Exploration of heavy metal uptake potential of three algal strains/consortia in suspended and attached growth systems

Abstract

Three different algal strains/consortia; Chlorella pyrenoidosa (CP), consortium of Chlorella pyrenoidosa and Phormidium (PA6) and consortium from Hauz Khas lake (HL), were studied for their potential in heavy metals' bioremediation. Batch experiments (HRT-6 days) were performed in two different modes of algae cultivation systems; suspension and attached biofilms. The study aimed to highlight the suitability of an algal strain/consortium to different cultivation systems for metal removal and biomass production. The six commonly found heavy metals in wastewater; Cd, Cr, Pb, Cu, Ni and Zn, were used for the study. The selected algae were tested for its performance on individual and multiple metals contaminants. In individual metal spiked cultures (suspension), the common heavy metals that were uptaken efficiently by the three algal strains/consortia were Zn, Pb, Cu and Cd (>55%). Zn was uptaken >80% in all these test cultures. In mixed metal spiked suspension systems, all the metals were uptaken >60% by PA6 only. In mixed metal spiked attached systems, except for Cr, all other metals were uptaken efficiently by PA6 in the order Zn > Ni > Cd > Pb > Cu in the range of 78–98%. HL and CP performed best in suspension systems with individual metal spiking. PA6 performed better than HL and CP in mixed metal spiked media, especially in attached systems. The uptake of multiple metals from a variety of effluents can be done using PA6-like consortium (preferably in attached systems), whereas in effluents where only a single metal is present, CP/HL-like consortium can be used in suspended cultures.