This research was performed to investigate the dynamics of microbial community by RBC (Rotating Biological Contactor) using Rhodococcus sp. EL-GT and activated sludge. Cell counts revealed by DAPI were compared with culturable bacterial counts from nutrient agar. Colony counts on nutrient agar gave values 20∼25% and 1∼15% of cell counts (DAPI). The cell counts for the dynamics of bacterial community were determined by combination of in situ hybridization with fluorescently-labelled oligonucleotide probes and epifluorescence microscopy. Around 90∼80% of total cells visualized by DAPI were also detected by the bacteria probe EUB 338. For both reactors proteobacteria belonging to the gamma subclass were dominant in the first stage (1 and 2 stage) and proteobacteria belonging to the gamma subclass were dominant in the last stage (3 and 4 stage).

This research studied the characteristics and applicability of electrocoagulation using aluminium electrode for the color and COD removal in textile wastewater. Electrocoagulation reactor used two different electrode, Fe and Al, since in the general chemical wastewater treatment, aluminium and ferrous salts were used as coagulants. Aluminium electrode showed higher removal efficiency of color and COD than ferrous electrode did. The COD and color removal efficiency improved at the 0.192A/dm2 current density. Thus, the electrocoagulation process with bipolar aluminium electrode showed better efficiency in the decolorization and COD removal rate of textile wastewater effluent than custom coagulants did.

Air-lift biofilm reactor should be an admirable process substituting conventional activated sludge process, because of its small area requirement as well as high volumetric loading capacity and stability against loading and chemical shocks. However most of the past research on the performance of ABR was focused on the sewage treatment. This research studied the applicability of ABR to treat high strength wastewater. A bench-scale ABR was operated to treat high strength synthetic wastewater, tannery wastewater and petrochemical wastewater, and its applicability was conclusive. In case of synthetic wastewater, ABR showed good performance in which the substrate removal efficiency was higher than 80 % even under short HRT(1.4 hr) and high volumetric loading rate(9.3 ㎏CODcr/㎥ day). When ABR was applied to treat tannery wastewater, it was suggested that the maximum volumetric loading rate and F/M ratio should be 7.7 ㎏CODcr/㎥ day, 0.76 day-1, respectively. And high substrate removal efficiency over than 90 % was observed with 4,000 ㎎CODcr/L of petrochemical wastewater. Even though effluent concentration was quite high, ABR should be applicable to treat the high strength wastewater, because of its high loading capacity.

Twenty organic chemical substances (Table 2) were isolated from untreated wastewater, as well as treated wastewater, collected at 76 companys of 9 industry group located in the basin of Youngsan River. Those organic compounds were analyzed by Gas Chromatography/Mass Spectrometry(GC/MS) and confirmed through comparison with each standard reagents. Phenol, which was not detected in the raw wastewater, was identified in the effluent of treatment facility, indicating that phenol is generated from isopropylbenzene of plant wastewater.

The diagnostic software for the wastewater treatment plant using activated-sluge process is developed in order to increase the efficiency of management of the wastewater treatment plant. This software is based on the expert system and the visualized user interface including the diagnosis of quantitative and qualitative data. For the generalization of this software, the initialization of each unit process and updating the files can be possible.

Dye wastewater was treated by using an electrochemical oxidation process. Various combinations of electrodes such as carbon, Al and Fe were investigated. In this study, electrode material, electrolyte concentration, electrode distance, current density, and pH value were found to have significant effect on both pollutant removal efficiency and current efficiency in electrochemical oxidation process. After electrolysis for 40min with carbon/Al, it was observed that COD, T-N, NH4+ -N and color of treated wastewater were reduced from 580㎎/ℓ to 145㎎/ℓ, 67.2㎎/ℓ to 26.8㎎/ℓ, 46.8㎎/ℓ to 1.4㎎/ℓ, and 4200 Pt-Co units to 336 Pt-Co units, respectively. The optimal conditions of the electrooxidation process to treat the wastewater for this study were found to be such as : current density ; 16.67mA/㎠, electrode distance ; 2.5cm, pH value ; 5.0 and carbon/Al electrode.

