Effects Of Carbon And Nitrogen Components On Oil-rich Tribonema Minus Growth Regulation And Food Processing Acidification Wastewater Moderate Aeration Low-cost Culture Research

Selecting suitable algal species,using low-cost culture medium,and reducing harvesting costs are the key points of microalgae culture engineering research.In this experiment,Tribonema minus with high lipid content and easy to harvest was selected as the research object to explore the effects of different concentrations and forms of nitrogen sources（ammonia nitrogen,nitrate nitrogen）,volatile organic acids on the growth characteristics of Tribonema minus,to study the effect of different nitrogen and carbon source combinations on the growth and cell biochemical composition of the oil-rich Tribonema minus.Try to use the cheap nitrogen and organic carbon sources in the acidification wastewater of food processing to carry out oil-rich Tribonema minus cultivation,adopt moderate aeration to reduce the energy consumption of the biological denitrification process,avoid the loss of nitrogen,and greatly reduce the input of carbon sources,the main contents are as follows:（1）The effects of single and mixed nitrogen sources on the growth characteristics of Tribonema minus was investigated.It was found that the growth of Tribonema minus was inhibited when only ammonia nitrogen was contained in the culture system,and the inhibition range was 30 mg/L;However,the growth of Tribonema minus was not inhibited by high concentration of nitrate nitrogen.When the total nitrogen content was240 mg/L,the ratio of ammonia nitrogen and nitrate nitrogen was adjusted,and the results showed that when the ammonia nitrogen content exceeded 120 mg/L,the growth of Tribonema minus was inhibited;The higher the ammonia nitrogen content,the higher the lipid content of Tribonema minus,up to 50.7%（ammonia nitrogen 120 mg/L）.（2）To investigate the effect of different organic carbon sources（acetic acid,propionic acid,butyric acid,valeric acid,glycerin）on the growth of Tribonema minus,it was found that Tribonema minus cannot metabolize propionic acid.In order to avoid drastic changes in p H,the p H of the culture system needed to be regulated;when the p H was adjusted artificially,when Tribonema minus used acetic acid as the carbon source,the biomass was the highest at 1.94 g/L;when 0.3%CO₂ was introduced to stabilize,undissociated fatty acids were found to inhibit the growth of Tribonema minus,reducing its photosynthetic performance,increasing the content of malondialdehyde,and decreasing the activity of antioxidant enzymes,while with glycerin as the carbon source,the biomass of Tribonema minus was up to 2.95 g/L,The lipid productivity was155.53 mg/（L.d）,and the palmitoleic acid content reached 45.95%;when the volatile fatty acid-glycerin compound was used as the carbon source to cultivate Tribonema minus the ratio of C_{acetic acid}:C_{butyric acid}:C_glycerinwas 1:1:2,the p H was neutral during the culture,Tribonema minus exhibited the best biomass accumulation at 2.22 g/L,and the lipid productivity of Tribonema minus was 108.16 mg/（L.d）.（3）The moderate aeration pretreatment of food processing acidification wastewater is coupled with Tribonema minus cultivation.The results showed that when the ammonia nitrogen in the effluent of the traditional process pretreatment liquid is controlled at 120 mg/L and 150 mg/L,after two stages of cultivation,organic matter,nitrogen,phosphorus,and other utilization rates have reached more than 90%.The lipid content of the pretreatment solution（ammonia nitrogen content 190 mg/L）in the groups of 15°C aeration for 7 h,25°C for 1.5 h,and 35°C for 1.2 h during the culture process of stage I and stage II They were 47.71%,51.25%,46.37%and 49.77%,49.61%and47.55%respectively,which were significantly higher than other groups.Under conditions where Tribonema minus could grow,the shorter the aeration time,the higher the ammonia nitrogen content in the pretreatment liquid,the lower the energy consumption,the more lipid accumulation of Tribonema minus.