Study On The Application Of Photocatalytic Synergistic Microalgae In The Treatment Of Aquaculture Wastewater

This topic aims to purify aquaculture wastewater,based on the research of Photocatalytic film（PF）and microalgae treatment of aquaculture wastewater,this paper discusses the feasibility of their synergistic effect on aquaculture wastewater and strengthens their treatment conditions,and provides some basic theoretical information for constructing aquaculture wastewater treatment technology based on microalgae culture.The findings are as follows:1.Using SEM（scanning electron microscope）,XRD（X-ray powder diffraction）and UV-Vis DRS（UV-Vis diffuse reflection absorption spectrum）to characterize PF,the photocatalyst was better attached to the interlaced fibers;the combination of Ti O₂and Si O₂nanoparticles does not affect their crystalline structure,so as not to affect their photocatalytic activity;PF had obvious light absorption characteristics between about 250～400nm bands and characteristic absorption at about 315nm,indicating that the PF has photocatalytic characteristics.The photodegradation of methylene blue solution was 89.59%after 10h of PF light reaction.2.A superior algae was isolated and purified by 96-well plate gradient dilution method,plate coating and streaking separation method,and the algae strain was identified as Chlorella by means of morphological and molecular biological techniques,which was named Chlorella sp.CFL1.The algae concentration was measured by optical density method,and after inoculation into BG11 medium,it reached the maximum value on the 40th day,and the OD680 was 3.67.3.After inoculating Chlorella CFL1 into aquaculture wastewater for 8 days,Chlorella CFL1+PF group compared with Chlorella CFL1 group,Chlorella CFL1 soluble protein content was significantly increased by 54.17%（P<0.05）,MDA content was significantly increased60.0%（P<0.05）,indicating that the addition of PF can stimulate the growth and material accumulation of algal cells to a certain extent,and can cause damage to algal cells.Through the measurement,it was found that the Chlorella CFL1+PF group had the best final removal rates of ammonia nitrogen,total phosphorus,nitrite and COD in sewage,which were 100%,56.76%,100%and 62.9%,respectively.This shows that the synergy between the PF and Chlorella CFL1has the potential to remove pollutants from aquaculture wastewater.4.Set the light intensity gradient to 1000,3000,5000,and 8000 Lux to study the effect of light intensity on the growth,physiological and biochemical indicators of Chlorella CFL1 and on the purification of aquaculture wastewater.The results show that:Chlorella CFL1 grows better under T-3000 and T-5000 treatment conditions,which was beneficial to material accumulation.When Chlorella CFL1 cooperated with PF to treat aquaculture wastewater,the T-3000 treatment group was better than the other three groups in the degradation of ammonia nitrogen at the beginning of the culture.The lower light intensity was not conducive to the removal of nitrite.After 8 days of culture,the T-3000 treatment group had the best degradation effect of total phosphorus and COD,with degradation rates of 77.90%and 68.76%,respectively.5.When the aeration was 100 l/h,the algal cell density reached maximum of 0.56±0.03after 7 days of culture,which was significantly different from the CK group（P<0.05）.After 8days of culture,the soluble sugar content was significantly increased by 44.97%（P<0.05）,and the MDA content was significantly reduced by 58.06%（P<0.05）,indicating that aeration was beneficial to the growth of Chlorella CFL1,and increases the accumulation of algae,decreases PF damage to algal cells.The final removal rates of ammonia nitrogen,total phosphorus,nitrite and COD in wastewater by PF synergistic Chlorella CFL1 were 100%,68.58%,100%and71.81%,respectively.In the early stage of culture,aeration had a significant effect on the removal of nitrite and COD;after the end of the culture,aeration had a significant effect on the removal of ammonia nitrogen and total phosphorus.