• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.12
• /
• pp.42-49
• /
• 2017

The application of electro-coagulation has been attempted to control the membrane fouling problem in a MBR (Membrane Bio-Reactor). This study examined the effects of the operating parameters (current density and contact time) of the electro-coagulation process on the change in the characteristics of activated sludge. The current density changed from 2.5 to 12, $24A/m^2$, and the contact time was varied from 0 to 2 and 6 hr, respectively. At a current density of $24A/m^2$ and 6 hr of operation, the MLSS changed from 6,800 to 7,000 mg/L (3% increase), but the MLVSS did not increase significantly. After 6 hr of operation, the soluble COD decreased from 71 to 37 mg/L under the $24A/m^2$ condition, from 113 to 67 mg/L under the $12A/m^2$ condition, and from 84 to 80 mg/L under the $2.5A/m^2$ condition. On the other hand, soluble-TN and -TP concentration showed slight changes. The soluble-EPS and Bound-EPS concentration decreased slightly with increasing current density. The membrane filtration performance of activated sludge before and after electro-coagulation was compared. The filtration resistances after electro-coagulation decreased from 6 to 61 %, particularly as the current density and contact time were increased. This indicates that electro-coagulation can be used to control membrane fouling in the MBR process.

• Korean Journal of Food Science and Technology
• /
• v.9 no.2
• /
• pp.123-130
• /
• 1977

A laboratory study was made to develop a simple and economic model method for the systematic determination of functional properties of 'Soy Protein Isolates (SPI)' prepared from defatted soybean meal. These are required to evaluate and to predict how SPI may behave in specific systems and such proteins can be used to simulate or replace conventional proteins. Data concerning the effects of pH, salt concentration, temperature, and protein concentration on the functional properties which include solubility, heat denaturation, gel forming capacity, emulsifying capacity, and foaming capacity are presented. The results are as follows: 1) The yield of SPI from defatted soybean meal increased to 83.9 % as the soybean meal was extracted with 0.02 N NaOH. 2) The suitable viscocity of a dope solution for spinning fiber was found to be 60 Poises by using syringe needle (0.3 mm) with 15 % SPI in 0.6 % NaOH. 3) Heat caused thickening and gelation in concentration of 8 % with a temperature threshold of $70^{\circ}C$. At $8{\sim}12\;%$ protein concentration, gel was formed within $10{\sim}30\;min$ at $70{\sim}100\;^{\circ}C$. It was, however, disrupted rapidly at $125\;^{\circ}C$ of overheat treatment. The gel was firm, resilient and self-supporting at protein concentration of 14 % and less susceptible to disruption of overheating. 4) The emulsifying capacity (EC) of SPI was correlated positively to the solubility of protein at ${\mu}=0$. At pH of the isoelectric point of SPI (pH 4.6), EC increased as concentration of sodium chloride increased. Using model system$(mixing\;speed:\;12,000\;r.p.m.,\;oil\;addition\;rate:\;0.9\;ml/sec,\;and\;temperature\;:\;20{\pm}1\;^{\circ}C)$, the maximum EC of SPI was found to be 47.2 ml of oil/100 mg protein, at the condition of pH 8.7 and ${\mu}=0.6$. The milk casein had greater EC than SPI at lower ionic strength while the EC of SPI was the same as milk casein at higher ionic strength. 5) The shaking test was used in determining the foam-ability of proteins. Progressively increasing SPI concentration up to 5 % indicated that the maximum protein concentration for foaming capacity was 2 %. Sucrose reduced foam expansion slightly but enhanced foam stability. The results of comparing milk casein and egg albumin were that foaming properties of SPI were the same as egg albumin, and better than milk casein, particularly in foam stability.

