• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1011-1019
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• 2000

The purpose of this study is to examine the basis of design condition of existing treatment processes, namely, Extended Aeration Process, Conventional Activated Process, High Rate Aeration Process and Modified Aeration Process, by clarifying the correlations of influent wastewater concentration, hydraulic retention time, food-to-microorganism ratio and sedimentation of sludge, as well as to ascertain the feasibility of design, regardless of the existing design condition. In particular, this study made a priority investigation of hydraulic retention time and sludge sedimentation, because sludge sedimentation is the main factor$^{1)}$ which determines the operating conditions of existing treatment processes. Therefore, it is generally known that in case exceeds the sphere of design presented for each treatment, sludge bulking may occur. The results of Lesperance's test$^{1)}$, which formed the basis of design, showed the sphere of loading without security of sludge sedimentation, as in Fig. 1. The reason for sludge bulking in a certain condition, as above, is due to failure in application of optimum loading corresponding to each retention time by employing a few operating condition, which proved to be consecutively workable after years of trials and failures by Lesperance, for test conditions. However, the result of this test showed that in case of proper maintenance of loading. sludge sedimentation can be ensured under 120 SVI. Therefore, this study suggested hydraulic retention time and its corresponding optimum loading, and identified the hydraulic retention time as a determinant of sludge sedimentation. And. on the basis of these findings, this study suggested the feasiblity of UHR(Ultra High Rate), a new operating process, exceeding several times the applicable loading value of High Rate Aeration Process under one hour retention time which has not yet applied to the existing treatment processes.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.215-221
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• 2006

This research presents results from laboratory and pilot-scale experiments to remove high-nitrate in pickling wastewater using the sequencing batch reactor (SBR) as a biological method. During the experimental periods, the influent concentrations of NOx-N and $Ca^{+2}$ were analyzed to be 350-1,600 and 700-800 mg/L, respectively. In order to provide carbon source for denitrification, methanol has been added in proportion to the influent nitrate loading. The mean concentrations of MLSS and MLVSS, the fraction of volatile solids in sludge and the sludge volume index were measured to be 27 g/L, 5 g/L, 18.5% and 7.5, respectively. The solid retention time was kept in the range of 18 to 22 days, specific denitrification rate ($U_{dn}$) was $0.301g{NO_3}^--N/gVSS/day$. The oxidized nitrogen concentration of effluent ranged 2-34 mg/L with an average of 5.2 mg/L, the overall reduction in total nitrogen was more than 99.2%. In order to treat the pickling wastewater including the high concentration of nitrate and $Ca^{+2}$, the continuous flow process is not suitable because the specific gravity of the sludge is considerably increased by $Ca^{+2}$, thus the SBR process is shown to be very effective to treat the pickling wastewater.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.5
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• pp.253-259
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• 2023

Bioreactors are devices used by sewage treatment plants to process sewage and which produce active sludge, and sediments separated by solid-liquid are treated in anaerobic digestion tanks. In anaerobic digestion tanks, the volume of active sludge deposits is reduced and biogas is produced. After dehydrating the digestive sludge generated after anaerobic digestion, anaerobic digested wastewater, which features a high concentration of organic matters, is generated. In this study, the decomposition of organic carbon and nitrogen was studied by advanced oxidation process. Ozone-microbubble flotation process was used for oxidation pretreatment. During ozonation, the TOC decreased by 11.6%. After ozone treatment, the TOC decreased and the removal rate reached 80.4% as a result of the Ultra Violet-Advanced Oxidation Process (UV-AOP). The results with regard to organic substances before and after treatment differed depending on the organic carbon index, such as CODMn, CODCr, and TOC. Those indexes did not change significantly in ozone treatment, but decreased significantly after the UV-AOP process as the linkage treatment, and were removed by up to 39.1%, 15.2%, and 80.4%, respectively. It was confirmed that biodegradability was improved according to the ratio of CODMn to TOC. As for the nitrogen component, the ammonia nitrogen component showed a level of 3.2×10² mg/L or more, and the content was maintained at 80% even after treatment. Since most of the contaminants are removed from the treated water and its transparency is high, this water can be utilized as a resource that contains high concentrations of nitrogen.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.347-353
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• 2014

