• 제목/요약/키워드: Fluoride removal

검색결과 97건 처리시간 0.017초

A critical review of fluoride removal from water by using different types of adsorbents

  • Prashant S. Lingayat;Rampravesh K. Rai
    • Advances in environmental research
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    • 제12권2호
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    • pp.77-93
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    • 2023
  • The water can be contaminated by natural sources or by industrial effluents. One such contaminant is fluoride. Fluoride contamination in the water environment due to natural and artificial activities has been recognized as one of the major problems worldwide. Among the commonly used treatment technologies applied for fluoride removal, the adsorption technique has been explored widely and offers a highly efficient simple and low-cost process for fluoride removal from water. This review paper the recent developments in fluoride removal from surface water by adsorption methods. Studies on fluoride removal from aqueous solutions using various carbon materials are reviewed. Various adsorbents with high fluoride removal capacity have been developed, however, there is still an urgent need to transfer the removal process to an industrial scale. Regeneration studies need to be performed to more extent to recover the adsorbent in field conditions, enhancing the economic feasibility of the process. Based on the review, technical strategies of the adsorption method including the Nano-surface effect, structural memory effect, anti-competitive adsorption and ionic sieve effect can be proposed. The design of adsorbents through these strategies can greatly improve the removal efficiency of fluoride in water and guide the development of new efficient methods for fluoride removal in the future. This paper describes brief discussions on various low-cost adsorbents used for the effective removal of fluoride from water.

Struvite 결정화를 이용한 반도체 폐수처리 시 불소제거를 위한 최적 조건 (Optimum Condition for Fluoride Removal Prior to the Application of Struvite Crystallization in Treating Semiconductor Wastewater)

  • 안명기;우귀남;김진형;강민구;류홍덕;이상일
    • 한국물환경학회지
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    • 제25권6호
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    • pp.916-921
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    • 2009
  • This study was aimed to both enhance the fluoride removal and to reduce the phosphorus removal in treating semiconductor wastewater using $Ca(OH)_2$ at low pH so as to facilitate struvite crystallization reaction. The struvite crystallization could be introduced after fluoride removal by retaining the phosphorus source. As the results, the method applied in this study achieved high fluoride removal efficiency (about 91%) with retardation of phosphorus removal at pH 4, compared to conventional methods where the removal of fluoride and phosphorus were done at pH 11. Therefore, the fluoride removal at low pH would contribute to the enhancement of nitrogen and phosphorus removals in a consecutive struvite crystallization reactor. Treatment of semiconductor wastewater at low pH using $Ca(OH)_2$ also had lower (about 20%) water content of precipitated sludge compared to conventional method. As the molar ratio of Ca to F increased the removal efficiencies of fluoride and phosphorus increased. Although the amount of seed dosage didn't affect the removal of fluoride and phosphorus, its increase reduced the water content of precipitated matter. Finally, considering consecutive struvite reaction, the optimum condition for the removal of fluoride and phosphorus was as follow: pH: 4, the molar ratio of Ca:F: 1:1.

Enhancement effect of phosphate and silicate on water defluoridation by calcined gypsum

  • Al-Rawajfeh, Aiman Eid;Alrawashdeh, Albara I.;Aldawdeyah, Asma;Hassan, Shorouq;Qarqouda, Ruba
    • Advances in environmental research
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    • 제2권1호
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    • pp.35-49
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    • 2013
  • Research work on removal of fluoride from water, referred to as water defluoridation, has resulted into the development of a number of technologies over the years but they suffer from either cost or efficiency drawbacks. In this work, enhancement effects of phosphate and silicate on defluoridation of water by low-cost Plaster of Paris (calcined gypsum) were studied. To our knowledge, the influence of silicate on defluoridation was not reported. It was claimed, that the presence of some ions in the treated water samples, was decreasing the fluoride removal since these ions compete the fluoride ions on occupying the available adsorption sites, however, phosphate and silicate ions, from its sodium slats, have enhanced the fluoride % removal, hence, precipitation of calcium-fluoro compounds of these ions can be suggested. Percentage removal of $F^-$ by neat Plaster is 48%, the electrical conductance (EC) curve shows the typical curve of Plaster setting which begins at 20 min and finished at 30 min. The addition of phosphate and silicate ions enhances the removal of fluoride to high extent > 90%. Thermodynamics parameters showed spontaneous fluoride removal by neat Plaster and Plaster-silicate system. The percentage removal with time showed second-order reaction kinetics.

