Nitrogen and organic matter removal in an intermittently aerated fixed-bed reactor for post-treatment of anaerobic effluent from a slaughterhouse wastewater treatment plant A.C. Barana a, *, D.D. Lopes b , T.H. Martins c , E. Pozzi c , M.H.R.Z. Damianovic c , V. Del Nery d , E. Foresti c a Department of Food Engineering, State University of Ponta Grossa, Av. Gal. Carlos Cavalcanti, 4748, CEP 84030-900, Ponta Grossa, PR, Brazil b Department of Civil Engineering, State University of Londrina, Rod. Celso Garcia Cid, km 380, CEP 86051-991, Londrina, PR, Brazil c Department of Hydraulics and Sanitation, School of Engineering, University of Sa˜o Paulo, Av. Trabalhador Sa˜o-Carlense, 400, CEP 13566-590, Sa˜o Carlos, SP, Brazil d Ce ´u Azul Alimentos Ltda., Rua Francisco Savaglia, 405, CEP 13569-590, Sa˜o Carlos, SP, Brazil Introduction Poultry slaughterhouse wastewater is characterised by high concentrations of organic matter, suspended solids, oil and grease, nitrogen and phosphorus. Blood, faeces and fat are the main sources of organic matter and nutrients. Due to the high concentrations of organic matter and nitrogen, biological treat- ment of these wastewaters usually occurs in units sequentially arranged to remove organic matter prior to the removal of nitrogen. Anaerobic processes normally remove a significant fraction of organic matter, but not nitrogen. However, anaerobic treatment prior to a nitrogen removal unit removes part of the organic carbon, leaving a sufficient amount of COD for use in denitrification [1]. Nitrogen removal from wastewater usually involves sequential biological processes of nitrification and denitrification. Autotro- phic and heterotrophic bacteria participate in these processes under aerobic and anoxic conditions, respectively. The denitrifica- tion stage can also occur through autotrophic processes. The anammox (anaerobic ammonium oxidation) process stands out as the most recent alternative for nitrogen removal from wastewater with a low concentration of organic matter. Conventional nitrogen removal systems involve the installation of several units of sequential operations, requiring large areas for the deployment of full-scale systems. One way to reduce deployment costs is by using systems that integrate nitrification and denitrification within a single unit [2,3]. Several authors have reported on the use of sequencing batch reactors (SBR) as a complementary treatment of anaerobic processing of slaughterhouse wastewater. Keller et al. [1] obtained final effluent with a concentration of 20 mgN/L and 5 mgP/L. Cassidy and Belia [4] found over 97% removal of nitrogen. De Nardi et al. [5] obtained 64% removal of COD and 100% removal of NH 3 -N in a lab scale SBR using anaerobic reactor effluent. Some authors have studied SBR for the treatment of raw effluent from slaughterhouses. Shengquan et al. [6] studied a membrane reactor (SBR), in which COD was reduced by 98% and NH 3 -N by 95%. Li et al. [7] obtained 96% reduction of COD, 96% reduction of total nitrogen, and 99% reduction of total phospho- rous. Bench-scale fixed-bed reactors such as the SBBR (sequencing batch immobilised biomass reactor) were also able to remove organic matter and nitrogen [3,8,9]. Journal of Environmental Chemical Engineering 1 (2013) 453–459 A R T I C L E I N F O Article history: Received 4 April 2013 Accepted 14 June 2013 Keywords: Nitrification Denitrification UASB effluent Poultry slaughterhouse Simultaneous nitrification and denitrification (SND) Anaerobic ammonium oxidation (anammox) A B S T R A C T This study evaluated the performance of a lab scale, fixed-bed reactor exposed to intermittent aeration for the removal of organic matter and nitrogen from anaerobic reactor effluent. The reactor was continuously fed with effluent from a UASB reactor used to treat wastewater from a poultry slaughterhouse. The hydraulic retention time (HRT) was maintained at 24 h during the five operational phases that the reactor was subjected to. The phases differed only for the duration of periods with and without aeration. The best results regarding nitrogen removal efficiency were obtained in phase V (8 daily cycles of 1 h of aeration and 2 h without aeration). Under these conditions, for influent with total COD of 418 mg L 1 , 169 mg L 1 of TKN and 112 mg L 1 of NH 4 + -N, effluent with a total COD of 22 mg L 1 , 6.4 mg L 1 of TKN, 6.4 mg L 1 of NH 4 + -N and 58 mg L 1 of NO 3 -N was obtained and NO 2 -N was not detected. During this phase, the average nitrogen removal efficiency was 62%. Optical microscopy and molecular biology analyses associated with the study of microbial activity detected the activity of bacteria that perform anammox, thereby contributing to the understanding of the processes involved. ß 2013 Elsevier Ltd All rights reserved. * Corresponding author. Tel.: +55 42 32203268. E-mail addresses: anabarana@yahoo.com, acbarana@uepg.br (A.C. Barana). Contents lists available at SciVerse ScienceDirect Journal of Environmental Chemical Engineering jou r n al h o mep ag e: w ww .elsevier .co m /loc ate/jec e 2213-3437/$ – see front matter ß 2013 Elsevier Ltd All rights reserved. http://dx.doi.org/10.1016/j.jece.2013.06.015