• Title, Summary, Keyword: first-flush

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Evaluation of the qualities of rainwater collected from the top of vinyl house : A Case Study in Jeju Island (비닐하우스에서 모은 빗물의 수질평가 연구 : 제주도 사례)

  • Lee, Bong-Joo;Moon, Sang-Ho;Kim, Yong-Cheol;Kim, Gee-Pyo;Kang, Bong-Rae;Koh, Gi-Won;Park, Ki-Hwa
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.3
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    • pp.315-322
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    • 2008
  • Recently there has been a great deal of interest in promotion of the utilization of rainwater. In this paper, we compared qualities of the rainwater collected from the top of vinyl houses to those of precipitated rainwater itself in Jeju Island. The pH of the collected rainwater was acidic and lower than the precipitated one. As a storm progresses, the pH of the collected water gradually increases. Ranges of EC of the precipitated and collected rainwater were 1-118 and $1-475{\mu}S/cm$. Most of Cl and turbidity values of the collected rainwater were less than 20 mg/L and 20 NTU, while those of the precipitated rainwater were less than 10 mg/L and 5 NTU. Differences in qualities between precipitated and collected rainwater indicate that qualities of the collected rainwater should be changed by the first flush effects, and imply that long term continuous monitoring for the qualities of collected rainwater is essential to quantify the first flush phenomenon more accurately.

Analyzing Runoff Characteristics of Nonpoint Sources During Rainfall in Urban Area - Focussing on upstream of Hongjechun watershed (강우시 도시지역 비점오염원 유출특성 분석 - 홍제천 상류 유역을 중심으로 -)

  • Hwang, Byung-Gi
    • Journal of Environmental Impact Assessment
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    • v.14 no.2
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    • pp.63-73
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    • 2005
  • This study was performed to characterize stormwater runoff of pollution material from nonpoint sources during rainfall in drainage basins of Hongjechun watershed, and to suggest management methods to control the first flush of nonpoint sources. We conducted 4 times of field surveys including 3 times of wet period and 1 times of dry period for 5 stations, which consist of 3 stations in main stream of Hongjechun and 1 station in tributaries of Sinyoungchun and Gukichun, respectively. The variation of pollutant concentrations in terms of BOD, COD, SS and TP was large depending on the flow rate of stormwater, while a little change of TN concentration was investigated. Depending on the rainfall event, the difference of flowrates, and runoff loadings was large, while the difference of those for dry wether period was not noticeable for various sub-basins. In the results of unit load calculation, the range of 153-277 kg/ha/yr for BOD, 222-422 kg/ha/yr for COD, 264-432 kg/ha/yr for SS, 40-70kg/ha/yr for TN, and 13-25 kg/ha/yr for TP was obtained for Hongjechun, Sinyoungchun, and Gukichun sub-basins. Compared with the previous studies, the result of this study was founded to be acceptable.

Runoff Characteristics of Non-point Pollutants Source in Suwon City (수원시 비점오염물질의 유출 특성)

  • Chi, Hong-Jin;Lee, Sang-Eun;Lee, Jae-Dong
    • Journal of Environmental Science International
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    • v.22 no.4
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    • pp.493-505
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    • 2013
  • This study was to investigate the runoff characteristics of non-point pollutants source at the urban area in Suwon city. The highest T-N and T-P concentration of rainfall runoff observed in agricultural area. In residential area, the highest $BOD_5$ and SS concentration of rainfall runoff was investigated. During rainfall events, the peak concentrations of SS and $BOD_5$ were observed after 1~2 hours of rainfall in urban area. Whereas, the peak concentrations occurred within 1~2 hours after rainfall and then the highest concentrations of SS and $BOD_5$ sharply decreased, showing strong first flush effect in urban area. The EMC results indicated that the highest value of T-N and T-P in agricultural area was observed. While residential area was shown the lowest EMC value as T-N and T-P. Non-point pollutant loads on the land use types in urban area were investigated in the order of residential>industrial>agricultural>highway. $BOD_5$ and SS loads on urban watershed were investigated in the order of Suwon>Hwangguji>Seoho>Wonchunri. Whereas, T-N and T-P loads on urban watershed were investigated in the order of Hwangguji>Suwon>Wonchunri>Seho.

