چكيده انگليسي :
Abstract
Nowadays, with the expansion of societies, the increase in population and the warming of the earth, there have been challenges related to the reduction of fresh water resources all over the world. In our country, due to the dry and semi-arid climate and the sharp reduction of surface and groundwater resources, the need to use alternative water sources is increasing more and more. Therefore, the use of saline and brackish water sources such as sea water, wells, etc. will be inevitable. One of the new, innovative and cost-effective methods related to desalination of water sources is biological desalination. In this method, microorganisms are used to purification and sweeten water. Microorganisms are living beings that grow and sweeten saline water by feeding on salts and substances in water. Based on this, in the current research, microalgae spirulina platensis, which is an economic and available sample of microorganisms, has been used to reduce salinity and remove water solutes. In the following, according to the laboratory conditions, the effect of each of the environmental parameters such as temperature, amount and hours of lighting on the amount of electrical conductivity, as well as the amount of changes in water-soluble ions such as sodium, calcium, potassium, magnesium, phosphate, sulfate, nitrate and chloride in the conditions before and after algae cultivation, the results are analyzed. One of the most important results obtained in this study is the reduction of electrical conductivity under the conditions of using spirulina platensis algae. In general, the reduction efficiency of electrical conductivity in water with salinity of about 6.8 dS/m after algae cultivation was 10% and for water with salinity of about 13.6 dS/m, it was 21%. As a result, the use of algae in the water sample with a higher electrical conductivity up to about 11% had a more suitable effect. In relation to the influence of the amount of lighting, it was observed that in samples with higher salinity, less light was needed, so that in less light, about 25% and in more light, about 22% desalination efficiency has been achieved. This happened in reverse in the sample with less salinity. In relation to the influence of the temperature of the cultivation environment, the suitable temperature is the middle temperature, i.e. 33 degrees Celsius. Also, in the longer cultivation period, for water with higher electrical conductivity and with a certain amount of radiant light, 12 hours of lighting hours and 24 hours of lighting hours for water with lower electrical conductivity has been more effective in the process of reducing electrical conductivity. In this research, due to the inoculation of Zaruk Cultivation environment, an increase in sodium, potassium and phosphate ions was observed in the water test results of the samples. The greatest effect was on the concentration of calcium and nitrate ions with the concentration reduction efficiency of 99%. The reduction of magnesium was also significant and was about 68% in both samples. The reduction efficiency of sulfate and chloride ions decreased by 12% and 6% respectively, for water with lower salinity and 14% and 23% for water with higher salinity, but chloride ion did not have much effect in water with lower salinity. Due to the increase of sodium and decrease of calcium and magnesium, SAR value has increased. The large decrease of calcium and magnesium in both water samples shows the decrease in water hardness, which has decreased by 88% in water with higher salinity and by 96% in water with lower salinity, so that water with lower salinity is from the very hard range moved to the soft range.
