Showing papers in "Journal of Korean Society of Water and Wastewater in 2011"

맛있는 물 지표 개발을 통한 국내 약수 평가

Abstract: 【This study was motivated by the purpose of improving the O-Index, currently used to quantify water tasty. The authors first develop the M-Index after normalizing Ca, K, and $SiO_{2}$ concentrations in the spring water, in that the concentrations are subject to their log-normal distributions. The M-Index is then compared with the O-Index based on the results of sensory tests, revealing that sensory tests are correlated with the M-Index much more than the O-Index. Furthermore, the developed index is applied to evaluate water sampled from 53 springs in Korea. It is concluded that water, sampled from five most famous springs, has high values in M-Index. In addition, water, collected from springs that are relatively accessible, contains low values, and thus is expected not to tasty good.】

Fluoride and nitrate removal in small water treatment plants using electro-coagulation

Abstract: In this study we verified if the electro-coagulation process can treat properly the nitrate and fluoride that are not removed well in the conventional small water treatment plants which usually employ chlorination and filtration only. As we gave a change of electrode material and gap-distance between electrodes, removal efficiency of the nitrate and fluoride was determined by electro-coagulation process which were equipped with aluminum and stainless steel (SUS304) electrodes. In addition, electrode durability was investigated by determination of electrodes mass change during the repetitive experiments. Removal efficiency was great when aluminum was used as an anode material. Nitrate removals increased as electric density and number of electrodes increased, but fluoride removal was less sensitive to both parameters than nitrate. After 10 minutes of contact time with the current density from to , nitrate and fluoride concentration ranged from 9.2 to 1.2mg/L and from 0.02 to 0.01mg/L, which satisfied the regulation limits. Regardless of the repeating number of experiments, removal efficiency of both ions were almost similar and the change of electrode mass ranged within 0.5%, indicating that the loss of the electrode mass is not so much great under the limited circumstances.

Introduction of Corrosion Index System for Stability of Drinking Water Quality

Abstract: Replacement of old water distribution pipes for protecting water quality induced by pipe corrosion requires enormous budget. Even after the replacement, however, corrosion can occur again at any times and, therefore, inhibitive measure of the corrosion will be not only economical but needed to diminish the consumers' distrust on tap water quality. In 2008, National Environmental Research Institute did a survey on 8 major drinking water source and proposed to establish the Langelier Saturation Index(LI) as a corrosion index in Drinking Water Quality Criteria. Among the water industries of Korea, K-Water is the only one that set up the level of pH over 7.0 and LI above -1.5 on yearly average basis. However, no systematic regulation including LI to inhibit the corrosive tendency has been established yet. In this paper, LI values out of 31 drinking water treatment plants were analyzed and two-stage control of LI value as a measure of corrosive tendency of water is proposed. Primarily, water treatment facilities may operate the system at a target LI value below -1.5. Following the investigation on the effect caused by adjusting the LI value on water quality and corrosiveness, it will be desirable to improve LI value below -1.0 in the long run. In addition to the LI, supplemental use of Larson's modified ratio (LMR) which incorporates hydraulic detention time will be necessary. Several methods to prove the inhibitive effect of improving the LI value on water quality have been also suggested.

Development of Water Demand Forecasting Simulator and Performance Evaluation

Abstract: Generally, treated water or raw water is transported into storage reservoirs which are receiving facilities of local governments from multi-regional water supply systems. A water supply control and operation center is operated not only to manage the water facilities more economically and efficiently but also to mitigate the shortage of water resources due to the increase in water consumption. To achieve the goal, important information such as the flow-rate in the systems, water levels of storage reservoirs or tanks, and pump-operation schedule should be considered based on the resonable water demand forecasting. However, it is difficult to acquire the pattern of water demand used in local government, since the operating information is not shared between multi-regional and local water systems. The pattern of water demand is irregular and unpredictable. Also, additional changes such as an abrupt accident and frequent changes of electric power rates could occur. Consequently, it is not easy to forecast accurate water demands. Therefore, it is necessary to introduce a short-term water demands forecasting and to develop an application of the forecasting models. In this study, the forecasting simulator for water demand is developed based on mathematical and neural network methods as linear and non-linear models to implement the optimal water demands forecasting. It is shown that MLP(Multi-Layered Perceptron) and ANFIS(Adaptive Neuro-Fuzzy Inference System) can be applied to obtain better forecasting results in multi-regional water supply systems with a large scale and local water supply systems with small or medium scale than conventional methods, respectively.

