• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.2
• /
• pp.174-180
• /
• 2004

This study is a fundamental research to test the applicability of abandoned eggshell as seed material for crystallization reaction. Eggshell was calcinated at $850^{\circ}C$ and ground to lesser than 0.42mm. The calcination characteristics of eggshell were examined by X-ray diffraction (XRD). The effect of initial calcium concentration, alkalinity, reaction temperature condition, seed dosage were studied by batch test. For the low concentration sample(P concentration is under 50mg/L), more than 90% of P can be removed. The effect of initial calcium concentration(0~120mg/L) was performed. At the result of the test, more than 50mg/L calcium concentration has high removal efficiency. Alkalinity effect was studied for synthetic solution(100mg/L initial P, 50mg/L calcium, 0.025% seed dosage) with 0~300mg/L bicarbonate alkalinities. For synthetic solution(100mg/L initial P, 50mg/L calcium, 100mg/L bicarbonate alkalinity, 0.025% seed dosage), the phosphorus concentration was examined with $10{\sim}35^{\circ}C$. In addition, calcinated eggshell was injected to swine wastewater to test the applicability to actual wastewater.

• Journal of environmental and Sanitary engineering
• /
• v.17 no.3
• /
• pp.89-98
• /
• 2002

The changes of conventional clarification process and an increase in treatment cost are required to meet increasingly stringent regulations related to the treated water quality. Although many enhanced coagulations have introduced to improve organic matter removal, the results to remove color, nitrogen and phosphorus as well as organic material have not been very efficient yet. The removal of waste matters such as SS, organic matter, color and turbidity contained in dyeing wastewater was carried out by using the combination of calcium hydroxide and magnesium sulfate. The flocculation was investigated as a function of coagulant dose, pH, mixing time, settling time and coagulant addition modes such as the sequential addition of the two coagulants and the simultaneous addition of them. The flocculation by the combination of calcium hydroxide and magnesium sulfate was compared with that by aluminum sulfate. The mechanism of flocculation was investigated as well. About 84% of color in dyeing watewater was removed by flocculation with combination of calcium hydroxide and magnesium sulfate.

• Journal of Acupuncture Research
• /
• v.29 no.2
• /
• pp.89-97
• /
• 2012

Objectives : The purpose of this report is to show that oriental medical treatments, chiefly using Sweet bee venom (SBV) are effective on symptom improvements and calcium removal in the patients diagnosed with calcific tendinitis in supraspinatus. Methods : We applied 0.3~0.6cc of SBV on $LI_{15}$ ($Gyeonu$) at a time and 0.1~0.2cc on each surrounding pressure point. In addition, we treated $Hwangryeonhaedok-tang$ pharmacopuncture on both acupoints of $GB_{21}$ ($Gyeonjeong$) with large intestine tonification of $Sa-Am$. Results : The symptoms improved within 3 weeks in case 1, 4 days in case 2, 5 weeks in case 3. The removal of calcium was detected by radiology at all cases. Conclusions : From the above results, it is considered that the oriental medical therapy including SBV is effective on the removal of calcium.

• Asian Journal of Atmospheric Environment
• /
• v.10 no.4
• /
• pp.190-196
• /
• 2016

The objective of this study is to obtain the optimal conditions to remove hydrogen fluoride (HF) generated from a variety of F-gas treatment processes. First, we selected $Ca(OH)_2$ and $CaCO_3$ as a reactant among the various alkali salts which have a high removal efficiency and a competitive price by forming a calcium fluoride precipitate. Additionally, various factors were investigated to improve the removal efficiency of HF. The conditions such as the settling time, agitating time and intensity, reaction temperature, and pH were considered as main factors. As a result, in the treatment process to remove HF through Ca-based alkali salts, the optimal conditions were a 120 min settling time, 30 min of agitation at 100 rpm, a pH of 4-8, and a reaction temperature of $40^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.6
• /
• pp.715-721
• /
• 2007

