Stabilization/solidification of heavy metal contaminated sediment using cement, fly ash and DTCR
- Received Date: 10/02/2012
- Accepted Date: 08/11/2011
- Available Online: 18/03/2013
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Key words:
- heavy metal /
- contaminated sediment /
- cement /
- fly ash /
- DTCR /
- compressive strength /
- leaching concentration
Abstract: A cement-fly ash-dithiocarbamate(DTCR)system was used to solidify and stabilize (S/S) river bottom sediments containing heavy metals, the optimum conditions were selected by testing of compressive strength and leaching toxicity. The results demonstrated that with the dosage of cement increased, compressive strength of the solidified products was also enhanced, but the concentration of heavy metals in leachate decreased. When the ratio of cement to dried sediment reached to 0.6, the compressive strength of the cement solidified products (after 7 d) was higher than the standard value of 0.98 MPa. Further studies showed that the compressive strengths of solidified products from 7 d and 28 d were 1.2 MPa and 2.7 MPa, respectively, when the mass ratio of cement∶ flyash∶ sediment was 0.54∶0.06∶1.0, however the leaching concentration of heavy metal increased. When cement∶flyash∶DTCR∶sediment was 0.54∶0.06∶0.012∶1.0, the compressive strengths of solidified products from 7 d and 28 d could reach to 1.1 MPa and 2.1 MPa, respectively. And after handled with the acetic acid buffer solution method the leaching concentration of Cd, Pb,Zn and Cu were 0.102, 0.189,0.180 and 0.033 mg/L, respectively.