A Study on Estimation of Pollutant Loads in Seonakdong River Using SWAT-SWMM Model

Abstract: Seonakdong river consists of stagnant sections whose flowrate is controlled by the Daejeo and Noksan gates. As a result, there is not a minimum flow during normal times. The Daejeo and Noksan gates are located at the upstream head and the downstream end of Seonakdong river, respectively. Seonakdong river is an estuarine tributary of Nakdong river, which is a reservoir-like river used for agricultural irrigation, with the gate at the estuary of the river to prevent the intrusion of saline. Since the construction of the water gates, the water quality of the river has become degraded. This could also be due to the internal loading of pollutants, especially nutrients, from the sediments of the river because of the elongated detention time by the water gates. This study was thus conducted for the purpose of evaluating the current hydrologic-cycle system and providing measures for the rehabilitation of the hydrologic cycle. In this research, the daily outflow in Seonakdong River was simulated using the SWAT and SWMM models, and the water quality concentration including BOD, SS, TN, and TP were analyzed. The possibility of the application of SWAT-SWMM hybrid simulation was determined through the verification of both models. The error analysis shows that the results of both SWAT and SWAT-SWMM simulations make good agreements with those of field observations. For the single simulation results of SWAT, and NSE are 0.758, 0.511, respectively. For the hybrid simulation results of SWAT-SWMM, those are 0.880, 0.452, which means that the hybrid simulation can give more accurate results for the watershed where both the agricultural and urban areas exist.

Feasibility Study on Installing a Multi-functional Storage Facility

Abstract: In the era of climate change, the feasibility of a 'multi-functional storage facility' was evaluated in terms of various key performance indices such as flooding prevention effects, urban pollution reduction effects, and rainwater harvesting effects. As a result, the Korea Ministry of Environment introduced a new concept of 'multi-functional storage facility' for sewer flooding prevention and urban non-point pollution reduction. Prior to introducing these infrastructure (a large underground storage facility), the more details were needed to be examined carefully in all of technical aspects of construction and management. It was also well known that the validity of installation of 'multi-functional storage facility' was sometimes weakened because of a low B/C ratio.

Characteristics of Red Tide Blooms in the Lower reaches of Taehwa River

Abstract: This study was analyzed to determine the cause of red tide at 10 and 30 days antecedental rainfall, stage and discharge inthe Taehwa River, tidal data of Ulsan port, also, it was analyzed variation of red tide population, salinity, BOD, COD, T-N, T- Pat S1, S2 each point. Most of the red tide in the Taehwa River occurred by provision of proper nutrients with antecedent, the proximity between discharge and low-flow capacity, and stage and discharge of stabilized condition after the sea water was inflowed by maximum tide difference. Red tide population is not nearly related to the change of salinity, the Taehwa River seem sspecific features of Non-coastal rivers downstream, because red tide was occurred when salinity quite low-end condition.Key words : Taehwa River, Red Tide, Antecedent Rainfall, Water Quality Variation주제어 : 태화강, 적조, 선행강우, 수질변화 ＊Corresponding author Tel:+82-52-259-2262, Fax:+82-52-259-2629, E-mail: hjcho@mail.ulsan.ac.kr(Cho, H.) 1. 서 론 적조의 사전적 의미는 ‘동물성 플랑크톤의 이상 번식으로 바닷물이 붉게 물들어 보이는 현상’이다. 이처럼 적조는 주로 바다에서, 특히 연안해역에서 많이 발생하였고, 많은 연구가 연안해역을 대상으로 이루어졌다(이 등, 2001; 이 등, 2006). 그러나 최근에는 남해와 남동해에 위치한 하천 하류부에서도 적조가 빈번히 발생하고 있으나, 이에 대한 연구는 많지 않은 실정이다(이, 2009). 일반적으로 식물성플랑크톤의 증식은 외양해수와 혼합이 어려운 연안하구지역이나 내해는 태평양 등의 외양해수와 특징이 다르지만(Fisher 등, 1992), 육지에서는 인, 바다에서는 질소의 영향을 크게 받는다(Hecky and Kilham, 1988, Mahoney, 1989)고 하였으며, 우리나라 연안해역에서 발생하는 적조와 관련한 연구를 살펴보면 다음과 같다. 최(2001)는 남해안 나로도와 소리도 사이의 해역을 대상으로 수온과 염분을 관측하여 적조의 발생, 진행, 소멸의 원인이 염분분포의 차이라고 주장하였다. 서 등(2003)은 나로도 주변해역에 대한 7년간의 위성영상을 분석하여 최초 발생하는 적조의 원인을 고온고염의 열염전선대와 관련된다고 추정하였다. 이 등(2007)은 여수반도를 중심으로 한 남해안에서 적조 발생에 기여하는 담수의 영향을 조사하여 집중 호우시 인근 섬진강 및 동천으로부터 유입하는 다

