| The mining wastelands destroy and take up a great deal of land resources, increasingly turn the confliction worse which our country have so many person but little land. The disposition of mining wastes brought a series of profound environment problem. In our country strengthen the restoration of the mining wastelands is much more urgent. The eco-environment was seriously damaged by the indigenous zinc smelting in Northwestern Guizhou Province. The waste residue were discarded everywhere, on the slope and the river side, making many tilth can't cultivate; The weathering, oxidation, and leaching of these residues also endanger to the water environment around the zinc smelting areas. The mining wastelands result to the ambient atmosphere, soil and the water environment to be seriously polluted, so the restoration treats and vegetation recultivation in the zinc smelting areas is urgent.This study explored the feasibility and existed problem of heavy metals pollution control by the sewage sludge, based on the investigation of Pb/Zn smelting area pollution in Northwestern Guizhou Province. By drawing lessons from the experience making use of sewage sludge, the pot experiment were performed to identify the effects of sewage sludge amended with coal fly ash at different ratio on Pb/Zn smelting slag, and the effects of different treatment on the growth, alimentation condition and the accumulation of the heavy metals in the plant. This study also discussed the foreground of the restoration of the mining wastelands by sewage sludge amended with coal fly ash, and provided a gist for the land use of sewage sludge and coal fly ash, attained the purpose of making use of these solid waste resourceses without polluting environment. Under this experiment condition, the main results obtained were summarized as follows:1.The heavy metals content in Pb/Zn smelting slag of Northwestern Guizhou Province is very high, the mean of Zn, Cd, Pb and Cu is 12310.39 mg·kg-1,79.08 mg·kg-1, 2626.63mg·kg-1, and 183.90 mg·kg-1, respectively, which resulted in high content in soil hereabout. The content of Zn, Cd, Pb and Cu in studied soil is higher than the means of Zn, Cd, Pb, and Cu of A layer in China. Zn, Cd, Pb and Cu in studied soil all exceed the Environmental Quality Standard for Soils (GB 15618-1995), while Cu pollution is less serious compared to Zn, Cd and Pb. And the heavy metals content in plant and crop in studied smelting area are higher than the Maximum Levels of Contaminants in Food, which has potential threat to the eco-environment and the mankinds in the Zn smelting areas. Therefore, we must manage with the improvement and restoration of the polluted soil.2. Using the sewage sludge to improve Zn smelting slag, when the sewage sludge content is lower, it can stabilized the heavy metals; but when the sewage sludge content is higher, it results in higher organic matter which will mobilize heavy metals in Zn smelting slag. Therefore, caution must be taken when sewage sludge is used in discarded land restoration. The appropriate ratio of sewage sludge to Zn smelting slag just can partially immobilize heavy metals in Zn smelting slag. This pot experiment shows that the sewage sludge is helpful to immobilize heavy metals(Zn,Cd,Cu) in Zn smelting slag when the ratio of Zn smelting slag to sewage sludge is 2:1 and 1:1.3. While the ratio of sewage sludge to Zn smelting slag is increased, the salinity is also increase. When the ratio of Zn smelting slag to sewage sludge is≥2:1, the salinity in experiment samples has slightly influence to the maize germination rate, but will not inhibit the growth of maize; When the ratio of Zn smelting slag to sewage sludge is < 2:1, it inhibits the maize germination rate, the growth of maize seedling and root. The research also indicates the coal fly ash can reduce salinity harm to maize growth.4.The pot experiment identified the treatment is comparatively in favor of the maize growth which Zn smelting slag:(sewage sludge + 50% coal fly ash) is 2:1, and this treatment is comparatively in favor of controlling the heavy metals(Cd,Pb) transfer to the plant. This indicates the appropriate ratio of sewage sludge amended with coal fly ash is favorable to the growth of maize.It can improve the leanness condition of the Zn smelting slag wastelands, keep the growth of maize, it also has a mitigable function to the poison of heavy metals.5. Under experiment condition, it can obtain a conclusion that the treatment of Zn smelting slag: (sewage sludge + 50% coal fly ash) being 2:1 is suitable maize growth.
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