Microbial regeneration of spent activated carbon dispersed with organic contaminants: mechanism, efficiency, and kinetic models

Abstract

Intraparticle mass transfer resistance, incomplete regeneration, and microbial fouling are some of the problems needed to be addressed adequately. A detailed techno-economic evaluation is also required to assess the commercial aspects of bioregeneration.

Mechanistic investigation of industrial wastewater naphthenic acids removal using granular activated carbon (GAC) biofilm based processes

“…However, an incomplete bioregeneration of the GAC surface might occur due to the irreversible adsorption of organics in the micropores of GAC (Aktas and Cecen, 2007;Nath and Bhakhar, 2011). After entering the biofilm, NAs can either remain in the biofilm (bioadsorption) or adsorb to the GAC surface.…”

“…After entering the biofilm, NAs can either remain in the biofilm (bioadsorption) or adsorb to the GAC surface. Bacteria in the biofilm may then start the exoenzymatic degradation of NAs with the degradation byproducts either remaining in the biofilm or being released back into the solution (Nath and Bhakhar, 2011). The excreted exoenzymes by microorganisms diffuse into GAC activated carbon pores where they may react with adsorbed substrates.…”

“…The excreted exoenzymes by microorganisms diffuse into GAC activated carbon pores where they may react with adsorbed substrates. The products generated by hydrolytic decay of the adsorbed substrates may have a lower affinity for the activated carbon and therefore desorption of these enzyme metabolites from the GAC surface results in the renewal of adsorption capacity (Aktas and Cecen, 2007;Nath and Bhakhar, 2011). Although the current removals of NAs by the biodegradation process are relatively low, process optimization such as seeding of specific bacterial assemblages that degrade NAs and use of flow through reactors may increase the role of biodegradation in the bioreactor treatment process.…”

“…GAC treatment is an interesting alternative because of the high adsorption capacity for organics given its high surface area containing interconnected micropores, mesopores, and macropores (Sulaymon et al, 2013). However, a prolonged contact of GAC with wastewaters diminishes the available sites for adsorption of organic pollutants, eventually leading to the need for the adsorbent to be either replaced or regenerated (Nath and Bhakhar, 2011). Fortunately, the irregularity, roughness, and porosity of the GAC surface provides an excellent environment for the development and growth of bacterial biofilms (Yapsakli and Cecen, 2010).…”

Sorption of chlorophenols on microporous minerals: mechanism and influence of metal cations, solution pH, and humic acid

“…Among these sorbent materials, activated carbons are the most widely used and exhibit good adsorption capacities for many organic pollutants due to their porous structures and large surface areas (Aksu and Yener 2001;Anbia and Ghaffari 2009;Nath and Bhakhar 2010;Zhou et al 2014). However, the application of activated carbons can be limited by a range of factors, including high cost, poor adsorption selectivity, poor mechanical strength, and expensive and difficult regeneration (Ferro-Garcia et al 1996;Anbia and Ghaffari 2009;Anbia and Lashgari 2009;Ahmad et al 2011;Shah et al 2011).…”