Reading guidance：The use of sewage sludge in agriculture at present sludge disposal is an important way, however, sludge agricultural use is restricted by many conditions, the sludge for agriculture also has a certain

    The use of sewage sludge in agriculture at present sludge disposal is an important way, however, sludge agricultural use is restricted by many conditions, the sludge for agriculture also has a certain risk to the environment. Therefore, sludge agricultural use should be carefully chosen route. Effect of municipal sludge agricultural another important factor is heavy metal speciation and bio availability of. Presence of heavy metals in sewage sludge and soil more shape, only a part can absorbed by plants, the rest is fixed in the municipal sewage sludge and soil. In the evaluation of urban sludge effects of heavy metals should be mainly consider the content of the effective state.
    Agricultural utilization test found, after application of municipal sewage sludge, heavy metals in a considerable part of the combined with the organic form existence, but different heavy metals slightly different: CD often to the high activity of exchangeable and loosely combined organic form, and the two types of Pb proportion most small. Due to the exchange of state the most easy absorption and utilization by plants, followed by loose bound to organic matter and other forms often lower activity, from the morphological point of view of different heavy metal elements analysis, urban sludge in CD, Zn activity highest Pb activity lowest Cu center. Recent sludge agriculture and research results will also confirm that.
    In general, availability of heavy metals is relatively large, easily absorbed by crops. The activity of the relatively strong Zn as an example, the content of continuous application of city sludge after 2 years of heavy metals in the body. The results showed that the leafy vegetables heavy metal accumulation ability, fruit vegetables and food crops with city sludge are relatively safe. Heavy metals into the plants are mainly distributed in the roots, followed by stems and leaves, fruit or seed content is often the lowest. Scholars at home and abroad with lime passivation to city sludge, reduce the content of heavy metals. In the practical application of city sludge, if higher heavy metal content available, you need to take certain measures to reduce the environmental risk of heavy metals.
    Because of the environmental risk of heavy metal pollutants in its shape, so the formulation of national standards, if we can consider the speciation of heavy metals is more scientific. Therefore, in the formulation of land use standard of city sludge, if the conditions are ripe, and the total and available in 2 aspects of the index. However, in view of the present condition and analysis of heavy metals around the level of equipment our detection is different, some areas do not have the conditions for the determination of heavy metal forms, at the same time, the current understanding of the effectiveness of heavy metal sludge in the city there is a big limitation, so from the perspective of management, the land use of city sludge in the standard can not consider the speciation of heavy metals.
 

：Use extracting chemical reagent to eliminate heavy metals in sludge ：Disposal and utilization of sludge at abroad; Perfect relevant standards to control heavy metal