Abstract
The present study focused on the synergistic effects bioremediation of phenol in aqueous solution using combination of anaerobic mixed culture and Granular Activated Carbon (GAC) as a biological GAC (BGAC). Meanwhile, the effect of contact time and various phenol concentrations on adsorption and biosorption process investigated. The phenol concentration was analyzed using UV/Vis spectrophotometer. The morphology and structure of two adsorbents (GAC and BGAC) were characterized by FESEM and BET specific surface area analysis. The batch experiments using mixed bacterial culture, isolated from wood and paper factory wastewater, were adapted to high concentrations of phenol and employed in order to evaluate the tolerance and biosorption capability of microorganisms for phenol biodegradation. The synergetic effect of phenol removal using combination of GAC with an anaerobic biofilm indicated that the removal efficiency for concentration of 700, 800, and 1000 mg/l at initial stages increased to 4, 10, and 12%, respectively and while by increment of the retention time did not shown significant impact on the removal efficiency. These results conducted both desorption of adsorbates due to biotransformation in the aqueous solution and direct assimilation of adsorbates on GAC by the microorganism’s biofilm. The adsorption data were fitted with pseudo-first-order and pseudo-second-order models and it was found that the pseudo-second-order model explains the adsorption kinetics more efficiently. The compatibility of the Freundlich and Langmuir adsorption models to equilibrium data were investigated. In fact, the Langmuir isotherm was found to be the best fitting isotherm.
Highlights
Phenolic compounds are priority pollutants with high toxicity even at low concentrations and beside the toxic effects, phenolic compounds create an oxygen demand in receiving waters, and impart taste and odor to water with minute concentration of their chlorinated compounds [1]
The results indicated that 84 to 90% of phenol was adsorbed within a period of initial 2 hours, and that the removal efficiency increases with increasing contact time
The present study shows that phenolic contaminated wastewater was effectively treated in anaerobic slurry batch reactor with Granular Activated Carbon (GAC) and combined with anaerobic bacteria attached on GAC as Biological GAC (BGAC)
Summary
Phenolic compounds are priority pollutants with high toxicity even at low concentrations and beside the toxic effects, phenolic compounds create an oxygen demand in receiving waters, and impart taste and odor to water with minute concentration of their chlorinated compounds [1]. A wide variety of methods have been proposed for the treatment of wastewater contaminated with phenolic compounds like oxidation [7], precipitation [8], ion exchange, solvent extraction [9], evaporation [10, 11], electrocoagulation [12] and adsorption [13, 14]. Micropollutants are concentrated on the GAC surface, which results in an increased contact time between the compounds and microorganisms [24]. The aims of this research were to compare the adsorption and biosorption of high phenol concentrations using Granular Activated Carbon (GAC) and Biological GAC (BGAC) in anaerobic slurry batch reactor and their synergistic effects. The effect of initial phenol concentration and contact time on the adsorption/biosorption process were evaluated. The morphology and structure of two adsorbent (GAC and BGAC) were characterized by FESEM and BET specific surface area analysis
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