Characteristics and Improvement of Tap Water Corrosivity in Korea

Abstract: To investigate corrosivity characteristics of tap water in Kore a, Langelier index (LI) of 30 multi-regional water treatment pl ants(WTPs) were evaluated. Weekly LI values of 30 WTPs were all neg ative, which means tap water in Korea might be very corrosive.Maximum LI decrease through water treatment processes was 0.95 under no additional corrosion control process. Based on thecorrelation results between LI and tap water qualities, pH and calcium concentration were confirmed as major parameters for LIcontrol. Addition of calcium hydroxide with CO 2 or calcium hydroxide or sodium hydroxide can be chosen based o n water quality.Continuous monitoring of LI and related parameters is recommend ed in water distribution system. Key words : Langelier index, internal corrosion, corrosion control, tap wa ter, water treatment, water quality monitoring 주제어 : 랑게리아 지수, 내부부식, 부식제어, 수돗물, 정수처리, 수질모니터링 ＊Corresponding author Tel:+82-64-754-3448, Fax:+82-64-725-2483, E-mail: kjinkeun@jejunu.ac.kr(Kim, J.K.)

A study on the corrosion control of tap water by lime and carbon dioxide

Abstract: A method to improve internal corrosion control efficiency by adding lime and carbon dioxide, which, in turn increases the Langelier Index (LI) for filtered water at a conventional drinking water treatment plant (WTP) was investigated. The SJ WTP (Q=100,000 /d) has been operating an internal corrosion control system since 2006. The system has achieved stable operation through technical development and trial and error over a period of several years. As a result of the operation, the LI of treated water has increased up to 29% by adjusting pH of filtered water to 7.8 with the addition of lime and carbon dioxide. Coupon tests in the distribution system indicated that the corrosion rate has been delayed by 24% when the internal corrosion method was implemented. The increase of LI by lime and carbon dioxide has been proven to be a practical method for controlling corrosion.

Effects of Pretreatment Time and pH low set value on Continuous Mesophilic Hydrogen Fermentation of Food Waste

Abstract: Since 2005, food waste has been separately collected and recycled to animal feed or aerobic compost in South Korea. However, the conventional recycling methods discharge process wastewater, which contain pollutant equivalent to more than 50% of food waste. Therefore, anaerobic digestion is considered as an alternative recycling method of food waste to reduce pollutant and recover renewable energy. Recent studies showed that hydrogen can be produced at acidogenic stage in two-stage anaerobic digestion. In this study, the authors investigated the effects of pretreatment time and pH low set value on continuous mesophilic hydrogen fermentation of food waste. Food waste was successfully converted to when heat-treated at for 60 min, which was milder than previous studies using pH 12 for 1 day or . Organic acid production dropped operational pH below 5.0 and caused a metabolic shift from fermentation to lactate fermentation. Therefore, alkaline addition for operational pH at or over 5.0 was necessary. At pH 5.3, the result showed that the maximum hydrogen productivity and yield of 1.32 .d and 0.71 mol/mol . Hydrogen production from food waste would be an effective technology for resource recovery as well as waste treatment.

Particle Separation and Flotation Efficiency by Dissolved Carbon Dioxide Flotation Process

Abstract: A series of laboratory experiments carried out to investigate the particle separation efficiency and flotation characteristics using bubbles. The primary objective of this study was to find out the feasibility of bubbles as an applicable unit of flotation process in tap-water and wastewater treatment plant. The fundamental measurements were conducted to characterize the bubble from the physical viewpoint in water including bubble size distribution and rising velocity under various operational conditions. In addition, the removal efficiency of solid was experimented using the lab scale plant applied bubbles, namely the dissolved carbon dioxide flotation (DCF) process. The DCF process using carbon dioxide bubble, which is an advantage as the decrease and the reuse of Green-House gas, can be a promising technology as an water treatment process. On the other hand, the further research to decrease the bubble size distribution of is required to enhance the particle separation efficiency.

