• Title/Summary/Keyword: coagulant pH

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A Study on Coagulation Process using Zirconium Silicate as a Coagulation-aid (지르코늄 실리케이트를 응집보조제로 이용한 응집공정에 관한 연구)

  • Cho, Jae-Seung;Yoon, Tai-Il;Jeon, Yu-Jae;Cho, Kyung-Chul
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.3
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    • pp.203-207
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    • 2009
  • The concern of seriousness and harmful effects of environmental pollution is rising by the various water pollutions, appearances of new micro-noxious substances and increase of sustainable pollutants. The method is suggested that can effectively increase the removal of organic substances and several pollutants using a coagulation process. The experiment for characteristics of $ZrSiO_4$ (zirconium silicate) as a coagulation-aid was carried out for application to coagulation process with domestic wastewater and lake water, and the removal rate of the organic substances depending on a dosage was evaluated by PDA (Photometric Dispersion Analyzer) in this study. Zeta-potential of zirconium silicate solution was -32.22 mv at pH 7 and the lower negative(-) charge was detected in the more acidic conditions. Absorbance on $UV_{254}$ presented higher when zirconium silicate was added than in a domestic wastewater itself. Besides, the results by PDA experiment represented that injection of zirconium silicate could promote growing of floc. Tests for coagulation process were conducted by three ways which are pre-injection, co-injection and post-injection of zirconium silicate with alum. Accordingly, removal efficiency of organic substances increased over 15% in co-injection than in using of alum as a sole reagent. When a 20 mg/L of alum was used with a 10 mg/L of zirconium silicate, the removal efficiency was high up to 90%. Removal efficiency of $COD_{Cr}$ was improved more than 15% in case of dosage of coagulant either PAC (Poly aluminium chloride) or PACS (Poly aluminium chloride Silicate) together with zirconium silicate. As a result, the removal efficiency of $COD_{Cr}$ were 5~10% higher in a co-injection of zirconium silicate with a coagulant than a pre-injection and a post-injection but it of soluble substances was lower in a co-injection.

Quality and Antioxidant Properties of Tofu Coagulated with 'Tsugaru' Apple (Malus domestica Borkh) Juice (쓰가루 사과즙을 이용한 두부의 품질 및 항산화 특성)

  • Kim, Dong-Ho;Hong, Kyeong-Nam;Lim, Yeo-Kyeong;Cha, Seung-Hyeon;Ryu, Ji-Eun;Cho, Jin-Ho;Kim, Dae-Il;Yoo, Do-Il;Jang, Keum-Il
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.45 no.8
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    • pp.1130-1137
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    • 2016
  • In this study, we investigated the quality, antioxidant properties, and sensory characteristics of tofu coagulated with 'Tsugaru' apple (Malus domestica Borkh) juice. Yield, $^{\circ}Brix$, pH, total acidity, total polyphenol content, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 'Tsugaru' apple juice were 60%, 10.3, 3.89, 0.51%, 2.26 mg gallic acid equivalent (GAE)/g, $20{\mu}g$ L-ascorbic acid equivalent (AE)/g, and $75{\mu}g$ AE/g, respectively. In case of Tofu coagulated with 20% (w/v) 'Tsugaru' apple juice, yield, $^{\circ}Brix$, pH, total acidity, hardness, chewiness, cohesiveness, total polyphenol content, ABTS radical scavenging activity, and DPPH radical scavenging activity were 165%, 6.23, 0.27%, 513 g, 315, 0.61, 12.04 mg GAE/g, $80.67{\mu}g$ AE/g, and $92.32{\mu}g$ AE/g, respectively. Both the manufacture yield and pH of tofu decreased with increasing amount of 'Tsugaru' apple juice, whereas total acidity increased. Regarding the texture and chromaticity of tofu coagulated with increasing amounts of 'Tsugaru' apple juice, hardness, chewiness, and a- and b-values increased, whereas cohesiveness and L-value both decreased. In terms of antioxidant activities, total polyphenol content and DPPH radical scavenging activity increased, whereas ABTS radical scavenging activity was maintained within a certain range. Finally, concerning the sensory evaluation (taste, color, flavor, and overall preference) of tofu coagulated with 30% (w/w) 'Tsugaru' apple juice showed the highest scores. Taken together, these results support the possible use of 'Tsugaru' apple juice in producing various foods, as addition of juice enhanced quality, antioxidant properties, and sensory characteristics of tofu.

