한무영 , 정팔진 , 이정학 , 정윤철 , 독고석 Moo Young Han , Paul Gene Chung , Jeong Hak Lee , Yun Chul Chung , Seok Dockko

DOI: Vol.13(No.3) 1-8, 1997

문병현 , 이택순 , 서정윤 , 서희정 Byung Hyun Moon , Taek Soon Lee , Jeoung Yoon Seo , Hee Jung Seo

DOI: Vol.13(No.3) 227-234, 1997

This study was conducted to use waste oyster shell as biofilm media for biological wastewater treatment. The comparison between the activated sludge and the submerged biofilm process with oyster shell media (5% of reactor volume) for domestic sewage treatment was made at various hydraulic retention times. The effluent quality of the submerged oyster shell reactor was more stable than that of activated sludge reactor. The BOD removal efficiencies of the submerged process was above 80% at the various organic loading rates of 0.12∼0.55㎏BOD/㎥/day. The COD and SS removal efficiencies of the submerged process were higher than that of the activated sludge process. Also, TKN and T-P removal efficiencies of submerged process were higher than that of the activated sludge process. The comparison between the submerged biofilm process with oyster shell media of 10% and 18% was made at various loading rates. The hydraulic retention time was fixed to 6hr. The BOD, COD_(Cr) removal efficiencies of 10% and 18% were above 80% at organic loading rates of 1.0㎏ BOD/㎥/day and 1.5㎏COD_(Cr)/㎥/day but the removal efficiencies of 18% reactor decreased as the organic loading rates were increased. The TKN removal efficiencies of 10% and 18% were above 70% at organic loading rates of 0.2㎏ TKN/㎥/day. However, the removal efficiencies of 18% reactor decreased at the higher loading rates. The phosphorus removal efficiencies of both reactors showed similar removal efficiencies.

박진용 , 김재진 , 서상봉 , 장문석 , 정두식 Jin Yong Park , Jae Jin Kim , Sang Bong Suh , Moon Seog Jang , Doo Sig Jung

DOI: Vol.13(No.3) 235-244, 1997

The spiral wound type RO (reverse osmosis) membrane module (BW30-2540) for brackish water showed the high values of salt rejection rate and recovery rate in the primary performance tests. Therefore, it was selected for applying RO membrane process to groundwater treatment to use the industrial water. In the field test of the groundwater the value of permeate rate was almost constant, 29.93L/㎡·hr, and very stable water quality, TDS (total dissolved solids)=10∼20㎎/L. After the operation of the RO membrane process during 750hrs, the membrane was disassembled from the module and investigated to find the membrane fouling and its sources. The components of the fouling layer in the membrane surface were Si, Mn, Fe, Ca and K, which were supposed to be the source of the membrane fouling. And, the insoluble organic materials, i.e. algae, were accumulated on the membrane surface, and the inorganic salt component involved in the fouling layer was 1.2282%.

김태응 , 임봉수 Tae Eung Kim , Bong Su Lim

DOI: Vol.13(No.3) 245-253, 1997

김용환 , 조재현 , 이용우 , 정용대 Yong Hwan Kim , Jae Hyun Cho , Yong Woo Lee , Yong Dae Jeong

DOI: Vol.13(No.3) 255-262, 1997

송준상 , 문형극 , 이홍근 Jun Sang Song , Hyung Keuk Moon , Hong Keun Lee

DOI: Vol.13(No.3) 263-273, 1997

Samkwang Aqua-Clear, Inc. has developed the fluidized bed biofilm method using the SAC Bio-Carrier made of waste tire powder and called Bio-SAC Process. The removal rate of organic matter of this method can treat the wastewater 4 times faster than the conventional activated sludge method and it has specially designed aerobic bio-reactor filled with 20% SAC Bio-carrier of the volume of reactor. We have done the application research for the municipal sewerage treatment and the results are summarized as follows: The removal rate of biochemical oxygen demand(BOD) and chemical oxygen demand(COD-Mn) was around 90% and the Hydraulic retention time(HRT) of the aerobic bio-reactor is 1.5 hours. Although the suspended solids(SS) concentration of raw water was very high and varied widely because this method has no primary sedimentation tank, its concentration of the effluent is only around 10㎎/L. Also nitrification reaction was occurred and the removal rate of total kjeldahl nitrogen(TKN) was around 80% during the short HRT. The removal rate of total phosphorus was around 70% with chemical coagulation process using the alum and polymer. Its rate was higher than that of the conventional activated sludge method. The bio-film microorganism grew abundantly on the surface of the SAC Bio-carrier. Epistylis spp. was observed as a predominant species, and the depth of the biofilm was 0.3∼1.0㎜. This species is one of the peritrichita that grow well in the aerobic reactor at the good treatment condition. The treatment coefficient(T₁) of Bio-SAC^R process from the Grau`s multicomponent degradation model was four times higher than that of the activated sludge method. This SAC treatment method can not only reduced the 50% of the building area of the wastewater treatment plant, but also reduced the 20% of the capital cost. Because the removal rate of the total phosphorus is much higher than the activated sludge method, this treatment method is more effective process as the tool of the prevention method for the point source control of the eutrophication.

