• 상하수도학회지
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• 제18권1호
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• pp.59-65
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• 2004

The change of the microbial community structure in excess sludge of different sewage treatment plants by ozone treatment was investigated by quinone profiles. The resulting ozone dosage ranged from 0.1 to $0.4gO_3/gTS$. In terms of overall sludge reduction, more than 50% reduction of the total sludge mass could be achieved by ozone treatment at $0.4gO_3/gTS$. Quinone concentration and type in sludge of different treatment plants were remarkably decreases with increasing ozone dose. Ubiquinones(UQs)-8, -10 and MK-8 were still remained in the ozonized sludge at $0.4gO_3/gTS$. The results of this study showed that the remaining microorganisms belong to UQs-8, -10 and MK-8 were difficult to destruct cell membrane or wall by ozonation. Fecal Streptococci and Salmonella were not detected at ozone dose of $0.2gO_3/gTS$, but Fecal Coliform was not detected at ozone dose of $0.4gO_3/gTS$.

• 상하수도학회지
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• 제14권4호
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• pp.311-317
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• 2000

The operation of flocculation process and the evaluation thereof have been mainly based on G, t and $G{\times}t$ values which are available from design guidelines and texts. However, their suggested ranges are too wide to find the optimum condition specific to a particular water treatment plant and none of the existing method can be used to evaluate and suggest the optimum operational condition. Recently, a commercially available particle counter is found to be useful in determining the flocculation process based on the particle dynamics. The optimum condition is defined as one that best suits the purpose of flocculation; the number of small particles should decrease, while that of large particles should increase. The experiments were performed at two conventional water treatment plants in Korea, one with horizontal mechanical flocculators, and another with vertical type mechanical flocculators. In this paper, experiences to evaluate the flocculation process and to suggest the optimum operation condition will be presented. Although particle counting method is found to be beneficial compared to any other existing methods, the optimum condition is very much site-specific and should be evaluated at each water treatment plant for different conditions.

• 청정기술
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• 제29권2호
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• pp.145-150
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• 2023

Tele-metering systems have been useful tools for managing domestic wastewater treatment plants (WWTP) over the last decade. They mostly generate water quality data for discharged water to ensure that it complies with mandatory regulations and they may be able to produce every operation parameter and additional measurements in the near future. A sub-big data group, comprised of about 150,000 data points from four domestic WWTPs, was ready to be classified and also analyzed to optimize the WWTP process. We used the Statistical Product and Service Solutions (SPSS) 25 package in order to statistically treat the data with linear regression and correlation analysis. The major independent variables for analysis were water temperature, sludge recycle rate, electricity used, and water quality of the influent while the dependent variables representing the water quality of the effluent included the total nitrogen, which is the most emphasized index for discharged flow in plants. The water temperature and consumed electricity showed a strong correlation with the total nitrogen but the other indices' mutual correlations with other variables were found to be fuzzy due to the large errors involved. In addition, a multilayer perceptron analysis method was applied to TMS data along with root mean square error (RMSE) analysis. This study showed that the RMSE in the SS, T-N, and TOC predictions were in the range of 10% to 20%.

• Asian-Australasian Journal of Animal Sciences
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• 제12권4호
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• pp.629-632
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• 1999

Constructed wetlands are being used for the removal of nutrients from livestock wastewater. However, natural vegetation typically used in constructed wetlands does not have marketable value. As an alternative, agronomic plants grown under flooded or saturated soil conditions that promote denitrification can be used. Studies on constructed wetlands for swine wastewater were conducted in wetland cells that contained either natural wetland plants or a combination of soybeans and rice for two years with the objective of maximum nitrogen reduction to minimize the amount of land required for terminal treatment. Three systems, of two 3.6 by 33.5 m wetland cells connected in series were used; two systems each contained a different combination of emergent wetland vegetation: rush/bulrush (system 1) and bur-reed/cattail (system 2). The third system contained soybean (Glycine max) in saturated-soil-culture (SSC) in the first cell, and flooded rice (Oryza sativa) in the second cell. Nitrogen (N) loading rates of 3 and $10kg\;ha^{-1}\;day^{-1}$ were used in the first and second years, respectively. These loading rates were obtained by mixing swine lagoon liquid with fresh water before it was applied to the wetland. The nutrient removal efficiency was similar in the rush/bulrush, bur-reed/cattails and agronomic plant systems. Mean mass removal of N was 94 % at the loading rate of $3kg\;N\;ha^{-1}\;day^{-1}$ and decreased to 71% at the higher rate of $10kg\;N\;ha^{-1}\;day^{-1}$. The two years means for above-ground dry matter production for rush/bulrushes and bur-reed/cattails was l2 and $33Mg\;ha^{-1}$, respectively. Flooded rice yield was $4.5Mg\;ha^{-1}$ and soybean grown in saturation culture yielded $2.8Mg\;ha^{-1}$. Additionally, the performance of seven soybean cultivars using SSC in constructed wetlands with swine wastewater as the water source was evaluated for two years, The cultivar Young had the highest yield with 4.0 and $2.8Mg\;ha^{-1}$ in each year, This indicated that production of acceptable soybean yields in constructed wetlands seems feasible with SSC using swine lagoon liquid. Two microcosms studies were established to further investigate the management of constructed wetlands. In the first microcosm experiment, the effects of swine lagoon liquid on the growth of wetland plants at half (about 175 mg/l ammonia) and full strength (about 350 mg/l ammonia) was investigated. It was concluded that wetland plants can grow well in at least half strength lagoon liquid. In the second microcosm experiment, sequencing nitrification-wetland treatments was studied. When nitrified lagoon liquid was added in batch applications ($48kg\;N\;ha^{-1}\;day^{-1}$) to wetland microcosms the nitrogen removal rate was four to five times higher than when non-nitrified lagoon liquid was added. Wetland microcosms with plants were more effective than those with bare soil. These results suggest that vegetated wetlands with nitrification pretreatment are viable treatment systems for removal of large quantities of nitrogen from swine lagoon liquid.