This work was performed to find the effect of operation parameters on the permeate flux through the activated sludge dynamic layer, and to indicate the relationship between the water quality of supernatant and flux based on the results. Since the effluent can be obtained through steady and stable formation of cake layer in the bio-filter media system, it is an important subject to keep and control microbes with activated state in the bio-reactor. Filtration resistance was drastically increased at more than 18000mg/L of MLSS. With filtration time continued, the flux was gradually decreased and the water qualities of supernatant monitored by turbidity and TOC were also deteriorated. This phenomenon indicated that the organic materials generated by microbes and accumulated in the reactor might affect the flux in the system. In addition, the decrease of flux was simultaneously observed in the sludge volume index. When SVI was controlled from 150 to 250, the flux was also decreased. The proper aeration time was recommended to 30 to 60 seconds in this system. In order to operate this system steadily, therefore, the control of water quality of supernatant and SVI should be proceeded.

• Environmental Engineering Research
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• v.25 no.2
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• pp.212-221
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• 2020

This work discusses the palm oil mill processing carried out at Jugra Palm Oil Mill Sdn Bhd, situated at Selangor, Malaysia with the capacity of 45-t fresh fruit bunch (FFB)/h. Typically, oil palm residues and palm oil mill effluent (POME) from FFB are generated while processing. Prior to discharge, POME should be treated to remove pollutants in the effluent. As such, the performances of anaerobic and aerobic ponds were assessed in this study to determine temperature, pH, biological oxygen demand (BOD), sludge volume index (SVI), and dissolved oxygen (DO). From the experiments, mesophilic temperature due to better process stability was applied in anaerobic ponds. The pH results displayed a fluctuating trend between lower control limit and upper control limit, and, the pH value increased from one pond to another. The final discharge BOD and SVI appeared to be lower than 100 mg/L and 10 mL/L indicating low degree of pollution and good settling ability for biomass/solid. DO was close to normal, mostly below 2 mg/L. The experimental outcomes revealed the effective treatability of POME in adherence to the standard regulation, which is the priority for environmental sustainability within this industry domain.

• Journal of Electrochemical Science and Technology
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• v.8 no.1
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• pp.35-42
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• 2017

In this study, the effect of electrolyte addition on the removal of organics and nutrients in electrochemical wastewater using a copper electrode, and the characteristics of the by-product of electrolysis were investigated. The removal of organics increased significantly as shorter reaction times upon the addition of chloride ion, and most of the electrolysis reaction was completed within 20 min. The reaction rate gradually increased in proportion to the $Cl^-$/COD ratio, whereas the highest removed mass of organic matter per mass of added electrolyte was observed at a $Cl^-$/COD ratio of 1. After the addition of electrolyte, significant removal of ammoniacal nitrogen was observed as a result of the enhanced generation of oxidizers such as hypochlorite. Excellent phosphorus removal was also achieved in a very short reaction time (within 2 min) by electro-coagulation. As the electrolysis progressed, the amount of by-product increased gradually, whereas a decrease of sludge volume index was observed after the addition of electrolyte. This indicated that the settling performance of the by-products was better, and their removal would be easily achieved.

• Textile Coloration and Finishing
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• v.8 no.5
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• pp.84-89
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• 1996

This study carried out batch and continuous experiments using calcium hydroxide as neutralization agent and immobilization media for removing the ethylene glycol in the pretreated polyester weight loss wastewater. The $TCOD_{Mn}$ concentration in the treated wastewater using culture of iramobilization and suspension for the synthetic wastewater were found as 650mg/l and 1,250mg/l after 48hours, respectively. SVI(Sludge Volume Index) and $TCOD_{Mn}$ concentration were 74 and 73mg/l at optimum F/M ratio, 1.32kg-TCO $D_{Mn}$ /day. kg-MLVSS. The $TCOD_{Mn}$ concentration and removal efficiency were 213mg/l and 93.5% by continuous experiments in the air-lift bioreactor, respectively. The $TCOD_{Mn}$ concentration was 82mg/l, and also the MLVSS concentration was 2,550mg/l, when the volumetric loading rate was 3.04kg-$TCOD_{Mn}/m^{2}$ day for real polyester weight loss wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2239-2245
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• 2000

