2. Removal of perchloroethylene in two methanogenic-denitrifying continuous systems Héctor M. Poggi-Varaldo CINVESTAV-IPN, Dept. Biotechnology and Bioengineering, Environmental Biotechnology R&D Group, México

6. Introduction

9. Series reactors and Simultaneous Electron Acceptor (SEA) systems

10. High chlorine content Penta-, tetra-, tri- Anaerobic Low chlorine content di-, and monochloro- Aerobic A good alternative: Series Reactors Brief example with a chlorinated organic compound Accumulation of

11. Series Reactors Anaerobic Reactor Reactor with second electron acceptor Tetrechloroethene TCE, DCE, VC Further removal of chlorinated aliphatics Garibay Orijel et al . (2005a) J. Chem. Technol. Biotechnol . In press Campos-Velarde et al . (1997). Battelle Press. What’s the problem with series reactors? 2 Reactors Costs X 2 Better try Simultaneous Electron Acceptors in One reactor Salto a la albóndiga

12. Protection via diffusion barrier in biofilm CH 4 CO 2 NO 3 - + org. matter N 2 +H 2 O Anaerobic zone Denitriying zone Liqued dif- fusion leayer Denitrifying microorganisms Methanogens Bulk liquid (adapted from López-Navarrete, 2002). Pollutant NO 3 - Concentration Carrier

14. Objectives

16. Methodology

21. Average performance of reactors 1/2

22. Average performance of reactors 2/2 Metabolites and dechlorination efficiencies

23. Poggi’s discrete divergence index n’ A = only green n’ B = only yellow n A = green plus white n B = yellow plus white Microbial community A Microbial community B Zárate-Segura et al. (2005). Battelle

25. Lanes 1 and 2, methanogenic period with no PCE; Lanes 3 to 5, methanogenic period with 20 mg/L PCE; Lanes 6 to 8 methanogenic period with 40 mg/L PCE. All lanes contain 5  g of 16S rDNA PCR product. Poliacrylamide gel at 8% (Acrylamide/N-N´methylenbisacrylamide 37.5:1) Buffer TBE 1X, Urea -Formamide 10-50% (8M of Urea and 40%v/v formamide equivalent to 100% denaturing agents); 30 V, 13-15 mA, 8 h, 60°C. DGGE profiles of major bacterial communities present in fluidized bed bioreactor

26. Variation of bacterial communities in methanogenic FBBR and CM reactors in a period of operation with no PCE in the influent: Diagonal: comparison between start and end of the period for a given bioreactor Other cells: comparison between bioreactors

27. Variation of bacterial communities in methanogenic FBBR and CM reactors in a period of operation with 40 mg PCE/L for FBBR and CM2 and 20 mg PCE/L in CM1: Diagonal: comparison between start and end of the period for a given bioreactor Other cells: comparison between bioreactors

28. Variation of bacterial communities in methanogenic FBBR and CM reactors between periods with no PCE and with PCE in the feed: Diagonal: comparison between periods for a given bioreactor Other cells: empty

29. Ref.: 1. Juteau, P., Tremblay, D., Villemur, R., Bisaillon, J.-G. and Beaudet R. (2004). Analysis of the bacterial community inhabiting an aerobic thermophilic sequencing batch reactor (AT-SBR) treating swine waste. Appl. Microbiol. Biotechnol . 66, 115-122. 2. Ghosh, S. and LaPara, T.M. (2004). Removal of carbonaceous and nitrogenous pollutants from a synthetic wastewater using a membrane-coupled bioreactor. J. Industrial Microbiol. Biotechnol . 31, 353 –361. 3. Tartakovsky, B., Manuel, M.F., Beaumier, D., Greer, C.W. and Guiot, S.R. (2001). Enhanced selection of an anaerobic pentachlorophenol-degrading consortium. Biotechnol. Bioeng . 73, 476-483. Dynamic divergence indices of bacterial communities of several bioreactors

30. Conclusions