Evaluation of effect of rapid mixing intensity on chemical phosphorus removal using Al hydrolysis speciation

Abstract: Mechanism of rapid mixing effect on chemical phosphorus removal is evaluated in this study. Assuming that chemical phosphorus removal is unaffected by mixing time, only rapid mixing intensity is evaluated. In order to find out the mechanism, it is hypothesized that rapid mixing affects the Al hydrolysis speciation, and that formation of more monomeric species () results in better removal of phosphorus. According to a ferron assay, more formed at higher mixing intensity than at lower intensity. Subsequent experiments revealed that better phosphorus removal was obtained at higher intensity than at lower intensity, in terms of the molar ratio of . The proposed hypothesis was proved in this study. Chemical phosphorus removal is affected by rapid mixing intensity due to its effect on the Al hydrolysis speciation.

Case study comparisons of computational fluid dynamics modeling versus tracer test to evaluate the hydraulic efficiency of clearwell

Abstract: Hydraulic efficiency was a vital component in evaluating the disinfection capability of clearwell. Current practice evaluates these system based on the tracer test only. In this paper, CFD(Computational Fluid Dynamics) was applied on the clearwell for alternating or supplementing the tracer test. The baffle factor derived from the CFD modeling closely matched the values obtained from full scale tracer testing. And, for suggesting proper numerical model in clearwell; the turbulence model, discretization scheme, convergence criteria were investigated through separate simulation runs. The model validation was conducted by comparing the simulated data with experimental data. In the turbulence model, the realizable model and the standard model were found to be more appropriate than RNG model. The residuals of convergence criteria should be used as not but or . In discretization scheme, the difference of simulated values in 1st, 2nd, 3rd upwind scheme was found to be insignificant. Moreover, the result of this study suggest that CFD modeling can be a reliable alternative to tracer testing for evaluating the hydraulic efficiency.

Comparison of physical cleaning applied to chemical backwashing of wastewater reuse membrane system

Abstract: Biologically treated water contains a large quantity of organic matters and microorganisms which can cause various problems to membrane. The membrane fouling occurred by these reasons is hard to control by single physical cleaning. This study analyzes the efficiency of aeration with chemical backwashing and foulants removal during chemical backwashing. The cleaning efficiency improves when the chemical concentration is high and the contact time of chemical is long. Chemical backwashing with aeration shows exceptional cleaning efficiency which leads the physical cleaning is required during chemical backwashing since it forms flow inside the membrane submerged tank. From the foulants removal analysis, the particles such as turbidity and TOC removal rate increase when the aeration is applied. Dissolved matter of DOC and UV254 removal is dependent on higher chemical concentration. According to FTIR analysis, one of major foulants, the polysaccharide is controlled by the chemical backwashing with aeration condition.

A Study on Pre-Red Mud and Bio-Solids Applicability as Soil Stabilizer

Abstract: Recycling as a stabilizer of industrial by-product can be terms of the proper handling of industrial by-product and positive side in terms of recycling of waste. This study was performed to evaluate has the possibility as stabilizer by primary processing Pre-Red Mud and Bio-Solids which are generated as waste in soils contaminated with heavy metals and compared the efficiency with steel slug being applied in an existing site. In evaluation of the arsenic-fixing ability of stabilizer in batch test, Bio-Solids have the similar arsenic-fixing ability with Pre-Red Mud, which shows 17% h igher arsenic-fixing ability than PS Ball. Since the stabilization periods using Bio-Solids and Pre-Red Mud are faster than the PS Ball, they seems to be better stabilizer than PS Ball to decrease the leaching of arsenic in contaiminated soil.

A Performance Evaluation of the Highly Efficient Coagulation System for the Treatment of Overflows from Primary Clarifier in WWTP

Abstract: This study is to develop highly efficient coagulation system(HECS) that runs treatment with a short retention time to cover t heoverflow in the rain, which coagulation, mixing and settling are contacted in a single reactor and to estimate the applicabilit y. Setting up 100ton/day-size pilot scale plant, the results of continuous operation in case of runoff, maintaining 20 minute-retention time at optimum chemical injection condition(Alum 100mg/L, Polymer 1.0mg/L) shows the highest removal efficiency(Turbidity 93.1%, TCODcr 80.6%, BOD 81.8%, SS 92.5%, TN 72.3% and T-P 87.3%). It was estimated that the large amount of cost for separate sewage system and the size of area for system instruction can be reduced if the HECS is applied for CSOs treatment because the HECS is so compact and quickly. When we see the results, HECS from this study could be able to treat the pollutant quickly within a short retention time only with coagulant and polymer, which could show high applicability. Key words : Overflows from Primary Sediment in WWTP, High Efficiency Coagulation System, CSOs주제어 : 일차침전지 월류수, 고효율 응집시스템, 합류식하수관거유출수

