Studies On The Effect Of Environmental Factors For Behavior Of Single Celled Microalgae Aggregation In Aquatic Environment

Aquatic microalgae as a kind of photosynthetic microorganism,possess high utilization of nitrogen and phosphorus,making it available of biological wastewater treatment.In addition,due to the much higher solar energy conversion efficiency and growth rate of algae comparing with that of terrestrial plant,the high-quality properties of algae,and good ability of carbon sequestration,algae is possible to be a very new promising sustainable energy.Nevertheless,algae outbreak in natural water caused by eutrophication creates huge influence and destruction of ecological and human-living environment.Therefore,collecting algae effectively and economically which is currently a bottleneck in this field of environmental research,would be very meaningful for algae biological wastewater treatment technology,algae biomass resource utilization and control of microalgae blooming in natural water.Current researches about the effect of environmental factors on algae aggregation mechanism is not complete,so this paper starting form behavior of algae aggregation,is going to study the influence of some environmental factors on aggregation behavior of algae.This would include: the influence of simulating Extracellular Polymeric Substances(EPS)on aggregation behavior of algae;the influence of bacteria on algae aggregation behavior;the effect of single celled microalgae for soil bacteria biodiversity and population distribution.Based on experimental research results,several significant conclusions were as follows:(1)EPS could make microalgae forming clusters apparently.Polysaccharide and protein which were main component of EPS obtained viscosity,could create viscous force when algal cells moved.Anion dissociated from polysaccharide and protein could reduce surface charge of algae cells and then lower repulsive force among cells,which would change motility of microalgae cells,creating clearly aggregation behavior of algae as a result of chaotic movement and collision.At the meantime,?-glycan polysaccharides would be excreted on the surface of algae aggregation in order to resist pressure from external environment.(2)Bacteria extracted from soil would significantly promote the formation of algae aggregation.Bacteria would improve their motility to forage organic carbon source(algae cells)in non-nutrition environment.Simultaneously,algae would respond to environmental stress and change their motility,tending to the behavior of aggregate together,chaotic collision and adhered to each other.At the same time,bacteria would accelerate their velocity to reach at the surrounding of microalgae and maintain their living through resolving the polysaccharides of microalgae.(3)Biological diversity and population distribution of soil bacteria would be significantly reduced while algae becoming the only the organic carbon source.Under this environment,Bacteroidetes would replace Acidobacteria in soil bacteria gradually becoming new dominate bacteria strains and Brevundimonas would be screened out.