Modelling Cr(VI) removal by a combined carbon-activated sludge system

• Published in: Journal of hazardous materials 2008-01, Vol.150 (1), p.46-52
• Main Authors: Orozco, A. Micaela Ferro, Contreras, Edgardo M., Zaritzky, Noemí E.
• Format: Article
• Language: English
• Subjects: Activated carbon; Activated sludge; Applied sciences; Biodegradation, Environmental; Biomass; Carbon - administration & dosage; Carbon - chemistry; Chemical engineering; Chromium - metabolism; Chromium removal; Combined activated carbon–biomass system; Exact sciences and technology; General purification processes; Kinetics; Lactose; Models, Chemical; Pollution; Reactors; Sewage - chemistry; Sewage - microbiology; Wastewaters; Water Pollutants, Chemical - metabolism; Water Purification - methods; Water treatment and pollution
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2007.04.043

The combined carbon-activated sludge process has been proposed as an alternative to protect the biomass against toxic substances in wastewaters; however, the information about the effect of powdered-activated carbon (PAC) addition in activated sludge reactors for the treatment of wastewaters containing Cr(VI) is limited. The objectives of the present study were: (a) to evaluate the removal of hexavalent chromium by (i) activated sludge microorganisms in aerobic batch reactors, (ii) powdered-activated carbon, and (iii) the combined action of powdered-activated carbon and biomass; (b) to propose mathematical models that interpret the experimental results. Different Cr(VI) removal systems were tested: (S1) biomass (activated sludge), (S2) PAC, and (S3) the combined activated carbon–biomass system. A Monod-based mathematical model was used to describe the kinetics of Cr(VI) removal in the system S1. A first-order kinetics with respect to Cr(VI) and PAC respectively, was proposed to model the removal of Cr(VI) in the system S2. Cr(VI) removal in the combined carbon–biomass system (S3) was faster than both Cr(VI) removal using PAC or activated sludge individually. Results showed that the removal of Cr(VI) using the activated carbon–biomass system (S3) was adequately described by combining the kinetic equations proposed for the systems S1 and S2.