정윤철 Yun Chul Chung , 손대희 Dae Hee Son

DOI: Vol.18(No.2) 103-112, 2002

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조경덕 Kyung Duk Zoh

DOI: Vol.18(No.2) 113-122, 2002

A bench-scale anoxic membrane bioreactor (MBR) system, consisting of a bioreactor coupled to a ceramic crossflow ultrafiltration module, was evaluated to treat a synthetic wastewater containing alkaline hydrolysis byproducts (hydrolysates) of RDX, The wastewater was formulated the same as RDX hydrolysates, and consisted of acetate, formate, formaldehyde as carbon sources and nitrite, nitrate as electron accepters. The MBR system removed 80 to 90% of these carbon sources, and approximately 90% of the stoichiometric amount of nitrate, 60% of nitrite. The reactor was also operated over a range of transmembrane pressures, temperatures, suspended solids concentration, and organic loading rate in order to maximize treatment efficiency and permeate flux. Increasing transmembrane pressure and temperature did not improve membrane flux significantly. Increasing biomass concentration in the bioreactor decreased the permeate flux significantly. The maximum volumetric organic loading rate was 0.72 kg COD/㎥/day, and the maximum F/M ratio was 0.50 kg N/kg MLSS/day and 1.82 kg COD/kg MLSS/day. Membrane permeate was clear and essentially free of bacteria, as indicated by heterotrophic plate count. Permeate flux ranged between 0.15 and 2.0 ㎥/㎡/day and was maintained by routine backwashing every 3 to 4 day. Backwashing with 2% NaOCl solution every fourth or fifth backwashing cycle was able to restore membrane flux to its original value.

김광수 Kwang Soo Kim , 서규태 Gyu Tae Seo , 이경호 Kyung Ho Lee , 김낙주 Nag Ju Kim

DOI: Vol.18(No.2) 123-130, 2002

Bench scale experiments were carried out with two biological nutrient removal(BNR) units, A/O and A^2O processes, to investigate the behavior of phosphorus in the system and to compare the characteristics of phosphorus removal in two BNR processes. To achieve this goal, COD/T-P and COD/TKN ratios of the influent was varied in the range of 23∼64 and 5∼24, respectively. In A/O process, influent COD/T-P ratio should be kept higher than 44mg/L to meet the final effluent T-P concentration lower than 1mg/L and in A^2/O process, influent COD/T-P and COD/TKN ratios higher than 56 and 10, respectively, were required for good phosphorus release and uptake with no influence of nitrate nitrogen in return sludge. At this conditions, the rate of phosphorus release in the anaerobic basin should be kept higher than 0.1 kg S-P/kg MLVSS·d In A/O process, the phosphorus content of anaerobic and aerobic sludges was increased as SRT of total system was becoming longer resulting in decreasing the difference of phosphorus content between two sludges while phosphorus release in anaerobic basin and phosphorus uptake in aerobic basin was not incident. In A^2/O process, the phosphorus content of anaerobic and aerobic sludges were not increased with higher SRT of total system due to the relatively high nitrate concentration in return sludge. However, the difference of phosphorus content between anaerobic and aerobic sludges was incident when phosphorus release and uptake was observed.

박재로 Jae Roh Park , 임현만 Hyun Man Lim , 김응호 Eoung Ho Kim

DOI: Vol.18(No.2) 131-140, 2002

Laboratory-scale membrane bioreactor added alum into the anaerobic basin as a flocculant and adsorbent was carried out to find removal efficient of nitrogen and phosphorus components in the mixed liquid and weather or not maintaining the stability for the permeate flux and pressure at various internal recycle conditions. It was found that denitrification efficient of maximum 65% was obtained when the ratio of internal recycle was 3Q. Additionally when the ratio of internal recycle was fixed at 3Q, BOD_5 and T-P concentration of permeate was much more reduced compared to not added alum in anaerobic basin but T-N concentration of permeate was relatively increased. In case of added alum as the flocculant and adsorbent in anaerobic basin, the permeate flux was maintained above 10ℓ/㎡/hr but the permeate pressure was relatively higher than alum was not added in anaerobic basin.

