title: Impacts of trace element supplementation on the performance of anaerobic digestion process: A critical review.
abstract: This paper critically reviews the impacts of supplementing trace elements on the anaerobic digestion performance. The in-depth knowledge of trace elements as micronutrients and metalloenzyme components justifies trace element supplementation into the anaerobic digestion system. Most of the earlier studies reported that trace elements addition at (sub)optimum dosages had positive impacts mainly longer term on digester stability with greater organic matter degradation, low volatile fatty acids (VFA) concentration and higher biogas production. However, these positive impacts and element requirements are not fully understood, they are explained on a case to case basis because of the great variance of the anaerobic digestion operation. Iron (Fe), nickel (Ni) and cobalt (Co) are the most studied and desirable elements. The right combination of multi-elements supplementation can have greater positive impact. This measure is highly recommended, especially for the mono-digestion of micronutrient-deficient substrates. The future research should consider the aspect of trace element bioavailability.
authors.affiliation: Environmental Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia.
authors.forename: Yee Yaw
authors.initials: YY
authors.lastname: Choong
authors.affiliation: Environmental Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia. Electronic address: norlii@usm.my.
authors.forename: Ismail
authors.initials: I
authors.lastname: Norli
authors.affiliation: School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang, Malaysia.
authors.forename: Ahmad Zuhairi
authors.initials: AZ
authors.lastname: Abdullah
authors.affiliation: Bioresource, Paper and Coatings Technology Division, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang, Malaysia.
authors.forename: Mohd Firdaus
authors.initials: MF
authors.lastname: Yhaya
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D019149:Bioreactors; D003035:Cobalt / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D009532:Nickel / Q000378:metabolism; D014131:Trace Elements / Q000032:analysis / Q000378:metabolism*
chemical_list: D056804:Biofuels; D005232:Fatty Acids, Volatile; D014131:Trace Elements; D003035:Cobalt; D009532:Nickel; D007501:Iron
keywords: Anaerobic digestion; Bioavailability; Metalloenzyme; Methanogenesis; Trace element supplementation