The Remediation Research Of Cu And Cd Contaminated In Wastewater Irrigation Farmland

Currently, the pollution caused by heavy metals in irrigation is more and more serious. Long-term accumulation will cause pollution to groundwater and plant.It is also harmful for the human health. So soils with heavy metals to repair is great significance.The pot experiment designed to study the repair agents for Cu and Cd in contaminated soils by bentonite and biomass ash and the enrichment of Cu and Cd in corn and lolium multiflorum. It is also study the adsorption behavior of Cu and Cd by the two repair agent and the soil by adding different combinations of the repair agent. The conclusions as followings:(1) The pot experiment shows that Maize and Lolium multiflorum both accumulate Cu and Cd. After adding5%bentonite and biomass ash, the accumulation of Cu and Cd has a degree of reduction. The Cu content in corn reduces by5%and8%after adding bentonite and biomass ash respectively. The Cd content in corn reduces by11%and18%after adding bentonite and biomass ash respectively. The Cu content in lolium multiflorum reduces by6%and12%after adding bentonite and biomass ash respectively. The Cd content in lolium multiflorum reduces by9%and12%after adding bentonite and biomass ash respectively.(2) The Cu, Cd distribution in the body of corn is:foot>leaf> stem>grain. The Cu conten in the corn's foot is0.405-0.698mg/kg.And in the maize is just0.012-0.081mg/kg which is lower than the limit of Cu in food hygiene standards (10mg/kg). The Cd conten in the corn's foot is0.261-0.553mg/kg.And in the maize is just0.009-0.020mg/kg which is lower than the limit of Cd in food hygiene standards (0.05mg/kg). The enrichment of Cu and Cd in corn is mainly concentrated in the roots.And seeds meet food requirements. So we can use corn as the enrichment plant to repair the heavy metal pollution soil.(3) The adsorption isotherm shows that:The fitting correlation of Langmuir equation is highest than Henry models, Langmuir equation, Freundlich equation and Temkin equation. The maximum adsorption capacity of Cu in biomass ash, bentonite and Inner Mongolia soil is11.262mg/g,9.524mg/g and7.163mg/g respectively. The maximum adsorption capacity of Cd in biomass ash, bentonite and Inner Mongolia soil is11.491mg/g,10.518mg/g and9.401mg/g respectively. The adsorption capacity is: biomass ash> bentonite.(4) The results of Cu and Cd adsorption experiments when the soil add different combinations of repair agent show that the maximum adsorption capacity of Cu is8.625mg/g,8.056mg/g and7.613mg/g when adding5%,3%and1%bentonite respectively. The maximum adsorption capacity of Cu is9.061mg/g,8.359mg/g and7.712mg/g when adding5%,3%and1%biomass ash respectively. The maximum adsorption capacity of Cd is10.238mg/g,9.923mg/g and9.753mg/g when adding5%,3%and1%bentonite respectively. The maximum adsorption capacity of Cd is11.046mg/g,10.089mg/g and9.719mg/g when adding5%,3%and1%biomass ash respectively. The adsorption capacity is:5%bentonite>3%bentonite>1%bentonite,5%biomass ash>3%biomass ash>1%biomass ash.