Study On Cadmium Adsorption Effect And Mechanism Of Dewater Sewage Sludge Adsorbent

In order to solve the problem in treatment process of nickel smelting acid wastewatercontaining cadmium, such as long treatment procedure, the residual cadmium ion concentrationafter treatment is hard to reach the demand of discharge limit(GB25467-2010), two kind ofadsorbent, including alkali modified sewage sludge adsorbent and alkali extract polymer adsorbent,were prepared with dewater sewage sludge through the screening of preparation method. Thecadmium adsorption capacity of these two adsorbents was determined, and the cadmiumadsorption mechanism of adsorbents was studied as well. The adsorbent made from dewatersewage sludge was used in the treatment of nickel smelting acid wastewater containing cadmium,and the operation condition was investigated. The results show that the maximum cadmiumadsorption capacity of alkali modified sewage sludge adsorbent is0.966mmol/g, the adsorptionmechanism of this adsorbent was the comprehensive effect of ion exchange, electrostatic attractionand carboxyl group complexation. The maximum cadmium adsorption capacity of alkali extractpolymer adsorbent is1.022mmol/g, the main adsorption mechanism of this adsorbent was ionexchange effect of cadmium and calcium ion. The adsorbent combined with lime neutralizationmethod was applied to the treatment of nickel smelting acid wastewater containing cadmium, theresidual cadmium, copper and nickel ion concentration of effluent can reach the discharge limit ofGB25467-2010.