박재로 Jae Roh Park , 임현만 Hyun Man Lim , 김응호 Eoung Ho Kim

DOI: Vol.18(No.2) 141-150, 2002

Two-stage membrane bioreactor using submerged hollow fiber membrane was applied in laboratory scale to treat nitrogen and phosphorus of domestic wastewater. Alum as the flocculant and adsorbent was added into the anaerobic basin of two-stage membrane bioreactor and mixed liquid of aerabic basin was recycled to the anaerobic basin for the purpose of nitrogen removal. Experiment was carried out to find removal efficient of phosphorous and nitrogen components in the mixed liquid, and the stability of the permeate flux and pressure of two-stage membrane bioreactor. In case of alum was added as the flocculant and adsorbent into the anaerobic basin, soluble phosphorus removal efficient was relatively higher and total permeate resistance (Rtot) was more increased out nitrogen removal efficient was lower as the result of lack of alkalinity and insufficient nitrification process than the case of alum was not added.

황문현 Moon H. Hwang , 현승훈 Seong H. Hyun , 장남정 Nam J. Jang , 조재원 Jea W. Cho , 김인수 In S. Kim

DOI: Vol.18(No.2) 151-157, 2002

Landfill leachate is one of highly contaminated and heterogeneous wastewater. The leachate from initial landfill can be treated by anaerobic process because it contains biodegradable matters, particularly, volatile fatty acids (VFAs). However, the anaerobic treatment of leachate is generally required longer hydraulic retention time (HRT) than aerobic process and another treatment process to satisfy effluent concentration. Therefore the modification of conventional anaerobic treatment is needed. Two phase anaerobic membrane process (TPAMP) is an integrated membrane process to be able to separate anaerobic metabolism into two phase which are acidogenesis and methanogenesis for improvement of anaerobic treatment efficiency. In this study, the efficiency of TPAMP and conventional anaerobic treatment were compared in terms of HRT, effluent SCOD, VFAs Membrane used in TPAMP was the UF of capillary type with the surface area of 0.048 ㎡. The average effluent SCOD of conventional anaerobic treatment was 1352 mg/L and the removal was 96 % at HRT 60 days, while in TPAMP, 927 mg/L and 98% at HRT 30 days.

차기철 Gi Cheol Cha , 황명구 Myoung Goo Hwang , 이명규 Myung Gyu Lee , 태민호 Min Ho Tae

DOI: Vol.18(No.2) 159-168, 2002

A lab-scale Reverse Osmosis(RO) membrane reactor was installed to investigate the membrane permeability, characteristics of membrane fouling at each conditions, and performance of elimination at different trans-membrane pressure(TMP) in the liquid fertilizer accumulated system. Experimental setup was divided to three different TMP conditions. As a result of experiment, permeability of RO membrane was proportional to the increase of TMP and temperature. After experiment was completed, two types chemical cleaning(remove the organic foulant and inorganic foulant) was done, and recover rate of permeability was each 99.8, 99.7 and 99.7%, respectively. From this experimental data, membrane fouling could be determined that the most of it was recoverable in this system, and major reason of fouling was concentration polarization. Elimination rate of solute substance in the liquid fertilizer indicated very stable(above 99%), except ammonia nitrogen, and the most stable elimination rate was investigated at the highest TMP condition (Run 3).

Heung Jin Choi , Il Kyu Kim

DOI: Vol.18(No.2) 169-187, 2002

The effects of important parameters such as reaction time and pH on the Fenton`s process were evaluated using a batch reactor. It was proven that organic materials and heavy metals in leachate could be successfully removed by Fenton`s reagent. Favorable operation conditions were investigated. It was observed that the reaction between ferrous iron and hydrogen peroxide with the production of hydroxyl radical was almost complete in 10 minutes. That is, the oxidation of organic materials by Fenton`s reagent was so fast that it was complete in 30 minutes with batch experiments. With the formation of carbonic acid, pH of the batch reactor decreased to favorable acidic conditions without acid addition. The oxidation of organic materials in the leachate showed a pH dependence and was most efficient in the pH range of 2-3.

정근진 Kun Jin Jung , 이상수 Sang Soo Lee , 김시현 Si Hyeon Kim , 박규홍 Kyoo Hong Park

DOI: Vol.18(No.2) 189-199, 2002

Nitrogen, in its various forms, can deplete dissolved oxygen levels in receiving waters, stimulate aquatic growth, exhibit toxicity toward aquatic life and affect the suitability of sewage for reuse. Pilot-scale Rotating Biological Contactor(RBC) experiments were conducted to examine biological nitrification, respectively, of municipal sewage with five different internal recirculation ratios of 0, 1, 2, 3, and 4 using the constant hydraulic loading of 205 U/㎡·day. The use of internal recirculation improved nitrification on account of the dilution of biodegradable organic carbon in influent sewage down to 15mg/L of SBOD_5 or less. Ammonium nitrogen of 14.3±2.4 % was consumed by cellular assimilation without the occurrence of denitrification. The thickness of biofilm didn`t seem effect significantly the nitrification and denitrification. Nitrification with internal recirculation was found to occur using hydraulic loading rate of as high as 205L/㎡·day, which was beyond the generally known values of it.

