Treatment agent and method for removing hexavalent chromium in sludge

Abstract

The invention provides a treatment agent and method for removing hexavalent chromium in sludge. The treatment agent comprises a Portland cement clinker, an aluminate cement clinker, fly ash, gypsum and a carbonate, and also comprises auxiliary agents such as a silane coupling agent, wherein a mass ratio of the Portland cement clinker to the aluminate cement clinker to the fly ash to the gypsum tothe carbonate to the silane coupling agent is 100:20-120:5-40:4-8:0.1-5:0.1-0.4. The above components are all readily available industrial-grade substances, and the preparation process is simple. Whenthe above-mentioned treatment agent is used to remove hexavalent chromium in sludge, the hexavalent chromium in the sludge replaces or partially replaces acid radical ions SO4<2-> in a sulfur reaction product of the Portland cement clinker and the aluminate cement clinker, and enters ettringite crystal lattices to form chromium-containingettringiteC3A.3(CaSO4.CaCrO4).32H2O and a chromate mineralC3A.3CaCrO4.32H2O with an ettringite structure, and thereby the pollution activity of the hexavalent chromium in the sludge is eliminated, and the purpose of environmental protection is realized. During the curing period, the sludge is continuously solidified and has certain strength, and thereby landfill requirements are met.

Description

technical field [0001] The invention relates to the technical field of environmental protection, in particular to the technical field of removing hexavalent chromium in sludge, and more specifically to a treatment agent and method for removing hexavalent chromium in sludge. Background technique [0002] The rapid development of urbanization has led to an increase in the amount of urban sewage treatment year by year, and the disposal of sludge generated in the process of sewage treatment is an unavoidable practical problem, especially high-water sludge containing hexavalent chromium (generally refers to the sludge with a moisture content of ~96%) sludge). Sludge has the characteristics of small solid particle size, good suspension, high water content, bulky volume, and complex components. At the same time, sludge also contains a large amount of organic matter, a large number of pathogenic bacteria, salts, and heavy metals such as hexavalent chromium. These are harmful substa...

AI Technical Summary

Problems solved by technology

Due to the large amount of sludge to be treated and the complex composition, the existing treatment methods have problems such as difficult treatment of adsorbents or adsorbents

The reduction treatment method will add other substances such as sulfate radicals to the sludge while reducing hexavalent chromium, and the difficulty of sludge retreatment will increase; the portland cement treatment method uses the ettringite generated by its hydration to capture hexavalent chromium, Minerals are formed by replacing sulfur with hexavalent chromium, but because the amount of ettringite in Portland cement is low, and the capture amount of hexavalent chromium is greatly affected by the content of gypsum, it is difficult to capture ettringite under the condition of gypsum saturation Hexavalent chromium is difficult to apply in practice

Images