• Journal of Korean Society of Water and Wastewater
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• v.31 no.2
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• pp.161-168
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• 2017

Microfiltration (MF) and Ultrafiltration (UF) membrane processes capable of producing highly purified water have been extensively applied as a pretreatment process in the wastewater reuse field with the improvement of membrane properties and resistance, development of operating protocols, and improvement of technologies of backwashing and physicochemical cleaning, and improvement of scale and antifoulants. However, despite of the development of membrane production and process technologies, fouling still remains unresolved. This study confirmed that foulants such as polysaccharides, proteins and humic substances existed in final treated effluent (secondary effluent) by fluorescence excitation emission matrix (FEEM) and fourier transform infrared spectroscopy (FTIR) analysis. In addition, when constructing ozone oxidation and coagulation processes as a hybrid process, the removal efficiency was 5.8%, 6.9%, 5.9%, and 28.2% higher than that of the single process using coagulation in turbidity, color, dissolved organic carbon (DOC), and UV254, respectively. The reversible and irreversible resistances in applying the hybrid process consisting of ozone oxidation and coagulation processes were lower than those in applying ozone oxidation and coagulation processes separately in UF membrane process. Therefore, it is considered possible to apply ozonation/coagulation as a pretreatment process for stable wastewater reuse by and then contributing to the reduction of fouling when calculating the optimal conditions for ozone oxidation and coagulation and then to applying them to membrane processes.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.38-45
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• 2008

There are still lots of areas where combined sewer pipes are covering in Seoul. All buildings within those areas are equipping septic tanks which take part in separating solids from flushing water of chamber pots. Septic tanks legally demand emptying and cleaning the those inner bodies once a year, resulting the generation of sludge which should be purified using the specified treatment plants as one of environmental infrastructures. Previous research showed that sludge volume continuously increase putting night soil treatment facilities in shortage by 3,549kL a day in 2020, which should be prepared by newly built facilities. This study aimed to define which process is more suitable especially in the points of cost and energy consumption. It was the main results that combining treatment of sewer with night soil, in fact same as nowaday process, is the very positive way beyond the treatment of night soil's own in respects of both costs and energy consumption.

• Journal of Korean Society on Water Environment
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• v.37 no.1
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• pp.20-31
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• 2021

In this study, an analysis of the characteristics of organic matter and nitrogenous oxygen demand (NOD) of 17 sewage effluent and wastewater treatments was conducted. High CODMn and carbonaceous biological oxygen demand (CBOD) concentrations were observed in the livestock treatment plants (LTP), wastewater treatment plants(WTP), and night soil treatment plants (NTP), but the highest NOD concentration and contribution rates of NOD to BOD5 were found in sewage treatment plants (STP). There was no significant difference in the CBOD/CODMn ratio for each of the six pollution source groups, but the LTPs, WTPs, and NTPs all showed relatively high CODMn concentrations in their effluent samples, indicating that they are facilities which discharge large amounts of refractory organic matter. The seasonal change of NOD in all facilities' effluent was found to be larger than the seasonal change of CBOD, and data results also revealed an elevation of NOD and NH3-N concentration from December to February, when the water temperature was low. There was no significant difference in NH3-N concentration in relation to pollution source group (p=0.08, one-way ANOVA), but the STP, which had a high NOD contribution rate to BOD5 of 48%, showed a high correlation between BOD5 and NOD (r2=0.95, p<0.0001). These results suggest that the effect of NOD on BOD5 is an important factor to be considered when analyzing STP effluent.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.5
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• pp.262-268
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• 2015

This study established an analytical method to simultaneously determine six organophosphorous pesticides [methyldemetone-S, diazinon, fenitrothion, parathion, phentoate, and O-ethyl O-(4-nitrophenyl) phenylphosphonothioate (EPN)] and carbaryl in water using a gas chromatography/mass spectrometry (GC/MS) system coupled with on-line micro extraction by packed sorbent (MEPS) and programmed temperature vaporizer (PTV) injector. Polystyrene divinylbenzene (PDVB) was used as a sorbent of MEPS. The effects of elution solvents, pH, elution volume and draw-eject cycles of samples on sample pretreatment process were investigated. Also, quality assurance and quality control (QA/QC) and the recovery of the pesticides in environmental samples were evaluated. The elution was performed using $30{\mu}L$ of a mixed solvent (acetone : dichloromethane = 80 : 20 (v/v)). Sample pretreatment processes were optimized with seven cycles of draw-eject of sample (1 mL) spiking an internal standard and sulfuric acid. At lower pH, the analytical sensitivity of diazinon decreased, but that of carbaryl increased. The method detection limit and the limit of quantification for this method were 0.02~0.18 and $0.08{\sim}0.59{\mu}g/L$, respectively. The method precision and accuracy were 1.5~11.5% and 83.3~129.8%, respectively, at concentrations of $0.5{\sim}5.0{\mu}g/L$. The recovery rates for all the pesticides except carbaryl in various environmental samples ranged 75.7~129.3%. The recovery rate of carbaryl in effluent sample was over 200% whereas carbaryl in drinking water, groundwater, and river water were in the acceptable range.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.969-975
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• 2010

