• Title/Summary/Keyword: Sand filter

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Removal of Algae in a Slow Sand Filter using Ecological Property of Macrobenthos (Pomacea canaliculata) (저서생물의 환경생태학적 특성을 이용한 완속 모래여과지의 조류제거)

  • Son, Hee-Jong
    • Journal of Environmental Science International
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    • v.22 no.3
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    • pp.371-378
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    • 2013
  • After identifying species by collecting the suspended and attached algae mat inhabiting in the slow sand-filter, Spirogyra sp., Mougeotia sp. and Closterium sp. were main green algae and Synedra sp. was diatom algae. Among them green algae Spirogyra sp. was dominant species. A result of observing the life mode of apple snail for a month after introducing into the slow sand-filter, apple snail eggs were discovered on the filter walls 2 weeks after introducing, 4 weeks later lots of eggs were observed all of the slow sand-filter walls, it means there is no problem for apple snail to live in the slow sand-filter. The observation result for algae removal potential by introduced apple snail after 2 months later, slow sand-filter where apple snail were introduced, a few algal mat were observed. On the other hand, no introduced apple snail into the slow sand-filter, lots of suspended algal mats were formed in the water and attached algal mats on the sand surface as well, these algal mat induced much of operating problems.

Soluble Manganese Removal Using Manganese Oxide Coated Media (MOCM) (산화망간피복여재를 이용한 용존망간 제거)

  • Kim, Jinkeun;Jeong, Sechae;Ko, Suhyun
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.6
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    • pp.813-822
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    • 2006
  • Soluble manganese removal was analyzed as a function of filter media, filter depth, presence or absence of chlorination, and surface manganese oxide concentration in water treatment processes. Sand, manganese oxide coated sand (MOCS), sand+MOCS, and granular activated carbon(GAC) were used as filter media. Manganese removal, surface manganese oxide concentration, turbidity removal, and regeneration of MOCS in various filter media were investigated. Results indicated that soluble manganese removal in MOCS was rapid and efficient, and most of the removal happened at the top of the filter. When filter influent (residual chlorine 1.0mg/L) with an average manganese concentration of 0.204mg/L was fed through a filter column, the sand+MOCS and MOCS columns can remove 98.9% and 99.2% of manganese respectively on an annual basis. On the other hand, manganese removal in sand and the GAC column was minimal during the initial stage of filtration, but after 8 months of filter run they removed 99% and 35% of manganese, respectively. Sand turned into MOCS after a certain period of filtration, while GAC did not. In MOCS, the manganese adsorption rate on the filter media was inversely proportional to the filter depth, while the density of media was proportional to the filter depth.

Infiltration characteristic of modified slurry and support efficiency of filter cake in silty sand strata

  • Sai Zhang;Jianwen Ding;Ning Jiao;Shuai Sun;Jinyu Liu
    • Geomechanics and Engineering
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    • v.34 no.2
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    • pp.125-138
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    • 2023
  • To improve the understanding of infiltration characteristic of modified slurry and the support efficiency of filter cake in silty sand strata, the slurry infiltration (SI) and filter cake formation (FCF) were investigated in a laboratory apparatus. The water discharge and the excess pore pressure at different depths of silty sand strata were measured during SI. The relationship between permeability coefficient/thickness ratio of filter cake (kc/ΔL) and effective slurry pressure conversion rate of filter cake (η) were analyzed. Moreover, the SI and FCF process as well as the modification mechanism of CMC (carboxymethyl cellulose) were clarified. The experimental results indicate the formation of only external filter cake in the silty sand strata. The slurry particles obtain thicker water membrane after being modified by CMC, which blocks partial water path in filter cake and decreases the water discharge significantly. The silty sand excavated from tunnel face also contributes to the water discharge reduction. The kc of the external filter cake ranges from 3.83×10-8 cm/s to 7.44×10-8 cm/s. The η of the external filter cake is over 96%, which decreases with increasing kc/ΔL. A silty sand content within 10% is suggested during construction to ensure the uniformity of the filter cake.

