• Applied Biological Chemistry
• /
• v.46 no.4
• /
• pp.291-298
• /
• 2003

A bacterial strain producing a high level of an extracellular phytase was isolated from livestock waste water, identified as a strain of Pseudomonas fragi and designated as Pseudomonas fragi Y9451. Under the phytase production medium, the activity of phytase reached the highest level after 120 hours of incubation. On the effect of carbon sources on the phytase production, the most favorable carbon source for phytase production was fructose. As for the effect of nitrogen sources, high levels of phytase activity were detected in the medium containing nutrient broth as the nitrogen source. Free $PO_4^{3-}$ inhibited phytase production with increasing concentration of $KE_2PO_4$ and phytate in the media. The addition of $CaCl_2$ and $MgSO_4$ also resulted in the inhibition of phytase production. To investigate the effect of aeration on the phytase production, different volumes of culture broth in Erlenmeyer flasks were incubated in rotary shaker at the speed of 200 rpm. As a result, a high level of phytase activity was detected at small volume of culture broth as compared to larger volume because of its more aerobic condition.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.1
• /
• pp.25-33
• /
• 2018

Renewable energy has been of interests in the area of modern alternative fuels. Biogas is produced in waste landfill sites through anaerobic digestion processes, including hydrolysis, acidogenesis, organic acid fermentation (acetogenesis), and methane fermentation (methanogenesis). High contents of fine dust and moisture limited its utilization for direct combustion, town gas and vehicle fuel. Thus, this study proposed a new design for a cooling device using a centrifugal cyclone for simultaneous removal of fine dust and moisture as a pretreatment in the purification processes. A heat exchanger and an ID fan, which are installed inside and outside of the cyclone, in order to cool the humid gas below the freezing point and form a foggy mist. Such an atmosphere enhanced to capture fine dust as recirculating the cold mist flow. The water removal rate was 80.8% at a relative humidity of 95%, and the particle removal efficiency was 98.3% for $2.5{\mu}m$. Simultaneous removal efficiency was 70.8% and 99.6% for particle and moisture respectively.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.1
• /
• pp.94-101
• /
• 2011

Squid (Todarodes pacificus) is processed as dried or seasoned-dried products and its catch gradually increased from 270,298 M/T in 2005 to 367,940 M/T in 2008 in Korea. Squid processing by-product (viscera) was usually discarded as a waste resulting in environmental problem. In order to utilize squid viscera for more value-added products, a natural squid seasoning was developed by fermenting with Aspergillus oryzae koji. Squid viscera at 5, 10 and 15% salt concentrations with fixed levels of 5% koji and 30% water was fermented at room temperature. The quality properties of squid fermented products such as amino-N, TMA, VBN, total viable cell count, pH and total acidity were determined at different fermentation periods. The contents of amino-N, TMA, and VBN of squid seasoning at 5% salt concentration fermented for 14 days were the highest. Based on amino-N content, squid viscera at 5% koji fermented for 14 days was selected for further assays: the content of moisture, crude protein, crude lipid, crude ash, and carbohydrate were 5.98, 35.19, 33.08, 11.30, and 14.45%, respectively. The content of glutamate, alanine, leusine and lysine were 7.06, 12.34, 9.90 and 10.22%, respectively. The $IC_{50}$ values of DPPH scavenging and $\beta$-glucuronidase inhibitory activity were 12.89 and 12.58 mg/mL, respectively. A natural squid seasoning was manufactured by mixing fermented squid viscera and an ingredient. Based on the results of sensory evaluation, the fermented squid viscera seasoning was almost equal to other natural complex seasonings such as anchovy, cow meat, and fisheries seasoning.