Estimating the organic matter loadings from individual treated sewage has become important for establishment of effective management strategies to control refractory organic matter (R-OM) in watersheds. For this study, regression equations were constructed using treated sewage data to convert the chemical oxygen demand (COD) concentrations, which are mostly available from open database, into total organic carbon (TOC) and R-OM concentrations. Effluent samples were collected from five major sewage treatment plants (STPs) located upstream of the lake Paldang. Variations in the OM concentrations were not associated with either the location of the STP or the sampling season. The effluent investigated were characterized by higher ratio of R-OM with respect to biodegradable organic matter (B-OM) and higher presence of dissolved organic matters (DOM) versus particulate organic matter (POM). Compared to $COD_{Mn}$, $COD_{Cr}$ exhibited higher oxidation efficiencies and greater variations in the concentrations. The concentrations of $COD_{Mn}$ were positively correlated with dissolved organic carbon (DOC), total organic carbon (TOC), and R-OM concentrations. There was nearly no seasonal and annual variation in the regression equations between $COD_{Mn}$ and TOC or R-OM concentrations. The constructed regression equations for TOC and R-OM were $0.650({\pm}0.071){\times}COD_{Mn}+1.426({\pm}0.575)$ and $0.340({\pm}0.083){\times}COD_{Mn}+2.054({\pm}0.670)$, respectively. The established equations are expected to contribute to estimating OM loadings from the STPs into the lake Paldang and also to compensating for the deficiency of the data for effluent OM concentrations in STP.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.251-251
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• 2011

해양 투기가 금지되면서 혐기소화를 통해 최종적으로 발생되는 폐기물 양을 줄이고 메탄 등의 바이오 가스를 얻어 이를 에너지로 얻기 위한 많은 공정들이 현장에 적용되고 있다. 하지만 혐기 소화 과정을 마친 후 유출되는 유출액은 고농도의 유기물질 및 암모니아성 질소, 인산염 등을 다량으로 함유하고 있어 적은 양이라도 하천이나 호수 등에 유입되면 수질 악화와 부영양화를 초래할 위험성이 크다. 이번 연구에서는 음식물류 폐기물로부터 바이오가스를 생산하기 위한 혐기소화 공정에서 발생하는 유출액의 방류수 수질기준 확보와 경제성을 만족시킬 수 있는 처리공정의 상용화 기술을 개발하기 위해 생물학적 처리， 물리 화학적 처리를 통합한 공정을 적용하였다. P건설사 혐기소화 유출액 pilot plant(1 ton/day) 운전 결과 50~70% 로 $NO_2$-N 이 약 1,000 mg/$\ell$정도로 축적되는 현상을 보였으며 상대적으로 $COD_{Cr}$의 농도는 400~600 mg/$\ell$로 C/N 비가 낮아 탈질이 어려울 것으로 판단하였다. 이에 실험실 규모에서의 실험을 진행하였다. $NO_2$-N와 $NO_3$-N을 기준으로 McCarty 양론비 기준 80% 에서 300%까지 메탄올을 주입해 제조 폐수와 실제폐수로 실험을 진행하였고 제조폐수로 실행된 실험에서 아질산 탈질의 효율을 확인하였다. 미생물이 메탄올에 순응 후 완전 탈질에 걸리는 시간은 약 2.5 일로 확인 되었으며 메탄올이 추가로 주입되지 않은 반응조의 $NO_2$-N의 탈질량은 메탄올이 이론값 100% 주입 된 반응조에 비해 30% 이하의 처리 효율을 나타냈다. 이론값을 기준으로 메탄올이 100% 주입된 반응조는 약 96.1%의 탈질 효율을 보였으며 메탄올 순응 후에 약 1.5 일의 HRT가 단축되었기 때문에 메탄올에 장시간 순응 시 탈질 효율이 더 좋아질 것으로 보인다. 아질산탈질에 대한 실험실 규모 연구결과를 토대로 pilot plant에서 재현성 검토를 목적으로 운전을 수행하였다. 무산소조의 HRT는 2.7 일 이었으며 호기조의 HRT는 4.1 일 이었다. 유입수의 평균 $COD_{Cr}$ 농도는 2,878 mg/L, T - N 농도는 2,723 mg/L로 나타났으며 $NO_2$-N 기준 C/N비 1.2-1.8의 메탄올을 주입하였을 때 96% 이상의 탈질율을 보였다.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.9
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• pp.526-532
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• 2015