황병기 Byung Gi Hwang

DOI: Vol.13(No.3) 275-282, 1997

In assessing water quality conditions of coastal bays in Maryland, two extensive monitoring efforts have been conducted in the summer months of 1983 and 1992, respectively. Data from these two studies were used for the model development and calibration effort presented in this paper. According to data analysis, tidal actions are the primary force responsible for the horizontal mixing and transport of pollutants in the bays. Thus, characterizing such a process and determination of the mass transfer coefficients such as advective flows and dispersion coefficients are important in modeling interactions between water quality constituents. To quantify the mass transport and flushing rates in the bays under summer seasonal conditions, a two-dimensional hydrodynamic model was developed for as part of this modeling effort. Results from the hydrodynamic model were analyzed to assign the advective flows in the eutrophication model. In this study, an ad-hoc approach, which compares a solution of the mass transport equation with the measured salinity distribution, was used to quantify the dispersion coefficients. For mass transport calculation, the current version of the eutrophication module in WASP was configured to simplify the model input file since only salinity calculation is needed.

윤제용 , 변석종 , 이상덕 Je Yong Yoon , Seok Jong Byun , Sang Duck Lee

DOI: Vol.13(No.3) 283-292, 1997

Chlorine is currently being used to control microorganism, odor, color and inorganics such as Fe, Mn in nearly all domestic water treatment plants. However, an overdose of chlorine can cause the formation of unexpectedly high disinfection byproducts(DBPs) such as trihalomethanes, besides being econonomically not sound. On the other hand, under dosage of chlorine may increase public health risk resulting from waterborne disease. Therefore, it is necessary to investigate the characteristics of chlorine dosage in water treatment plants to provide the proper guideline of chlorine practice. In this study, five water treatment plants were selected for investigating for characteristics of chlorine dosage and distribution of residual chlorine. Three major characteristics of chlorine dosage were found. First, for raw water with high ammonia concentration(3∼5㎎/L), a large quantity of chlorine was added to get rid of ammonia through breakpoint chlorination. Post-chlorination practice in this case becomes unnecessary because the chlorine residual prior to clear well is sufficiently high in maintaining chlorine residual in distribution system. Second, for the same type of raw water with first case in terms of ammonia content, only small amount of chlorine was added to the water two sites (as pre-chlorine & post -chlorine) to form the combined chlorine as residual chlorine. This type of chlorine practice is called as $quot;chloramination$quot;. Chloramination in Korea is unique in two ways. 1) naturally occurring ammonia was used far ammonia source 2) this was chosen due to the shortage of chlorine capacity not for the control of chlorinated byproducts. Third, for the water which does not contain high ammonia content, dual chlorine addition practice was selected. Pre-chlorination is performed to meet the chlorine demand of raw water. Post-chlorination is performed to maintain the proper residual chlorine in distribution system.

김광수 , 최희철 , 배영진 , 안재환 , 조형래 Kwang Soo Kim , Hee Chul Choi , Young Jin Bae , Jae Hwan Ahn , Hyung Lae Cho

DOI: Vol.13(No.3) 293-298, 1997

An experiment was conducted to compare the adsorption capacity and characteristics between activated carbon made of rice-hull(RHAC) and F-400 by Calgon to remove phenol, heavy metal and ammonia-nitrogen. While F-400 could not remove ammonia-nitrogen, RHAC was able to adsorb it. This is considered to be due to the ion exchange capability of SiO₂ remaining on the surface of RHAC. From the isotherm equilibrium test, it was found that RHAC has higher adsorption capacity than the existing activated carbon. In column tests, however, the slope of breakthrough curves of RHAC which represent the affinity of adsorbent, was observed to be more gradual than F-400. This may be attributed to the competitive reaction between ion exchange and physical adsorption. For heavy metals, F-400 would remove Cr and Pb except Cd, whereas RHAC was able to remove Cd, Pb except Cr.

