title: Autotrophic denitrification and chemical phosphate removal of agro-industrial wastewater by filtration with granular medium.
abstract: A novel granular medium consisting (1.5-5 mm in diameter) of inert perlite particles as nuclei and an effective surface layer containing sulfur, CaCO3 and Mg(OH)2 was developed for advanced treatment of agro-industrial wastewater. The performance of the medium was examined with a laboratory-scale down-flow fixed-bed column reactor using piggery wastewater, which had been treated by an upflow anaerobic sludge blanket reactor and a trickling filter. The removal efficiency of NOx- -N was more than 70% with a NOx- -N loading rate of less than approximately 0.3 kg Nm(-3) d(-1); the removal efficiency dropped due to the accumulation of nitrite when the loading rate exceeded that value. A significant drop of phosphate and Mg2+ concentrations occurred when the effluent pH exceeded 7.9. Ammonium was removed with an average removal efficiency of 12.4%. These results indicated that the crystalline reaction of PO4(3-), Mg2+ and NH4+ (MAP reaction) under alkaline conditions contributed to the removal of phosphate. This medium could be useful for the simultaneous reduction of nitrogenous and phosphorus compounds in biologically treated agro-industrial wastewater.
authors.affiliation: Waste Recycling Laboratory, National Institute of Livestock and Grassland Science, Ikenodai 2, Tsukuba-shi, Ibaraki 305-0901, Japan. osuya@affrc.go.jp
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yatagai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Masujima
authors.forename: Miyoko
authors.initials: M
authors.lastname: Waki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yokoyama
mesh_terms: D005374:Filtration / Q000379:methods*; D007220:Industrial Waste; D009566:Nitrates / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*
chemical_list: D007220:Industrial Waste; D009566:Nitrates; D010710:Phosphates