Residual calcium concentration is high, in general, at the effluent of the fluoride removal process in the electronics industry manufacturing semiconductor and LCD. To increase the stability of the membrane process incorporated for reuse of wastewater, the residual calcium is required to be pre-removed. Hyperkinetic Vortex Crystallization(HVC) process was installed in the electronics industry manufecturing semi conductor as a pilot scale for accelerating calcification of calcium ion. Compared to the conventional soda ash method, the 31% higher calcium removal efficiency was achieved when HVC was applied at the same sodium carbonate dosage. In order to maintain the economic calcium removal target of 70% preset by manufacturer, the dosing concentration of the soda ash was 530 mg/L based on influent flowrate. The seed concentration in the reactor was one of the critical factors and should be maintained in the range of $800\sim1,200mg$ SS/L to maximize the calcium removal efficiency. The calcite production rate was 0.30 g SS/g $Na_2CO_3$ in the average. The economic HVC passing time of the mixture was in the range of $2\sim5$ times. Relatively, stable calcium concentration was maintained in the range of $30\sim72$ mg/L(average 49 mg/L) although the calcium concentration in the feed was severely fluctuated with $74\sim359$ mg/L(average 173 mg/L). The HVC process was characterized as environment-friendly technology reducing chemical dosage and chemical sludge production and minimizing maintenance cost.

• Restorative Dentistry and Endodontics
• /
• v.42 no.4
• /
• pp.290-300
• /
• 2017

Objectives: This study investigated the removal efficacy and cytotoxicity of a newly developed calcium hydroxide paste (cleaniCal, Maruchi) using N-2-methyl-pyrrolidone (NMP) as a vehicle in comparison with ApexCal (Ivoclar Vivadent) and Calcipex II (Nishika), which use different vehicles such as polyethylene glycol and propylene glycol, respectively. Materials and Methods: Thirty maxillary premolars with oval-shaped canals were divided into 3 groups and the teeth were filled with one of the pastes. After removal of the paste, micro-computed tomographic (${\mu}$-CT) imaging was obtained to assess the volume of residual paste in the root canal of each tooth. The teeth were then split longitudinally and the area of the paste-coated surface was evaluated by stereomicroscopy. The cytotoxicity of each product was assessed using an agar overlay assay. The effect of each vehicle on cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The data were analyzed using one-way analysis of variance and Tukey's tests to detect any significance (p < 0.05). Results: In the ${\mu}$-CT and stereomicroscopic analysis, cleaniCal exhibited less remnants of medicament than ApexCal and Calcipex. cleaniCal showed a higher cytotoxicity than the other pastes in the agar overlay assay. Furthermore, NMP exhibited lower cell viability compared to the other vehicles. Conclusions: cleaniCal showed better removal efficacy compared to the other products. However, clinicians should be aware of the higher cytotoxicity of the NMP-based material and consider its possible adverse effects on periradicular tissue when it is overfilled.

• Restorative Dentistry and Endodontics
• /
• v.40 no.1
• /
• pp.44-49
• /
• 2015

Objectives: This study compared the ability of several techniques to remove calcium hydroxide (CH) from the root canal and determined the influence of CH residues on the accuracy of the electronic apex locator. Materials and Methods: Root canals of 90 human maxillary lateral incisors with confirmed true working length (TWL) were prepared and filled with CH. The teeth were randomly assigned to one of the experimental groups according to the CH removal technique (n = 14): 0.9% saline; 0.9% saline + master apical file (MAF); 17% ethylenediamine tetraacetic acid (EDTA); 17% EDTA + MAF; 5.25% sodium hypochlorite (NaOCl); 5.25% NaOCl + MAF. Six teeth were used as negative control. After CH removal, the electronic working length was measured using Root-ZX (Morita Corp.) and compared with TWL to evaluate Root-ZX accuracy. All specimens were sectioned longitudinally, and the area of remaining CH (CH) and total canal area were measured using imaging software. Results: The EDTA + MAF and NaOCl + MAF groups showed better CH removal than other groups (p < 0.05). Root-ZX reliability to prevent overestimated working length to be > 85% within a tolerance of ${\pm}1.0mm$ (p < 0.05). There was strong negative correlation between amount of CH residues and EAL accuracy (r = -0.800 for ${\pm}0.5mm$; r = -0.940 for ${\pm}1.0mm$). Conclusions: The mechanical instrumentation improves the CH removal of irrigation solutions although none of the techniques removed the dressing completely. Residues of CH medication in root canals affected the accuracy of Root-ZX adversely.