Study on decentralized options of the in-stream flow for restoring the Gyobang cheon: application of the Urban Volume and Quality (UVQ) model to examine feasibilities in water quantity and quality

Abstract: This study has a purpose of examining technical feasibility of supplying the in-stream flow for the Gyobang cheon by using treated water from small wastewater treatment facilities as a decentralized option. To do this, the water and contaminant flow in study areas of the Gyobang cheon are defined from the context of the integrated urban water cycle, and analyzed by using the Urban Volume and Quality (UVQ) model. First, the UVQ model was built for the study areas of the Gyobang cheon and calibrated with observation data. Second, the decentralized options of the in-stream flow was explored with consideration of availability of water sources. The UVQ simulation then led to selecting the best option which would meet the criteria of water quantity and quality. It was finally concluded that using water sources out of study areas 1 and 2, adjoining the upper part of the Gyobang cheon, in the decentralized manner can be a feasible option for in-stream flow. It also seems that the UVQ model is useful to understand the water cycle in study areas of the Gyobang cheon.

A Study on the Evaluation of Water Consumption in Electric Appliances using Water Footprint - Focusing on Washing Machine -

Abstract: In this study, by using the Water footprint technique, the water consumption by washing machines, which holds higher ranks in using water than any other electric appliances, was analyzed during their life cycle. The life cycle is defined as raw materials production step, manufacturing step, and using step. In raw materials production step, Input materials were researched by using LCI DB(Life Cycle Inventory Database) and the water consumption was calculated with consideration of approximately 65% Input materials which were based weight. In manufacturing step, the water consumption was calculated by the amount of energy used in assembly factories and components subcontractors and emission factor of energy. In using step, referring to guidelines on carbon footprint labeling, the life cycle is applied as 5 years for a washing machine and 218 cycles for annual bounds of usage. The water and power consumption for operating was calculated by referring to posted materials on the manufacture's websites. The water consumption by nation unit was calculated with the result of water consumption by a unit of washing machine. As a result, it shows that water consumption per life cycle s 110,105 kg/unit. The water consumption of each step is 90,495 kg/unit for using, 18,603 kg for raw materials production and 1,006 kg/unit for manufacturing, which apparently shows that the using step consume the most water resource. The water consumption by nation unit is 371,269,584tons in total based on 2006, 83,385,649 tons in both steps of raw material production and manufacturing, and 287,883,935 tons in using step.

Effects of sludge and $CO_2$ addition on advanced treatment of swine wastewater by using microalgae

Abstract: The potential of algal-bacterial culture was investigated for advanced treatment of animal wastewater. Fed-batch experiments were carried out to examine treatability of nitrogen and phosphorus in different microbial consortium: Chlorella vulgaris, activated sludge, three microalgae strains (Scenedesmus, Microcystis, Chlorella) and Bacillus consortium, and three microalgae strains and sludge consortium. Single culture of C. vugaris showed the better efficiency for nitrogen removal but was not good at organic matter and phosphorus removal compared with activated sludge. Three microalgae and Bacillus consortium was best culture among the culture and consortium for pollutants removal tested in this experiment. Effect of addition was studied by using three microalgae and Bacillus consortium. addition enhanced T-P removal efficiency up to 60%. However, removal efficiencies of T-N and ammonia nitrogen reduced on the contrary.

Understanding Uncertainties in Projecting Water Demand and Effects of Climate Change for Adaptive Management of Water Supply Risk of the Water Resources System

Abstract: A special concern is paid to the risks with which small-sized water resources systems are confronted in supplying water in the far future. Taking the Gwangdong dam reservoir as a case study, the authors seek to understand demand-side and supply-side disturbances of a reservoir, which, respectively, corresponds to effects of water demand changes on the intake amount and those of climate changes on the inflow amount. In result, it is demonstrated that both disturbances in the next 50 years are almost unpredictable. Yet the projection ranges, thought of as relatively reliable information that models offer, reveal that severity and period of water shortage is very likely to change. It is therefore concluded that water resources management requires more rigorous approaches to overcoming high uncertainties. The methods and models for projecting those disturbances are selected, based on practicality and applicability. Nevertheless, they show a large usefulness, especially in dealing with data shortage and reducing the needs for expensive modeling resources.

