ADSORPTION CHARACTERISTICS OF SOLUBLE HEAVY METALS IN ANAEROBICALLY DIGESTED SEWAGE SLUDGE UNDER ACIDIC CONDITIONS BY FIBROUS CHELATING AGENT

Abstract

 In this study, with the aim of developing a method for removing harmful heavy metals from anaerobically digested sewage sludge by using solid chelating agents, the effects of reaction time and pH on the adsorption of soluble heavy metals in acidic simulated wastewater and anaerobically digested sewage sludge were investigated by using a fibrous chelating agent. First, in an adsorption experiment with simulated wastewater, it was found that the chelating agent could adsorb heavy metals in about 1 hour, and fully exerted its adsorption effect when the pH is higher than or equal to 3. Next, in the adsorption experiment of heavy metals eluted by acidifying the sewage digested sludge (pH = 2), the amount of heavy metals adsorbed to the chelating agent was increased by increasing the pH from 2 to 2.5 or 3, although re-adsorption of Cu and Pb to the sludge solid also occurred. Adsorption of heavy metals to chelating agent was observed even at pH 2, indicating that soluble heavy metals could be adsorbed and removed from anaerobically digested sewage sludge using a solid polymeric chelating agent even under strongly acidic conditions.