Study On Root Decomposition And Chromium Release Of Wetland Plant Coix Aquatica Under The Condition Of Domestic Sewage Irrigation

This study provides a theoretical support for further discussion of the re-release of chromium in the environment into the environment,the degree of secondary pollution caused by the environment,and whether the long-term operation of constructed wetlands still have efficient purification capacity.Plant wetland systems that were irrigated by two different waterflooding models(long-term flooding,intermittent water)under conditions of continuous run for 2 years with different concentrations of chromium(0 mg/L and 20 mg/L)The content and morphology of chromium in the barley,the growth status of the barley plant and the residual amount and morphology of chromium in the matrix,and the change of the chromium content and the chromium content in the root during the decomposition of the barley.In the first months when buried root decomposition,intermittent water(C)and water for a long time(J)died in two kinds of water model root decomposition rate is very high,then the root decomposition rate drop,after 3 months after buried root,root residue to eventually break down.Decomposition of chromium in the root of the weak acid extraction and can also square one change is more significant in the root,but does not change significantly oxidation state,state residue is relatively stable,the increase of content of the state is helpful to reduce secondary pollution to the environment of heavy metals.As the processing time is extended,transfer coefficient increases,Coix plant transport ability of chromium in water for a long time case,as the processing time is extended,transfer coefficient increases,also constantly improve the transport capacity.Intermittent water transfer coefficient of Coix will gradually decreases with time extend.As a result,more conducive to long-term water flooding Coix from the underground part of chromium element to the aboveground.In 0 mg/L,20 mg/L Cr concentrations,intermittent water to remove the matrix chromium content is 1.3 times of water for a long time.That intermittent water is advantageous to the Coix remove heavy metal chromium from the substrate.Different sewage irrigation condition,the continuous operation in 2 years of artificial wetland plants Coix can still effective removal of chromium content in matrix,and its own death decomposition root secondary pollution to the environment impact is low.