• 한국환경농학회지
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• 제31권4호
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• pp.351-358
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• 2012

수생식물은 인공습지 오 폐수처리장에서 여재의 입단 형성을 촉진시켜 폐수의 투수속도를 증가시킬 뿐만 아니라 악취를 줄이고 미관상 혐오감을 크게 줄일 수 있으며, 수처리효율과 밀접한 관련이 있다고 보고하였다. 이에 본 연구는 수생식물여과조-활성슬러지-인공습지를 하나의 시스템으로 시공한 축산폐수처리장에서 수생식물의 생육특성 및 영양염류의 흡수특성을 조사하기 위해 3차 수직 흐름조에는 갈대, 4차 수평 흐름조에는 노랑꽃창포 및 5차 수평 흐름조에는 갈대, 노랑꽃창포 및 부들을 2010년 7월에 이식하였으며, 축산폐수 처리시일을 1, 3 및 5개월로 구분하여 각 수생식물의 생육특성과 영양염류 흡수특성 조사하였다. 수생식물의 생육특성은 갈대, 노랑꽃창포 및 부들 모두 처리시일 3개월인 10월까지는 수생식물의 성장과 동시에 수생식물이 무성하게 퍼졌으며, 특히 노랑꽃창포의 경우 타 수생식물에 비해 생육이 매우 좋았다. 수생식물의 생육 5개월 후인 2010년 12월의 경우는 겨울철 식물의 고사로 인하여 수생식물의 생육이 저조하였다. 수생식물의 영양염류 흡수특성은 수생식물 이식 후 1개월까지 점점 증가하였으나 증가폭이 크지 않았고, 수생식물 이식후 3개월 후인 가을철에는 수생식물의 질소 흡수량이 최대가 되었다. 그러나 수생식물 이식 후 5개월 후인 겨울철에는 수생식물의 고사로 인해 수생식물의 잎과 줄기가 고사하여 영양염류의 흡수량이 다시 감소하였다. 또한 수생식물 종별 영양영류의 흡수특성은 노랑꽃창포 ${\gg}$ 부들 > 갈대 순이었고, 특히 노랑꽃창포가 다른 수생식물에 비해 영양염류의 흡수량이 매우 높았다.

• 대한환경공학회지
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• 제28권4호
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• pp.389-396
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• 2006

고도폐수처리장의 원생동물의 분포를 주별로 조사하였다. 통계방법을 이용하여 원생동물의 개체수와 운영조건, 유출수질을 분석하였다. 유입수의 성상과 처리장의 운영조건에 영향을 받아 처리장별로 원생동물 분포가 다르게 나타났다. 통계분석을 통해, 원생동물의 분포로 현재 운영중인 처리장의 운영조건을 알 수 있고 가까운 미래의 유출수질을 예측할 수 있었다. 처리장의 원생동물 분포, 유출수질, 운영조건 자료들이 충분히 확보되면 원생동물 관찰에 의해 처리장의 운영현황 및 가까운 미래의 수질예측이 가능해진다. 수질예측이 가능함으로 운영조건을 조기변동 하여 처리수질을 양호하게 유지할 수 있다. 장기적으로는 가장 좋은 유출수질때 나타나는 원생동물의 분포를 얻을 수 있도록 처리장의 운영조건을 변경함으로 좋은 유출수질을 얻을 수 있다.

