| The key objectives of algae research are the selection of suitable algae species,utilizing low-cost culture media,optimizing cultural environmental conditions,and reduction of harvest costs.In the present research the filamentous microalgae Tribonema sp.was selected due to its higher lipid contents and convenience to harvest.The growth characteristics of Tribonema sp.were investigated under magnetic field intervention,in various cultural conditions such as(various light intensities,temperature,batch and semi-continuous culture,etc).Moreover,its feasibility to cultivate in starch wastewater had been investigated in order to seek a novel cultivation technique,which not only increases its growth rate but also decreases the production cost that provides new ideas for promoting the industrial production of microalgae.The main results are as follows:(1)The study explored the effects of low-intensity magnetic field and light intensities(2500-11000 lux)on the growth of Tribonema sp.The results showed that the maximum biomass 4.38 g/L was obtained with 8700 lux light intensity and 130 mT-24 h magnetic field intervention.At the optimal light intensity of 8700 lux,the lowest lipid content of the 70 mT-1h magnetic treatment culture group was 43.2%,while the lipid content in control culture group was 46.5%,and the highest lipid content of the 180 mT-24 h magnetic treatment culture group was 51.3%.(2)The study explored the effects of temperature on the growth of Tribonema sp.cultured in BG-11 medium and starch wastewater.The results showed that when the algae was cultivated in BG-11 medium,the maximum biomass 4.81 g/L was obtained at the temperature of 35?,130 mT-24 h magnetic field intervention,which was an increase of 11.34% compared with the control group;The algae was cultured in starch wastewater,so its temperature adaptability was found to be changed.The maximum biomass 4.68 g/L was obtained with 30°C and 130 mT-24 h magnetic field intervention,at 25°C and 30 mT-24 h,the lipid content was reached at the highest 47.90%,but Tribonema sp.could not survive at 35°C.(3)The Tribonema sp.was cultivated in starch wastewater for a semi-continuous culture under 8700 lux light intensity and 30°C.The results showed that the daily average growth rate of microalgae was up to 752.80 mg/(L?d)at 130 mT-24 h,compared with batch cultivation,got an increase of 44.77%.However,in this culture mode,the minimum lipid content of Tribonema sp.in the blank group was 19.75%,the 30 mT-24 h group was 25.2%;Under the outdoor cultivation in summer,the 30 mT-24 h and 130 mT-24 h,the average daily removal rate increased by 8.28%,9.69% as compared with the blank group(446.67 mg/(L?d)),respectively;Under the outdoor cultivation in autumn,under the magnetic field intervention of 30 mT-24 h and 130 mT-24 h,the average daily growth rate increased by 14.66% and 5.76% compared with the blank group(218.33 mg/(L?d)).The component analysis of the Tribonema sp.was cultivated in outdoor,the lipid content in the 30 mT-24 h,and 130 mT-24 h groups were 44.70% and 45.11% respectively,which was an increase of 8.60% compared to the blank group 9.01% in summer;in the autumn environment,the lipid content of Tribonema sp.in the 30 mT-24 h and 130 mT-24 h groups was 40.60%,42.7%,respectively,which were 5.70% and 7.80% higher than the blank group.16S rRNA high-throughput sequencing was used to study the microbial diversity in microalgae systems during its outdoor culture process.The results show that more abundant bacterial diversity were observed from microalgae system in summer.In the autumn environment,the relative abundance of Proteobacteria accounts for more than 90%,the abundance of Proteobacteria in the environment is related to the removal efficiency of wastewater.In the outdoor environment,the coupled system of Tribonema sp.and wastewater was relatively stable,and the algae species were the dominant that can be used for outdoor cultivation. |
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