Screening Of Heat-resistant Microalgae And Its Treatment Of Heavy Metals

The desulphurization wastewater from coal-fired power plants contains many kinds of heavy metals,and the harmful effects of heavy metals are very serious.Therefore,how to remove heavy metals in desulfurization wastewater from power plants bacomes a key issue.Biosorption technology has become a research hotspot due to its low cost and strong ability to adsorb heavy metals.In this experiment,we choose microalgae as biosorbents.We collected 120 kinds of soil samples and water samples from all over the country for cultivation,and set incubation temperature to 40°C to select high-temperature resistant microalgaes.A total of 11 kinds of high temperature resistant microalgae was obtained through molecular biological identification of the high temperature resistant microalgae,which consists of Scenedesmus,Volvox,Micractinium,Chlorella,Chlamydomonas,Chroococcus,Cryptococcus,Platymonas,Dunaliella,Leptolyngbya and Nostoc.The screened high-temperature resistant microalgae were put in medium containing Cr⁶⁺with different concentrations respectively to select the microalgae with good Cr⁶⁺effect.The concentration of Cr⁶⁺in the laboratory was determined by diphenylcarbazine spectrophotometry.The experimental results show that,8 kinds of microalga which include soil 2-2,soil 14-2,soil 43-3 and so on can resist Cr⁶⁺toxicity in Cr⁶⁺medium,but hardly adsorb Cr⁶⁺.9 kinds of microalga like water 1-1,soil 5-1 and soil 48 and so on can absorb 30%to 50%Cr⁶⁺.Moreover,12 kinds of microalga show good effect on Cr⁶⁺and the adsorption efficiency for Cr⁶⁺at 1 mg/L is between 50%and 80%,such as soil 2-1,soil 11-1,soil 34,soil 53,etc.Notably,soil 13-1 exhibits best effect of absorbing Cr⁶⁺,and the absorbing efficiency of up to 99.07%.The absorption effect of high concentrations Cr⁶⁺is good with increase inputs of soil 13-1 microalgae,and therefore,soil 13-1 has become the emphases for this research.Comparing the adsorption effect of Cr⁶⁺between living microalgae and dried microalgae powder of soil13-1,we found that the removal effect of living microalgae was much higher than that of dried algae powder,and the main site of adsorption of Cr⁶⁺by living microalgae was extracellular.Put the soil 13-1,soil 2-1,and soil 53 into the desulfurization wastewater from the power plant to conduct research on the treatment of a variety of heavy metals.The results illustrate that the soil 13-1 can absorb 7 kinds of heavy metals which come from desulfurization wastewater from the power plant,and the adsorption efficiency can reach more than 90%.The efficiency is far higher than soil 2-1 and soil 53.Therefore,use microalgae to adsorb heavy metals in wastewater has a very good application prospect.