Investigation On The Stabilization Of Heavy Metal And The Degradation Of PAHs In Sediment

In general,contaminated sediment can do harm to water quality and aquatic ecosystem, and then have a negative influence on production and life of human being. Considering that the in-situ remediation of contaminated sediments would confront with the problems of reducing the water storage capacity and hampering the voyage,dredging is necessary sometimes. Because contaminated sediment contains heavy metal and such organic pollutant as PAHs, it can result in secondary pollution if not be treated properly.The effect of immobilization materials, such as CaO, M1 (one kind of Mg colloid) and different phosphate, on the heavy metal stabilization treatment in sediment were investigated in this paper. This paper also focused on the effect of different additives ,such as surfactant(TW-80, Soybean Lecithin), nature carbon source (sawdust, Os), chemical carbon source(sodium acetate, sodium lactate), spent mushroom compost, aged refuse,urea and zero-valent iron, on the removal of Phenanthrene (PHE)and Anthracene(AN) in Sediment . CaO and M1 had the ability to the stabilization of Zn,Pb,Ba and Mn. After the treatment of 75 g CaO per kilogram sediment, 72.8 % of Zn, 67.6 % of Pb, 34.9 % of Ba and 94 % of Mn were reduced when compared with the untreated sediment. After the treatment of 200 g M1 per kilogram sediment, 85.1 % of Zn, 76.1 % of Ba and 99 % of Mn were reduced, meanwhile the concentration of eluted Pb was decreased more than 95 % over the untreated control.In the research of stabilization of heavy metal with phosphate, when the addition amounts of MAP (NH4H2PO4), MCP (Ca(H2PO4)2), DAP ((NH4)2HPO4), MSP (NaH2PO4) were 100 g/kg, 70 %-85 % of eluted Zn, 40 %-90 % of eluted Mn were decreased and more than 95 % of eluted Ba were also declined. In addition, by the treatment of MAP, MCP, DAP, MSP, the concentration of eluted total phosphorus were markedly increased, which may result the environmental risk.The transfer rate of PHE and ANT increased linearly with time, they were dramatically reduced at the present of air drying aged refuse(DAR). However, the addition of DAR could not promote the degradation rate of PHE and ANT during 40 days. Fresh aged refuse(FAR) can retain a higher dehydrogenase activity (DHA) and a larger degradation rate of PHE and ANT in the condition of water-flooded than non-water-flooded. In the anaerobic environment, the addition of FAR can improve the degradation rate of PHE and ANT in sediment.From the result of the effect of different additives on the removal of PHE and ANT in the anaerobic environment, the DHA of sediment was dramatic increased with addition of SL,sodium acetate,sodium lactate and SMC. Os and sawdust enhanced the degradation rate of PHE and ANT in sediment , the degradation rates of PHE and ANT were increased 19.2 % and 11.7 % respectively with addition of 2 % Os, and these were enhanced 14.4% for PHE and 7.5 % for ANT with addition of 1 % sawdust compared with the untreated sediment during 30 days. Sodium acetate and sodium lactate increased the degradation rate of ANT notability, the degradation rates of PHE and ANT were increased 12.9 % and 53.4 % respectively with addition of 40mM/kg sodium acetate, and these were enhanced 18.2 % for PHE and 62.6 % for ANT with addition of 40 mM/kg sodium lactate compared with the untreated sediment during 30 days. And the degradation of PHE and ANT can be improved considerably with addition of SMC, the degradation rates of PHE and ANT were increased 34.8 % and 52.7 % respectively with addition of 10 % SMC compared with the untreated sediment during 30 days. Zero-valent iron can improve the removal of PHE and ANT to a certain extent, the removal rate of PHE and ANT were increased 13.1 % and 6 % respectively with addition of 1 % zero-valent iron compared with the untreated sediment during 30 days.