• Journal of Bio-Environment Control
• /
• v.28 no.4
• /
• pp.342-351
• /
• 2019

The optimum N concentrations incorporated as pre-planting nutrient charge fertilizer were determined for seedling raising using cylindrical paper pots. A root medium was formulated by blending of peat moss (particles smaller than 2.84 mm were 80-90%) and perlite (1 to 3 mm) with the ratio of 7:3 (v/v). The treatment N concentrations incorporated during the root medium formulation were adjusted to 0, 150, 250, 500, and $750mg{\cdot}L^{-1}$ and the concentrations of essential nutrients except N were equal in all treatments. After making of paper pots and putting into the 40-cell tray, the seeds of Chinese cabbage ('Chunmyeong Bom Baechu') and pak-choi ('Hanog cheonggyeongchae') were sown. During the raising of seedlings, weekly analysis of medium pH, EC and concentrations of inorganic elements were conducted. After 21 and 20 days after seed sowing of Chinese cabbage and pak-choi, the growth of the above-ground parts were measured and contents of inorganic elements in the plant tissues were analyzed. During the growing period, pH of the root media rose gradually and the EC decreased rapidly at week 3. The pH of root media at harvest was in the range of 5.3 to 5.9 in Chinese cabbage and 4.93 to 5.39 in pak-choi. Growth of the aboveground parts in terms of fresh and dry weight in both the plants were the highest in the $250mg{\cdot}L^{-1}$ N treatment and the lowest in the control treatment. The elevation of pre-planting N concentrations in root medium resulted in the increase of tissue N content and decrease of P, Ca, and Mg contents. The regression equation derived from the influence of varied pre-planting N concentrations on dry weight of above-ground tissue were $y=-0.0036x^2+0.0021x+0.0635$ ($R^2=0.9826$) in Chinese cabbage and $y=-0.16x^2+0.0009x+0.032$ ($R^2=0.991$) in pak-choi. When the low critical concentration of pre-plant N is taken at the point where dry weight of above-ground tissue is 10% less than maximum (0.40 g in Chinese cabbage and 0.16 g in pak-choi), those point are 0.36 g and 0.144 g per plant in Chinese cabbage and pak-choi, respectively. The lower critical N concentrations of root media calculated from the regression equations are $196mg{\cdot}L^{-1}$ for Chinese cabbage and $187mg{\cdot}L^{-1}$ for pak-choi. These results indicate that optimum pre-plant N concentrations for seedling raising using paper pots are in the range of 196 to $250mg{\cdot}L^{-1}$ for Chinese cabbage and 187 to $250mg{\cdot}L^{-1}$ for pak-choi.

• Korean Journal of Environmental Agriculture
• /
• v.19 no.2
• /
• pp.134-141
• /
• 2000

For electrochemical treatment of industrial wastewater, the effects of voltage, distance between electrodes, initial pH and NaCl concentrations on removal of pollutants were investigated in a batch electrolysis system. Temperature and pH in electrochemical reactor increased with increase in supplied voltage, but no significant change in EC was found. Removal of COD, turbidity, T-N and T-P were also enhanced with increase in the voltage. On the conditions of short distances between electrodes and long electrochemical reaction times, it was found that COD and T-N were very effectively removed in the system. Regardless of the distances, more than 80% of turbidity and T-P were removed at the beginning of reaction. When initial pH of the wastewater was about 7, the highest efficiency of COD removal was found in the system. On the other hand, removal efficiency of turbidity was unlikely affected by initial pH of the wastewater. T-N removal was increased with increase in initial pH. T-P was successfully removed in the pH range of 5 to 9 with varying removal efficiency of 79 to 96% after 2 minutes of electrochemical reaction time. Addition of NaCl into the electrochemical reactor increased removal efficiency of electrochemical treatment. The highest removal efficiency of COD and T-P, turbidity and T-N was obtained at NaCl concentrations of 500mg/L, 1,000 mg/L and 500mg/L, respectively.

• Journal of Mushroom
• /
• v.15 no.4
• /
• pp.183-189
• /
• 2017

This study investigated the synergistic effect of single inoculation and co-inoculation of phosphate-solubilizing bacteria (PSB) Burkholderia metallica JH-7 and Burkholderia contaminans JH-15. Phosphate-solubilizing abilities of these strains were assessed by measuring phosphorus content in culture media that were singly inoculated or co-inoculated with these strains for 7 days. B. metallica JH-7 was found to release the highest content of soluble phosphorus ($140.80{\mu}g\;mL^{-1}$ ) into the medium, followed by single inoculation of B. contaminans JH-15 ($135.95{\mu}g\;mL^{-1}$ ) and co-inoculation of two strains ($134.84{\mu}g\;mL^{-1}$ ). The highest pH reduction, organic acid production, and glucose consumption were observed in the medium inoculated with B. metallica JH-7 alone compared with that in the medium co-inoculated with both the strains. Results of a plant growth promotion bioassay showed 17.4% and 7.48% higher leaf and root growth, respectively, in romaine lettuce inoculated with B. metallica JH-7 alone than in romaine lettuce inoculated with a control strain. However, no significant difference was observed between single inoculation and co-inoculation of these strains with respect to phosphorus release and plant growth. Although the results of the present study did not show the synergistic effect of phosphate solubilization by the PSB strains examined, these results indicate that treatment with PSB exerts a beneficial effect on crop growth.