김동현 Dong Hyun Kim

DOI: Vol.13(No.3) 299-305, 1997

Separation of silver ions(Ag(I)) from aqueous solution by TiO₂(titanium dioxide) thin film photocatalysis was investigated. Disappearance of silver ions from solution was due to the reduction of silver ions as metal silver deposits on the surface of TiO₂ thin film during photocatalytic reactions. As the thickness of TiO₂ thin film increased, the amount of silver ions reduced to metal silver increased. Meanwhile, as silver deposits on TiO₂ thin films increased, the reduction rate of silver ions and the degradation rate of formic acid were decreased. It was found that the silver ions competed with oxygen for the electrons during photocatalytic reactions.

이찬기 , 류돈식 Chan Ki Lee , Don Sik Ryu

DOI: Vol.13(No.3) 307-315, 1997

The objective of this study is to solve the problems related to the effluent quality in RBC process : media clogging and the biomass sloughing. Three stage RBC with Autoxidation phase was operated along with the existing three stage RBC operation by varying the operational parameters in order to compare removal efficiencies of organics and nitrogen. The BOD removal efficiencies in the three stage RBC with Autoxidation phase were over 95% at a organic loading of 98.4g BOD/㎡/day. The existing three stage RBC process showed a 95% removal at a organic loading of 49.2g BOD/㎡/day. Suspended solids removal efficiency was between 61 and 70 percent in the Autoxidation phase at 1st stage RBC by biomass sloughing, and that of the existing RBC was between 45 and 61 percent. Removal of ammonia-nitrogen determined by varying NH₃-N loading rate showed a 85.3∼92.1 percent in the Autoxidation phase and a 67∼76percent for the existing three stage RBC process. NO₃-N level in the effluent increased with decreasing influent loading. In the determination of the kinematic coefficient, area capacity constant(P) in the first stage Autoxidation phase of RBC was 39.9gBOD/㎡·day and half velocity constant(Ks) was 306㎎/L. In the existing three stage RBC, they were 46.6gBOD/㎡·day and 467㎎/L, respectively.

오윤근 , 김정호 Youn Keun Oh , Jung Ho Kim

DOI: Vol.13(No.3) 317-324, 1997

To obtain the effects of residual organochlorine pesticides in the coastal environment on the Cheju Island, the ocean environment of Cheju city and Wimi was surveyed in May, August and October 1996. The qualification defection concentration of captan, chlorothalonil and dicofol of organochlorine pesticides in the water were 0.009ng/㎖, 0.005ng/㎖ and 0.023ng/㎖ by GC-ECD, respectively. The qualification defection concentration of captan, chlorothalonil and dicofol of organochlorine pesticides in the plant and animal were 0.018ng/g, 0.010ng/g and 0.046ng/g by GC-ECD, respectively. Captan, chlorothalonil and dicofol of organochlorine pesticides used in the farm were not detected in any water, sediment, seaweed cava(Ecklonia Cava), Agar(Gelidium amansii), turban sell(Batillus cornutus) and sea urchin(Anthocidaris Crassispina). The coastal environment in the cheju island was not effected the captan, chlorothalonil and dicofol of organochlorine pesticides used in the farm on cheju island

김순래 , 김성석 , 박상균 , 정의호 Soon Rae Kim , Sung Seok Kim , Sang Gyun Park , Eui Ho Cheong

DOI: Vol.13(No.3) 325-330, 1997

Methylene blue method has been mainly used for the analysis of anion surfactants which are an influential pollutant in rivers. But this method have various defects, because its analysis procedure needs long pretreating time. In this study, methylene blue method of anion surfactants was compared with the Co-PADAP method using a bit solvent to simplify the procedures. It was concluded that there is no significant difference between the two methods, so Co-PADAP method must be adapted to the Korean Standard Methods.

이원호 , 서인석 , 이상일 Won Ho Lee , In Seok Seo , Sang Ill Lee

DOI: Vol.13(No.3) 331-338, 1997

In this research, 4-stage intermittently aerated activated sludge system was investigated for simultaneous nitrogen and phosphorus removal with swine wastewater. COD_(Cr), TKN and Po₄³-P concentration of swine wastewater were 3151, 192 and 25.2㎎/L, respectively. Operational conditions were SRT 20day, HRT 24hr and aeration/ nonaeration time lhr/lhr, respectively. Organic matter in influent was devided into total, filterable, readily biodegradable and soluble inert organic. Portion of particulate, readily biodegradable and soluble inert organic to the influent organic were 65.6, 24.4 and 5.4%. The effluent TSS and COD concentrations has been consitently below 30㎎/L and 200㎎/L. In first reactor, release-uptake of PO₄³-P was observed very well but in third and fourth reactor, PO₄³-P concentration showed almost no change at below 0.1㎎/L. Nitrification and denitrification were observed to progress almost completely. COD_(Cr), T-N and PO₄³-P removal efficiency were 93.8, 88,6 and 95%, respectively.