• Korean Chemical Engineering Research
• /
• v.43 no.1
• /
• pp.60-65
• /
• 2005

The electrosorption of U(VI) from waste water was carried out by using activated carbon fiber(ACF) felt electrode in a continuous electrosorption cell. In order to enhance the electrosorption capacity at lower potential, ACF felt was chemically modified in acidic, basic and neutral solution. Pore structure and functional groups of chemically modified ACF were examined, and the effect of treatment conditions was studied for the adsorption of U(VI). Specific surface area of all ACFs decreases by this treatment. The amount of acidic functional groups decreases with basic and neutral salt treatment, while the amount increases a lot with acidic treatment. The electrosorption capacity of U(VI) decreases on using the acid treated electrode due to the shielding effect of acidic functional groups. Base treated electrode enhances the capacity due to the reduction of acidic functional groups. The electrosorption amount of U(VI) on the base treated electrode at -0.3 V corresponds to that of ACF electrode at -0.9 V. Such a good adsorption capacity was not only due to the reduction of shielding effect but also the increase of $OH^-$ in the electric double layer on ACF surface by the application of negative potential.

• Journal of the Korean Chemical Society
• /
• v.50 no.1
• /
• pp.23-31
• /
• 2006

carbon modified methods were used for the preconcentration and determination of copper in some real samples using the flame atomic absorption spectrometry. The copper ions was adsorbed quantitatively on the activated carbon due to their complexation with 4- amino-2, 3-dimethyl-1-phenyl-3-pyrazoline (ADMPP) or 4-(4- methoxybenzylidenimin) thiophenole (MBITP). The adsorbed copper on solid phase was eluted quantitatively using small amount of nitric acid. The influence of important parameters including pH, amount of carrier, flow rate, amount of activated carbon and type and concentration of eluting agent for obtaining maximum recovery were investigated. The methods based on ADMPP and MBITP at optimum conditions is linear over concentration range of 0.05-1.5 g mL-1 and 0.05-1.2 g mL-1 of copper with correlation coefficient of 0.9997 and 0.9994 and both detection limit of 1.4 ng mL-1, respectively. The preconcentration leads to enrichment factor of 310 and break through volume of 1550 mL for both ligands. The method has a good tolerance limit of interfering ion and a selectivity that has been successfully applied for the determination of copper content in real sample such as tap, spring, river and waste water.

• Resources Recycling
• /
• v.14 no.6 s.68
• /
• pp.3-9
• /
• 2005

In this study, the separation and recovery of cerium hydroxide was investigated from the wasted cerium polishing powders. Waste cerium polishing powder contains $64.5\;wt\%$ of rare earth oxide and the content of cerium oxide is $36.5\;wt\%$. Since cerium oxide, $56.3\%$ of rare earths, is the most stable state in rare earth, the dissolution of cerium oxide in acid solution is not easy. Therefore the process of rare earth oxide by sulfation and water leaching was examined in order to increase the recovery of rare earth. Rare earth elements were recovered in the form of $\Re{\cdot}Na(SO_{4})_{2}$ by the addition of sodium sulfate to leached solution. The slurry of rare earth hydroxide was prepared by the addition of $\Re{\cdot}Na(SO_{4})_{2}$ to sodium hydroxide solution. After the oxidation of cerous hydroxide($CE(OH)_{3}$) to ceric hydroxide($CE(OH)_{3}$) by aeration, ceric hydroxide was separated from other rare earth hydroxides by controlling the acidity of solution.

• Microbiology and Biotechnology Letters
• /
• v.47 no.1
• /
• pp.64-68
• /
• 2019

To utilize soybean leaf, which is a waste product in soybean production, as a value-added food material, this study aimed to investgate the extraction efficiency of isoflavone from soybean leaf and to characterize physicochemical properties of the extract. Maximum isoflavone content of $59.74{\pm}4.54mg/l$ was obtained from soybean leaf extracted at $90^{\circ}C$ for 12 h. DPPH (1,1-diphenyl-2-pricylhydrazyl) radical-scavenging activity and total polyphenol contents reached maximum levels of $67.26{\pm}3.64%$ and $1,688.68{\pm}97.37{\mu}g/ml$ chlorogenic acid equivalent, respectively. Based on the contents of isoflavone and total polyphenol, and DPPH radical-scavenging activity, optimum extraction conditions for soybean leaf using water as solvent were $90^{\circ}C$ and 12 h.

