Research On The Formation Mechanisms And Resource Utilization Of Algal Bacterial Granular Sludge

Aerobic granular sludge(AGS)has the advantages of excellent sedimentation performance,high biomass,and strong impact load resistance.However,it also has the disadvantages of high aeration energy consumption and easy disassembly for long-term operation.Microalgae can absorb carbon dioxide for photosynthesis and produce oxygen and energy substances at the same time,but the use of microalgae to treat wastewater has problems such as low metabolic efficiency and difficult recovery.Organic coupling of AGS and microalgae can not only solve the problems of low metabolic efficiency and difficult harvesting of microalgae,but also save energy for aeration and maintain particles through gas exchange between bacteria and algae,metabolic complementation and material circulation.The structural stability of the sludge.In this paper,by combining the advantages of aerobic granular sludge and microalgae,a high-efficiency,low-consumption,stable operation of algal-bacterial granular sludge(ABGS)system to solve the existence of existing processes The shortcomings and problems of the waste water treatment,improve the efficiency of sewage treatment and achieve resource utilization.this paper studies the effects of different types of inoculated sludge and inoculated algae on the formation of ABGS.The results show that neither the type of sludge nor the inoculation of microalgae is a necessary condition for the formation of ABGS.After the formation of ABGS,reducing the aeration intensity will not affect the stability of the reactor,but the light reactor collapsed after stopping ABGS.The physical and chemical properties of ABGS formed under different culture conditions are not significantly different,but the distribution and content of microalgae are significantly different.ABGS formed by AGS is rich in microalgae.In addition to the dense distribution of ring-shaped bands at 100 ?m from the edge,microalgae still exist in the core of the particles,while the ABGS formed by AS only shows ring-shaped bands at the periphery;Finally,the community structure of ABGS was analyzed.Chlorella and Neochlorella were the main microalgae in the system,and Chlorella was the dominant species.Fatty acid methyl esters(FAMEs)in ABGS were extracted,and the main types of FAMEs were found to be methyl palmitoleate,palm oil methyl ester,and cis-9-oleic acid methyl ester;the content of microalgae and FAMEs were Obvious linear relationship,the correlation coefficient reaches more than 0.9,and the production of ABGS formed by AGS has the highest FAMEs output,which is 9.04 mg/g;Then,using chlorella as the inoculated algae,the effects of AGS with different particle size ranges as the inoculated sludge on the formation process of ABGS,the removal of pollutants and the physical and chemical properties were investigated.On this basis,the formation mechanism of ABGS was explained.Denitrification pathway and microalgae maintain ABGS stability mechanism.The formation mechanism of ABGS is that microalgae attach to free bacteria first,and then adhere to AGS.Due to the different adhesion of AGS with different particle sizes,under the dual selection of light and oxygen,microalgae penetrate into the particulate pollution through the gap condition Mud inside or attached to the surface of the particles.The mechanism by which microalgae affects the stability of ABGS is that microalgae are distributed inside the granules and secrete a large amount of polysaccharides and proteins at their distribution,which plays a role in stabilizing the structure,and the microalgae produce oxygen to inhibit the activity of internal anaerobic flora To prevent the hydrolysis of polysaccharides and proteins inside the particles and prevent the disintegration of the granular sludge structure due to the collapse of the anaerobic core;the formation of ABGS is beneficial to the enrichment of bacteria such as Soxhella and Sphingomonas in the system and enhances the removal Nitrogen effect and maintaining the structural stability of the particles,providing light is conducive to the enrichment of photosynthetic bacteria-Rosebacteria in the system,and the larger the particle size,the higher the advantage.The content of FAMEs has an obvious linear relationship with the cultivation time,and the correlation between the particle size range of 0.4-0.8 mm The strongest,the correlation coefficient reached 0.99,but its yield was the lowest,the largest was only 5.74 mg/g,the correlation between the particle size range of 0.8-1.4 mm was weak,the correlation coefficient was only 0.95,but its yield was the highest,reaching 12.10 mg /g.