1. 1 Problems at the biogas plant Henrik Bangsø Nielsen Biogasforum, seminar, 29/11-2005

2. 2  Strategy and objectives  Data obtained from Danish biogas plants  On going experiments  Future experiments  Comments from the audience Outline

3. 3 Danish centralized biogas plants Lemvig biogas plant Animal manure362 t/day Alternative biomass:75 t/day Biogas production51,6 m 3 /m 3 Temperature53 o C Reactor capacity7600 m 3 HRT18 days Post storage18 o C/ 3d (Al Seadi, 2000) (Biogasforum)

4. 4 Strategies and objectives  2001 status * : 1,5% of the production is lost via imbalances and technical problems, but what about suboptimal performances?  The project mainly focuses on the microbiology of the process  Research along with practical ”real life” experiences * Planenergi, Midtjylland 2001: Årsager til hæmning af biogasprocessen Visits at biogas plants Data collection Experiments and results that can be 1) directly related and used by specific plants and 2) can be published AB C

5. 5 H 2, CO 2 Acetate VFA, Lactate, Alcohols Biological polymers Carbohydrates, lipids, proteins Mono- and oligomers CH 4, H 2 O Fermentative bacteria Syntrophic bacteria H 2 -consuming methanogens Aceticlastic methanogens Hydrolytic extracellular enzymes Acetate oxidizing bacteria Homo- acetogenic bacteria The biogas process

6. 6 Visits at biogas plants Main conclusions:  “No problems”  Pre-storage tanks are not useful  Substrate composition is unknown  Substrate degradation characteristics is unknown  Inadequate surveillance, especially with regard to VFA

7. 7 Process breakdown Blåbjerg LCFA-inhibition

8. 8 Process breakdown

9. 9 Ammonia inhibition from pigmanure og mucosa Process breakdown

10. 10 Suboptimal reactor performance + -

11. 11 Suboptimal reactor performance

12. 12 Fra 1/11-04 sker der et skifte fra kogt madaffald til Daka-fedtaffald. Suboptimal reactor performance

13. 13 Case story:  Whey replaced with blood from pigs at the 1. of September 2005  Slow inhibition of biogas production observed in the beginning of October  Biogas production constituted only 40% of normal production at the 8. November  Propionate extremely high date VFA date Suboptimal reactor performance/breakdown

14. 14 Suboptimal reactor performance/breakdown Reasons for inhibition:  Combination of increasing pH and increasing ammonia concentration  Increase in ammonia concentration was related to the feeding with pig blood  Increase in pH was caused by the increase in ammonia and omission of whey from the feedstock  Construction of the plant forced the operator to add further amounts of blood even after the imbalance had occurred  Inadequate measurement of VFA (Figure by Hinrich Hartmann)

15. 15 Studsgaard biogas plant

16. 16 Suboptimal conditions Foaming starts april 2003Foaming ends march 2005

17. 17 Suboptimal conditions

18. 18 Sinding-ørre biogas plant

19. 19  Screening of various wastes in batch experiments  Toxicity  Biogas potential  Waste index  Tests of the most inhibitory compounds in reactor experiments  Effect on microbial activity  Effect on microbial composition (DNA extraction and TGGE)  Maximum loading rate  Identification of suitable parameters for indication of process imbalances (VFA, Methane….) On going experiments related to full-scale experiences

20. 20 Screening of various wastes in batch experiments with regard to toxicity and biogas potential Lipids Meat and bone meal Mixture 1.0 gVS/l 5.0 gVS/l 2.0 gVS/l 10 g/lVS

21. 21 Waste typeTemperatureInhibition level g VS/l = kg VS/t Blood from pigs37 o C0,5-1,0 Blood from pigs55 o C<0,5 Shrimp sludge37 o C1,0-5,0 Shrimp sludge55 o C0,5-1,0 Meat and Bone meal37 o C1,0-5,0 Meat and Bone meal55 o C0,5-2,0 100% Fat, DAO55 o C<1,0 Flotations fedt, pigs55 o C0,5-1,0 Bakery (mainly fat)55 o C5,0-10,0 Flotationsfedt, pigs55 o C5,0-10,0 Flotationsfedt, pigs55 o C5,0-10,0 Limfedt (fat)55 o C5,0-10,0 Food waste (fat)55 o C>10,0 Flotationsfedt, chickens 55 o C>10,0 Waste index. Examples

22. 22 Effect of MBM pulses 5 gVS/l Inadequate process surveillance

23. 23 Effect of MBM pulses Acetate Propionate Isovalerate Isobutyrate Butyrate Valerate VFA dynamics

24. 24  Recovery of reactors following process imbalances:  Dilution  Re-inoculation  Continued feeding with waste  Feeding with manure only  No feeding at all  Foaming in biogas plants  Microbial phenomenon?  Physical phenomenon? Future experiments related to full-scale experiences

25. 25 Conclusions ?

26. 26 Acknowledgements Thanks to Henard Meer de Soto and Elena Pueyo Abad for sharing their results Thanks to Hector Garcia and Prasad L. Kaparaju for their technical assistance The work is supported by Energistyrelsens Energiforsknings-program (EFP-2005) Thank you for your attention!!!!