• BMB Reports
• /
• v.33 no.3
• /
• pp.202-207
• /
• 2000

The depletion of intracellular calcium stores by thapsigargin treatment evoked extracellular calcium-dependent membrane currents in Xenopus laevis oocytes. These currents have been compared to those evoked by microinjection of a calcium influx factor (CIF) purified from Jurkat T lymphocytes. The membrane currents elicited by thapsigargin treatment (peak current, $163{\pm}60$ nA) or CIF injection (peak current, $897{\pm}188$ nA) were both dependent on calcium entry, based on their eradication by the removal of extracellular calcium. The currents were, in both cases, attributed primarily to well-characterized $Ca^{2+}-dependent$ $Cl^-$ currents, based on their similar reversal potentials (-24 mV vs. -28 mV) and their inhibition by niflumic acid (a $Cl^-$ channel blocker). Currents induced by either thapsigargin treatment or CIF injection exhibited an identical pattern of inhibitory sensitivity to a panel of lanthanides, suggesting that thapsigargin treatment or CIF injection evoked $Cl^-$ currents by stimulating calcium influx through pharmacologically identical calcium channels. These results indicate that CIF acts on the same calcium entry pathway activated by the depletion of calcium stores and most lanthanides are novel pharmacological tools for the study of calcium entry in Xenopus oocytes.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.7 no.4
• /
• pp.231-233
• /
• 2002

The potential of calcium peroxide to act as an agent for waterblooming control was In-vestigated by examining the growth inhibition of Microcystis aerusinosa. Due to the chemical nature of calcium peroxide, it can remove dissolved phosphate by forming an Insoluble precipitate, generating radicals, coagulant, and oxygen as byproducts as it dissolves in water. The growth of M. aerusinosa was severely inhibited and the chlorophyll-n concentration was drastically decreased in the presence of calcium peroxide. With 200 ppm of calcium peroxide dosage, a chlorophyll-a concentration of 1,700 mg/m$^3$ was lowered to below 10% of its initial concentration after 4 days. One possible explanation for this growth Inhibition is the removal of the available phosphate by calcium peroxide.

• Restorative Dentistry and Endodontics
• /
• v.31 no.3
• /
• pp.186-191
• /
• 2006

This study evaluated the effect of two different calcium hydroxide ($Ca(OH)_2$) paste removal techniques on the apical leakage of canals obturated with gutta percha cones and sealer after removing a $Ca(OH)_2$ dressing using an electrochemical method. Seventy extracted single-rooted teeth were instrumented on with Profile rotary files under NaOCl irrigation. Fifty-eight canals were filled with calcium hydroxide paste, which was then removed using one of the following two techniques. In group A, calcium hydroxide was removed using only NaOCl irrigation, and in group B, the canals were re-prepared with a Profile rotary files-one size larger than the previous instrument and were irrigated with NaOCl. In both groups, the root surfaces were coated twice with nail varnish from CEJ to an area 4 mm away from the apex after canal obturation. Apical leakage was measured using an electrochemical method for 24 days. All the specimens showed leakage that increased markedly in the first three days. There was no significant difference between the two groups (p>0.05). The effect of two calcium hydroxide paste removal techniques on the apical leakage was not different during a short period.