• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.436-441
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• 2008

This work experimentally determined the effect of operating parameters such as temperature and solid retention time (SRT) on the phosphorus removal of municipal wastewater with waste-tire media. The experiments were carried out in pilot-scale moving bed biofilm reactor filled at a 0.15 filling ratio with the media. Total phosphorus (TP) removal efficiency was $91{\pm}5$, $75{\pm}16$, and $59{\pm}14%$ at the temperature of 9~10, 10~20, and $20{\sim}26^{\circ}C$, respectively. TP removal efficiency was $71{\pm}17$, $74{\pm}16$, $74{\pm}16$, and $68{\pm}18%$ at the SRT of 3.5~5, 5~10, 10~15, and 15~20 days, respectively. At the nitrate concentration of 1~3, 3~6, and 6~9 mg/L, TP removal efficiency was $82{\pm}9$, $68{\pm}18$, $47{\pm}7%$, respectively. The concentration of total phosphorus in the effluent was $0.1{\sim}1.8(0.8{\pm}0.4)mg/L$ regardless of operating conditions, which meets Korean phosphorus limit value, 2 mg/L, for discharge into receiving waters.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.2
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• pp.60-69
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• 1999

In this paper, we have obtained the initial and near-field dilution rates of wastewaters discharged from the ocean outfall of Masan-Changwon municipal wastewater treatment plant from both of field measurements and CORMIX model simulations. In the summer of 1998, water temperature and salinity profiles was measured at 16 stations in the vicinity of the Masan outfall and the dilution rates were analyzed by salinity deficit method. The transport of the wastefields and their initial dilution rates were calculated by CORMIX model using field data as model input. Both of observed and predicted results are shown In very low dilutions with the range of 32～48 from the field data analysis and 29～43 from the model prediction, respectively. This indicates that the water quality in the Masan outfall area can be worsening due to the low dilution rates of diswastewaters, especially, when the ambient currents are very weak in a neap tide and ambient water density is highly stratified in summer.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.107-113
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• 1999

A new biological nutrient removal system combining $A^2/O$ process with fixed film was developed in this work and the characteristics of denitrification 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 $NO_x-N$, COD, DO and nitrite effects on $NO_x-N$ 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% / 130% / 25% based on its reactor volume, respectively. It was found that COD rarely limited dentrification in the anoxic reactor because of high $C/NO_x/-N$ ratio in the anoxic reactor, while DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent inhibited denitrification in the anoxic reactor. It was proved that the critical points of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent were 0.15mg/L and 10%, respectively. As the internal recycle ratio increased, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent increased. Especially, at the condition of internal recycle ratio, 200%, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent exceeded the critical points of 0.15mg/L and 10%, respectively. Then, denitrification efficiency considerably decreased. Consequently, it was represented that the control of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent can assure effective denitrification.

• Journal of Wetlands Research
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• v.22 no.2
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• pp.139-144
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• 2020

Recently, high-concentration linked wastewater has been introduced into a nearby municipal wastewater treatment plants(MWTPs), but it is difficult to MWTP in local governments due to an unreasonable linked treatment charge system, and there is insufficient evidence or data to prove this. However, the MWTP, which is a national essential infrastructure, is generally exempt from the preliminary feasibility study, so there have been no cases where economic evaluation was conducted. Therefore, we proposed an improvement plan that can compensate for the disadvantages of the existing linked processing charges through previous studies. In this study, a comparative evaluation of how much economic feasibility can be improved compared to the existing ones when applying the improvement plan by conducting an economic analysis. For this, reference was made to the preliminary feasibility assessment data of the existing environmental facilities and the cost factors and benefit factors established during the modernization of the old sewage treatment facilities. As a result of the study, the B/C(Benefit/cost) value was quite low in the past, but when the improvement proposal proposed by the researchers was applied, it was confirmed that the B/C value increased close to 1. Therefore, it is considered to be very reasonable to calculate the linkage processing charge according to the linked wastewater load proposed by the researchers.

• Clean Technology
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• v.8 no.2
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• pp.85-92
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• 2002

Red mud is generated as a by-product during the production of aluminum hydroxide from bauxite ore. In this study the red mud coagulants were prepared by reacting 100 ml of 5 M $H_2SO_4$ solution with 10g of red mud at $85^{\circ}C$ or by reacting 100ml of 9M HCl solution with 10g of red mud at $25^{\circ}C$. The prepared red mud coagulants were tested for their coagulation performance of pollutants in the municipal and industrial wastewater. In addition, the coagulation performance was compared with that of a commercially available coagulant ($FeCl_3$). As a result, the red mud coagulants were found to have a good removal efficiency of pollutants in the municipal wastewater (turbidity, phosphate phosphorus) and in the plating wastewater (turbidity, $Pb^{2+}$, $Cd^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Cr^{3+}$). In the experiment to remove COD in the petrochemical wastewater, the COD removal efficiency by the red mud coagulants was a little poor, but it was better than that by $FeCl_3$.

• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.190-195
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• 2004

A new technology for advanced wastewater treatment was developed using a modified Rotating Biological Contactor (RBC) process, named as Rotating Activated Bacillus Contactor (RABC) process that utilizes Bacillus sp., the facultatively anaerobic or activated microaerophilic bacteria on multiple-stage reticular rotating carriers, as a predominant species. The RABC process for a municipal wastewater with relatively low concentrations of organics, nitrogen, and phosphorus showed stable and high removal efficiencies, less than $BOD_5$ 10 mg/L, T-N 15 mg/L, and T-P 1.5 mg/L in final effluent. The performance load of RABC process was shown to be $1.23kg{\cdot}BOD/m^2{\cdot}day$ for the first stage (average $0.31kg{\cdot}BOD/m^2{\cdot}day$ for the total stages) based on both removed BOD and converted disc area corresponding to the reticular one. The sludge produced in the RABC process is characterized by low generation rate (about $0.18kg{\cdot}MLSS/kg{\cdot}BOD$) and excellent settleability. The number ratio of Bacillus ($2.4{\times}10^6CFU/ml$) to heterotrophic bacteria ($3.6{\times}10^7CFU/ml$) inhabiting in the biofilms of the RABC process was 6.7 %, indicating that Bacillus sp. was a predominant species in the biofilms. The RABC process with reticular rotating carriers showed its excellent performance for the advanced wastewater treatment without any offensive odor problem due to organic overloading.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.47-52
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• 2005

This study was conducted to evaluate the performance of submerged hollow fiber MF processes to treat secondary wastewater for water reuse. Specifically, membrane productivity and filtrate water quality were investigated under various operating conditions (i.e. flux, recovery, and backwash rate) at pilot-scale. Membrane fouling became more severe with increasing flux and recovery, suggesting that low flux operation (< 25 LMH) was desirable. At high flux operating(> 37.5 LMH), increasing backwash rate showed only limited success. The biofouling, quantified by PEPA and BFHPC, was also significant in wastewater reclamation, and biogrowth control by chlorine, were necessary to improve membrane productivity. Filtrate water qualities are in good compliance with water reuse regulations regardless of operating conditions (flux, recovery and backwash rate). Particle (e.g. turbidity) removal ranged from 89 to 98%, while only 11 to 21% of organics (e.g. NPDOC) were removed by MF membrane. Only small improvement in biostability (e.g. AOC) was achieved by MF system, and thus, without post disinfection, significant microorganisms might be present in the filtrate due to regrowth. Lastly, in order to further investigate pathogen removal, controlled microbial challenge tests were performed by monitoring Giardia, Cryptosporidium, bacteria and virus, and showed relatively good microbial removal.

• Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.205-214
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• 2007

Surface water and sediment samples collected from the Mokpo coast of Korea were analyzed for molecular markers of organic municipal wastewaters, i.e., 11 fecal sterols including coprostanol (Cop) and nonylphenolic compounds (NPs), to characterize the main routes of these wastewaters to the coast and to assess contamination levels. Concentrations of Cop ranged from 94 to 7,568 ng/L in surface water and from 43 to 38,108 ng/g dry weight in sediments. Concentrations of NPs [nonylphenol (NP) and nonylphenol mono- and di-ethoxylates ($NP_{1-2}EOs$)] ranged from 123 to 4,729 ng/L in surface water and from 4 to 2,119 ng/ng dry weight in sediments. The levels of these compounds were much higher at stations near the rivers that pass through the urban center of Mokpo and the outfall of the wastewater treatment plant (WWTP). The spatial distribution of Cop levels was statistically similar to that of NPs (r=0.809 and 0.982 in surface water and sediments, respectively), indicating that these compounds may have similar discharge points, transport, mixing, and deposition in the study area. These results suggest that considerable amounts of organic wastewater compounds are discharged through rivers and WWTP effluent to the Mokpo coast.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.3
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• pp.205-225
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• 2021

Due to the large-scale production and use of synthetic chemicals in industralized countries, various chemicals are found in the aquatic environment, which are often termed as micropollutants. Effluents of municipal wastewater treatment plants (WWTPs) have been identified as one of the major sources of these micropollutants. In this article, the current status of occurrence and removal of micropollutants in WWTPs and their management policies and options in domestic and foregin countries were critically reviewed. A large number of pharmaceuticals, personal care products, and industrial chemicals are found in WWTPs' influent, and are only partially removed by current biological wastewater treatment processes. As a result, some micropollutants are present in WWTPs' effluents, which can negatively affect receiving water quality or drinking water source. To better understand and assess the potential risk of micropollutants, a systematic monitoring framework including advanced analytical tools such as high resolution mass spectrometry and bioanalytical methods is needed. Some Western European countries are taking proactive approach to controlling the micropollutants by upgrading WWTP with enahnced effluent treatment processes. While this enahnced WWTP effluent treatment appears to be a viable option for controlling micropollutant, its implementation requires careful consideration of the technical, economical, political, and cultural issues of all stakeholders.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.4
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• pp.97-105
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• 2012

This study examined for possibility of the food wastewater incineration treatment method as one of overland treatment method by incineration through liquefied spray of food wastewater when incinerating domestic wastes under operation and for the relationship, etc of air discharge material discharged in incineration, and the results of study are as follow: The food wastewater as one of overland treatment method was analysed 94-96% of moisture contents. Temperature of incinerator outduct during mixed incineration of food wastewater with MSW was average $897^{\circ}C$ and incineration of only MSW was $925^{\circ}C$. Temperature of the mixed incineration of food wastewater was dropped about $28^{\circ}C$ by incineration of only MSW. Concentration of nitrogen oxides(NOx) among air discharge gases was studied by 50ppm, 46ppm when inputting $200{\ell}/hr$, $300{\ell}/hr$ into the incinerator as the quantity of food wastewater. In the mixed incineration of food wastewater, generation speed of scales in the inside of a tubular exhaust gas boiler became rapid and the scale generation quantity became large but the exhaust gas boiler normally operated since scales were removed in cleaning of the tube with a compressive air cleaning facility and there was no opening clogging phenomena in a filter cloth of the filtering dust collector. The overland treatment method, not ocean dumping of food wastewater can be proposed as a technology since mixed incineration of food wastewater with MSW in the existing domestic waste incineration plant is possible, and operation costs of the incineration facility were reduced since use of chemicals such as ammonia and urinary hydrogen ion excretion, etc used in incineration facilities for removing nitrogen oxides(NOx).