Effects Of AM Fungi On Treatment Of Salty Wastewater By Ecological Floating Bed

In 21st century,environmental pollution becomes more and more serious with increasing urbanization.A large of municipal wastewater and industrial wastewater that contained salts are discharged into the surface water and soil,which have destroied the ecological environment.Salt removal from wastewater has attracted much attention.Presently,there are several methods that can successfully remove salts from wastewater with high salt(TDS>1 0000mg/L).However,these methods need great construction investment,and have great operation costs,so they are not suitable to dispose wastewater with low salts(TDS<1 0000mg/L).The ecological floating bed(EFB)can extract salts from wastewater by plants,and has some advantages,such as environmental freiendly,low operation cost,and easy mangagement,so EFB technology can be used to dispose wastewater with low salts.However,EFB also have some disadvangements,such as low plant tolerance to pollution stress,low disposal efficiency,and poor plant growth.If we want to use EFB to dispose wastewater,it is necessary to enhance plant growth and tolerance to environmental stress.Arbuscular mycorrhizal(AM)fungi widely exist in wetland environment,and it may promote plant growth,tolerance to environmental pollution stress.Therefore,we investigated the effects of AM fungi inoculation on plant salt tolerance and on treatment of saline wastewater by EFB in this study.The main results are as follows:(1)Pot culture experiment showed that AM fungi well colonized canna plants at TDS 0,2500 and 5000mg/L respectively.Total mycorrhizal colonization rate was not affected by increasing salt concentrations.Colonization structure analysis indicated that compared with TDS Omg/L treatment,hyphal and arbuscular colonization reates were high at TDS 2500mg/L but were low at TDS 5000mg/L.Vescular colonization rate showed contrary trend as hyphal and arbuscular colonization reates.(2)Pot culture experiment showed that AM fungi inoculation significantly incread plant growth at three salt treatments,and compared non-mycorrhizal plant,total plant weight increased by 29.2%,18.7%and 22.0%respectively.AM fungi inoculation also increased chlorophyll contents,chlorophyll fluorescence,and uptake to K,Na,Ca and Mg.(3)EFB experiment showed that AM fungi inoculation increased SOD enzyme activity and decreased MDA content at TDS 5000mg/L compared nonmycorrhizal plant.This indicated that AM increased plant tolerance to salt stress.AM fungi inoculation not only increased plant uptake to P,but also increased plant uptake to salts.This indicates that it is possible to increase treatment efficiency of EFB in saline wastewater..(4)EFB experiment indicated that AM fungi inoculation increased treatment efficiency of EFB.Compared with non-AM EFB,the removal rates of TDS,COD,TN and TP were increased by 21%,33%,24%and 22%within 15 days respectively.The removal rates of K,Ca,Na and Mg in wastewater were increased by 23%,11%,13%,17%respectively.