title: Particle size and metal distributions in anaerobically digested pig slurry.
abstract: Particle size distribution and trace element patterns were studied in a full-scale anaerobic digestion plant treating pig slurry. Mass balance was established for major (N, P, K, Ca, Fe, Mg and S) and minor (Al, Cu, Mn and Zn) elements. Most of the elements were conserved through the process but part of the P, Ca, Mg and Mn was deposited as crystals lining the digester. In the dry matter of the slurry, Cu and Zn occurred at between 170 and 2600 mg kg(-1) due to pig diet supplements. Analyses of particle size distributions in raw and digested slurries showed a general shift in distribution towards larger sizes due to degradation of small and easily degradable particles as well as formation of large microbial filaments. Graded sieving of digested slurry showed metals to be mainly present on 3-25 microm particles. Less than 2% Cu and Zn was removed by passage through a 250 microm rotary screen.
authors.affiliation: Agronomy Environment and Ecotoxicology Laboratory, National School of Agronomy - Toulouse (INP-ENSAT) BP 32607, Auzeville-Tolosane, 31326 Castanet-Tolosan, France.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Marcato
authors.forename: Eric
authors.initials: E
authors.lastname: Pinelli
authors.forename: Philippe
authors.initials: P
authors.lastname: Pouech
authors.forename: Peter
authors.initials: P
authors.lastname: Winterton
authors.forename: Maritxu
authors.initials: M
authors.lastname: Guiresse
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D008670:Metals / Q000737:chemistry*; D010316:Particle Size; D013552:Swine
chemical_list: D008670:Metals