title: Integrated anaerobic-aerobic fixed-film reactor for slaughterhouse wastewater treatment.
abstract: An integrated anaerobic-aerobic fixed-film pilot-scale reactor with arranged media was fed during 166 days with slaughterhouse wastewater. Operation temperature was 25 degrees C and the anaerobic-aerobic volume ratio was decreased from 4:1 to 3:2 and finally to 2:3. Overall organic matter removal efficiencies of 93% were achieved for an average organic loading rate of 0.77 kg COD/m3 d, and nitrogen removal efficiencies of 67% were achieved for nitrogen loading rates of 0.084 kg N/m3 d. The high internal recirculation associated to the air-lift effect linked to the aeration of a part of the reactor section caused high mixing between the anaerobic and aerobic zones, so that most organic matter was removed aerobically. The nitrification process achieved an efficiency of 91% for nitrogen loads of 0.15 kg N/m3 d when the anaerobic-aerobic volume ratio was 2:3 and was limited by dissolved oxygen concentration below 3 mg/l. The influence of the heterotrophic biomass growing in the outer biofilm was checked. Denitrification only implied the 12-34% of the total nitrogen removal and was limited by dissolved oxygen concentration in the anaerobic zone above 0.5 mg/l caused by the mixing regime. Most removed nitrogen was employed in synthesis of heterotrophic bacteria.
authors.affiliation: Department of Chemical Engineering, Faculty of Science, University of Burgos, Misael Bañuelos s/n, Burgos 09001, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Del Pozo
authors.forename: V
authors.initials: V
authors.lastname: Diez
mesh_terms: D001420:Bacteria, Aerobic / Q000502:physiology*; D001421:Bacteria, Anaerobic / Q000502:physiology*; D018441:Biofilms; D019149:Bioreactors; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism; D009584:Nitrogen / Q000302:isolation & purification; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
chemical_list: D009573:Nitrites; D012722:Sewage; D009584:Nitrogen; D010100:Oxygen