Preparation of Inorganic Coagulants Using Red Mud (적니를 이용한 무기응집제의 제조연구)

  • Kim, Jung-Sik;Lee, Jae-Rok;Han, Sang-Won;Hwang, In-Gook;Bae, Jae-Heum
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.11
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    • pp.2085-2095
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    • 2000
  • Red mud is generated as a by-product during the production of aluminum hydroxide from bauxite ore. In this study inorganic coagulants were prepared by leaching aluminum and iron from red mud with acids under various operating conditions. The optimum leaching efficiency of Al and Fe was obtained by contacting red mud with acids of 5M $H_2SO_4$ and 9M HCI with the ratio of 1/10(g/mL) at $85^{\circ}C$ and $25^{\circ}C$, respectively. In addition. the removal experiments of heavy metal ions($Pb^{2+}$, $Cd^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Cr^{3+}$), turbidity and phosphate phosphorus($PO_4{^{3-}}-P$) in aqueous solutions were also studied in various experimental conditions. As a result, the developed coagulants are found to show a good removal performance of heavy metal ions. turbidity and phosphate phosphorus in aqueous solutions.

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The quality and sensory characteristics of tofu with various levels of black garlic extract (흑마늘 추출물 첨가 두부의 품질특성)

  • Sim, Hye-Jin;Hwang, Cho-Rong;Kang, Min-Jung;Kim, Gyeong-Min;Shin, Jung-Hye
    • Food Science and Preservation
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    • v.21 no.5
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    • pp.688-693
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    • 2014
  • The quality and sensory characteristics of tofu were investigated with various levels of black garlic extract (BE) added to it in 0, 1, 3, 5 and 7%-weight soymilk, before it was coagulated with $MgCl_2$ (MC, BEM-A, BEM-B, BEM-C and BEM-D) and concentrated to $8^{\circ}Brix$ deep ground sea-like water (SC, BES-A, BES-B, BES-C and BES-D). The overall acceptability of the tofu samples was higher (SC > BES-A > BEM-A) than that of the other samples. The addition of BE was influenced by the color, flavor and taste of the tofu, and the more BE was added, the tougher the tofu became. The tofu yield with various amounts of black garlic extract did not significantly differ among the samples. The pH range was 5.61~6.15 and decreased as more BE was added, whereas the turbidity increased. Also, the L value of the tofu decreased as more BE was added. The a value showed a tendency opposite that of the L value. The b value did not significantly differ among the samples. The texture profile analysis of the tofus showed that the hardness, chewiness, and gumminess significantly increased as more BE was added. In conclusion, it was found that the addition of 1% BE will improve the quality and sensory characteristics of tofu.

Development of the Inorganic Coagulants Using Red Mud and Evaluation of Its Coagulation Performance (적니를 이용한 무기응집제의 개발 및 응집성능 평가)

  • Lee, Jae-Rok;Hwang, In-Gook;Bae, Jae-Heum
    • Clean Technology
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    • v.8 no.2
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    • pp.85-92
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    • 2002
  • Red mud is generated as a by-product during the production of aluminum hydroxide from bauxite ore. In this study the red mud coagulants were prepared by reacting 100 ml of 5 M $H_2SO_4$ solution with 10g of red mud at $85^{\circ}C$ or by reacting 100ml of 9M HCl solution with 10g of red mud at $25^{\circ}C$. The prepared red mud coagulants were tested for their coagulation performance of pollutants in the municipal and industrial wastewater. In addition, the coagulation performance was compared with that of a commercially available coagulant ($FeCl_3$). As a result, the red mud coagulants were found to have a good removal efficiency of pollutants in the municipal wastewater (turbidity, phosphate phosphorus) and in the plating wastewater (turbidity, $Pb^{2+}$, $Cd^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Cr^{3+}$). In the experiment to remove COD in the petrochemical wastewater, the COD removal efficiency by the red mud coagulants was a little poor, but it was better than that by $FeCl_3$.

