چكيده به لاتين
In recent years, the use of microalgae as a renewable energy source to be substitute with fossil fuels has become increasingly popular. In addition, microalgae can be used as an effective environmental technology to reduce greenhouse gases. Despite these benefits, industrial production of microalgae is currently not cost-effective due to high process costs. Biofilm cultivation of microalgae is a novel method that can be a solution to reduce process costs. If properly designed, this method can reduce consumption of culture medium, also reduce the cost of dewatering compared to suspended cultivation. The aim of this project is to cultivate Chlorella vulgaris microalgae in a new biofilm photobioreactor and study the rate of carbon dioxide fixation in the system. In this photobioreactor, a ceramic membrane with pore size of 0.7 microns was used as the substrate and a peristaltic pump was used to continuously transfer the BG-11 culture medium to the membrane surface. The above system was used to capture carbon dioxide in the air at different concentrations. Carbon dioxide was supplied through a carbon dioxide tank and mixed with air in different proportions and injected into a photobioreactor. The air flow rate was adjusted by a rotameter at 50 ml per minute. The amount of carbon dioxide absorbed was determined by measuring the concentration of carbon dioxide in the inlet and outlet air to the photobioreactor via an infrared sensor. According to the experimental results, the growth rate of biofilm was very low in the absence of sodium bicarbonate in the culture medium. Sodium bicarbonate with a concentration of 5 mM was added to the culture medium and the absorption of carbon dioxide in three different concentrations of CO2 in the inlet air (1.5% -2.5% -3.5%) was investigated. Based on the results, the biomass productivity in these three concentrations was 3.773, 4.045 and 4.118 g/m2/day, respectively and the carbon dioxide stabilization rate was 6.78, 7.85, 8.13 g/m2/day, respectively. Accordingly, by increasing carbon dioxide concentration from 1.5% to 2.5% biomass productivity and the carbon dioxide stabilization rate increased dramatically. However, further increase in the concentration of carbon dioxid did not significantly improved the results.
