Removing high concentration of nickel (II) ions from synthetic wastewater by an indigenous microalgae consortium with a Revolving Algal Biofilm (RAB) system

Abstract

This work is to evaluate the feasibility of using a revolving algal biofilm (RAB) reactor for nickel (Ni) removal from high strength industrial wastewater. The RAB reactor can grow an indigenous microalgal species consortium in a wastewater containing up to 5000 mg/L of Ni. The tolerance of RAB biomass to the high strength nickel was attributed to maintaining cells membrane integrity, which is possible due to its high amount of extracellular polymer substances (EPS). The RAB system also demonstrated a superior Ni removal performance with >90% Ni removal efficiency and 534 mg/L-day Ni removal rate. The advantage of RAB system in nickel removal over suspended-based system might be attributed to the high contents of EPS in RAB biofilm, given the fact that the extracellular nickel occupied 60% or higher of the total nickel in the RAB biofilm. The adsorption of Ni by the biomass harvested from the RAB reactors was also studied. The “biomass-physical-adsorption” was less effective than “growing-algae-while-removing-Ni” for Ni removal. Collectively, the results in this study demonstrated that the RAB reactor is a potential system for Ni removal from high strength industrial wastewater.