산화전리수를 이용한 질소와 황 계열 악취 및 악취전구물질의 제거

Abstract: An electrolytic oxidation process was applied to remove odorous compounds from non-point odor sources including wastewater pipelines and manholes. In this study, a distance between the anode and the cathode of the electrolytic process was varied as a system operating parameters, and its effects on o...

Degradation Of 4-chlorophenol By Photo-Fenton Process and Fenton Process in Aqueous Solutions

Abstract: The degradation of 4-chlorophenol by various AOPs(Advanced Oxidation Processes) including the Fenton and the photo-Fenton process has been examined. In sole Fe, UV or process without combination, low removal efficiencies have been achieved. But the photo-Fenton process showed higher removal efficiency for degradation of 4-chlorophenol than those of other AOPs including the Fenton process. Generally more hydrogen peroxide was required to achieve higher removal efficiencies of 4-CP at constant dosage of in both of the Fenton and the photo-Fenton processes. Based on the results, The photo-Fenton process is proposed to be the most efficient alternative for degradation of 4-chlorophenol among the processes studied in this research.

Analysis on the result of I/I calculation by the exiting method and the standardized maual method

Abstract: The purpose of sewer system is to separate rain water from sewage water. Through this, it is possible to prevent the flood and preserve public water territory. For the past few years, many problems of the sewer system have been solved by the execution of sewer rehabilitation project. However, they still exist in sewer system caused by I/I, which are divided into infiltration and inflow. Infiltration means the rain water and underground water that infiltrate through breakage point on pipes, inflow means the water that flows in through misconnection on pipes. This study shows how the I/I calculation has changed according to the new standardized manual and identifies the I/I difference between the new calculation and the existing one. Through the analysis on the two calculation methods we examined the appropriacy of the new method by comparing it to the old one. The result points out that the new standardized manual is more appropriate than the old in aspect of objectivity and reproducibility(establish standardization), rationality(alteration of inflow unit).

Degradation of 2-chlorophenol by Ferrate(VI)

Abstract: The degradation characteristics of 2-chlorophenol(2-CP) by Ferrate(VI) were studied. The degradation efficiency of 2-CP in aqueous solution was investigated at various values of pH, Fe(VI) dosage, initial concentration and aqueous solution temperature. The maximum degradation efficiencies of 2-CP were obtained at pH 7.0 and aqueous solution temperature of 25. The degradation efficiency was proportional to dosage of Fe(VI). Also, the initial rate constant of 2-CP degradation increased with decreasing of the 2-CP initial concentration. In addition, the degradation pathway study for 2-CP was conducted with GC-MS analysis. Acetic acid, formic acid, benzaldehyde and benzoic acid were identified as reaction intermediates of the 2-CP degradation by Ferrate(VI).

Continuous Removal of Nitrate and Coliform using Bipolar ZVI Packed Bed Electrolytic Cell

Abstract: Nitrate is a common contaminant in industrial wastewater and ground water. The maximum contaminant level set by EPA for nitrate of 10 mg/L as N. In this study, nitrate was removed using bipolar ZVI packed bed electrolytic cell that maximized the contact area between each electrode and contaminants under 600 V. Also this study investigates the simultaneously deals with removal of ammonia by operating air stripping tower. In addition to the air stripping also helped to precipitate iron ions to the form of iron oxides. Bipolar ZVI packed bed electrolytic cell was also effective in removing coliform by electrical power. In the continuous experiments for the simulated wastewater (initial nitrate for 25 mg/L as N), maximum 96.3% removal of nitrate was achieved in the applied 600 V at the flow rate of 6 mL/min.

