Enhanced Adsorption Of Nitrogen And Phosphorus From Eutrophicated Water By Assembled Substrate Ecological Floating Raft

Ecological floating raft?EFR?technology has been become one of major approaches in the remediation of eutrophicated surface waters including river,reservoir,pool and lake,since it can not only improve the water quality but also beautify the landscape.However,current EFR technology mainly relies on the capability of the plants in absorbing the pollutants in water,resulting in an insufficient cleanup efficiency in most cases.In addition,the performance of the EFR is unavoidable to be restricted by the growth period of plants and climate conditions.Substrate is an important component of EFR.An ideal substrate should have a strong adsorption capability toward nitrogen?N?and phosphorus?P?in water bodies,and thereafter provide these nutrients in stimulating the growth of the plants on EFR.Meanwhile,the substrate creates a good niche for the water-borne microorganisms.Therefore,screening good substrates is one of hotspots in EFR technology development in an attempt to pursuit a highly efficiency in cleaning up the eutrophicated water.In this study,the basic chemico-physical properties and adsorption characteristics toward NH₄⁺-N a nd total phosphorus?TP?of different substrates and their combinations,which were from different sourc es?including animal-oriented oyster shell;plant-oriented activated carbon,sawdust biochar and,bambo o biochar;mineral-oriented vermiculite;and solid-waste-oriented sludge biochar?,were investigated.n t he basis of a series of batch experiments,two optimal combinations of different substrates,modified oys ter shell:vermiculite=1:2?compound substrate A,CSA?and modified oyster shell:vermiculite:sawdust b iochar=1:1:1?compound substrate B,CSB?were determined,which removal rates of NH₄⁺-N and TP re ached 53.85%and 55.56%,74.07%and 76.92%,respectively.In addition,removal effects of NH₄⁺-N and TP from eutrophicated water by ten different aquatic plants were evaluated and compared.In accordance with the results,Canna indica,Myriophyllum verticillatum,Ceratophyllum demersum Linn.,Thalia dealbata,Cyperus alternifolius had a better capability in absorption to TP while Myriophyllum verticillatum,Ceratophyllum demersum Linn.,Cyperus alternifolius,water fennel,Thalia dealbata showed a stronger assimilation of NH₄⁺-N.The combinations of the compound substrates?CSA and CSB?together with 3 aquatic plants?Myriophyllum verticillatum,Canna indica,Cyperus alternifolius?,which had a good removal capacity of both NH₄⁺-N and TP,were tested to quantify their performance in terms of the removal of NH₄⁺-N and TP as well as influence on the total population of microbes.It was expected to optimize the combination of substrates and aquatic plants for the real application The results showed that the combination of“Myriophyllum verticillatum+Canna indica”and CSB had the best effect on the purification of eutrophicated water,which removal rates of NH₄⁺-N and TP reached 93.05%and 98.32%.The outcomes are hoped to provide a technological reference for the future study related to EFR development.