| The treatment and recovery of anaerobic digested effluents from piggery wastes(swine wastewater)is becoming a major concern due to serious pollution of groundwater and ecological environment.In addition,it is a research hotspot of microalgae and energy industry to realize the scale of microalgae fixed CO2.Microalgae can be used for assimilation of nitrogen,phosphorus and other elements in swine wastewater for algal cell growth.Therefore,the coupling of microalgae to purify swine wastewater and CO2 fixation can not only reduce the level of swine wastewater and slow down carbon emissions,but also can obtain microalgae products.This thesis aims to investigate the purification of primitive swine wastewater and the fixation efficiency of CO2 by Chlorella vulgaris MBFJNU-1 under different experiment conditions.Furthermore,the important differences in microalgae proteome are comprehensively illustrated by using proteomics technology under different levels of CO2 during the microalgae treatment for swine wastewater.The main results are as follows:(One)During the microalgae treatment,the effects of environmental factors(CO2 concentration,ventilation mode,gas-flow rate,ventilation time and light intensity)on the growth of Chlorella vulgaris MBFJNU-1 were studied using the purification of swine wastewater and fixation CO2 efficiency as indexes.The results showed that:(1)The growth of Chlorella vulgaris first increased and then decreased with increasing CO2 concentration.The biomass of 1.22 g/L for Chlorella vulgaris MBFJNU-1 were observed in the CO2 concentration of 10%,and the highest CO2 fixation rate was 273 mg/(L-d)after the cultivation of 8 d.In the control group,the highest removal rate of TN(total nitrogen)and NH4+-N(ammonia nitrogen)were 54.60%and 90.21%.Chlorella vulgaris showed the highest total phosphorus removal rate(43.58%)in the 5%CO2 concentration.In addition,the COD removal rate(about 20%)of each experimental group showed no significant difference.(2)The biomass was increased with the increase of illumination intensity,the maximum biomass was 1.36 g/L,and the highest CO2 fixation rate was 239 mg/(L·d),under the illumination intensity was 8000 Lux.Chlorella vulgaris showed the highest total nitrogen removal rate(90.59%)and the highest ammonia nitrogen removal rate(98.72%)under the illumination intensity was 6000 Lux.(3)Two strategies(Method 1:the continuous aerate of 5%CO2;Method 2:the continuous aerate of 5%CO2 before 8 d and continuous aerate of air after 8 d)were used to evaluate the performances of microalgae treatment.There is no difference in biomass under the different air flow rate.At 800 mL/min gas-flow rate,the Chlorella cultured in aeration mode 1 had the highest total nitrogen(79.82%)and ammonia nitrogen(80.68%)removal rates.Under the same conditions,ventilation Mode 2 has a higher rate of total nitrogen and ammonia nitrogen removal(>90%)than ventilation Mode 1.Method 1 and Method 2 gave the highest CO2 fixation rate with 454 mg/(L·d)and 294 mg/(L·d)at 800 mL/min gas-flow rate,respectively.(4)The biomass of Chlorella vulgaris MBFJNU-1 increased with the increase of aeration time.Compared with other groups,when the continuous ventilation time was 24 h/d,the maximum biomass of Chlorella vulgaris obtained by ventilation mode 1 and mode 2 was 2.23 g/L and 1.66 g/L,respectively,and the highest CO2 fixation rate was 273 mg/(L·d)and 196 mg/(L·d).(Two)Using the in the outdoor conditions,this paper studied the purification of primitive swine wastewater and CO2 fixation rate of Chlorella vulgaris MBFJNU-1 in the cylindrical photobioreactor with batch culture and semi-continuous culture.Find the following results:(1)For the batch culture,The biomass of Chlorella vulgaris first increased and then decreased with increasing CO2 concentration.Under the condition of 3%CO2 concentration,the maximum biomass of chlorella was 0.75 g/L,and the maximum CO2 fixation rate was 68 mg/(L·d).At the same time,the removal rate of total nitrogen decreased with the increase of CO2 concentration,and the removal rate of total nitrogen(49.14%)and removal rate of ammonia nitrogen(81.41%)was highest in the air group.(2)The results of semi-continuous culture with different CO2 concentration showed that the biomass and CO2 fixation rate of chlorella were the highest under the condition of 3%CO2 concentration.(3)Effect of different renewal rate of primitive swine wastewater on the performance of the semi-continuous continuous culture experiment.In the 80%renewal rate,Chlorella showed the highest CO2 fixation rate during the entire culture.(Three)A scaled-up experiment was performed with a raceway photobioreactor to study the effect of 3%CO2 and air on the purification of primitive swine wastewater and fixed CO2 by Chlorella vulgaris MBFJNU-1.The biomass of the experimental group with CO2 was 0.48 mg/L,which was 17.75%higher than that of the control group.At the same time,the fixation rate of CO2 at a 3%CO2 concentration of Chlorella was 63 mg/(L·d),which was 1.62 times that of control group.(Four)Using the iTRAQ proteomics technology,proteomic analysis was performed on the algal cells of Chlorella vulgaris MBFJNU-1 in different CO2 concentrations.Through mass spectrometry analysis,44257 spectra were identified,the spectrum utilization was 16.1%,the number of specific peptides was 14719,the total number of proteins was 1928,and the number of dynamically changing proteins was 582.And bioinformatics analysis was applied to analyze the differential protein of screening by the method of Paragon algorithm(Protein Pilot Software v.5.0).By KEGG pathway analysis,a total of 74 metabolic pathways with significant differences(p<0.05)were identified in the 6 differential groups.Among them,the significant metabolic pathway shared by each group was the photosynthesis pathway,which indicated that changing CO2 conditions had a significant effect on the photosynthesis pathway of Chlorella vulgaris MBFJNU-1.Furthermore,the model of cellular metabolic change was constructed by preliminary analysis of metabolic pathways when changed the CO2 conditions.The correlation between the metabolic changes of Chlorella vulgaris MBFJNU-1 and changed CO2 conditions was investigated to insight into the mechanism of fixation CO2 for the treatment of primitive swine wastewater by microalgae biotechnology. |
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