جستجوی مقالات مرتبط با کلیدواژه « RSM-CCD » در نشریات گروه « علوم پایه »

Pigments such as Chlorophyll and Carotenoid are of particular interest due to their antioxidant and therapeutic properties. Spirulina is a great source to commercial pigments production due high pigment percentage and simple extraction processes. The aim of this study was chlorophyll and carotenoid optimization of spirulina biomass by innovative photobioreactor. In this experimental study, by designing and constructing an innovative photobioreactor for the elimination of some defects of commercial open cultures, spirulina combined culture was investigated. Using RSM-CCD method, the effect of circulation cycle factors, control volume, and irradiance intensity on total value of pigments were evaluated. The data were analyzed by SPSS 16, using linear regression. The highest amount of total Chlorophyll (3.63mg/l) was obtained in Test No. 7 with the shortest circulation cycle (2hr) and control volume of 30%. In this situation, total carotenoid was 0.90mg/l and the whole amount of two pigments was maximum. But, the highest amount of total carotenoid (1.59mg/l) was obtained in the least control volume (20%), circulation cycle of 9.5hr, and light intensity of 10500Lux. In order to attain the highest level of chlorophyll, the optimal irradiance intensity to increase the biomass and the short-range circulation cycle to increase content are the top priority. But, to attain the maximum level of carotenoid, long-range circulation cycle to increase biomass and irradiance intensity at high level to increase content is predominate. The importance of the effect of increasing irradiance intensity on the increase of carotenoid content as well as the reduction of the circulation cycle on the increase of chlorophyll content is greater than its negative effect on the dry weight of biomass and results in an increase in the pigmentation.

The increasing development of microalgae applications has led to the concentration of new multidisciplinary studies to facilitate commercial cultivation of these organisms due to cost reduction and productivity enhancement. The aim of this study was the growth and quality optimization of Spirulina biomass by changing the dilution of medium and using the aeration cycle. In this experimental study, the effect of concentration of Zarrouk medium (0 to 100% dilution) and aeration cycle on specific growth rate and dry weight, as well as the content of chlorophyll and carotenoids of Spirulina were investigated, using response surface method, central design. A total duration of 16 hours was aerated in any 24-hour period; the interval time between these aerated periods varied between 1 to 8 hours. The data were analyzed by SPSS 16 software, using multiple regression test. Findings: The highest biomass (0.659mg/ml) was obtained at 80% concentration of culture media and aeration cycle of 2.75 hours and the highest specific growth rate (0.230 daily) was obtained at 60% concentration and aeration cycle of 4.5 hours. The highest aeration cycle (8 hours) resulted in a significant and simultaneous increase in the content of chlorophyll and carotenoids (11.65 and 2.67 mg/g, respectively). The growth and quality optimization of Spirulina biomass can be accomplished by changing the dilution of the medium and using the aeration cycle.

Special properties and various applications of Spirulina species have led to the growing focus of biotechnology to the cost effective cultivation. Open ponds used in the most commercial cultivation have many deficiencies such as risk of contamination, lack of light penetration, inefficient mixing and low productivity. In this study, an innovative reactor was designed and manufactured. By adding a control area, it was possible to control some environmental conditions for a limited amount of open pond volume. The conventional pumping system was replaced by a new elevator system to reduce the damage of to the fragile cells. The baffles structure and aeration from bottom, contributed to better mixing system. The effect of tree factors (Circulation Cycle (Cir. Cyc.), Control Volume (Con.Vol.) and Irradiance Intensity (Irr. Int.) in units of hours, percentage and Lux respectively) on the quantity of biomass (Specific Growth Rate (SGR, day-1) and fifth and seventh day dry weight (g/L)) were evaluated using RSM-CCD. The maximum biomass dry weight (0.915 g/L) was achieved in longest circulation cycle (12 hours), 30% Con. Vol. and 7000 Lux light intensity. The optimal irradiance intensity to achieve the highest biomass was 8700 Lux. According to the results, due to the great influence of Con. Vol. and Cir. Cyc., it is possible to increase the productivity and enhance the culture dry weight by controlling a limited amount of ponds volume (20%), subject to economic considerations. These successful results can provide the context using a control zone for several open ponds to improve the overall efficiency.

Microalgal culture can be a combination of three environmental factors, treatment of wastewaters, production of renewable energy resources for replacement of fossil fuels and reduction of the greenhouse gas emissions. Microalga Spirulina is not just a good candidate forwastewater treatment (due to the ability toremove ofnitrogen andphosphorus), but also it plays a roleinreduction of greenhouse gas emissions because of the consumption of atmospheric CO2. Severalfactorscontributetothegrowth of thisspecies. In this study, the influence oftwo factors, aerationcycle(15 minutes to 12hours) andZarroukmediumconcentration(20-100%), on quantitative(specific growth rateanddry weight) and qualitative indices(chlorophyll andPhycobiliproteinscontent) of this species has been evaluated by usingRSM-CCDmethod. The results indicatedthat increase in frequency ofaerationand the concentration ofthe medium can enhance the specificgrowth rateand also the dry weight. The highestchlorophyll content was obtained in median values of bothfactors. According to phycobiliproteins, the effect of the medium concentration on these pigments is the same as the effects on chlorophyll, but the influence of aerationcycle is completely vice versa. It seems that aeration cycle has an important role on quantitative and qualitative indices of biomass, although it is not well studied yet. This factor can partially offset the negative effects of the culture medium dilution and reduce the costs of total processes.