산업폐기물인 적니를 이용한 불소 제거 (Fluoride Removal from Aqueous Solutions using Industrial Waste Red Mud)

  • 엄병환;조성욱;강구;박성직
    • 한국농공학회논문집
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    • 제55권3호
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    • pp.35-40
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    • 2013
  • The present study was conducted to investigate the adsorption potential of red mud for fluoride removal. Different operation parameters such as the effect of contact time, initial concentration, pH, competing anions, seawater, adsorbent dose amount, and adsorbent mixture were studied. Nearly 3 hr was required to reach sorption equilibrium. Equilibrium sorption data were described well by Langmuir model and the maximum adsorption capacity of red mud was 5.28 mg/g. The fluoride adsorption at pH 3 was higher than in the pH range 5-9. The presence of anions such as sulfate, nitrate, phosphate, and bicarbonate had no significant effect on fluoride adsorption onto red mud. The fluoride removal by red mud was greater in seawater than deionized water, resulting from the presence of calcium and magnesium ion in seawater. The use of red mud alone was more effective for the removal of fluoride than mixing red mud with other industrial waste such as oyster shells, lime stone, and steel slag. This study showed that red mud has a potential application in the remediation of fluoride contaminated soil and groundwater.

전기응집을 이용한 소규모 수도시설의 질산성질소와 불소이온 제거 (Fluoride and nitrate removal in small water treatment plants using electro-coagulation)

  • 한송희;장인성
    • 상하수도학회지
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    • 제25권5호
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    • pp.767-775
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    • 2011
  • In this study we verified if the electro-coagulation process can treat properly the nitrate and fluoride that are not removed well in the conventional small water treatment plants which usually employ chlorination and filtration only. As we gave a change of electrode material and gap-distance between electrodes, removal efficiency of the nitrate and fluoride was determined by electro-coagulation process which were equipped with aluminum and stainless steel (SUS304) electrodes. In addition, electrode durability was investigated by determination of electrodes mass change during the repetitive experiments. Removal efficiency was great when aluminum was used as an anode material. Nitrate removals increased as electric density and number of electrodes increased, but fluoride removal was less sensitive to both parameters than nitrate. After 10 minutes of contact time with the current density from $1{\times}10^{-3}$ to $3{\times}10^{-3}A/cm^{2}$, nitrate and fluoride concentration ranged from 9.2 to 1.2mg/L and from 0.02 to 0.01mg/L, which satisfied the regulation limits. Regardless of the repeating number of experiments, removal efficiency of both ions were almost similar and the change of electrode mass ranged within ${\pm}$0.5%, indicating that the loss of the electrode mass is not so much great under the limited circumstances.

유동상 반응기를 이용한 반도체 폐수의 불소 처리 (Treatment of Fluoride in Semiconductor Wastewater by using Fluidized Bed Reactor)

  • 안명기;김금용;류홍덕;이상일
    • 대한환경공학회지
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    • 제32권5호
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    • pp.437-442
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    • 2010
  • 본 연구에서는 반도체 폐수에 함유된 불소 처리 시 유동상 반응기 (FBR)을 이용하여 불소 제거 효율을 극대화 시키는 조건에서 발생하는 슬러지의 함수율을 최소화 시키고 $CaF_2$의 순도를 높이고자 하였다. 이를 위해 최적 pH 및 $Ca^{2+}$ 주입몰 비 ($[Ca^{2+}]/[F^-]$)가 도출되었다. 연구 결과 pH 및 $Ca^{2+}$ 주입 몰비가 증가함에 따라 불소 제거효율은 증가하였으며, 최적조건에서 79.8%의 불소제거효율이 관찰되었다. 불소 제거 효율이 최적인 조건에서 인 제거 효율은 약 9.3% 로서 불소 제거시 $Ca^{2+}$${PO_4}^{3-}$-P의 부 반응이 거의 발생하지 않아 높은 순도의 $CaF_2$이 침전 슬러지로 발생하는 것으로 나타났다. 또한 이때 슬러지 함수율은 약 19.3%로 매우 낮은 것으로 나타나 불소 제거, 슬러지 순도 및 함수율 측면에서 FBR은 매우 효과적인 불소 제거 공정인 것으로 나타났다.

Polysulfone으로 Al(OH)3를 고정화한 PSf-Al(OH)3 비드에 의한 불소 이온의 제거 특성 (Removal Characteristics of Fluoride Ions by PSf-Al(OH)3 Beads Immobilized Al(OH)3 with Polysulfone)