This study was conducted to evaluate capability of dyeing wastewater treatment for 3 type reactors. These reactors were Packed Bed Reactor(PBR), Fluidized Bed reactor(FBR) and Moving Media Complete Mixing Activated Sludge reactor(MMCMAS). Experiments of PBR and FBR were performed by various packing ratios and organic loading rates, experiments of MMCMAS were performed by various organic loading rates In order to obtain SBOD_5 removal efficiencies of more than 90%, the F/Mv ratios of PBR, FBR, MMCMAS were 0.11 ㎏BOD/㎏MLVSS·d, 0.12 ㎏BOD/㎏MLVSS·d, and 0.37 ㎏BOD/㎏MLVSS·d, respectively. So MMCMAS system which has more active microorganisms showed better capability of organic removal and also stronger dynamic and shock loadings than those of PBR and FBR. In PBR and FBR, the media packing ratio of 20% showed better performance of organic matters removal effciencies than 10% and 30%, but sludge production rate at media packing ratio of 30% was relatively lower than that of 10% and 20%. When more than 90% organic matters removal efficiency was obtained, the ratios of attached biomass to total biomass at PBR, FBR, MMCMAS were 89∼99%, 87∼98%, and 54∼80%, respectvely. The ratio of attached biomass to total biomass was low in MMCMAS. This was formation of thin biofilm due to shear force between rotating disc and water. The average sludge production rates(㎏VSS/㎏BODrem.) of PBR, FBR and MMCMAS were 0.20, 0.29 and 0.54, respectively.

This study was conducted to evaluate the treatment efficiency including reaction kinetics and hydraulic characteristics of food processing wastewater by using an ejector-type aeration system (ETAS) in activated sludge process. The oxygen transfer efficiency in ETAS can be changed in accordance with the depth of reactor. However, the optimum air velocity was found less than 1.82 m/hr at a superficial liquid velocity of 634 m/hr. The ETAS process showed higher organic material removal efficiency than that of the existing activated sludge process under hydraulic detention time ranged from 6 to 12 hours. This process, which can maintain MLVSS highly, is able to have high organic material removal efficiency at short HRT and deal with variable organic material loading.

A new biological nutrient removal system combining A2/O process with fixed film was developed in this work and the characteristics of denitrifcation were especially investigated in the combined fixed film reactor(CFFR). Media was added in the anaerobic, anoxic and aerobic reactors, respectively. Tests were made to establish the effluent level of NOx-N, COD, DO and nitrite effects on NOx-N removal in the CFFR by decreasing hydraulic retention time (HRT) from 10.0 to 3.5 hours and by increasing internal recycle ratio form 0% to 200%. The influent was synthesized to levels similar to the average influent of municipal wastewater treatment plants in Korea. SARAN media with a porosity of 96.3% was packed 40%/30%/25% based on its reactor volume, respectively. It was found that COD rarely limited denitrification in the anoxic reactor because of high C/NOx-N ratio in the anoxic reactor, while DO concentration in the anoxic reactor and NO2-N/NOx-N from the aerobic effluent inhibited denitrifcation in the anoxic reactor. It was proved that the critical points of DO concentration in the anoxic reactor and NO2-N/NOx-N from the aerobic effluent were 0.15㎎/L and 10%, respectively. As the internal recycle ratio increased, DO concentration in the anoxic reactor and NO2-N/NOx-N from the aerobic effluent increased. Especially, at the condition of internal recycle ratio, 200%, DO concentration in the anoxic reactor and NO2-N/NOx-N from the aerobic effluent exceeded the critical points of 0.15㎎/L and 10%, respectively. Then, denitrification efficiency considerably decreased. Consequently, it was represented that the control of DO concentration in the anoxic reactor and NO2-N/NOx-N from the aerobic effluent can assure effective denitrifcation.