Development of High-rate Nitrogen Removal Process Using Submerged MBR Packed with Granular Sulfur of Pilot Scale Plant

Abstract: In this study, a process combined biofiltration with sulfur-utilizing autotrophic denitrification and membrane separation was proposed to examine the efficiency of nitrogen removal. As an experimental device, hollow-fiber module was installed in the center of reactor to generate the flux forward sulfur layer in the cylinder packed with granular sulfur. In addition, a simple module was installed in activated sludge aeration tank which inside and outside of sulfur-using denitrification module was covered with microfilter and the module was considered as an alternative of clarifier. The experiment for developing new MBR process was carried out for three years totally. As the results of first two-year experiment, successful nitrogen removal performance was revealed with lab-scale test and pliot scale plant using artificial wastewater and actual plating wastewater. In this year, pilot scale test using actual domestic wastewater was performed to prove field applicability. As the results, high-rate nitrogen removal performance was confirmed with about 0.19 kg day of rate. Also significant fouling and pressure increase were not found during the experiment. And, the production ratio of sulfate and the consumption ratio of alkalinity showed a slightly higher value about 311 mg and 369 mg /L, respectively. In conclusion, the developed MBR process can be utilized as an alternative for retrofiting existing wastewater plants as well as new construction of advanced sewage wastewater treatment plants, with cost-effective merit.

Measures to improve water quality of Lake Euiam by controlling the incoming pollutants to the lake

Abstract: 【The purpose of this study was to suggest the alternative measures to properly manage the water quality of Lake Euiam, Chuncheon. Current pollution level of Gongji stream (influent to Lake Euiam) and sources of contamination in Lake Euiam were investigated. Particle size, organic matter and nutrient contents, heavy metals were analyzed for sediment samples taken from lower region of Gongji stream. Average organic matter content of nine sediment samples was 5.7%, and for nitrogen and phosphorus it was 750 mg/kg and 977mg/kg, respectively. Heavy metals including aluminum, iron, manganese and zinc were measured, whereas Cd and As were not detected. Effluent from Chuncheon Wastewater Treatment Plant appeared to be one of the main cause of organic matter and nutrients level in Lake Euiam. Inhibition of primary production and consequent reduction of organic matter content within the Lake should be a key measure to protect the water quality of Lake Euiam. Preventive measures to reduce the level of nutrients in wastewater treatment effluent were found necessary.】

Evaluation on Chemical Cleaning Efficiency of Organic-fouled SWRO Membrane in Seawater Desalination Process

Abstract: Membrane fouling is an unavoidable phenomenon in operation of seawater reverse osmosis (SWRO) and major obstacle for economic and efficient operation. When fouling occurs on the membrane surface, the permeate flux is decreased, on the contrary, the trans-membrane pressure (TMP) is increased, therefore operation and maintaining costs and potential damage of membranes are able to the pivotal risks of the process. Chemical cleaning process is essential to prevent interruptions for effective RO membrane filtration process. This study focused on proper chemical cleaning condition for polyamide RO membranes of 4 companies. Several chemical agents were applied for chemical cleaning under numbers of operating conditions. Additionally, a monitoring tool of FEEM as autopsy analysis method is adapted for the prediction of organic bio-fouling.

Analysis of Infiltration/Inflow at Dry and Rainfall Periods in Separated Sewer System of Nakdong River Basin

Abstract: This study was conducted to provide a basic information for the establishment of operation and treatment processes in sewer system of Nakdong river basin to minimize the overall pollutants loading to water body. Sewage flowrates were regularly measured and monitored at various sampling points of newly-built separated sewer system located in G City GA sites. To assess the inflow sewage flowrate, various calculating methods such as water-use evaluation, average-minimum daily flow quality evaluation, minimum daily flow evaluation, night water-use evaluation were used. Average I/Is were calculated except water-use evaluation. Average I/Is were found to be 6.5 , 3.5 , 7.7 at GA-1, GA-2, GA-3 points respectively. I/I ratios of three areas were found to be 4.8 %, 2.0 % and 2.7 % respectively and were obviously lower than those of the other separated sewer systems as shown in the previous studies.

Removal of boron in seawater by activated carbon adsoprtion

Abstract: Adsorption characteristics of boron on activated carbon was investigated in order to evaluate the use of activated carbon for the removal of boron in desalination processes using SWRO. Boron was removed ranging from 54~60% when the concentration of activated carbon was 1,000 mg/L in 6 hours under the initial boron concentration of 5 mg/L. The removal of boron increased by 20~22% with the increase of pH from 5 to 9. Organic matter had adverse effect on the adsorption of boron on activated carbon. Boron removal decreased by 10-12% when EDTA was added at 1 mg/L under 5 mg/L of boron and 200mg/L of activated carbon. In this results, activated carbon would be a good candidate for a pretreatment of desalination processes by SWRO from the view of mitigating the feed boron concentration to RO and meeting the effluent boron concentration without post-treatment after RO.