For the treatment of wastewater being discharged in large quantities as in these modern times, qualitative and quantitative concepts should be introduced in consideration of the recycling. In view of a qualitative concept, high rate aeration process is known as the most effective process up to now. However, Lee suggested UHR process showing the superiority over high rate process in treatment rate and quantity. Therefore, this study was performed to investigate the basic sphere of design and treatment quality, such as applicable $BOD_5$-loading and influent wastewater concentration of UHR process, based on Lee's suggestions1). Consequently, this process showed applicable $BOD_5$-loading of $2.2{\sim}7.0kg-BOD_5/kg-MLSS{\cdot}day$, exceeding three times or more of high rate process with maximum applicable loading of $2.25kg-BOD_5/kg-MLSS{\cdot}day$. Meanwhile, with the range of influent wastewater concentration from 200 to 450 mg/L. it showed the treatment rate from 94.7 to 97.3%, it indicated very good condition. In view of quantitative concept of treatment, UHR process is considered an epoch-making treatment process being superior to existing ones.

• Journal of Korean Society on Water Environment
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• v.35 no.3
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• pp.201-208
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• 2019

In this study, we analyzed composition of the bioflocculant, which strain YG-02 produces. First, supernatant and suspension from centrifugation of culture fluid of the strain, were used in the flocculation experiment. As a result, the SVI(sludge volume index) added with the suspension, was 182 mL/g, same as the control group with no additive, and the SVI added with supernatant, was 164 mL/g. So, the result above showed that flocculation capacity of the bioflocculant, was dependent on the substance which strain YG-02 produces, not on factors such as the body of germs. As a result of the thermostability test on substances that cause flocculation, the flocculation effect was significantly reduced, compared to the result of the flocculation test, before applying heat to the culture fluid, and it was able to assume that the substance that causes flocculation, was damaged by heat. Additionally, to understand the component of the bioflocculant, analyzation of sugar composition and fatty acid, was conducted. As a result, sugar composition was the polysaccharide consisting of glucose: lactose with molar ratio of 90.75:9.25. Fatty acid content was detected, as 0.0012 g/100g, showing that it contained glycolipid in the bioflocculant. Such results show that the bioflocculant which strain YG-02 produces, is the new bioflocculant, different from bioflocculantstudiedto date.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.71-80
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• 2001

Blood and urine mercury level of three workers were monitored during 60~80 days after high exposure to mercury at the silver refining plant. Mercury was used to form silver-mercury amalgam from plating sludge. Workers were exposed to mercury about 70 days at the several processes, such as hand held weaving, vibration table, and heating from the furnace. mercury was analysed by atomic absorption spectroscopy-vapor generation technique. Recovery from the biological sample was 95.51% and pooled standard deviation was 0.033. At the time of study, there was no work at the workplace. So, airborne mercury concentration was measured with area sampling 5 days after the work, ranged from 0.1459 to 1.2351 mg/㎥(Arithmatic mean 0.4711 mg/㎥, Geometric mean 0.3566 mg/㎥) at the inside of the plant, that is far above the ACGIH's TLV(0.025 mg/㎥) and ranged from 0.0073 to 0.0330 mg/㎥ at the outdoor. Blood mercury levels at the beginning of the monitoring were 4~14 times greater than the American Conference of Governmental Industrial Hygienists Biological Exposure Index(ACGIH BEI, 15 ug/L). Blood mercury levels were decreased logarithmically, that is, rapidly at the high level and slowly at the low level but sustained above the level of the ACGIH BEI 60~80 days after the work. Urine mercury levels at the beginning of the monitoring were 8~16 times greater than the ACGIH BEI(35 ug/g creatinine). Urine mercury levels were decreased logarithmically, but correlation between urine level and off-days were lower than those of blood. Decreasing pattern of blood mercury levels were little affected than that of urine levels when the chelating agent, D-penicillamine, was administered. There was correlation between blood mercury level and urine mercury level(0.81~0.83) but it didn\`t mean that the highest blood mercury level corresponded the highest urine mercury level. In our study, Case 1 always shows the highest level in urine but case 3 always shows the highest level in blood. Creatinine correction represented better correlations between urine mercury levels and blood levels, and between urine levels and off-days rather than by urine volume. Spot urine sampling had a wide variation than that of whole day urine sampling. So, We recommend spot urine sampling for screening and whole day urine sampling for exact diagnosis.