Advanced water treatment in pilot scale BAC-sand filter (Pilot Scale 생물활성탄 여과공정을 이용한 상수의 고도처리)

  • 이윤진;문철훈;김재우;남상호
    • Journal of environmental and Sanitary engineering
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    • v.17 no.4
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    • pp.47-52
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    • 2002
  • This study was carried out to examine the characteristics of dual media filter with BAC and sand on a pilot scale which was installed in T Water Treatment Plant of Seoul. The conclusions drawn from experimental results are as follows : For the BAC-Sand filter, the preceded gravity sand filter did not largely affect the removal of organics and turbidity causing matters, tut the frequency of backwashing was explicitly reduced to two times with the stable growth of microorganisms. The biomass on media in case of existence of preceded sand filter was 1.4 times higher than that of nonexistence. In case of backwashing with water, the time needed to comply with below 10NTU took 22, 10, and 5 minutes respectively with the expansion ration of 1.2, 1.5 and 1.8. The higher the expansion ration was, the shorter the backwashing time was.

A column study of effect of filter media on the performance of sand filter

  • Kim, Tae-hoon;Oh, Heekyong;Eom, Jungyeol;Park, ChulHwi
    • Membrane and Water Treatment
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    • v.11 no.4
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    • pp.247-255
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    • 2020
  • Sand filter is a key unit process for particle removal in water purification treatments. Its long-standing use is due to on-site customized retrofit. Proper selection of filter media is one of the retrofit approaches to improve filter performance. This study described a series of controlled laboratory column tests and examined the effects of media property on filtration and backwash. When sand media of 0.51 mm in effective size was replaced by sand of 0.60 mm, the filter run increased up to 5 times in the given bed depth. The change of media property required an increase of backwash rate by 0.05 m/min to satisfy the requirement of bed expansion, more than 20%. When the anthracite was changed with lower effective size and uniformity coefficient, correlation with sand in the filter bed could be satisfied within the permissible error between media and bulk characteristics. Besides, this selection resulted in a well-stratified configuration of media layers after bed expansion. The column study showed that the correlation of property between the dual media had a significant effect on the filter productivity and backwash interval.

Improving the Initial Effluent Turbidity by Polyaluminium Chloride(PAC) Coating in Rapid Sand Filtration (급속모래여과에서 PAC 피복에 의한 초기 유출수의 탁도 개선)

  • Yoon, Tae-Han;Kim, Woo-Hang
    • Journal of Korean Society on Water Environment
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    • v.18 no.3
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    • pp.253-260
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    • 2002
  • The purpose of this research was to describe the mechanisms and prevention of initial degradation in turbidity of the sand filter effluent. The method used was by adding a coagulant (PAC) to the sand filter after backwashing as a means of reducing turbidity. It was found that adding 80 mg/L of PAC solution to the sand filter was very effective in improving the initial effluent turbidity. A turbidity removal efficiency of 99 % was observed in the initial term period as compared to a 70% efficiency without PAC addition. The PAC solution added to the sand filter resulted in high aluminum concentration at the upper layer as compared with the bottom layer of the sand filter column. A change in the zeta potential to a strong positive-ions at upper layer was observed at this time but only a small change was obtained at the bottom. This result showed that the zeta potential of the sand was changed to positive with PAC coating. The effect of pH on zeta potential with PAC addition was also investigated. Zeta potential was greatly changed to positive-ion at pH 4~6. A series of experiments was then conducted in this study to optimize the pH of the PAC solution to be added to the sand filter after backwashing. The removal efficiency of turbidity was found to be highest at pH 5. This result suggested that hydrolyzed aluminium species attached to the surface of the sand enhanced the removal of turbidity of the effluent.

Treatment of Recycling Wastewater of Aquaculture Using DynaSand Filter( I ) (상향류식 연속역세여과를 이용한 양어장 순환수 재이용(I))

  • 박종호;김이오;황규덕;황금희;조규석;김동식
    • Journal of Aquaculture
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    • v.15 no.2
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    • pp.87-93
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    • 2002
  • To improve the efficiency of biological filters used for treating recycled wastewater of aquaculture, the conventional and advanced DynaSand Filters were tested. Applying the fluid mechanics and physical chemistry theories to wastewater treatment plant, the advanced filter focuses on detection of wastewater characteristics and automatic operation of DynaSand Filter to improve backwashing, oxygen transport, turbidity removal and continuous head loss. The Filter removes COD, ammonia, and suspended solids (SS), the major pollutants in aquaculture wastewater. The total volume of the DynaSand Filter is 70 L, while the working volume is 35 L per cycle. The removal efficiency of the advanced DynaSand Filter is 71 % for SS (as against 55 % for the conventional filter), 84 % for ammonia, 85 % for T-P, and 88 % for SRP.