• Advances in environmental research
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• 제3권2호
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• pp.173-183
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• 2014

A comprehensive mathematical model was developed for this study to estimate on-site and off-site GHG emissions from wastewater treatment plants (WWTPs). The model was applied to three different hybrid WWTPs (S-WWTP, J-WWTP, and T-WWTP) including anaerobic, anoxic, and aerobic process, located in Seoul City, South Korea. Overall on-site and off-site GHG emissions from S-WWTP, J-WWTP, and T-WWTP were $305,253kgCO_2e/d$, $282,682kgCO_2e/d$, and $117,942kgCO_2e/d$, respectively. WWTP treating higher amounts of wastewater produced more on-site and off-site GHG emissions. On average, the percentage contribution of on-site and off-site emissions was 3.03% and 96.97%. The highest amount of on-site GHG emissions was generated from anoxic process and the primary on-site GHG was nitrous oxide ($N_2O$). Off-site GHG emissions related to electricity consumption for unit operation was much higher than that related to production of chemicals for on-site usage. Recovery and reuse of biogas significantly reduced the total GHG emissions from WWTPs. The results obtained from this study can provide basic knowledge to understand the source and amount of GHG emissions from WWTPs and strategies to establish lower GHG emitting WWTPs.

• 상하수도학회지
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• 제31권6호
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• pp.491-499
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• 2017

The chemical structures of perfluorinated compounds(PFCs) have unique properties such as thermal and chemical stability that make them useful components in a wide variety of consumer and industrial products. Two of these PFCs, perfluorooctane sulfonate(PFOS) and perfluorooctanoic acid(PFOA), have received attention and were the most commonly detected. In this study it was analyzed the concentrations of 8 PFCs in samples were collected from drinking water treatment plants for 5 years(2012-2016). PFOS and PFOA were also high concentration and frequency. The mean concentrations of PFOA and PFOS were detected $0.0026-0.0069{\mu}g/L$ and $0.0009-0.0024{\mu}g/L$ in samples from drinking water treatment plants. These were relatively lower or similar compared to PFOS concentrations in Osaka(Japan). In general, these levels are below health-based values set by international authoritative bodies for drinking water. These results will be serve as the first monitoring data for PFCs in drinking water and be useful for characterizing the concentration distribution and management of PFCs in future studies.

• Membrane and Water Treatment
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• 제11권2호
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• pp.123-130
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• 2020

Submerged Membrane bioreactor (SMBR) is one of the last techniques that allow a high quality of treated industrial effluents by coupling biological treatment and membrane separation. Thus, this research was an effort to evaluate performance of a SMBR treating a model textile wastewater (MTWW). Different SMBR operating parameters like mixed liquor suspended solids (MLSS) and Dissolved oxygen concentration, hydraulic retention time (HRT), and nutrients addition (N and P) have been investigated. MTWW (influent to the SMBR) was generated using the reactive azo-dye, Novacron blue FNG (100mg/L feed concentration). Results of MTWW treatment using SMBR under optimal operating conditions (MLSS, 4.2-13.3g/L; HRT, 4 days; pH, 6.9-7.2; conductivity, 400-900 μS/cm and temperature, 19.4-22.2 ℃) showed that COD and blue colour treatment performances are between 94-98% and 30-80%, respectively. It is concluded that SMBR can be used in large scale textile wastewater treatment plants to improve effluent quality in order to meet effluent discharge standards.

• 한국환경과학회지
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• 제27권11호
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• pp.1059-1072
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• 2018

Bioremediation has been recognized as a suitable alternative to conventional methods of removing contaminants, and it uses fungi, bacteria and microalgae. In contrast to other organisms, microalgae are unique in that they have the ability to perform photosynthesis like plants and to utilize organic/inorganic carbon substrates, in a process called phytoremediation. Microalgae can populate a reaction site rapidly and enhance the bioremediation efficiency. In this study, Chlorella vulgaris was used to evaluate the removal potentials of the nutrients (N and P) and heavy metals (Cu and Zn) from swine wastewater. The optimum growth conditions for Chlorella vulgaris and the removal potentials of N, P, Cu, and Zn from synthetic wastewater using Chlorella vulgaris were investigated. Based on the results, the applicability of this microalga to on-site wastewater treatment was examined. Optimal growth conditions for Chlorella vulgaris were established to be $28^{\circ}C$, a pH of 7, and light and dark cycles of 14:10 h. As the concentrations of the nutrients were increased, the efficiencies of N and P removal efficiencies by Chlorella vulgaris were decreased in the single and binary mixed treatments of the nutrients, respectively. Further, the efficiencies of Cu and Zn removal also decreased as the heavy metals concentrations added were increased, both in the single and binary mixed treatments. In addition, the efficiency of Cu removal was higher than that of Zn removal. Our results indicate that Chlorella vulgaris could be used in treatment plants for the removal of nutrients and heavy metals from swine wastewater.