Research Of Coix Aquatica Roxb Constructed Wetland Matrix Cr State Distribution Characteristic And Microorganism Quantity

The study took the Coix aquatica Roxb constructed wetland as the background to analysis determination of the constructed wetland system matrix conventional physical and chemical properties(moisture content, pH and organic matter).Studied the chromium various chemical speciations of distribution in the constructed wetland substrate of different layers,and took the physical and chemical properties as the background,as well as the chromium influence on microbial biomass and enzyme activity.The results were as follows:1Under the two kinds(WCA and HCA) of processing conditions,physical and chemical properties of the matrix showed a certain regularity, plant system water content is generally greater than the non-plant system,upper<middle<lower level in the both system. The pH change tendency of plant system is upper layer<intermediate layer<lower layer,but The difference of non-plant system in the three layers is not remarkable. The matrix pH of the living sewage system is smaller than it in the nutrient solution system,matrix pH in earlier period of two nutrition source processing is bigger than the later period’s.The matrix pH of the low concentration(0,20mg/L) Cr6+processing is bigger than the high concentration (40mg/L),but the disparity reduces in the later period,pH of non-plant low concentration Cr6+processing is bigger than highly concentrated processing through the entire trial period.The plant system upper layer organic matter content is morer than the intermediate and the lower layer. In the non-plant system,the organic matter content is in turn:The upper layer>the intermediate layer>the lower layer, in the earlier period,the plant system is slightly bigger than non-plant one;Later period the disparity enlarge,the organic matter in the wasterwater plant system is bigger than the nutrient solution system far,later period the disparity reduces.The disparity of the non-plant system in later period reduces gradually.2Three microorganisms(Bacteria,Fungi, Actinomyces) in the non-Cr6+stress condition as the tendency a long with the time which increases with steady steps,the increase tendency reduces under20mg/L Cr6+stress condition,even few negative growths.Microorganism under the stress of40mg/L Cr6+receives the bigger pressure, showed a significant negative correlation.Urease activity in the plant system was significantly higher than the non-plant system,subject to heavy metal stress conditions,urease activity decrease as Cr6+concentration increase and non-plant systems urease activity change trend is similar to the plant system,but the degree of inhibition in the plant system is significantly smaller than the non-plant system.3Effective state of Chromium in the upper layer of plant system is more than the middle and lower layer, the rhizosphere environment is conducive to transformation of other forms to effective state,help plants to absorb chromium and reduce the toxicity of chromium in water..Chromium exchangeable(Fl) and the residual fraction(F5) accounted for the major part of various forms of chromium in different time, continuous add Cr6+let the chromium of effective state at a high level,the system with high concentrations Cr6+has been in an unhealthy operating environment which is not conducive to effect of the sustainable operation of the constructed wetland.Non-plant system change tendency is not remarkable.