Comparison of the filtration performance by different media in pretreatment of seawater desalination by reverse osmosis (여재 종류에 따른 역삼투법 해수담수화 시설 전처리 여과공정의 성능비교)

  • Kim, Seung-Hyun;Yoon, Jong-Sup;Lee, Seockheon
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.2
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    • pp.215-222
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    • 2009
  • This study compares the performance of the filters with various media in pretreatment of seawater desalination by reverse osmosis. For this purpose, Masan bay seawater is used as raw water. The filter performance is evaluated by the filtrate quality and the head loss development. Five media is selected in this study: anthracite, $Filtralite^{(R)}$, sand, Pumice, $AFM^{(R)}$. These media are used in combination for dual media filter and alone for mono media filter. The comparison results show that NC0.8-1.6 is the best $Filtralite^{(R)}$. The dual media filter of NC0.8-1.6 and sand outperformed other filters in particle removal. The dual media filter of anthracite and sand showed good performance in organic removal. The mono media filter of Pumice produced the similar filtrate quality as the mono media filter of sand although the effective size of Pumice is considerably greater than that of sand. Due to big size, head loss development is maintained slow in the filtration of Pumice.

Study on Algae and Turbidity Removal by Floating-media and Sand Filter (부상여재 및 모래 여과장치에 의한 조류와 탁도 제거에 관한 연구)

  • Kwon, Dae-Young;Kwon, Jae-Hyun
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.5
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    • pp.659-668
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    • 2012
  • In Korea, almost every water treatment plant suffers from seasonal problem of algae and turbidity which result from eutrophication and heavy rainfall. To relieve this problem, experimental investigation was performed to study the applicability of a floating-media and sand filter to preliminary water treatment in terms of algae and turbidity removal. Experimental results using pure-cultured algae influent showed that the shape of algae species as well as filtration velocity affects the removal efficiency. From the experiments using natural river water, it was concluded that algae removal is more sensitive to floating-media depth but turbidity more sensitive to sand depth. As the filtration velocity increased, the removal of turbidity decreased but that of algae was not affected. The floating-media and sand filter removed more than 30 % of TP, TN, turbidity, Chl-a and CODcr, and less than 20 % of DOC and $UV_{254}$.

Removal Efficiency of TSS Loadings from Expressway by Road Sweeping and Sand Filter Facility Using ROADMOD (ROADMOD를 이용한 도로청소 및 모래여과시설에 의한 고속도로에서의 강우시 TSS 저감효과 분석)

  • Heeman Kang;Ji-Hong Jeon
    • Journal of Korean Society on Water Environment
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    • v.39 no.1
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    • pp.38-45
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    • 2023
  • In this study, the removal efficiency of road sweeping and sand filter facility for removing total suspended solid (TSS) as nonpoint source pollution from expressway was evaluated for the last 10 years (2012~2021) using ROADMOD. ROADMOD is a screening level model and was calibrated for runoff rate and TSS loading both at the inlet, which is the loading from the drainage area, and the outlet, from the sand filter facility. The drainage area is 715 m2 and the dimensions of sand filter facility are 1.5 m (wide) × 3.8 m (length) × 1.5 m (depth). The monitoring period for model calibration was the rainfall event during Aug. 31~Sep. 1, 2021 and the amount of rainfall was 74.5 mm. As a result of calibration, the determination coefficients (R2) of the flow rate were 0.66 and 0.86, for the inlet and outlet, respectively, and those of TSS loading were 0.50 and 0.84, for the inlet and outlet, respectively. Considering that ROADMOD is a screening level model, the calibration results were reasonable to evaluate the best management practices (BMPs) on the expressway. Using ROADMOD simulation results for 2012~2021, the average yearly runoff rate from the expressway was 82% and removal efficiency was 9% for road sweeping, 35% for sand filter facility, and 39% for both road sweeping and sand filter facility.