• Resources Recycling
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• v.24 no.5
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• pp.33-39
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• 2015

A basic study was conducted to effectively recover nitric acid from a waste solder stripper by diffusion dialysis using anion exchange membranes. The effects of flow rate, flux ratio, nitrate concentration, and metallic ion types and concentration on the recovery percentage of nitric acid were investigated. The recovery percentage of nitric acid was decreased with the increase of flow velocity. But the recovery percentage of nitric acid was increased as the increase of flux ratio(W/F) and showing a recovery percentage of nitric acid of about 99% at a flux ratio of 1.5 or more. As the increase of nitric acid concentration in feed solution, the recovery percentage of nitric acid was increased up to 3.0M, but in case of greater than 3.0M, the recovery percentage gradually was decreased. Leakage percentage of metallic ions through the membrane were in the order of Pb, Na and Cu but Fe and Sn did not leakaged. As a result of diffusion dialysis using real waste solder stripper at a flow rate of $0.9L/hr-m^2$, W/F = 1.3, a recovery percentage of nitric acid of approximately 94% was gained.

• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.2
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• pp.25-34
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• 1999

The effects of copper on the anaerobic degradation of propionate were studied using anaerobic batch reactors. The apparent inhibitory effects of copper on the anaerobic degradation of propionate could be observed from behaviors of intermediates, ultimate methane yield(UMY) and specific methanogenic activity(SMA) There was little inhibition at the concentration of $2.5mg\;Cu^{2+}/L$. Beyond this concentration, the inhibitory effects increased with increasing dose of coppers. The 50% inhibition of UMY and SMA occurred at copper dosage of 33.8 and $24.1mg\;Cu^{2+}/gVSS$, respectively. The inhibitory effect based on the UMY was gradually reduced with the operation time dueprobably to the acclimation of microorganisms and/or binding of the added copper by ligands(and possibly ion exchange sites)contained on the cell membrane and extracellular polymer matrix whereas it based on the SMA might exclude the this phenomena. Therefore, the methodology for interpretation of inhibition data based on the SMA was more accurated than the UMY. There was no inhibitory effect in batch reactors supplemented with sulfate due to an antagonistic action of the sulfate reducing bacteria. Propionate degradation was initially retarded for copper inhibited samples but it gradually degraded afterward. Based on the mass removal considering take into account the propionate to acetate conversion, propionate degradation may appeal more affected than acetate. This result revealed that the hydrogenotrophic methanogens were the most affected by copper.

• KSBB Journal
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• v.25 no.5
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• pp.429-436
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• 2010

Keratinase is widely used in certain industrial applications. The present study sought to improve the culture conditions of Bacillus subtilis SMMJ-2 to facilitate mass production of keratinase. Strain SMMJ-2 was irradiated by ultraviolet light and the resulting isolates were tested for keratinase activity. Isolates displaying elevated keratinase activity were selected and used to determine the optimum temperature (24, 30, 37, 45, $55^{\circ}C$) for bacterial keratinase production during a 4 day incubation period. The highest enzyme activity (55 units/mL/min), from a Bacillus subtilis SMMJ-2 mutant (mutant No. 2) was demonstrated following incubation at $30^{\circ}C$. The effects of carbon and nitrogen sources on keratinase production were confirmed by measuring the enzyme activity from the culture broth of the mutant strain cultured in various media containing different carbon source and nitrogen sources during a 4 day period. The optimal medium composition for producing keratinase consisted of 1% glucose, 0.7% $K_2HPO_4$, 0.2% $K_2HPO_4$, and 1.2% soybean meal. Optimal initial pH and temperature for producing keratinase were 7.0 and $30^{\circ}C$, respectively. Keratinases produced by B. subtilis SMMJ-2 and the mutant No. 2 were purified from the culture broth which used soybean meal as a nitrogen source. Membrane ultrafiltration, DEAE-sephacel ion exchange and Sephadex G-100 gel chromatography were used to purify the enzymes. The purified keratinases from both B. subtilis SMMJ-2 and the mutant No. 2 showed single bands and their molecular weights were estimated as 28 kDa and 42 kDa, respectively on SDS-polyacrylamide gel electrophoresis.

• KSBB Journal
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• v.15 no.2
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• pp.167-173
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• 2000

For selective elimination of salt from boiled oyster extract (BOE), electrodialyzer was used and the desalination conditions of B BOE were investigated. The ion-exchange membrane with a molecular weight cut off 100 Da was used for desalting of B BOE. The desalination efficiency at pH 4.0 was 13% higher than that at pH 9.0 when BOE was desalted for 90min. The e electrodialysis pro$\infty$ss could remove above 90% of the initial salt content when 5% BOE was desalted at pH 5.62 for 1 100min. The initial volume and concentration of permeation solution did not have significant effects on desalination time and r ratio. The important factors for the desalination of BOE were found to be pH and concentration of BOE. The results obtained prove that electrodialysis is a practical solution to the problem of selective elimination of salt from BOE.