Studies On The Key Process Of Combination Of Soil Fushing And Plant-extracting Technology To Remediate The Soil Arsenic

Leaching technology is an effective technique for repairing arsenic-contaminated soil, which has the advantages of high efficiency, short cycle, simple process and so on.However, there are also some shortage such as high cost, difficult collection and treatment of leachate, easy to cause secondary pollution, reduction of the leaching efficiency with the decreasing pollutants concentration in the soil and restrictive limitations by soil texture, and so on. Phytoremediation has the following advantages of such as fast growth of plant and wide distribution, applicability, low cost, and the controllability of secondary pollution, etc.. Therefore, phytoremediation technique could overcome the above disadvantages of leaching technology to a certain degree. This paper take the combination of leaching technology and phytoremediation remediation of As-polluted soil and to explore As environmental behavior in As-polluted soil at the combined remediation of plants-leaching arsenic bioremediation technology and its influencing factors. and it was aimed at comprehensive understanding of the critical process and various controlling factors of combined remediantion of soil washing-plant extraction for As-contaminated soil, and providing the theoretical basis for applications of leaching engineering technology of arsenic contamination. The main results were as follows.The study results showed that:(1) After8days different treatment, including rinsed in distilled water,10%KH2PO4leaching, the centipede grass+10%KH2PO4leaching and ryegrass+10%KH2PO4treatments arsenic content in non-rhizosphere soil from133mg/kg were reduced to130mg/kg,123mg/kg,115mg/kg and118mg/kg respectively, and reduced by2.5%,7.5%,13.5%and11.3%respectively; arsenic content in rhizosphere soil treated by the P. vittata+10%KH2PO4leachingand ryegrass+10%KH2PO4were reduced from133mg/kg to76.3mg/kg,86.2mg/kg, and reduced by42.6%and35.1%, respectively; centipede grass-leaching jointrepair technology to some extent overcome the scope, cost-effective and leaching efficiency of the soil washing technology, and also solve the problems of long life cycle, low efficiency problem of single phytoremediation.(2)After30days different treatment, centipede the grass+10%KH2PO4leaching treatment for a soil rsenic removal, amounted to47.0%, arsenic content of the upground part and underground part of the centipede grass were increased than by6.8times and3.2-times respectively, and its biomass accumulation increased by5.4-times in plant. the treatment of P. vittata+10%KH2PO4leaching could promote the leaching and plant enrichment of soil arsenic.It make the soil loosely bound arsenic, aluminum bound arsenic and iron bound arsenic increased by11.7%,5.2%and4.5%, and the calcium bound arsenic and the residual arsenic decreased by22.8%and1.1%, respectively. The leaching-plant bioremediation technology also gradually changed soil water pH from acidic to alkaline (6.0-8.0), and increased nitrogen, phosphorus and potassium content in soil leaching water.(3) The iron oxide+activated carbon (V:V=1:1) treatment had the best effiency for removing arsenic in the arsenic leachate and its removing rate reached100%, the material has the advantages of high efficiency, low cost, repairing arsenic contamination better waste materials. When considering the leachate barrier material screening, screening arsenic removal plants, the eluent concentration screening and their combined effect seems comprehensively, iron oxide+activated carbon (V:V=1:1) as a leachate barrier material, centipede grass+10%KH2PO4leaching treatment is a treatment for arsenic contamination joint repair.