Treatment of zinc-containing wastewater by immobilized Chlorella-activated sludge symbiotic system

The removal efficiency of zinc ions from wastewater was researched using an immobilized chlorella-activated sludge symbiotic system as the adsorbent. The effects of various factors were analyzed, including the status of bacteria and algae, initial wastewater zinc concentrations, pH values, adding quantity of immobilized bacteria-algae balls and the volume ratio of bacteria and algae. The results showed that, Zn²⁺ removal efficiencies of the immobilized activated sludge system, immobilized chlorella system and the immobilized chlorella-activated sludge system were better than the suspended chlorella system, with the immobilized chlorella-sludge system being the highest; the removal rate of Zn²⁺ by the immobilized chlorella-activated sludge system reached 90.5% when the initial Zn²⁺ concentration was less than 100 mg/L; the optimal conditions for Zn²⁺ removal by the immobilized chlorella-activated sludge system are initial zinc concentration of 80 mg/L, pH value of 7, adding quantity of 80 mL, and volume ratio for bacteria and algae of 1:2.