Effectiveness of Settling Treatment System to Reduce Urban Nonpoint Source Pollutant Load by First Flush (초기 강우에 의한 도시 유역 비점오염 부하의 유입 저감을 위한 침강 처리 시설 적용 타당성 분석)

  • Kim, Jaeyoung;Seo, Dongil;Lee, Tongeun
    • Journal of Korean Society of Environmental Engineers
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    • v.39 no.3
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    • pp.140-148
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    • 2017
  • The effectiveness of the first flush treatment system using settling process was evaluated to reduce urban nonpoint source pollutant loads to surface water during storm events. A pilot scale system was constructed and tested in the field and surface runoff samples were collected automatically according to pre-defined conditions. Nine rainfall events were tested and average removal efficiencies of TSS (Total Suspended Solid), TP (Total Phosphorus) and TN (Total Nitrogen) were evaluated as 87.4%, 75.3%, and 43.6%, respectively. Concentration and removal efficiency of pollutants were found to be affected by an amount of rainfall and rainfall intensities of the respective events. This seemed to be caused by the greater particulate fractions of first flushed samples than the samples collected in later time periods during the same rainfall events. The study showed that it is possible to remove a significant portion of the nonpoint source pollutant loads in initial rainfall runoff by using a simple settling process for TSS and TP without requiring additional power or chemicals.

Water Quality and Particle Size Distributions of Road Runoff in Storm Event (강우시 도로유출수 수질특성 및 입경분포)

  • Lee, Jun-Ho;Cho, Yong-Jin;Bang, Ki-Woong
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.7
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    • pp.777-784
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    • 2005
  • The first flush phenomenon is defined as the initial period of road runoff during which the concentration of pollutants was significantly high. Road runoff contains significant loads of micro-particles, heavy metals and organic constituents. There were two major objectives of this study. The first objective was to characterize the road runoff. The second objective was to measure and evaluate particle sire distribution of the road runoff, Stormwater runoff was monitored on two sites of four lane road areas along with traffic volume. A total six storm events were monitored to characterize the road runoff. The quantity of road runoff and quality constituents, including chemical oxygen demand ($COD_{Cr}$), suspended solids(SS), total Kjeldahl nitrogen (TKN), ortho-phosphorus ($PO_4-P$), total phosphorus(TP), heavy metals and particle size distribution were analyzed. The results indicate that the concentration of SS, $COD_{Cr}$, TKN and TP ranges were $45{\sim}2,396\;mg/L$, $40{\sim}931\;mg/L$, $0.1{\sim}19.6\;mg/L$, and $0.2{\sim}25.1\;mg/L$, respectively. The results of the regression analysis between SS and the others constituents shows that $COD_{Cr}$, TP, Cu, Pb were highly correlated. And the results showed that the mean range of particle size and uniformity coefficient for road runoff were $6.7{\sim}23.4{\mu}$ and $6.4{\sim}10.2$, respectively.

Breeding and Cultural Characteristics of Newly Bred Lentinula edodes Strain 'Sanjanghyang' (신품종 표고버섯 '산장향'의 교배 육성 및 재배 특성)

  • Park, Youngae;Jang, Yeongseon;Ryoo, Rhim;Lee, Bonghun;Ka, Kang-Hyeon
    • The Korean Journal of Mycology
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    • v.47 no.2
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    • pp.143-152
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    • 2019
  • A new cultivar 'Sanjanghyang' was bred from monokaryotic strains of 'Sanbaekhyang' and 'Jangan 1ho'. Pileus was flat, round, and reddish brown. The diameters of the pilei and stipe length of the fruiting bodies were 67.1 mm and 16.9 mm, respectively. The scales were white or slightly brown and distributed evenly. The gill density was sparse and showed a rippled texture. The stipe was cream in color and the fluff was medium. 'Sanjanghyang' had a short cultivation period and fruiting bodies occurred sporadically. Temperature for fruiting body formation was a medium, between 15 to $19^{\circ}C$. 'Sanjanghyang' was different from 'Sanbaekhyang' with regard to its pileus diameter (67.1 mm) and autumn and spring fruiting body production period. 'Sanbaekhyang' had pileus diameter of 74.7 mm, and fruiting body formation occurred in spring and autumn. The rate of fruiting body formation was 89% (first flush), 4% (second flush), and 7% (third flush).

MLC-LFU : The Multi-Level Buffer Cache Management Policy for Flash Memory (MLC-LFU : 플래시 메모리를 위한 멀티레벨 버퍼 캐시 관리 정책)

  • Ok, Dong-Seok;Lee, Tae-Hoon;Chung, Ki-Dong
    • Journal of KIISE:Computing Practices and Letters
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    • v.15 no.1
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    • pp.14-20
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    • 2009
  • Recently, NAND flash memory is used not only for portable devices, but also for personal computers and server computers. Buffer cache replacement policies for the hard disks such as LRU and LFU are not good for NAND flash memories because they do not consider about the characteristics of NAND flash memory. CFLRU and its variants, CFLRU/C, CFLRU/E and DL-CFLRU/E(CFLRUs) are the buffer cache replacement policies considered about the characteristics of NAND flash memories, but their performances are not better than those of LRD. In this paper, we propose a new buffer cache replacement policy for NAND flash memory. Which is based on LFU and is taking into account the characteristics of NAND flash memory. And we estimate the performance of hit ratio and flush operation numbers. The proposed policy shows better hit ratio and the number of flush operation than any other policies.

