Formation Process And Mechanism Of Granular System Of Bacteria And Algae

The granular system of bacteria and algae has the advantages of good mass transfer conditions,settling performance,high treatment efficiency,and has been widely concerned in the field of sewage treatment.At present,it has been reported that the system can effectively remove nitrogen and phosphorus from wastewater,but most of the articles only discuss the best conditions of the formation and adsorption of the system.The study on the formation process and mechanism is relatively less.Therefore,in this study,the formation process of system was studied,Zeta potential,pH change and extracellular polymer substance(EPS)composition were analyzed.The formation process and mechanism of adsorption of the system were studied.In this study,the best factors affecting the formation and rapidly establishment of the system were discussed.The experimental results confirmed that Aspergillus niger added in the form of mycelial pellets was likely to absorb Chlorella vulgaris to form the system.In addition,it was found that the best adsorption conditions were 25~oC,160 rpm and pH 6.0.The method of rapidly formation of the system was established,and it was determined that the performance of the system was the best when cultured for 8 h,and could adapt to large-scale application.The formation mechanism of the system mainly included physical adsorption and biosorption.When the system was formed,the pH and Zeta potential were similar to the mycelial pellets.So the mycelial pellets played an important role in the formation process.The specific structure of mycelial pellets played an important role in the adsorption,and the Zeta potential also showed that the surface electricity was conducive to the adsorption.In the experiment,when the system were put into the simulated domestic sewage containing carbon,nitrogen and phosphorus for treatment.It was found that the system treated the pollutants through synergistic action.The synergistic action can improve the tolerance of mycelial pellets and Chlorella vulgaris to sewage environment.And it also can enhance the stability of the system.The result showed that the COD removal rate was 83.33%,the TN removal rate was 89.15%,and the TP removal rate was 82.65%.