START-UP OF HYBRID ANAEROBIC BIOFILM

Transcription

1 START-UP OF HYBRID ANAEROBIC BIOFILM REACTOR TREATING EFFLUENT AND USING A LIGNOCELLULOSIC BIOMASS AS A CARRIER SUPPORT Mohamed Ali WAHAB, Frédéric HABOUZIT, Nicolas BERNET, Jean-Philippe STEYER, Naccer JEDIDI, Renaud ESCUDIE Lab. for Environmental Biotechnology (LBE) National Institute for Agronomic Research Narbonne - France Lab. of Wastewater Treatment (LWT) Water Research and Technology Centre Tunis -Tunisia

2 Context: agro-industries Lignocellulosic solid matter Wastewater effluent Solid anaerobic digester AD Biofilm reactor (fixed bed) Slow growth rate Poor breakdown of cellulose and lignin Water supply Hybrid anaerobic biofilm reactor Long start-up expensive plastic support Clogging problems Lignocellulosic residue as a low cost carrier support Sequential operation to treat both effluent and solid residue in a same reactor Operational, economic and environmental benefits.02

3 Sequential operation with two stages Operating conditions First stage : Continuous fixed bed reactor Second stage: Solid anaerobic digester in batch mode Packed material Carrier support Solid residue (wheat straw) Substrate Substrate Advantages of the hybrid reactor Wastewater Treatment of effluent (biogas and treated water) Colonization of the solid residue by strongly adhered biofilm Activation of the biofilm Wheat straw Treatment of solid waste (biogas and digestate) Faster start-up Sequential operation adapted to seasonal fluctuations.03

4 Objectives Investigation of the ability to use solid residues as a carrier support displace to plastic and mineral materials Start-up of biofilm reactor in a short period Sequential operation of the hybrid reactor to treat both wastewater and solid residue.04

5 Materials and methods.05

6 Experimental set-up Influent Biogas Biogas volume Biogas composition Effluent Synthetic winery wastewater Wheat straw (1 Kg) Physico-chemical analysis COD VFA Diluted wine complemented with nitrogen and phosphorus (COD/N/P = 400/7/1) Fixed bed reactor 16L Control ph (6.8).06

7 Experimental phases Wastewater treatment Solid waste degradation Start-up of biofilm reactor OLR from 0.65 to 24 g COD.L -1.d -1 Solid anaerobic digester in batch mode 1 40 Time (Day) 75 Inoculation: - batch mode during 1 day No influent feeding Start-up: fast washout of suspended µorg. - Constant and short HRT (18 h) - Exponential increase of OLR by increasing the substrate concentration.07

8 Results and discussion Phase I - Start-up period of biofilm reactor.08

9 OLR and COD removal during the start-up period Acclimation phase COD reduction (%) OLR COD removal OLR increase Stable phase OLR (g L -1 d -1 ) Time (d) 0 12 days needed to reach 80% of COD removal Increase OLR from 0.65 to 24 g COD.L -1.d -1 occurred rapidly in 24 days COD removal was > 80 % along the start-up period.09

10 1 VFA concentrations during the start-up period 0,8 Acclimation phase total VFA Acetate VFA concentration ( g.l -1 ) 0,6 0,4 0,2 OLR increase Stable phase Time (d) VFA started to accumulate from OLR of 6 g COD.L -1.d -1 VFA concentration reached 0.7 g.l -1 at the end of the start-up phase VFA concentration decreased during the stationary phase.010

11 Potential of solid residues Supports OLR (g COD.L -1.d -1 ) Start-up period (d) COD removal (%) Wheat straw Loofa Cactus Sunflower stems Grape stalks

12 Potential of solid residues Supports OLR (g COD.L -1.d -1 ) Start-up period (d) COD removal (%) Wheat straw Loofa Cactus Sunflower stems Grape stalks Ceramic particles Activated carbon 6, Polyethylene PVC Han et al., 2013 Zhao et al., 2013 Ganesh et al., 2010 Habouzit,

13 Results and discussion Phase II - Solid anaerobic digester in batch mode.013

14 Phase II: Solid anaerobic digester in batch mode ml CH4 g VS Time (d) Methane production rate: 1.2 ml CH4.g VS -1.d -1 Methane production: 40 ml CH4.g VS -1 (25% of BMP) in 35 days.014

15 Phase II: Microbial community structure Start-up biofilm reactor OLR from 0.65 to 24 g COD.L -1.d -1 Solid anaerobic digester in batch mode 1 40 Time (Day) 75 Sampling Sampling Bacteria Archaea Microbial Fingerprint SSCP day 40 day 75 day 40 day 75 Maintaining microbial diversity? Restart-up of the biofilm reactor.015

16 Results and discussion III.Restart-up phase.016

17 Start-up and restart-up of grape stalks COD removal (%) Restart-up after 3 months Start-up OLR (g.l -1. d -1 ) Time (d) 0 restart of the biofilm reactor in only 10 days with 77% COD removal Biofilm conserved its activity during the nonfeeding period.017

18 Potential of solid residues Supports OLR (g COD.L -1.d -1 ) Start-up period (d) COD removal (%) Loofa Loofa (restart) Sunflower stems Sunflower stems (restart) Grape stalks Grape stalks (restart)

19 Conclusions and perspectives Lignocellulosic residues can be used as low cost biofilm carrier in place of conventional supports Start-up of hybrid reactors occurred rapidly within 35 days Hybrid reactor restarted easily (seasonal operations) Investigation of the efficiency of this hybrid reactor using real wastewater (clogging).019

20 Thank you for your attention LBE, INRA (France)