Carbon Nitrogen Phosphorus Removal Pathway And Influential Factors Research Of Vegetation-SBR Process

The landscape ecological activated sludge system is an innovative environmentfriendly wastwater treatment system comprised of decontaminated vegetation and conventional activated sludge process,e.g.Sequencing Batch Reactor(SBR),which has been termed as vegetation activated sludge process(V-ASP).By allocation of these vegetation,it has been revealed that V-ASP has stably excellent pollutants removal efficiency and landscaping function.However,the pollutants removal pathways by every functional unit in V-ASP is still unclear.In the present work,isotope tracer technique was used to label pollutants in V-ASP influent to investigate the transformation and removal pathways of organic and nutrients from wastewater.Meanwhile,the effects of temperature and coexisting nanoparticles,such as Ag and Zn O nanoparticles(Ag NP and Zn O NP),on the system performance and pollutants removal ways were also examined.The obtained results herein are useful to comprehensive understand the V-ASP system and to guide its practical application.The removal pathways of organic and nutrients from wastewater in the V-ASP were investigated by loaded with Isotope Tracer.The results showed that 54.6%18.3% and 4% of the organic carbon was removed by microbial metabolism,biomass assimilation and vegetation utilization,respectively,while more than48.6%,18.3% and 6.0% of ammona was removed in V-SBR by the way of microbial metabolism in term of nitrogen gas,bioass assimilation and vegetation utilization,respectively,among which the contribution of the root microorganisms was rather significant.As for phosphorus removal in V-ASP,there was 62.0% was retained in the sludge solids,and more than 8.2%,3.7% and 3.9% of TP was removed by absorption of the vegetation roots,stems and leaves,respectively.Although the main pathway of pollutants removal was activated sludge metabolism,the removal of pollutants by allocated vegetation could not be underestimated as it counted more than 10% of total pollutants removal.It was thus found that with a vegetation density of 125 plants/m2,the contribution of the allocated vegetation in V-ASP of total carbon,total nitrogen and total phosphorus was 4%,6% and 14%,respectively.The effect of temperature on the pollutant removal of the V-SBR was evaluated,and resulted pollutants removal capabilities of varied functional units were estimated.It was observed that the effect of operational temperature onto the total carbon removal pathway were insignificant.In contrary,the temperature changed from 15 ? to 30 ? induced the total TN removal rate by microbial nitrification and denitrification increased from 46.5% to 65.5%,and that of microbial assimilation and vegetation utilization increased from 12.1% to 24.1%,and from 5% to 8%,respectively,reflecting that the temperature affected the vegetation root microorganisms eventually.The increase of temperature had also great influence on the total phosphorus removal pathway,which could enhance the activated sludge assimilation,vegetation uptakeing and root microbial assimilation of phohsphorus.The effect of coexisting nanoparticles in influent on the pollutants removal pathway and the effectiveness of each functional unit were investigated,and the results demonstrated that once the coexisted Ag NP concentration increased to 10 mg/L,the assimilation of total carbon and total nitrogen by activated sludge decreased by 3% and 0%,respectively,while the contribution of root microorganisms decreased by 1.4% and 1.8%,respectively.In contrary,the concentration of coexisted Zn O NPs increased up to 100 mg/L began to result in the changes of the pollutants removal efficiency of varied functional units,and the total carbon and total nitrogen through biomass assimilation decreased by 3.3% and 1.5%,respectively,while the total carbon and total phosphorus assimilated by root microorganisms decreased by 1.4% and 2.5%.