• Journal of the Korean Geotechnical Society
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• v.39 no.8
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• pp.7-16
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• 2023

This study aimed to evaluate the sulfate removal capacity of the enzyme-induced carbonate precipitation (EICP) technique through the chemical precipitation of sulfate with calcium ions. The optimal EICP recipe was obtained to retain the excess calcium cations in the solution for the generation of a sufficient amount of calcium carbonate (CaCO₃) mineral. The effect of gypsum precipitation on the EICP-treated sand specimen was investigated by measuring the shear wave velocity and by visual inspection via scanning electron microscopy. The EICP solution using soybean crude urease, as an alternative to laboratory-grade purified urease, exhibited a lower sulfate removal efficiency at a similar CaCO₃ production rate compared with the optimal EICP recipe because of soybean impurities.

• Resources Recycling
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• v.16 no.4
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• pp.27-32
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• 2007

The characteristics of fluorine removal from wastewater have been investigated by precipitation method using calcium as a precipitant for the purpose of the reuse of treated wastewater. In the conditions of 10 mM of the initial concentration of fluorine and pH 4, the precipitation of fluorine was rapidly progressed within a few minutes after the precipitant was added and the precipitation of fluorine was observed to follow a second order reaction. Also, as the addition of precipitant was increased, the reaction rate constant of fluorine precipitation was found to rise. Postulating that the maximum fluorine removal was attained at pH 4, about 70% of fluorine was precipitated compared with the maximum removal when 10 times of equivalent amount of calcium was employed at pH 2 and the fluorine removal was about 96% compared with its maximum value at pH 3 under the same addition of precipitant. The fluorine precipitation reaction was found to be endothermic and the coexistence of $SiF_6{^{2-}}$ with fluorine resulted in its less removal. Finally, the isoelectric point of the precipitate was examined to be ca. pH 5.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1097-1103
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• 2001

TiO$_2$anchored on a porous clay ceramic support (PCS) for use in lightweight photocatalyst were synthesized by the dropping precipitant method. A PCS of macro and micro pore size of around several mm~${\mu}{\textrm}{m}$ in diameter were prepared by the rapid heat treatment at, 1,15$0^{\circ}C$ for 10 min from low grade of clay. The change in pH of reaction solution due to the different addition rate of NH$_4$HCO$_3$as a precipitant, the reaction temperature and the concentration of TiCl$_4$had a pronounced effect on the nature of precipitated TiO$_2$particles on the surface of a PCS and the crystal structure of precipitated TiO$_2$particles. At an addition rate of 0.8 ml/min of NH$_4$HCO$_3$and pH=6 of reaction solution, homogeneous precipitation of TiO$_2$particles on a PCS was achieved. TiO$_2$particles with anatase phase was precipitated on the surface of a PCS at the low concentration of TiCl$_4$, the high addition rate of NH$_4$HCO$_3$and the high reaction temperature.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.1-8
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• 2013

A pilot scale coagulation system, which has a function of physicochemical treatment, was developed to treat Combined sewer overflows(CSOs). This coagulation system requires evaluation of optimum design factors whether it has reflected those of lab scale system, moreover, the pilot scale system can be evaluated differently according to the characteristics of influent CSOs even though it has reflected lab scale's design factors. We conducted an experiment using lab scale system that could treat $1m^3$ of CSOs in a day, and also pilot-scale system with $100m^3/day$ CSOs flowed into the Cheongju sewage treatment plant. Therefore the aim of this study is to evaluate a hydraulic similarity between the design factors of pilot scale and those of lab scale coagulation system, and to evaluate feasibility of the coagulation system for the CSOs treatment with optimum operation conditions. From the result of pilot-test, we drew the optimum operation factors of in line mixer and flocculator having similarities with those of lab scale system as well as the optimum coagulant dose. Finally we confirmed that the coagulation system has feasibility to treat the CSOs with high removal efficiency.

• Journal of Adhesion and Interface
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• v.2 no.4
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• pp.10-23
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• 2001

In order to increase the lower values of % grafting and monomer conversion in the emulsion graft polymerization of methylmethacrylate(MMA) onto sodium alginate (SA; a polymer electrolyte) with alginic acid-g-PMMA, the graft polymerization with water soluble (methanol and acetone) and insoluble solvents was carried out using a varity of solvent amounts and agitating rates. And some physical properties of the graft polymer were also investigated. In the polymerizations with water insoluble solvent, there were pronounced improvements in both % grafting and MMA conversion by the promotion of MMA diffusion from the core to the SA adsorpted on the outer layer of particle and that of MMA complex formation with SA. And the effect was larger for the solvents (cyclohexane, decalin) which do not dissolve PMMA. On the other hand, in the polymerization with water soluble solvent, there was an significant increase in MMA conversion and a considerable increase in the % grafting by the destruction of electrical double layer around the SA chains, abstracting the hydrated water in the layer and the effect was more potential in the case of methanol which is a precipitant of PMMA.

• Resources Recycling
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• v.2 no.2
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• pp.1-8
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• 1993

This study was carried out in order to define the effective collectors and the opitimum conditions for the removal of iron ion in waste water by flotation method. The results obtained in this study are summarized as follows. Fe(II) and Fe(III) were removed effectively at pH7 and 6 respectively by using sodium lauryl sulfate, an anionic collector. The anionic collector, aeropromotor 845, removed both Fe(II) and Fe(III) effectively in pH ranges of from 5 to 9. The cationic collector, trimetyl dodecyl ammonium chloride, removed both Fe(II) and Fe(III) effectively in pH ranges from 10 to 11 and from 4 to 10, respectively. Therefore, Fe(II) and Fe(III) could be effectively removed by forming the iron hydroxide precipitates by simple pH adjustment of the solutions above precipitation point of ferrous and ferric ion by flotation method. Then, the effective pH regulator and collector were NaOH and $Na_2CO_3$,aeropromotor 845 and trimetyl dodecyl ammonium chloride, respectively.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.73-74
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• 2002

수세공정을 거치지 않고 어육 단백질의 용해도 특성을 이용하여 pH 2.5 부근과 pH 10.5 부근에서 어육 단백질을 가용화 시킨 후 최소 용해도를 보이는 pH 5.2 부근에서 침전시켜 회수하고, pH를 7.0으로 조절한 후 법동 변성 방지제를 첨가하여 수리미를 조제하는 공정이 개발(Choi and Park, 2000; Yongsawatdigul and Park, 2001)됨에 따라 소실되는 근형질 단백질을 회수함으로서 수리미 수율을 최대로 증가시킬 수 있게 되었다(Kim et al., 2001, 2002; Choi et al., 2002). (중략)

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.394-395
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• 2009

• Journal of the korean veterinary medical association
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• v.6 no.2
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• pp.39-42
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• 1962

• Environmental engineer
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• s.123
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• pp.42-43
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• 1996

중금속을 함유하는 폐수는 일반적으로 단일성분의 원소로 되어 있지 않고 여러 종류의 금속성분이나 유기물이 혼합된 상태로 발생되기 때문에 화학적인 중화나 분해로서 처리하기 곤란하므로 흡착성이 풍부한 광물질의 무기화학성분을 추출하여 흡착, 침전, 분리하는 방법을 이용할 수 있다. Aqua # 219는 폐수 처리용 약품으로 현재 사용하고 있는 설비를 일부 개조하거나 또는 기존설비를 그대로 사용하여 저렴한 가격으로 처리할 수 있는 중금속 흡착제이다.