Immobilized biofilms on granular activated carbon for removal and accumulation of heavy metals from contaminated streams

Abstract

Biofilms consisting of a matrix of exopolysaccharide and microorganisms developed over granular activated carbon (GAC) enhance metal uptake from solution several times more than that achieved by GAC alone. By specifically employing GAC, there is also the opportunity of developing biofilm/GAC systems that can both entrap metals and also adsorb, and ultimately degrade, polluting organic residues such as pesticides. Targets for this type of process could be dump site leachates, mine tailings and other industrial wastes. The conditions under which the biofilm is developed, including pH and temperature have, therefore, been studied in terms of subsequent influence on metal bisorption.

Biosorption of heavy metals from aqueous solution using modified activated carbon: comparison of linear and nonlinear methods

“…carboxylate, phosphate and amino groups) on the fungal cell walls. 38,39 The carboxylate and phosphate groups carry negative charges which allow the microbial cells to be potent scavengers of metal ions. 38,42 The experimental results are presented in Fig.…”

“…4 pH was increased from 4 to 7.4, but this seemed to level off very close to the fungal cell walls when the pH was greater than 7.4. 23,24,38,39 It should be noted that the metal ion-binding properties of an alginate are primarily determined by its monomeric composition and the length of the G-blocks. 40 The interaction of heavy metal ions with both Ca-alginate and immobilised fungus preparations could be primarily related to the carboxylate groups of the Ca-alginate and the cell wall components of the mycelia.…”

“…One possible cause of reduction in the biosorption capacity of the ACFCA beads could be the adverse effects of the desorbing agent on the binding sites of the fungal cell wall components (10 mmol L −1 HCl/HNO 3 hydrolyses most of the bead macromolecules). 23,24,38,39 The regeneration of the beads shows that the biosorption/desorption process is a reversible process and that the beads can be used repeatedly for the removal of heavy metal ions from wastewater.…”

Biological Fixed‐Film Systems

“…Procedures were suggested to control biofilm growth and to use bioindicators to predict total organic carbon (TOC) and COD removal efficiencies, using the observed strong positive correlation between the abundance of some protozoa in the liquid phase of the BAC bed and COD concentration in the effluent. Scott and Karanjkar (1998) presented studies showing the benefits and effects of a matrix of microorganisms developed on GAC in enhancing metal uptake and degradation from solution. The conditions under which the biofilm developed, including pH and temperature were studied in terms of subsequent influence on metal biosorption.…”

A seasonal study of a passive abandoned coalmine drainage remediation system reveals three distinct zones of contaminant levels and microbial communities

“…Several studies have confirmed a strong microbial influence in passive remediation systems from both acidic and alkaline AMD (Bier, Voss, & Bernhardt, 2015;Jones et al, 2015;Senko, Wanjugi, Lucas, Bruns, & Burgos, 2008;Whitney, Tracey, & Jeanne, 2013). Bacteria can remove metals through adsorption to a surface, biosorption to biomass, immobilization, and precipitation, as has been successfully demonstrated in bioreactors (Chang, Hsu, Chiang, & Su, 2006;Diels et al, 1995;Scott & Karanjkar, 1998;Scott, Karanjkar, & Rowe, 1995;Travieso et al, 2002). They can also resolubilize metal precipitates, increasing soluble contaminant levels.…”