Study And Application On Treatment Of Typical Heavy Metal Pollutant By Fluidized-bed Fenton Process

With the rapid development of industry,the pollution of heavy metal wastewater is becoming more and more serious,posing a threat to the ecological environment quality and human health.Therefore,it is necessary to develop an efficient treatment for heavy metal removal.As a new type of water treatment process,Fenton fluidized-bed can simultaneously realize the high-efficiency degradation of organic pollutants and the crystallization of iron ions under acidic conditions.Iron oxide layer is formed on the surface of the carrier during the process of iron crystallization,which has a good removal effect on heavy metals.In this paper,the iron crystal carrier produced by the Fenton fluidized bed process was used to study the removal of typical heavy metals（arsenic and lead）,the fluidized removal law and mechanism of the target heavy metal ions in the Fenton fluidized bed system was investigated additionally.The exploratory application treatment study has also been completed on simulated arsenic-containing industrial wastewater.The main results are as follows:（1）The iron oxides on the iron crystal carrier existed in the form of Fe OOH,and its surface hydroxyl group could realize the retention of heavy metals.When the amount of carrier was 50 g and p H was 3,0.1 m M As O₄^3-could be completely removed within 1 h.It was speculated that the mechanism is mainly due to the bidentate binuclear complexation of As（Ⅴ）and iron oxide on the carrier surface.However,the iron crystal carrier has a low affinity for As（Ⅲ）.By introducing Fenton reagent(Fe²⁺+H₂O₂),As（Ⅲ）was oxidized to As（Ⅴ）which could be effectively removed.And the new surface formed by iron crystallization was lilunsconducive to the continuous fixation of arsenic in theory.（2）The removal of Pb²⁺by the iron crystalline carrier was mainly affected by the amount of the carrier and the p H.When the amount of the carrier was 250 g and the p H was6,the removal rate of Pb²⁺could reach more than 95%.In an acidic environment,only a small amount of Pb²⁺was immobilized by surface precipitation,and more was retained on the iron crystal carrier by surface adsorption.The law of simultaneous removal of lead and iron in the Fenton fluidized-bed system was also investigated,and it was found that the presence of iron ions inhibited the retention of lead on the iron crystal carrier to a certain extent.（3）Simulated arsenic-containing organic wastewater was obtained by adding arsenite into the actual comprehensive wastewater of an industrial park.A study on Fenton fluidized-bed long-term continuous flow treatment of simulating wastewater was carried out,and it realized the effective and stable simultaneous removal of COD,arsenic and iron.The initial p H,residence time,Fe²⁺/H₂O₂ dosage and other important operating parameters were investigated,and it was found that the COD removal rate was mainly affected by the initial p H and the amount of Fenton reagent.Appropriately reducing Fenton reagent dosage and increasing of residence time could improve the removal efficiency of As（Ⅲ）.The results showed that the Fenton fluidized-bed process has application value in the simultaneous degradation of organic pollutants and removal of arsenic.