Abstract:The red mud was dealkalized by microbial dealkalisation, and the neutral red mud residue after dealkalization was used as an adsorbent to treat lead-containing wastewater. Under the suitable conditions, the single dealkalization rate of red mud reaches 30.2% with the breeded Bacillus fuscus miliaris from red mud, and the total dealkalization rate of red mud can reach 75.8% after 5-stage addition of bacteria, and the pH value of dealkalized residue is stable at 6.68. The experiment of adsorption of heavy metal lead by the dealkalizsed red mud residue was carried out. The results show that the adsorption rate of 100 mg/L Pb(Ⅱ) solution is about 80% under the conditions including dosage of dealkalized slag of 1.0 g/L, adsorption temperature of 30 ℃, pH value of adsorbent of 6.5, and adsorption time of 180 min. The theoretical saturated adsorption capacity of the dealkalized slag is 461.43 mg/g. The adsorption of Pb(Ⅱ) by the microbial dealkalized slag of red mud conforms to the quasi-secondary model, the chemical adsorption process playes a dominant role, and the process is spontaneous. After adsorption of Pb(Ⅱ) from red mud dealkalization slag, Pb(Ⅱ) mainly exists in the form of PbCO3, Pb(OH)2 and Pb(Ⅱ)-Complex.