Biogas production from source sorted municipal solid waste impact of operational temperature and organic load

Size: px

Start display at page:

Download "Biogas production from source sorted municipal solid waste impact of operational temperature and organic load"

Ursula Parker
10 years ago
Views:

1 Biogas production from source sorted municipal solid waste impact of operational temperature and organic load Simon Isaksson, Peter Malmros, Anna Hörberg, Sara Frid, Ewa Lie and Anna Schnürer Cooperation between SLU, Uppsala Vatten och Jönköping Energi

2 Aim: To evaluate impact on process in respons to increased organic load during operation at either mesophilic or thermophilic temperature Study objects Uppsala Biogas plant Initial temperature; 52 o C Substrate; SSMOW+ slaugtherhouse waste (9,5 % VS) Can a decrease in temperature (and NH 3 level) improve stability? Jönköping biogas plant Initial temperature; 37 o C Substrate; SSMOW (9,7% VS) Is it possible to use integrated hygiensiation?

3 Experimental set-up digesters Experiments was run in semicontinous lab-scale reactors (5L) feed 6 times/week Inoculum and substrate was taken from the from the investigated biogas plants Process evaluation was peformed by analysis of biogas, methane, VFA, TAN, ph, temperature as well as analysis of methane potential and key organisms

4 Experimental set-up digesters Temperature change during operation (1-2 degree celcius/week) C 6 5 Batch test evaluation 52 C Temperature [ C ] C Temperature [ C ] C Time [days] Time [days] Uppsala biogas plant Jönköping biogas plant

5 Experimental set-up digesters Increase in load at both operational temperatures Organic loading rate [ gvs L -1 day -1 ] HRT 29 days HRT 22 days HRT 17 days HRT 14 days Gradual increase of OLR with a stop corresponding to at least one HRT at 3, 4, 5, 6 g VS/L day Time [days]

6 Experimental set-up microbiology DNA based method giving information about quantity (qpcr) and community structure (TRFLP) ORGANIC MATERIAL SOLUBLE MONOMERS TRFLP analysis qpcr analysis VOLATILE FATTY ACIDS qpcr analysis Methanobacteriales Methanomicrobiales SAOB/Acetogens HYDROGEN CARBON DIOXIDE ACETATE Methanosarcinaceae Methanosaetaceae HYDROGENOTROPHIC METHANOGENS ACETICLASTIC METHANOGENS METHANE CARBON DIOXIDE

7 Results Continuous system Uppsala Specific methane production in response to decrease in temperature Uppsala Decrease in specific methane production and accumulation of VFA (mainly acetate) at around 42 degrees but recovery of process Thermophilic after about 2 HRT Mesophilic Ammonium-nitrogen 2.4 g L -1 2,4 g L -1 Free ammonia.81 g L -1.4 g L -1

8 Results Continuous system Uppsala Specific methane production in response to OLR increase Specific methane production [ NmL gvs -1 ] C 37 C Time [days] Organic loading rate [ gvs L -1 day -1 ] Double total amount of biogas compared to initial phase

9 Results Continuous system Uppsala VFA production in response to OLR increase 7 37 C 8 Organic loading rate [ gvs L -1 day -1 ] C VFA [g L -1 ] Time [days] Acid accumulation at 4HRT at mesophilic temperature

10 Results Batch test Uppsala Volume CH 4 [Nml gvs -1 ] Time [days] 52 C 37 C The degradation rate and the methane potential was comparbly lower at the lower temparture

11 Results Continuous system Jönköping Specific methane production during change of temperature - No difference after an temporary decrease at ca 44 o C Specific methane production (Nml gvs -1 ) 37 o C o C 52 o C Uppsala Temperature ( o C) Mesohilic Termophilic Ammonium-nitrogen 2,1 g L -1 2,1 g L -1 7 % more biogas compared to initial phase Free ammonia.16 g L -1,3 g L -1

12 Results Continuous system Jönköping Specific methane production in response to OLR increase Specific methane production (Nml gvs -1 ) Specific methane production (Nml gvs -1 ) 52 o C 37 o C 52 o C 37 o C Organic loading rate (gvs L -1 dag -1 ) Organic loading rate (gvs L -1 dag -1 ) Small decrease in specific methane production in response to increase in OLR and no accumulation of VFA Introduction of substrate from Uppsala biogas plant

13 Results Batch test Jönköping 7 Volume CH 4 [Nml gvs -1 ] C 52 C No significant difference in specific methane prodcution at the different temperatures Time [days]

14 Results Methanogens Uppsala (impact of temperature change Only small difference in respons to the change in temperature MMB MBT Volume CH 4 [ml gvs -1 day -1 Relative ] gene abundance (log-scale) Temperature Time [days] Specific methane production Msc Mst Temperature [ C] 1 1

15 1 Results Methanogens Uppsala (impact of OLR increase Only small difference in respons to the increase in OLR MMB MBT Msc Mst Volume CH 4 [ml day -1 gvs -1 ] Specific methane production OLR Time [days] Organic loading rate [gvs l -1 day -1 ] CH4 prod. OLR

16 Results Acetogens Uppsala 1% 1% 9% 9% 8% 8% 7% 6% 5% 4% 3% Relative abundance 7% 6% 5% 4% 3% Increase in OLR caused a significant decrease in species richness, likely explaining the subsequent process failure 2% 2% 1% 1% % % VS g/l/day 55 C 37 C OLR 37 o C

17 Conclusions The operational temperature can be changed from mesophilic to thermophilic temperature and vice versa Operational temperature can be an important paramter for optimisation of gas prodcuction from SSOMW Thermophilic temperature allowed a more effeicent degradation and methane prodcution at higher OLR in Uppsala biogas plant, possibly due to high levels of fat Efficient degradation at high ammonia levels is possible also at thermohilic temperature. An upcoming failure in the digester can be targeted by analysis of the acetogenic community.

18 Thank you for your attention! Acknowledgment Uppsala Vatten Jörnköping Energi Svenya Mayer Bettina Müller The biogas group at SLU ( Mikrobiologisk övervakning ett nytt koncept för process-styrning och optimering

Anaerobic Digestion: Biology and Benefits

Anaerobic Digestion: Biology and Benefits In: Dairy Manure Management: Treatment, Handling, and Community Relations. NRAES-176, p.63-72. Natural Resource, Agriculture, and Engineering Service, Cornell University, Ithaca, NY, 2005. Anaerobic Digestion: