Migration and transformation of phosphorus during pyrolysis process of sewage sludge

doi:10.11949/j.issn.0438-1157.20171509

Abstract

Abstract:

The migration and transformation of phosphorus in sewage sludge during the pyrolysis process were studied based on standard measurement testing (SMT), analyzing the phosphorus in the treated sludge samples using nuclear magnetic spectrum and X-ray diffraction, and also the occurrence and distribution of phosphorus in the residue of the sewage sludge sample after pyrolysis. From the results obtained, with increasing heat treatment temperature, the organic phosphorus continuously transformed to inorganic phosphorus. Phosphorus was concentrated in the residue of the sludge after pyrolysis when the pyrolysis temperature was below 800℃. With increasing pyrolysis temperature, the content of total phosphorus (TP), inorganic phosphorus (IP), apatite phosphorus(AP) in the sludge showed a trend of gradual increases, while the non-apatite inorganic phosphorus (NAIP) content indicated a trend of fluctuation with an increase and then decreases. The increase of pyrolysis temperature led NAIP transform into AP, and AP content reached the maximum in 800℃. XRD results showed that the main forms of NAIP in the sludge were aluminum phosphate and ferric phosphate. The content of calcium phosphate in the sludge sample increased with increasing temperature. From the results of ³¹P NMR, the orthophosphoric acid monoester was converted to orthophosphate after heating, and orthophosphate was the most stable form of phosphorus. After the heat treatment, phosphorus was mainly in the form of orthophosphate. The new understanding on phosphorus migration and transformation in the process of sludge pyrolysis was discovered, and the theoretical support for the harmless, resource utilization and phosphorus pollution control technology of sludge was provided.

Key words: sewage sludge, pyrolysis, phosphorus, migration of phosphorus

摘要：

采用SMT方法研究磷在热解产物中的赋存形态和分布。结果发现，热处理促进污泥中有机磷（OP）向无机磷（IP）转化。热解温度在800℃以下时，污泥中的磷富集在热解后的污泥固体中。随热解温度升高，污泥中全磷（TP）、无机磷（IP）和磷灰石无机磷（AP）的含量均表现出逐渐升高的趋势，非磷灰石无机磷（NAIP）含量则表现出先升高再降低的趋势。热解温度升高会促使NAIP向AP转化，800℃时AP含量达到最大。污泥中NAIP的主要存在形式为磷酸铝盐和磷酸铁盐，磷酸钙盐含量随温度的升高逐渐增加。污泥中正磷酸单酯和焦磷酸盐受热转化为正磷酸盐，热解后的污泥中磷基本以正磷酸盐的形式存在。该结论为污泥的无害化、资源化利用提供了理论支持。

关键词: 污泥, 热解, 磷, 迁移转化

CLC Number:

X703

MENG Xiangdong, HUANG Qunxing, YAN Jianhua, GAO Huaping. Migration and transformation of phosphorus during pyrolysis process of sewage sludge[J]. CIESC Journal, 2018, 69(7): 3208-3215.

孟详东, 黄群星, 严建华, 郜华萍. 磷在污泥热解过程中的迁移转化[J]. 化工学报, 2018, 69(7): 3208-3215.

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