. Algae growing method, pretreatment technology, and fermentation steps still require advanced technology, which can improve economic feasibility.
      PubDate: Tue, 31 Mar 2020 00:00:01 +010
       
  • Effects of the Pyrolysis Temperature on Adsorption of Carbamazepine and
           Ibuprofen by NaOH ...

    • Abstract: Objective: The main purpose of this study was to examine the impacts of the pyrolysis temperature on the removal of pharmaceuticals (i.e., ibuprofen (IBF) and carbamazepine (CBZ)) using NaOH pre-treated biochars produced from pine sawdusts.Methods:Two different types of kinetic and isotherm models were applied to investigate the adsorption mechanisms of IBF and CBZ by the NaOH pre-treated biochars produced at 600
      PubDate: Sat, 29 Feb 2020 00:00:01 +010
       
  • Biogas Reforming Conversion Character on Microwave-heating Carbon Receptor

    • Abstract: Objectives:Methane (CH4) and carbon dioxide (CO2) are the main components of biogas and are produced from biomass gasification. These two gases are a by-product gases that can be used as an energy source and is known as a greenhouse gas that affects global warming. In order to convert the gas which is the main cause of global warming into high-quality fuel energy, the microwave reforming characteristic research was conducted. In this study, the reforming characteristics of microwave carbon receptor pyrolysis-gasification gas were investigated. In addition, reforming gas conversion characteristics according to the reforming temperature, flow rate, and CH4 / CO2 ratio, which are the main influence variables, were studied.Methods:Experiment was achieved in a microwave convertor which was installed a quartz tube reactor. The reactor was irritated by a microwave energy to heat carbon receptor in a sample basket which was placed at the center of the quartz tube. A simulated gas mixture of methane and carbon dioxide was fed into the carbon receptor in the reactor, and a reformed product gas was collected and analyzed using a GC-TCD.Results and Discussion:In the case of microwave reforming of a mixture gas of carbon dioxide and methane, hydrogen and carbon was produced by thermal decomposition of methane. The produced carbon was adsorbed to the receptor and interfered with the catalytic activity. The attached carbon was reacted with the carbon dioxide by gasification reaction to produce carbon monoxide, and was cleaned to maintain a constant reforming conversion.Conclusions:As a result, the conversion rate and the product gas yield were high when the receptor bad reforming temperature was high and the space velocity in the convertor was low. The increase in methane in the simulated gas resulted in low conversion due to carbon adsorption.

      PubDate: Sat, 29 Feb 2020 00:00:01 +010
       
  • Optimization of Initial Turbidity and Coagulant Concentration to Remove
           Turbidity Using Moringa ...

    • Abstract: Objective:Coagulation of Moringa oleifera seeds was studied to determine the optimal conditions in treating a turbid water.Method:Jar-test experiments were performed at various rapid mixing (90-250 rpm; 1-2 min), slow mixing (10-60 rpm; 10-50 min), initial turbidity (100-500 NTU), coagulant doses (200-1,500 mg/L), and pH (2-12) in synthetic wastewater. Response surface analysis was used to optimize the coagulation in jar-test experiments.Results and Discussion:The optimal conditions for turbidity removal with M. oleifera were 200 rpm of rapid-mixing speed for 1 min, 40 rpm of slow-mixing speed for 20 min, and pH 8. The coagulation efficiency was found to be dependent on initial turbidity of water samples. Highest turbidity removals (96.5%) were obtained for water with very high initial turbidity (500 NTU). The effects of initial turbidity and coagulant dose were successfully analyzed by the response surface analysis. Within the design boundaries, turbidity removal was more sensitive to changes in initial turbidity than to changes in coagulant dose.Conclusions:The quadratic model between initial turbidity and coagulant for turbidity removal was shown. M. oleifera can be used as a potential coagulant especially for high turbidity water.

      PubDate: Sat, 29 Feb 2020 00:00:01 +010
       
  • Effects of Oxidative and Alkaline Post-treatments on Removal of Trivalent
           Iron and Hexavalent ...