In recent years increasing production and disposal of wastewater have caused an accelerated eutrophication of receiving waters. Therefore, in order to alleviate the detrimental impact of wastewater discharge, there is an increasing demand for removing the main nutrients, nitrogen and phosphorus, as well as the organic content of the waste water prior to disposal. This is effectively achieved by extended conventional treatment technology. However, the working expenses and energy requirements of such advanced treatment systems are rather high. So in a sparsely populated rural community is required development of wastewater treatment system combined with the regional characteristics. In this study, the systems are planted with Reeds and Amaryllis in A.C and estimated purification potential of system. The results obtained are as follows. BOD removal rate is 20% in the early stage, the last removal rate is 35% in A.C process and is 65% in Amaryllis+A.C process and is 50% in Reed+A.C process. T-N removal rate by Amaryllis is average 2.6g/㎡·d, T-N removal rate by Reed is average 1.76g/㎡·d. T-P removal rate by Amaryllis is average 0.27g/㎡·d, T-P removal rate by Reed is average 0.25g/㎡·d. BOD removal rate constant with retention time is 1.4494(l/d), T-N removal rate constant is 0.5428(l/d), T-P removal rate constant is 0.5287(l/d)

The Soysauce wastewater removal characteristics of submerged biofilters filled with two filter media respectively were experimentally examined with constant temperature, pH value and variable BOD loading and recirculation ratio. The decreasing order of BOD removal is Netring(random plastic media), cubic wire meshes(plastic module). This is mainly due to the media characteristics such as void ratio, specific surface area and media shapes. The BOD removal ratio decreases with increasing BOD_5 volumetric loading rate, and the loading rate for the BOD removal over 85% is lower than 1.5㎏BOD_5/㎡d for the plastic media of Netring and cubic wire meshes. The BOD_5 removal rate increases with the recirculation ratio, but the rate of increase become smaller as the recirculation ratio increases over 20. When BOD_5 volumetric loading is 1.5㎏BOD_5/㎡d, the required recirculation ratio to obtain 85% BOD_5 removal is about 20 for Netring and it was about 30 for cubic wire meshes.

A microorganism, Klebsiella gr. 47, capable of degrading BTX(benzene, toluene and xylene) was isolated from oil-contaminated soil and its characteristics of BTX degradation were investigated. When benzene and toluene were fed to Klebsiella gr. 47 simultaneously, they showed competitive inhibition. The degradation rate of xylene was enhanced as much as 3 times when xylene was fed with benzene or toluene. Degradation rate of benzene and toluene was also enhanced by cocultured with Alcaligenes xylosoxidans. When benzene-adapted microorganism was used, each BTX compound was degraded efficiently within 5 hours.

Nanofiltration[NF45] and reverse osmosis membrane[HR98PP] separation treatment of dyestuff wastewater was carried out in order to seperate relatively pure water from synthetic dyestuff wastewater, which consists of reactive dye, acid dye, basic dye, direct dye, and disperse dye. The experiments were performed by using the plate and frame membrane module. In the nanoflltration and reverse osmosis membrane separation, When the NaCl concentration was 0.1, 5.0, and 20.0%, retention was 63.0, 46.0, 0.9%, respectively. When permeate flux was 125.0, 67.5, and 45.0 L/㎡·h, the osmotic pressure increased with increasing the NaCl concentration. Permeate flux of two membranes increased as temperature increased due to segmental movement of polymer of the membrane and the rejection rate of dyestuff was decreased gradually. It was found that the rejection rate was about 95% in the nanofiltration, while the reverse osmosis membrane showed a high rejection rate of 99% under all temperature and pressures conditions.

This study was conducted to assess the characteristics of pigment wastewater and the removal rates of appropriate treatment by physical, chemical and biological process, and the possibility of reuse for effluent. Based on the results, the wastewater qualities of pigment were pH 5.1±3.4, temperature 43.0±5.0℃ BOD 1,431.4±589.6㎎/ℓ, COD 2,282.8±66.5㎎/ℓ, turbidity 1,340±82ONTU, color 243.0±147.Ounit, Pb 36.5±9.5㎎/ℓ and Cr^+6 10.3±1.3㎎/ℓ, respectively. The removal rates of adsorption by activated carbon and filter process were BOD 40.6%, COD 57.0%, turbidity 89.6%, color 87.2%, Pb 86.0% and Cr^+6 10.6%, respectively. And the removal rates of reduction, neutralization, coagulation and air floatation process were BOD 18.2%, COD 24.3%, turbidity 74.3%, color 56.7%, Pb 68.6% and Cr^+6 97.8%, respectively. The removal rates of activated sludge process were BOD 95.9%, COD 86.0%, turbidity 27.8%, color 25.2%, Pb 26.9% and Cr^+6 50.0%, respectively. The total removal rates of treatment by physical, chemical and biological process were BOD 98.0%, COD 95.4%, turbidity 98.1%, color 95.8%, Pb 97.0% and Cr^+6 99.0%, respectively. According to the test results for possibility of reuse with coagulation-adsorption by activated carbon process of effluent, COD was higher than that of raw water and others were similar to that of raw water, thus, it is considered to be reused.

