A method for treating heavy metal wastewater

Abstract

This invention discloses a method for treating heavy metal wastewater, comprising: refluxing a portion of the filtrate into the raw water to be treated for mixing; sequentially adding a heavy metal precipitant and a magnesium source for reaction; adding a rate-controlled crystallization inducing composite agent composed of ammonium dihydrogen phosphate and sodium tripolyphosphate, and initiating a temperature and shear force cross-control program to smoothly raise the temperature and simultaneously decrease the stirring linear velocity before heat preservation and aging; and directly feeding the liquid into a filter press for solid-liquid separation without adding organic polymer flocculants. This invention utilizes thermodynamic desorption to induce heterogeneous crystallization of inorganic minerals on the surface of heavy metal colloids, forming an incompressible core-shell structured particle skeleton. This method effectively avoids heavy metal leakage caused by fine colloids penetrating the filter cloth, significantly reduces the sludge specific resistance and water content, and solves the problem of difficult sludge dewatering in conventional treatment processes.

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