A bioreactor filling with pellets and stones was equipped to the swine manure treatment system, which is expected to emit high concentration of odor in the process of the organic wastewater treatment system, and in comparison with the activated sludge process as the control process, the reactor operation state, treatment water quality and odor emission concentration were measured. The reactor using the bioreactor proved to be much more stable in the bubble condition, treatment water transparency, etc, and BOD removal efficiency was also much better. The removal efficiency of T-N and T-P, however, showed little difference in the two reactors. Odor, as a result of examining $NH_3-N$, $NH_3$ concentratio, and complex odor, was 4 times to 24 times less emitted in the system using bioreactor than in the activated sludge system. $H_2S$, methyl mercaptan, dimethyl sulfide, and dimethyl disulfide were not found or were found in only 5 ppbs in each reactor and showed little difference between the two reactors. In the bioreactor process, Bacillus sp./ Pseudomonas sp. species were mainly found and in the activated sludge process, acterium sp. Chryseobacterium sp. species were mainly found.

• Membrane Journal
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• v.21 no.3
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• pp.277-289
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• 2011

Since 1980s, wastewater treatment facilities in Korea have been rapidly expanded by 90 percent as the government invested them continuously. Considering social and environmental factors such as the needs of alternative water resources for water shortages, energy saving and new energy production sources for decrease of greenhouse gases, and the demand for the improvement of the water quality in rivers and lakes, advanced technologies in wastewater treatment are essential in the 21st century. In this aspect, new conceptual technology is systematically combined with the advanced treatment technology such as the control and treatment technology of hazardous and toxic material, customized reusing skill, and energy saving/recovery technology. The new R&D project for advanced technology of wastewater treatment and reuse will focus on these advanced technologies which will improve the water quality and foster the competitiveness in world environmental markets, building a solid foundation particularly in the market of developing countries. The project will be divided up into high quality reusing of wastewater, energy self-sufficiency, and integrated management system. It will be carried out for five years, 2011~2015, as Phase I.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.215-230
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• 2019

The objective of this research is to evaluate the water quality characteristics using the statistical analysis of major tributaries in the Han River and to provide water quality improvement plan by selecting tributaries that should be preferentially managed by river grade classification method. The major 15 tributaries in Han River watershed were monitored for discharge and water quality during January-December 2017. As a result of the correlation analysis, the river discharge has been not correlation with other water quality constituents (p>0.05) but COD and TOC were significantly correlated (r=0.957, p<0.01). The main cause of water quality fluctuation was organic pollutants and nutrients in the principal component analysis (PCA) method. The BOD, COD, TOC, TN, and TP were found to be significantly different (p<0.05) by seasonal in result of one-way ANOVA analysis. Result of river grade classification by quantitative indicators the tributaries requiring improvement of water quality were Gulpocheon, Anyangcheon, Wangsukcheon, and Tancheon which affected by wastewater treatment plant.In this research, we determined tributaries that need to improve the water quality of Han River watershed and it can be used as an important data for efficient water quality management.

• The Korean Journal of Pesticide Science
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• v.10 no.2
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• pp.124-130
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• 2006

Rice plant extracts of brown planthopper (BPH) resistant rice varieties, Jangseongbyeo (JSB) and Hwacheongbyeo (HCB) at different growth stages (seedling, tillering, heading and ripening) were sequentially fractioned using hexane, ethyl ether, ethyl acetate, butanol, and distilled water. The extracts were applied to BPH susceptible rice variety, Dongjjnbyeo (DJB), to investigate the insecticidal and repellent effects against BPH. BPH insecticidal effects were not clearly observed with almost all of the extract fractions obtained from both JSB and HCB varieties for 12 h, whereas the ethyl ether and hexane extract fractions showed about 10 to 30% of BPH mortality in 24 to 48 h of application periods. An effective BPH repellent activity was found with the applications of ethyl ether extract fractions obtained from JSB variety. The extract fractions obtained from HCB variety did not show any different repellence among the various fractions. The BPH repellent effects of the extract fractions obtained at different growth stages of either JSB or HCB varieties did not show any correlations. The effect of ethyl ether fraction on BPH repellent was continually increased by 30 h after treatment and thereafter decreased. In addition, the first sub-fraction separated by a flash column chromatography eluted with chloroform:methanol (9:1, v/v) from the BPH effective ethyl ether faction in JSB variety might be meaningful to repel BPH from BPH susceptible target rice plants. The results indicated that the ethyl ether fraction obtained from JSB was higher in repellent activity than in insecticidal activity, and suggesting that there might be specific substance(s) in the first sub-fraction (sF1) of the ethyl ether fraction in JSB that could provide repellent activity against BPH.