Characteristics of Pollutant Washed-off from Highways with Storm Runoff Duration (아스팔트 포장 고속도로의 강우 지속시간별 오염물질 유출 경향)

  • Kim Lee-Hyun;Lee Eun-Ju;Ko Seok-Oh;Kang Hee-Man
    • International Journal of Highway Engineering
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    • v.8 no.1
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    • pp.99-106
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    • 2006
  • During the dry periods, many types of pollutant are accumulating on the paved surface by vehicle activities. Particularly, the highways are stormwater intensive landuses because of high imperviousness and high pollutant mass emissions from vehicles. The accumulated pollutants in highways are washed-off during a rainfall event and are highly contributing on water quality of receiving water bodies. The stormwater runoff from the highways are containing various pollutants such as metals, oil & grease and toxic chemicals originated from vehicles. Therefore, this research is performed to find pollutant characteristics in the magnitude of statistical pollutant concentrations during storm periods. During the monitoring periods, the first-flush phenomenon is visibly occurred on most storm events, which is confirmed from hydro- and pollute-graphs. The 95% confidence intervals of washed-off pollutant concentration are ranged to 154.7-257.1 mg/L for 755,138.9-197.6 mg/L for COD, 3.5-6.4 mg/L for oil & grease, 6.3-9.2 mg/L for TN and 2.3-3.31 mg/L for TP. The first flush effect is mostly occurred within initial 30 min of storm duration.

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Effect and Control of the Sediment in the Combined Sewer on CSOs (합류식 하수관거내 퇴적물이 CSOs에 미치는 영향 및 제어방안)

  • Lim, Bongsu;Kim, Doyoung;Lee, Kuangchun
    • Journal of Korean Society on Water Environment
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    • v.27 no.1
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    • pp.36-43
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    • 2011
  • This study is selected two points of combined sewer that occurred Fish Kill after first flush, that analyzed generation of pollutants and stream runoff generation of combined sewer overflows (CSOs) as fine weather and rainfall. In addition, this study was to analyze the relationship between CSOs and sediments, to propose measures to reduce the sediment relevant with CSOs and rainfall runoff from entering sewage treatment plants and measures for discharged directly into streams when indicate relatively good water quality after overflow. Sediments in combined sewer system was discharged about 50~80% as overflows during rainfall and we can reduce the amount of the CSOs at least 50% or more if the sewer does not exist in the sediments because of the amount of discharge about the amount of intercept has been investigated by 3~5 times. Because of velocity at sediment interval in sewer is very low, sewage velocity of about 3~5 times as much as it can increase the amount of sediment can be reduced if the separation wall is installed. Effective control of BOD overflow load is respectively 77.5%, 75.8% at first point, second point by the separation wall is installed. Drainage area greater than area in this study or many combined sewer overflows region is increased the more effective control of separation wall. Turbidity to measure changes in water quality of overflows can be used as an factor to control the intercept flows because the intercept flows(3Q) after the first flush has lowered removal efficiency and increases the operational load of sewage treatment plants. Sewage water quality after a overflow when the reasonable turbidity was measured at this point flows to excluded intercept flow(1Q) can be discharged to stream.

Characteristics of Road Runoff depending on the Rainfall Intensity (강우강도에 따른 노면유출수의 유출 특성)

  • Kim, Seog-Ku;Kim, Young-Im;Yun, Sang-Leen;Lee, Yong-Jae;Kim, Ree-Ho;Kim, Jong-Oh
    • Journal of Korean Society on Water Environment
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    • v.20 no.5
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    • pp.494-499
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    • 2004
  • Growth in population and urbanization has progressively increased the loadings of pollutants from non-point sources as well as point sources. Therefore, it is necessary to manage both point and non-point sources contaminations for protecting water environment and improving water quality. This study investigated the characteristics of pollutant release over a wide range of rainfall intensities as a requisite to control road runoff that accounts for the largest portion of non-point source contamination in urban areas. Samples of runoff rainwater collected from real road surfaces were analyzed for physicochemical parameters such as pH, suspended solids, and heavy metals. A experimental model road ($30cm{\times}30cm$) was also used to evaluate wash-off properties of pollutants deposited on the surface as functions of time and rainfall intensity. Analysis of runoff samples on rain events showed that the pollutant wash-off patterns for heavy metal and suspended solids were similar. This implies that the particles in rainwater adsorb heavy metals. Experiments using the model road made of impervious asphalt demonstrate a strong first flush phenomenon. At high rainfall intensity, approximately 80% of total pollutants were released within 15 min. The pollutant wash-off rates rapidly increase from 9 mm/hr to 12 mm/hr of rainfall intensity and decrease over 12 mm/hr of rainfall intensity.