title: Residual organic matter and microbial respiration in bottom ash: Effects on metal leaching and eco-toxicity.
abstract: A common assumption regarding the residual organic matter, in bottom ash, is that it does not represent a significant pool of organic carbon and, beyond metal-ion complexation process, it is of little consequence to evolution of ash/leachate chemistry. This article evaluates the effect of residual organic matter and associated microbial respiratory processes on leaching of toxic metals (i.e. arsenic, copper, chromium, molybdenum, nickel, lead, antimony and zinc), eco-toxicity of ash leachates. Microbial respiration was quantified with help of a respirometric test equipment OXITOP control system. The effect of microbial respiration on metal/residual organic matter leaching and eco-toxicity was quantified with the help of batch leaching tests and an eco-toxicity assay - Daphnia magna. In general, the microbial respiration process decreased the leachate pH and eco-toxicity, indicating modification of bioavailability of metal species. Furthermore, the leaching of critical metals, such as copper and chromium, decreased after the respiration in both ash types (fresh and weathered). It was concluded that microbial respiration, if harnessed properly, could enhance the stability of fresh bottom ash and may promote its reuse.
authors.affiliation: Department of Hydraulic and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, Norway aamir.ilyas@ntnu.no.
authors.forename: A
authors.initials: A
authors.lastname: Ilyas
authors.affiliation: Division of Water Resources Engineering, Lund University, Lund, Sweden.
authors.forename: K M
authors.initials: KM
authors.lastname: Persson
authors.affiliation: Division of Water Resources Engineering, Lund University, Lund, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Persson
mesh_terms: D000332:Aerobiosis; D000818:Animals; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D002244:Carbon / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D060729:Coal Ash / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects* / Q000378:metabolism; D008670:Metals / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D009930:Organic Chemicals / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D010100:Oxygen / Q000378:metabolism; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*
chemical_list: D060729:Coal Ash; D008670:Metals; D009930:Organic Chemicals; D012989:Soil Pollutants; D002244:Carbon; D010100:Oxygen
keywords: Residual organic matter; bottom ash; eco-toxicity; leaching; microbial respiration