Performance Intensification Of CO₂ Absorption And Microalgae Conversion （CAMA） Hybrid System Via Low Temperature Plasma （LTP） Treatment

CO₂ capture,reuse and storage（CCUS）technology is an important part of China’s technical route to achieve the goal of carbon neutralization.It is a strategic choice to reduce CO₂ emissions and ensure energy security.It is of great practical significance for China to build ecological civilization and achieve sustainable development.In order to solve the problems of high energy consumption of high-temperature thermal regeneration of CO₂ absorption solution captured by traditional chemical absorption method and carbon escape caused by poor CO₂ solubility in traditional microalgae carbon sequestration method,a CO₂ absorption and microalgae conversion system was established with bicarbonate as the link,and the high-temperature thermal regeneration of absorption solution in traditional CO₂ chemical absorption method was replaced by microalgae biological regeneration,At the same time,the problems of high energy consumption and carbon escape in thermal regeneration are solved,and the low energy consumption capture and green resource utilization of CO₂ are realized simultaneously.Although the coupling system has many advantages,its research time is still short and the mechanism is not perfect,such as the slow growth of microalgae in the coupling system,the cycle feasibility of the coupling system is not clear,and the carbon migration path of the coupling system is not clear.Based on the above problems,this study has achieved the following results:（1）In this study,Chlorella L166 was improved by low-temperature plasma mutation breeding technology,and two algae strains（Chlorella L166-M₃ and Chlorella L166-M₄）with better performance in the coupling system were obtained.Then the mutant algae strains were connected back to the coupling system for various evaluation.Among them,the maximum specific growth rate of the mutant algae strain Chlorella L166-M₃ was 27.5%higher than that of the initial algae strain,The highest carbon fixation rate was 93.7%,the lipid content increased by 15.4%and the protein content increased by 11.7%,which provided a new idea to solve the slow growth of microalgae in the coupling system.（2）The lean solution of absorption solution and circulating solution was obtained through primary culture,and the circulating solution was treated by activated carbon adsorption,dilution and H₂O₂/UV respectively.It was found that compared with the primary culture,the sum of NADP⁺and NADPH content（89.99 nmol/L）in the untreated group was significantly lower than 116.69 nmol/L in the primary culture group,resulting in the decline of photosynthetic efficiency and the decrease of od680from 0.94 to 0.79.After H₂O₂/UV treatment,the sum of NADP⁺and NADPH content in microalgae cells reached 132.40 nmol/L,which promoted the photosynthetic efficiency of microalgae and restored the od680 to 0.94,Biomass concentration increased by 19%.In addition,after H₂O₂/UV treatment,the oil yield and protein yield of microalgae reached 9.88 mg/L and 122.21 mg/L,which were higher than those of primary culture（7.91 mg/L and 117.76 mg/L）.（3）High throughput transcriptome sequencing was used to analyze the gene expression of microalgae in primary and secondary culture.In the primary culture and untreated subculture of microalgae,871 genes were significantly up-regulated and 602genes were significantly down regulated.During the subculture of microalgae,the processes of photosystem I,photosystem II and electron transfer of microalgae were inhibited,resulting in the decline of photosynthetic capacity and carbon capture capacity of microalgae.After H₂O₂/UV treatment,the photosynthetic performance of microalgae was restored to a certain extent,The carbon capture capacity was restored to the primary culture level.