염규진 Kyu Jin Yum , 이정훈 Jeong Hun Lee , 김선미 Sun Mi Kim , 최원석 Weon Seok Choi

DOI: Vol.18(No.2) 201-212, 2002

The objective of this study was to investigate the treatment efficiency, kinetics, and morphological characteristics of biofilm in upflow Biobead^ⓡ process, a kind of biological aerated filter(BAF). The Biobead^?? system showed high removal rates of COD_Mn, (76∼83%), BOD_5(67∼88%) and SS(71∼91%) for food wastewater with high salt concentration (>4,000㎎/ℓ) under short reaction times(2∼3hrs). Even at aerobic condition, the system had high treatment efficiency for both T-N (51∼63%) and T-P(62∼81%). The removal kinetics of COD_Mn, BOD_5, T-N, T-P, and Cl^- in the Biobead^?? system showed a plug-flow pattern with reaction rate constants(hr^-1) of 0.58, 0.63, 0,30, 0.48, and 0.38 respectively. A backwashing process to remove excess biomass and filtered solids was needed at least once during 22-hour operation at 0.5kg BOD m^-3·d^-1 loading. At the higher loading(1.0kg BOD m^-3·d^-1) the backwashing interval was shorten by 8 hours. The COD, BOD, T-N, and T-P were removed from 43 to 66% only by aerobic biodegradation. The SS was removed over 70% by the filtering of Biobead^?? media in the treatment system. The first one of three serial Biobead reactors showed the highest removal values for COD_α(52.3%), COD_Mn(38.8%), BOD(62.5%), and T-N(40.0%). The SS and T-P had the highest removal values(47.5% and 29.2%) at the second one of the serial reactors. The biofilm had non-homogeneous spatial distribution and the colonies were embedded in the sunk area of the Biobead. The thickness of the biofilm was very thin (5.0∼29.4㎛) compared to the biofilm thickness(200∼300㎛) used in other BAF systems

Seon Hong Kang

DOI: Vol.18(No.2) 213-220, 2002

In this study the effects of initial pH, temperature, dissolved oxygen concentration, and sediment depth on the release of phosphorus from sediment in Lake Sihwa were investigated. No phosphorus release occurred at 10℃ for all pH values. DO concentrations were decreased and equilibrium was obtained 4-8 days after phosphorus release started. The DO concentrations were less than 1 mg/L. Sediment depth had little effect on phosphorus release rate. In order to control the released phosphorus, raw sludge and chalk were used. Results showed that a portion of phosphorus was removed by adsorption to chalk and raw sludge. About 90 % phosphorus removal was observed using sludge and calcinated chalk from the water sample in Lake Sihwa.

윤상린 Yun Sang Leen , 김동하 Dong Ha Kim , 이영규 Young Kyu Rhee

DOI: Vol.18(No.2) 221-228, 2002

Abundant growth of algae in raw water sources caused by eutrophication brings about significant side effects on water supply, such as taste and order problem, oxygen depletion, toxic material secretion, and filter clogging problem in water treatment process, etc. The purpose of this research is to remove the algae and phosphorus compounds in the Pal-dang reservoir promptly by using the upflow filtration system with coagulant addition. The filter tower consisted of sand media and sieve filter with air back-washing process. By using coagulation and filtration with 132㎛ pore size filter, about 55% and 70% of algae and phosphorus compounds were removed respectively. The experimental conditions were as follows; head loss of 0.2m, linear velocity of 200m/day, and filtration flux of 1000(L/㎡/day). In the case of filtration with cartridge type filter of 25㎛ pore size, the filtration flux was about 7800 LMH, and the removal ratios of COD, SS, T-P, and Chlo-a. were 61%, 99%, 54%, and 98%, respectively. However, high pressure air back-washing process with should be required for the maintenance of such high filtration flux.

학회자료

DOI: Vol.18(No.2) 229-229, 2002

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