Because permeate flux was very low as it has the suspension solid of high concentration in the ultrafiltration membrane separation treatment of dyestuff wastewater, pre-treatment of Fenton reaction was carried out. In the case of pH 3, COD removal rate was the highest of 58%. When PAC was added into the pre-treatment supernatant, the COD removal rate was found to be 53%, and when COD was 153㎎/L, the removal rate was 92.3% in the ultrafiltration separation. In addition, the effect of the addition of PAC on the permeate flux was also investigated. The decrease of permeate flux in the presence of PAC was higher than in the abscence of PAC, but the recovery of permeability by cleaning was better in the case of PAC system.

This study was conducted to use oyster shell as media for biological wastewater treatment. The comparison between the removal efficiencies of the activated sludge and the submerged biofilm process with oyster shell media (5% of reactor volume) for domestic sewage treatment was made. The contaminant removal efficiencies of the submerged process were higher than that of the activated sludge process. And the removal efficiencies of the submerged biofilm process with oyster shell media of 10% and 18% were investigated at various loading rate. The removal efficiencies of 10% were higher than that of the 18% during the experimental period. The effluent concentration from the submerged biofilm process using oyster shell media was prediceted by the Stover-Kincannon model.

This study was conducted to investigate the treatment of wastewater from acetaldehyde manufacturing plant by activated sludge process with Micrococcus roseus AW-6, Micrococcus luteus AW-22, Microbacterium lacticum AW-38 and Microbacterium laevaniformans AW-41. The COD_Mn and BOD_5 of the wastewater were 5,260㎎/L and 6,452㎎/L, respectively. pH was 1.85. The main organic component in the wastewater was acetic acid which was contained 67,600㎎/L. Optimum dilution time for activated sludge process was shown 10 times. The specific substrate removal rate(K_e) was 1.95day^-1 and the nonbiodegradable matters(S_n) were 23.2㎎/L. Saturation constant (K_e) and maximum specific growth rate(q_max) were 1,640㎎/L and 2.33day^-1, respectively. Sludge yield coefficient(Y) and endogenous respiration coefficient(K_d) were 0.28㎎ MLVSS/㎎COD and 0.02day^-1, respectively. COD_cr removal efficiency was 91% for 1.95day of hydraulic retention time.

Varing the flow velocity of solution and particle diameter, the mass transfer coefficient of the local electrode on current feeder has been measured in an empty flow reactor, an inert fluidized bed electrode reactor, and an active fluidized bed electrode reactor. It had its maximium value when the bed porosity was 0.6 to 0.65 and decreased with increasing the height of local electrode. The mass transfer coefficient was found to be high especially when bigger particle was fluidized. Electrochemical deposition of copper dissolved in the synthesized wastewater has been performed in the active fluidized bed electrode reactor. The deduction rate was higher than 90% and the residual concentration of copper decreased to less than 5ppm.

An inverse fluidized-bed biofilm reactor (IFBBR) was used for the treatment of highly-emulsified oily wastewater. When the concentration of biomass which was cultivated in the synthetic wastewater reached to 6000㎎/L, the oily wastewater was employed to the reactor with a input COD concentration range of 50㎎/L to 1900㎎/L. Virtually the IFBBR showed a high stability during the long operation period although some fluctuation was observed. The COD removal efficiency was maintained over 90% under the condition that organic loading rate should be controlled under the value of 1.5 ㎏COD/㎥/day, and F/M ratio is 1.0㎏COD/㎏VSS/day at 22℃ and HRT of 12 hrs. As increasing organic loading rates, the biomass concentration was decreased steadily with decreasing of biofilm dry density rather than biofilm thickness. Based on the experimental results, It was suggested that the decrease in biofilm dry density was caused by a loss of biomass inside the biofilm.