    • Abstract: Objectives:The main goal of this study was to compare the removal efficiency of trivalent iron and hexavalent chromium by peanut shell biochars (i.e., PB), post-treated peanut shell biochars using KMnO4 (i.e., PB-Ox), and secondary post-treated peanut shell biochars using KOH (i.e., PB-Ox-A).Methods:The adsorption mechanisms of trivalent iron and hexavalent chromium by PB, PB-Ox, and PB-Ox-A were investigated using two types of adsorption kinetic and isotherm models. Furthermore, the adsorption experiments were performed under different adsorbent dosages (0.8 - 2.4 g/L), temperatures (15 - 35
      PubDate: Sat, 29 Feb 2020 00:00:01 +010
       
  • Patterns of Heavy Metals in a Continuous Toxicity Monitoring System using
           Bioluminescent Bacteria

    • Abstract: Objectives:The purpose of this study is to evaluate the effects of heavy metals (Zn2+, Pb2+, Hg2+, Cd2+) toxicity in a real-time biosensor which is based on measuring the attenuation of light intensity emitted by Vibrio fischeri.Methods:The inhibition test included four heavy metals and the spiked effluent wastewater. The toxicity of the test samples was assessed by freeze-dried bacteria (Vibrio fischeri NRRL-B-11177). The pH of the samples was adjusted to 7
      PubDate: Sat, 29 Feb 2020 00:00:01 +010
       
  • Risk Assessment for Co-contaminated Soil Including As and Hg in the
           Vicinity of Abandoned Metal Mine

    • Abstract: Objectives:In Korea, about 2,000 abandoned mine area has been polluted by harmful waste such as mine tailing, waste rock and acid mine drain without prevention facility. Mine waste contains high concentrations of various hazardous metallic and nonmetallic materials. Also, it can be a source of pollution for nearby soil, rivers, and ground water. Heavy metals may exist in ecosystems for a long time and may be taken by the residents through crops and drinking water. In this study, human risk assessment for heavy metal contamination was carried out.Methods:About the 564 soil samples were analyzed for heavy metal. The risk assessment of polluted soils was carried out in accordance with guideline of Korea Soil Environment Conservation Act. It was implied with hazard identification, exposure assessment, toxicity assessment, and risk characterization.Results and Discussion:The number of exceed sites for the worried level of soil concentration were 185 for As, 3 for Hg, 7 for Zn, 1 for Pb, 1 for Cu. Soil contact was the biggest impact on adults and children for carcinogenic risk followed by crop intake, soil intake, and soil inhalation. Non-carcinogenic risk for adults, were in order of crop intake> soil intake> soil contact> outdoor air inhalation (volatilization)> ground water intake and soil inhalation. For children, it was in the order of soil intake> crop intake> soil contact> outdoor air inhalation (volatilization)> ground water intake> soil inhalation.Conclusion:The carcinogenic purification target concentration for the site was determined to be 7.17 mg / kg level of arsenic, considering adult and child concentrations. However, carcinogenic purification target concentration by arsenic dermal absorption carcinogenic coefficients (SFabs) of USEPA method was 20.08 mg/kg, therefore requiring research for domestic risk assessment factor.
      PubDate: Sat, 29 Feb 2020 00:00:01 +010
       
  • Optimization and Performance Evaluation of Pilot-scale Electrochemical
           H2O2 Generator according ...

    • Abstract: Objectives:In this study, We developed pilot-scale bipolar-electrochemical generator (or bipolar-electrolyzer) for generating hydrogen peroxide (H2O2). By comparing H2O2 concentration and generation efficiency of H2O2 according to structure and arrangement of anode/cathode spacer, the structure and arrangement of spacer have been optimised for high H2O2 concentration and generation efficiency. Methods:The concentration and generation efficiency of H2O2 were evaluated by changing the width of the channel supporter in anode/cathode spacer and we optimised the arrangement of anode/cathode spacer in electrochemical generator. Additionally, we also evaluated the efficiency of H2O2 generation with different concentration catholyte (Na2SO4).Results and Discussion:The electrochemical H2O2 generator applied anode/cathode supporter with narrow channel supporter showed high H2O2 concentration of 2023.83 mg/L. Electrochemical H2O2 generator with N-C type spacer (anode: no channel supporter, cathode: channel supporter) showed the highest H2O2 concentration (2295.95 mg/L) and H2O2 generation efficiency (86.87%). also, we observed that the electrolyzer with 20 PSU has higher H2O2 concentration (4217.74 mg/L) and generation efficiency (74.80%).Conclusions:As a results, We generated H2O2 with high concentration and high generation efficiency by optimising structure and arrangement of spacer in electrochemical H2O2 generator. Also, We concluded that the developed bioplar-electrochemical generator in our study could be applied to the real industry.
      PubDate: Sat, 29 Feb 2020 00:00:01 +010
       
