Continuous microbial Pb removal by an industrially obtained consortium using an upflow anaerobic sludge blanket reactor

Abstract

The objective of the research outlined in this article was to gain a deeper understanding of the microbiome involved in the bioremoval of Pb under continuous flow conditions. A continuous lead removal system, utilizing an upflow anaerobic sludge blanket reactor (UASB) was employed to remove Pb(II) while monitoring factors such as microbial growth along with Pb(II) and nitrate concentrations at two axial heights in the system. The microbiome was assessed to identify any alterations resulting from changing the amounts of Pb(II) in the reactor feed. The UASB was operated under anaerobic conditions, and a nutrient-rich broth comprising exclusively of 5 g/L yeast extract (YE) along with 1g/L of sodium chloride (NaCl) served as the growth medium. The results indicated an effective, robust method of Pb(II) removal. In this study the growth medium was spiked with: 80, 500 and 1000 ppm of Pb(II). The results showed that lower concentrations of Pb(II) were effectively removed with only 5 g/L YE, suggesting a cost-effective option for Pb(II) bioremoval. A maximum Pb-removal rate of 350.6 ppm/d Pb(II) and a maximum specific growth rate of 2.25 per day were observed. Increased concentrations of Pb(II) resulted in reduced metabolic activity (MA) and Pb removal. As is, the system is able to achieve approximately 100% of lower concentrations of Pb and increasing the yeast extract concentration could improve the system. This is the first known study conducted on a continuous flow column Pb(II) removal system. It provides a basis towards developing methods to remove lead (and by extension other heavy metals) which can be carried out at ambient temperatures. This study also provides basis for development of methods to recover and reuse lead from industrial effluents and lead waste sites.