Study On Deactivating Heavy Metal In Sludge By Modified Fly Ash And Application On Agriculture

Firstly,this paper discussed the feasibility of modified fly ash deactivat the heavy metal in sludge and application on argriculture on the basis of test for basic physical and chemical properties of fly ash. More than at home and abroad by reading related literature, the optimal development of modified fly ash preparation programs, preparation of modified fly ash, through the passivation experiments, analysis of modified fly ash to the sludge of heavy metals Pb, Cu, Cd's passivation effect and the impact of physical and chemical properties of sludge, and the mechanism of passivation were studied; through the soil column leaching test, analysis of the passivation of heavy metals in sewage sludge on soil Pb, Cu, Cd form and the impact of nutrients , according to experimental results to discuss the application of passivation sludge in the agricultural viability; of original fly ash and fly ash modified for SEM, XRD, specific surface area analysis, discussion of modified fly ash to absorb heavy metals in soil effective The main reason state reaction and modified internal structure of fly ash produced by the specific impact. The main conclusions are summarized below:â‘ The city sludge for the test, regardless of organic matter, total N, the entire content of P in soil are much higher than the corresponding ingredients. However, a higher sludge containing heavy metals are also Pb, Cu, Cd, in particular Pb, Cu, up to 2400.0mg ? kg-1, 460mg ? kg-1, far beyond the standards of China's agricultural sludge. Therefore, the provision of organic matter from sludge and N, P nutrient point of view, for the sludge is an excellent test of fertiliser, has a higher value. However, its high heavy metal content to limit their use, so in the use of this sludge, it is important to pre-treatment. For the test of fly ash containing high SiO2 and Al2O3, respectively, as high as 50.3% and 23.20%, and also because of fly ash as a combination of spherical particles, mainly glass, silicon constitute a zeolite, aluminum centering on a certain law of spherical particles was distribution will help in the fly ash coated layer formed on the surface of zeolite, therefore, of fly ash chemical composition and structure of fly ash have been modified so that the material basis. After passivation of the modified fly ash of municipal sewage sludge, as a result of the internal pH, DOM and other factors change, so that heavy metals in municipal sewage sludge into a bio-effective state of steady-state, reducing the possibility of contamination of agricultural soils; municipal sludge internal structure, and the modified fly ash changed the resistance of municipal sewage sludge and other reasons, so that after passivation also has some sludge adsorption and thus the heavy-metal contamination in the soil also has a certain degree of adsorption.â‘¡More than at home and abroad by reading related literature, the optimal development of modified fly ash preparation programs, including the choice of cosolvent, fly ash and the ratio of cosolvent, modified temperature, modified time, preparation of modified powder ash, by passivation, soil leaching simulation, three types of modified fly ash to sludge and heavy metals passivation performance comparison, three kinds of modified fly ash to the sludge in the Pb,Cu,Cd has a certain passivation effect,which,NaOH modified fly ash to the sludge in the Pb,Cu,Cd passivation effects are very good.This effect can be modified fly ash from the micro-structure analysis:First of all,a lot of modified fly ash with a specific surface area than the original fly ash 31~67-fold increase,it has a strong physical adsorption capability.At the same time makes enhanced chemical adsorption.Modified reaction of fly ash increase in the number of internal voids,gaps in the surface roughness change,addition,modification of fly ash generated aluminum silicate and silicate-type ion-exchange has a strong performance,with the sludge of occurrence of ion exchange adsorption of heavy metals,and generally do not reversible.At the same time modified fly ash is also conducive to the strong alkaline precipitation of heavy metals in sludge.â‘¢Will passivation soil sludge used for agricultural fertilization,the Chengdu Plain simulated acid rain,heavy metals from soil and soil fertility patterns before and after the changes in content analysis,three kinds of passivation of sludge on soil Pb,Cu,Cd adsorption biological effective state ability to compare the actual situation must be analyzed under the comparison,because the passive role of the soil environment pH,humus content,soil sticky, soil temperature,as well as other heavy metals content.Passivation three sludge effects on soil fertility analysis results for:BaCO3 passivation of modified fly ash to improve soil fertility effects of sludge on the more obvious, according to the Chengdu Plain soil status,BaCO3 passivation modified sludge fly ash used in the Chengdu Plain soil is very suitable for the status quo. â‘£By modified fly ash to the analysis of economic and social benefits,proved to be modified fly ash with the use of broad prospects.