  • 전진우;이민규
    • 청정기술
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    • 제20권1호
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    • pp.51-56
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    • 2014
  • 본 연구에서는 폴리술폰(polysulfone, PSf)으로 알루미늄 수산화물(aluminum hydroxide, $Al(OH)_3$)을 고정화한 PSf-$Al(OH)_3$ 비드를 제조하였다. 제조한 PSf-$Al(OH)_3$ 비드에 의한 불소 이온 제거실험은 회분식으로 수행하였으며, pH, 초기농도, 공존이온과 같은 변수들의 영향을 살펴보았다. Langmuir 등온식으로 구한 불소 이온의 최대 제거량은 52.4 mg/g이었으며, 최적 pH 범위는 4~10이었다. PSf-$Al(OH)_3$ 비드에 의한 불소 이온의 제거과정은 전 단계에서 외부물질전달이 나중 단계에서 내부확산이 지배인 것을 알 수 있었다. 또한 PSf-$Al(OH)_3$에 의한 불소 이온의 제거에서 $HCO_3{^-}$, $SO{_4}^{2-}$, $NO_3{^-}$, $Cl^-$와 같은 공존 음이온들은 불소 이온의 제거에 방해를 하는 것으로 나타났다.

유동상 반응기를 이용한 반도체 폐수 내 불소 처리 시 $CaF_2$ 주입량, pH 및 처리수 재순환의 영향 (Effects of $CaF_2$ dosage, pH and Treated Water Recirculation on Fluoride Removal in Treating Semiconductor Wastewater with Fluidized bed Reactor (FBR))

  • 안명기;김진식;김금용;류홍덕;이상일
    • 대한환경공학회지
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    • 제32권6호
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    • pp.593-598
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    • 2010
  • 본 연구에서는 유동상 반응기를 이용하여 고농도의 질소, 인 및 불소가 동시에 존재하는 반도체 폐수 내 불소 처리시 불소 제거효율 향상, 함수율 저감 및 생성 슬러지($CaF_2$)의 순도 향상을 꾀하고자 하였다. 이를 위해 pH 및 seed 주입량, 유출수의 순환여부에 따른 영향을 살펴본 결과 유출수 재순환 시 불소제거효율, 슬러지 순도 및 함수율을 모두 고려할 경우 최적의 pH는 5, seed 주입량은 150 g으로 관찰되었다. 이때의 불소 및 인 제거효율은 94.24 및 8.97%로 나타났고, 함수율은 12.94%로 확인되었다. Seed 주입량의 증가는 불소제거효율을 증가시킬 뿐만 아니라 유출수 재순환 및 pH 변동에 따른 불소제거효율 감소도 억제시키는 것으로 나타났다.

산업폐수에서 불소함유가 미생물활성도 및 기질제거에 미치는 영향에 관한 연구 (Effects on Microbial Activity and Substrate Removal in Industrial Wastewater with Fluoride Content)

  • 최정수;주현종;진오석
    • 한국물환경학회지
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    • 제28권5호
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    • pp.717-722
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    • 2012
  • Fluoride can be easily found in semiconductor and display industry. However, there is a lack of research for its effects on the related wastewater treatment. The objective of this study is to evaluate the microbial inhibitory effect by fluoride injection. The research entailed the assessment of removal efficiency of $TCOD_{Cr}$ according to the fluoride concentration and also the Specific Oxygen Uptake Rate (SOUR) was measured. The laboratory scale reactor was prepared and operated with the fluoride concentrations of 0, 10, 50, 100, and 200 mg/L based on concentrations frequently occurring in the wastewater. The results from this study showed that, as the fluoride concentration increase, the Specific Substrate Utilization Rate (SSUR) tend to decrease as expected. Also, the increase in fluoride concentrations resulted in the decrease in SOUR. It is determined that fluoride injection affects the microbial activity. Especially, The addition of above 200 mg/L fluoride into reactor caused rapidly decreased SSUR and SOUR due to the inhibitory effects of fluoride.

폐콘크리트분말을 이용한 불산폐수 처리 (Fluoride Wastewater Treatment using Waste Concrete Powder)

  • 김은이;강완협;박주양
    • 상하수도학회지
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    • 제19권2호
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    • pp.125-134
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    • 2005
  • Waste concrete powder was used to remove fluoride ions in highly concentrated fluoride wastewater. 92.6% of fluoride in 100 mg F/L wastewater was removed by 1% dose of the cement paste powder that represents characteristics of waste concrete powder, whereas the removal efficiencies of raw cement and lime were 47.3% and 96.4%, respectively. The cement paste powder was competitive to lime, common fluoride removal agent. Various Ca-bearing hydrates such as portlandite, calcium silicate hydrate, and ettringite in cement paste slurry can remove fluoride by precipitating $CaF_2$ and absorbing $F^-$ ions. In the experiments using both cement paste and lime, 50~67% of lime can be substituted by cement paste to satisfy fluoride effluent limitation of 15 mg/L. Since cement paste has higher acid neutralization capacity than lime, it can be recycled to neutralize more acid and to remove more fluoride. Therefore waste concrete powder can be more economical and viable alternative for lime in fluoride wastewater treatment.