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Determination of Set Point of Streaming Current for Optimum Coagulation (최적 응집을 위한 Streaming Current의 기준값 설정에 관한 연구)

  • Yu, Myong-Jin;Jang, Mi-Jeong;Park, Gui-Su
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.1
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    • pp.34-41
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    • 2006
  • The objectives of this study were to investigate the affecting factors on streaming current(SC) and to evaluate set point(SP). For the study, a pilot scale apparatus with a capacity of 12 L/min was operated at Guui water intake of Seoul. SC was monitored with varying poly aluminium chlorides(PACs) dose and water quality parameters like conductivity, turbidity, temperature, and pH. The removal efficiencies were evaluated in terms of turbidity and dissolved organic carbon(DOC) with varying coagulation conditions. The effects of affecting factors on SC and SP were also estimated. According to the result observed from the variation of SC with water quality parameters during the experimental period, tendencies of SC and conductivity were very similar, and SC and conductivity had a strong linear relation. At the optimum condition of coagulation, SP decreased as the rainy season changed to the dry season, during the experimental period. Especially, in condition of low turbidity, conductivity had relatively more effect on SC than turbidity. As conductivity increased, SP decreased and coagulant dose per unit increase of SC gradually increased. In view of the results so far obtained, it may be possible to determine the SP range considering the real time variation of water quality, especially conductivity.

A feasibility of coagulation as post-treatment of the anaerobic fluidized bed reactor (AFBR) treating domestic wastewater (도시하수 처리 혐기성 유동상 반응조의 후속공정으로서 화학응집의 가능성 평가)

  • Yang, Seung Yong;Bae, Jae Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.28 no.6
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    • pp.623-634
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    • 2014
  • This study examined a feasibility of coagulation as post-treatment to remove sulfide and phosphorus for the effluent of anaerobic fluidized bed reactor (AFBR) treating domestic wastewater. Removal efficiencies of sulfide, phosphorus and COD by coagulation were not affected by pH in the range of 5.9 to 7.2. Alkalinity requirement could be estimated by the amount of $Fe^{3+}$ to form $Fe(OH)_{3(S)}$ and to remove sulfide and phosphorus. At coagulant aid dosage of 2 mg/L, anionic polymer showed best results regarding size and settleability of flocs. Sulfide removal for the AFBR effluent at the $Fe^{3+}/S^{2-}$ ratio of 0.64, close to the theoretical value of 0.67 found with a synthetic wastewater, was only 75.2%. One of the reasons for this high $Fe^{3+}/S^{2-}$ ratio requirement is that the AFBR effluent contains sulfide, phosphorus, hydroxide and bicarbonate which can react with $Fe^{3+}$ competitively. Concentrations of sulfide and phosphorous reduced to below 0.1 and 0.5 mg/L, respectively, at the $Fe^{3+}/S^{2-}$ ratio of 2.0. Average effluent COD of 80 mg/L, mostly soluble COD, was obtained at the dosage 50 mg $Fe^{3+}/L$ ($Fe^{3+}/S^{2-}$ ratio of 2.0) with corresponding COD removal of 55%. For better removal of COD, soluble COD removal at the AFBR should be enhanced. Coagulation with $Fe^{3+}$ removed sulfide, phosphorus and COD simultaneously in the AFBR effluent, and thus could be an alternative process for the conventional wastewater treatment processes where relatively high quality effluent is not required.