Different Additive Treatment Sludge Experimental Study Of Agricultural Resource

Sewage sludge is an inevitable outcome from wastewater treatment plant, and there is a dramatic increase in the sewage sludge. It may play a positive role for soil-plant system, for lots of nutrients and organic matter contained in sewage sludge. However, there are harmful substances in sewage sludge, such as harmful heavy metals, so sewage sludge should be treated properly before being used in agriculture.The pot experiment was carried out to investigated the effect of sewage sludge by modified fly ash, quicklime, cement on amount of TN, TP and heavy metals in lettuce and chilli. The results showed that:(1) Soil modified sludge increased the TN, TP and heavy metal in soil. Because TN and TP is0of fly ash, quicklime and cement, changes of TN and TP of soil is not obvious with the sludge content added. There is no effect of Fly ash, quicklime and cement on Fe, Mn in soil. The passivation of quicklime and cement to effective Zn was obvious in the treatment of1%sewage sludge; the slight passivation of quicklime to Cu was occurred in the treatment of3%sewage.(2) Application of sewage sludge could increase the yield of lettuce, and the yield was highest in the treatment of3%sewage and10%fly ash. The concentration of TN, TP and Fe, Mn, Cu, Zn, Cd in lettuce was increased with the increasing of sludge applied. The concentration of Mn in lettuce was reduced with the increasing of fly ash and quicklime.In the treatment of1%sludge, application of quicklime could reduce the concentration of Cu and Cd, while in the treatment of3%sludge, application of fly ash could reduce the concentration of Zn and Cd. After harvesting lettuce, the concentration of TN and TP in soil in the treatments of sludge was higher than that in CK. The passivation of fly ash and quicklime to the Cd was obvious.(3) Sewage sludge could increase the yield of pepper, and the yield was highest in the treatment of3%sewage and5%fly ash. The concentration of TN and TP in chilli was increased with the increasing of sludge. The concentration of Cd in chilli was reduced with the increasing of fly ash. In the treatment of1%sludge, application of cement reduced the concentration of Mn in the treatment of1%, while in the treatment of3%sludge, application of Fly ash reduced the concentration of Cu、Zn and application of quicklime reduced the concentration of Mn and Cd in chilli. The passivation of fly ash to Cd and the passivation of cement to Mn were obvious in the treatment of1%sludge. The passivation of fly ash to Cu and the passivation of quicklime to Zn and Cu was obvious in the treatment of3%sludge.Application of sludge increased vegetable yield and the amount of TN and TP. With the prolongation of passivation time, the effect of passivation on heavy metals would change. Considering vegetable growth and heavy metal toxicityapplication of3%sludge with10%fly ash to soil was reasonable for planting lettuce, and3%sludge with5%fly ash was reasonable for planting pepper.