  • A Study on Particulate Matter Footprint Calculation on Transportation
           Modes

    • Abstract: Objective : In this study, we proposed the concept of the particulate matter footprint (PM Footprint) and assessed the PM Footprint in transportation modes (road, rail, and water transportation). In addition, we assessed the contribution of secondary particulate matter formation gas emissions, which contribute to particulate matter formation.Method : To calculate the PM Footprint in the transportation sector, the ReCiPe life cycle impact assessment method in life cycle assessment (LCA) was used. For the PM Footprint of each transportation mode, the life cycle inventory data were multiplied by the characterization factors of PM10, PM2.5 and secondary particulate matter formation emissions such as NOx, SOx, NH3. The PM Footprint values were shown in kg PM2.5 eqv. value.Results and Discussion : The road transportation (trucks) had a much higher PM Footprint value than rail and water transportation in tkm unit based. In the road transportation mode, small size truck such as 3.5 tons (1.37E-03 kg PM2.5 eqv./tkm), 3.51~5 tons (9.65E-04 kg PM2.5 eqv./tkm), 1.25 tons (8.38E-04 kg PM2.5 eqv./tkm), and 1 ton (7.83E-04 kg PM2.5 eqv./tkm) had higher PM Footprint value than big size trucks. In the rail transportation mode, the diesel rail transportation had the highest PM Footprint value, followed by electric + diesel rail transportation and electric rail transportation. In the water transportation mode, the tanker LNG_100 dwt had the highest PM Footprint value, followed by ro-ro ship coastal, and tanker coastal 500~20,000 dwt. The secondary particulate matter formation emissions (NOx, SOx, NH3) contributed to PM Footprint value with 59% in road transportation, 80% in rail transportation, and 61% in water transportation. Conclusions : The PM Footprint values, which shown in this study and the results of the directed polluted PM and secondary gas emissions should be considered for national PM reduction policy and planning. Finally, a certification system using the PM Footprint in this study should be developed and settled down for national PM reduction.

      PubDate: Fri, 31 Jan 2020 00:00:01 +010
       
  • Adsorption of Methylene Blue from Aqueous Solution by Pumpkin-Seed Residue

    • Abstract: Objective : Present research discussed the utilization of pumpkin-seed residue (PSR) after oil extraction with methanol as an adsorbent for methylene blue (MB) removal from aqueous solution.Method : The experiment was carried out to evaluate the influence of PSR adsorbent dose (7.5-25 g/L), initial MB concentration (25-200 mg/L), contact time (30-120 min), pH (3-11), and temperature (293-333 K). Adsorption isotherms were modeled with the Langmuir, Freundlich, and Temkin isotherms. The kinetic data were analyzed using pseudo-first-order and pseudo-second-order models.Results and Discussion : A pseudo-equilibrium state was reached within 30 min of contact time at low initial MB concentration (25-50 mg/L) and 90 min at high concentration (100-200 mg/L). Increasing pH and temperature caused an increase in adsorption capacity. Thermodynamic studies demonstrated that the adsorption process was spontaneous with Gibb
      PubDate: Fri, 31 Jan 2020 00:00:01 +010
       
  • A Study on Distribution and Characteristics of Radon Concentration in
           Metro Line 1 in Busan

    • Abstract: Objective : Adverse health effects of Radon with a particular focus on indoor environment has been outlined. Most of the metro stations and platforms are situated under the ground where relatively enhanced concentration of radon has been observed.Method : On-line measurements of indoor Radon have been made in Metro Line 1 in Busan using RAD-7.Results and Discussion : The average concentration of Radon was 8.9 Bq/m3 (n=40). In general, a positive relation was shown between the level of radon and the depth of station. Slightly enhanced radon concentrations were observed between 0 a.m. ~ 5 a.m. when the station is closed under the non-operation of ventilation system. Interestingly, the negative relation was seen between the radon revel and temperature.Conclusions : Relatively low levels of indoor radon has been observed in Metro Line 1 in Busan, which may be associated with geographical location of non-granite regions.

      PubDate: Fri, 31 Jan 2020 00:00:01 +010
       
 
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