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Irene Bohn

Irene Bohn. LUND UNIVERSITY. Anaerobic digestion of crop residues at low temperatures. Department of Biotechnology. Digestion of manure on the farm Degradation of low strength wastewaters + high strength wastewaters Post digestion or storage. Background. Low temperature digestion:.

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Irene Bohn

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  1. Irene Bohn LUND UNIVERSITY Anaerobic digestion of crop residues at low temperatures Department of Biotechnology

  2. Digestion of manure on the farm Degradation of low strength wastewaters + high strength wastewaters Post digestion or storage Background Low temperature digestion: Is low-temperature digestion of crop residues feasible?

  3. ? Motivation Nordberget al.1998. Biogaspotential och framtida anläggningar i Sverige. Kretslopp och avfall No 17, JTI, VBB Viak, Uppsala. The Swedish Biogas Association, 2001. Swedish Biogas production 2001.

  4. Commercially available reactor High High Low Modified manure tank Low Low High Cost Capacity vs. volume Heat loss Reactor types

  5. Kg Digester set-up Inoculum: Digested cow manure from unheated anaerobic digestion tank Total volume:2.2 m3Active volume: 1.8m3 Substrate: Ensiled sugar beet tops and straw 4.5 % volatile solids in ready substrate

  6. Effect of temperature on yield Loading rate: 0.5 kg VS m-3 d-1 andhydraulic retention time: 90 days Methane yield decreased with decreasing temperature but no VFAs accumulated at the high hydraulic retention time Hydrolysis was limiting the methane yield

  7. Yield and rate Methane yield Methane production rate

  8. Stirrer Heating-substrate Heating-reactor Substrate Gas Energy-balance 30C 15C

  9. Stirrer Heating-substrate Heating-reactor Substrate Gas Energy-balance 30C 15C

  10. The yield in the batch-experiment was higher than in the reactor Yield obtained in batch-experiments 23 23 21 28 • The effect of temperature on yield was lower for the sludge adapted to 15C

  11. Acetic acid Propionic acid Butyric acid Valeric acid OLR in -3 -1 kg VS m day Accumulation of acetate and propionate Results from continuously stirred pilot scale reactors fed with beet top slurry 15 C 30 C

  12. Packed-bed methane-filters Inoculum: Sludge from pilot-scale reactors or lake sediment Substrate: Leachate from ley-crop silage

  13. Acetic acid Propionic acid OLR in -3 -1 kgCOD m day After1 year: Results from methane-filters 15 C 10 C During start-up:

  14. Acetate Propionate other VFAs Unidentified CH4 produced Results from methane-filters 15 C 10 C Reactor sludge Lake sediment

  15. Results from methane-filters

  16. Yield from solid substrate decreases with temperature Feasibility of low temperature digestion depends on insulation of the reactor utilization of the capacity High yield is obtained for soluble substrate at 10°C Conclusions

  17. Acknowledgements Financiation: The Energy Supply Comittee of Southern Sweden (DESS)The Swedish Research Council (VR)The Swedish Energy Agency (STEM) Co-authors: Bo MattiassonLovisa BjörnssonAndreas BengtssonMelvice Bessem Ayuk

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