| Algae play an important role in the process of natural water self-purification,they can remove nitrogen and phosphorus nutrient which cause eutrophication and heavy metal pollutants from wastewater effectively with low cost,and microalgae can be coupled with activated sludge resolving the problems that the energy consumption of activated sludge process to remove organic matter,nitrogen and phosphorus in sewage aeration is too high and the residual sludge disposal is too difficult.Therefore,based on the quorum sensing phenomenon and under the condition of no external aeration,this paper studied the suspension symbiosis of algae and bacteria under the condition of agitation and the cultivation process of algal-bacterial aggregation under the condition of static force,and investigated the regulatory effect of exogenous acyl-homoserine lactone signal molecules on the symbiosis system of filamentous algae and bacteria.At the same time,a mathematical model was established to reasonably predict the treatment efficiency of the bioreactor scale algal-bacterial symbiosi system.The research results were as follows:?1?The activated sludge obtained from the sewage treatment plant after cultivation in the laboratory were extracted and detected by high performance liquid chromatography and mass spectrometry and compared with AHLs standards,and similar substances of AHLs could be detected.The activated sludge and pieces of Oscillatoria were adopted as the ratio of 3:1 in the beaker building dynamic mixing algal-bacterial symbiotic system without additional aeration device.The concentration of exogenous signaling molecules added into four groups were 0,5,50,200 nmol/L respectively.After running for five days in a row,the COD removal rate of R1 and R4is above 90%,ammonia nitrogen removal efficiency has nonlinear relationship with the concentration of exogenous acyl-homoserine lactone signal molecules.?2?Under static conditions,when the symbiotic aggregation of bacteria and filamentous algae is cultured in a 10 m L glass vial,Oscillatoria can be used as a good immobilized biological carrier.Exogenous addition of AHLs signal molecules at 10-9mol/L?nmol/L?level can significantly regulate the operation state of the system.In this experiment,the removal efficiency of pollutants in the Filamentous algal-bacterial system showed a trend of low concentration promoting and high concentration inhibition.Among them,the 100 nmol/L addition group had a good COD degradation rate of 95.8%in the process of culture,until the formation of a compact filamentous algal-bacterial aggregation.Since the outer layer of filamentous algae affected the gas exchange and metabolic efficiency,the COD degradation efficiency decreased slightly.Quorum sensing can regulate the composition and content of EPS in the algae-bacteria system by regulating the amount of polysaccharide secretion,and promote the embedded growth and combination of activated sludge and filamentous algae.?3?On the basis of the above experimental research results,the effect of exogenous addition of signal molecules on the bioreactor scale symbiotic system of bacteria and filamentous algae was considered.An filamentous algal-bacterial symbiotic dynamic model was established with ASM3 model framework and successfully predicted pollutant removal efficiency,changes of dissolved oxygen content and biomass parameters in 4 h simulation cycle of filamentous algal-bacteria symbiotic system without external aeration.The simulation is successful and the model is reliable,at the same time,the simulation results show that the components of algal-bacterial symbiotic system under the action of signaling molecules are able to maintain a good processing performance and biological activity. |
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