• Korean Journal of Environmental Agriculture
• /
• v.24 no.3
• /
• pp.222-231
• /
• 2005

Most of the tailings have been left without any management in abandoned metalliferous mines and have become the main source of heavy metal contamination of agricultural soils and crops in the these areas. To compare of environmental assessment of heavy metals in tailings derived from various 25-metalliferous mines in Korea, 3 different analysis methods such as water soluble, 0.1 M-HCl extractable, and total acid digestion method (aqua regia) were used. The chemical composition of water soluble in mine tailing were in the order ${SO_4}^{2-}>Ca^{2+}>Mn^{2+},\;Na^+,\;Al^{3+}>Mg^{2+},\;Fe^{3+}>Cl^-$. Specially, pH, EC, ${SO_4}^{2-},\;and\;Ca^{2+}$ concentrations in tailing varied considerably among the different mines. The average total concentrations of Cd, Cu, Pb, Zn, and As in tailing were 31.8, 708, 4,961, 2,275 and 3,235 mg/kg, respectively. Specially, the contents of Cd, Zn and As were higher than those of countermeasure values for soil contamination (Cd : 4, Zn : 700 and As : 15 mg/kg in soil) by Soil Environmental Conservation Act in Korea. The rates of water soluble heavy metals to total contents in tailings were in the order Cd > Zn > Cu > Pb > As. The rates of 0.1M-HCl extractable Cd, Cu, Pb, Zn, and As (1M-HCl) to total content were 17.4, 10.2, 6.5, 6.8 and 11.4% respectively. The enrichment factor of heavy metals in tailings were in the order As > Pb > Cd > Cu > Zn. The pollution index in tailing Au-Ag mine tailing were higher than those of other mine tailing. As a results of enrichment factor and pollution index for heavy metal contaminations in mine tailing of metalliferous mines, the main contaminants are mine waste materials including tailings.

• Journal of Soil and Groundwater Environment
• /
• v.8 no.2
• /
• pp.62-69
• /
• 2003

The aim of research is the evaluation of the $Cr^{6+}$ emission features of the liquid injection through emission experiments in varying conditions, based on a field-mixing ratio. The results showed that the content of $Cr^{6+}$ content in cement measured had an Ordinary Potland Cement (OPC) of 25.3 mg/kg, which constitute the largest portion among the other materials. Likewise, the emission experiment of homo-gel and sand-gel generally satisfied the standard of KSLT (Korea Standard Leaching Test) in waste of 1.5 mg/L, but in case of the standard of KSLT in soil the emission of OPC $Cr^{6+}$ of 4.85 mg/kg. These conditions is a little exceeded the criteria in the ‘Ga’ area in terms of Korea Soil Environmental Preservation Law. In addition, results generated by the mock-up injection facilities revealed that $Cr^{6+}$ emission increased as Water/Cement and injection pressure increased. At injection pressure higher than 4 kg/㎤, $Cr^{6+}$ emission exceeded the water preservation standard of 0.5 mg/L. Similarly, a pattern experiment of C $r^{6+}$ emission according to pH was conducted, in order to evaluate the $Cr^{6+}$ emission features of grout materials in leachate below pH 5 such as pH 4 acid rain or landfill. Results show that $Cr^{6+}$ emission dramatically increased in high acidic or basic state. It indicates that $Cr^{6+}$ emission will probably increase in an environment where grout materials are injected. On the other hand, concentration of leachate was determined in areas where grout materials are used. The results show that the concentration of emission in an ultra purity condition does not manifest intensity, and is affected in the OPC>MC>SC order. It means that the pollutants or $Cr^{6+}$ emission increases with decreasing concentration. As such, $Cr^{6+}$ emission will probably exceed the countermeasure criteria according to the types of gout materials. Similarly, high pressure or injection will cause increased $Cr^{6+}$ emission. Therefore, the selection of materials or mixing ratio should be considered in general as well as according to specific industries, based on the strength and pH of $Cr^{6+}$ emission.