title: Economical and ecological comparison of granular activated carbon (GAC) adsorber refill strategies.
abstract: Technical constraints can leave a considerable freedom in the design of a technology, production or service strategy. Choosing between economical or ecological decision criteria then characteristically leads to controversial solutions of ideal systems. For the adaptation of granular-activated carbon (GAC) fixed beds, various technical factors determine the adsorber volume required to achieve a desired service life. In considering carbon replacement and recycling, a variety of refill strategies are available that differ in terms of refill interval, respective adsorber volume, and time-dependent use of virgin, as well as recycled GAC. Focusing on the treatment of contaminant groundwater, we compare cost-optimal reactor configurations and refill strategies to the ecologically best alternatives. Costs and consumption of GAC are quantified within a technical-economical framework. The emissions from GAC production out of hard coal, transport and recycling are equally derived through a life cycle impact assessment. It is shown how high discount rates lead to a preference of small fixed-bed volumes, and accordingly, a high number of refills. For fixed discount rates, the investigation reveals that both the economical as well as ecological assessment of refill strategies are especially sensitive to the relative valuation of virgin and recycled GAC. Since recycling results in economic and ecological benefits, optimized systems thus may differ only slightly.
authors.affiliation: Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany. peter.bayer@uni-tuebingen.de
authors.forename: Peter
authors.initials: P
authors.lastname: Bayer
authors.forename: Edda
authors.initials: E
authors.lastname: Heuer
authors.forename: Ute
authors.initials: U
authors.lastname: Karl
authors.forename: Michael
authors.initials: M
authors.lastname: Finkel
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry / Q000191:economics*; D003247:Conservation of Natural Resources; D004463:Ecology; D008962:Models, Theoretical; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification / Q000191:economics* / Q000379:methods; D014881:Water Supply
chemical_list: D014874:Water Pollutants, Chemical; D002244:Carbon