Digestaatbehandeling en recirculatie: invloed op de anaerobie

Transcriptie

1 Digestaatbehandeling en recirculatie: invloed op de anaerobie Tetraproject N e Vlaams Vergistingsforum 14 december 2017 KU Leuven Campus De Nayer

2 Inhoud van de presentatie Inleiding Doel van het ReciDigest-project Opbouw van het ReciDigest-project Projectpartners Resultaten en bevindingen Invloed oxidatietechnieken op aanwezige N: omzetting tot NO 3 /NO 2 Stripping & scrubbing: verwijdering van N uit digestaat Continue vergisting in combinatie met digestaatbehandeling: case studies Conclusies 2

3 Inleiding Doel van het project Huidige situatie in anaerobe vergistingspraktijken Electricity Heat Biogas Organic waste (manure, waste sludge, ) Limited conversion efficiency Digestate Non-biodegradable material [ammonia nitrogen] in digester 3

4 Inleiding Doel van het project These bottlenecks are addressed in the ReciDigest project Electricity Heat Biogas Organic waste (manure, waste sludge, ) Digestate # disintegration techniques (AOP) Ammonia stripping/scrubbing 4 Reduction of ammonia Biodegradability

5 Inleiding Doel van het project Verhoging biodegradeerbaarheid: 3 technieken Peroxidatie (H 2 O 2 ) Ultrasoon Ozon 5

6 Inleiding Doel van het project Scrubbing ph en/of T Stripping ph NH3

7 Opbouw van het project 7

8 Resultaten 3 verschillende stromen Runderveemest (Biolectric) ph neutraal, veel organisch materiaal, medium N-belasting Aardappelafval (Mydibel) ph zuur, veel organisch materiaal, lage N-belasting Gemengd organisch afval (Q.E.F) ph basisch, weinig organisch materiaal, hoge N-belasting Onderzocht (KU Leuven) Invloed van N-oxidatie: ammoniak [N(-III)] geoxideerd tot nitriet [N(+III)] of nitraat [N(+V)] Invloed op anaerobie: wordt de biogasopbrengst verhoogd door de technieken? Onderzocht (Ugent): kan ammoniak effectief verwijderd worden door stripping/scrubbing? 8

9 Resultaten N-oxidatie Reactor A Reactor C Reactor B o 50 ml feed o 100 ml feed o 200 ml feed o 2450 ml digestate o 2400 ml digestate o 2300 ml digestate Feed: 50x diluted Feed: 25x diluted Feed: 12.5x diluted Picture of (classic) setup used: 9

10 Biogas experiments Mesophilic digestion Different ratios feed : digestate (reference experiments) MYDIBEL FEED DIGESTATE TOC [g.l -1 C] COD [g.l -1 O 2 ] NH + 4 [g.l -1 NH 4+ -N]

11 Resultaten N-oxidatie Mesophilic digestion Investigation of inhibitory effect of NO 2- /NO 3- in combination with extra NH 4 + besides what is naturally present Addition of NaNO 2 (2.5 g/l NO 2- -N) + NH 4 Cl (2.5 g/l NH 4+ -N) OR Addition of NaNO 3 (2.5 g/l NO 3- -N) + NH 4 Cl (2.5 g/l NH 4+ -N) OR Equimolar amount of NaCl as in the above cases These experiments were performed with 50 ml soup (diluted 50x), 100 ml soup (diluted 25x) and 200 ml soup (diluted 12.5x) 11

12 Biogas experiments Mesophilic digestion Investigation of inhibitory effect of NO 2- /NO 3- in combination with extra NH 4 + besides what is naturally present o o 50 ml soup Analyses after digestion: NH 4+ -N: unchanged for all cases NO 2- -N: completely removed (formation of N 2 gas) NO 3- -N: 1.2 g/l NO 3- -N left (rest: N 2 gas) 12

13 Biogas experiments Mesophilic digestion Investigation of inhibitory effect of NO 2- /NO 3- in combination with extra NH 4 + besides what is naturally present o o 100 ml soup Analyses after digestion: NH 4+ -N: unchanged for all cases NO 2- -N: completely removed (formation of N 2 gas) NO 3- -N: 0.3 g/l NO 3- -N left (rest: N 2 gas) 13

14 Biogas experiments Mesophilic digestion Investigation of inhibitory effect of NO 2- /NO 3- in combination with extra NH 4 + besides what is naturally present o o 200 ml soup Analyses after digestion: NH 4+ -N: unchanged for all cases NO 2- -N: completely removed (formation of N 2 gas) NO 3- -N: 0.1 g/l NO 3- -N left (rest: N 2 gas) 14

15 5/15 Introduction Objective Part 1 Part 2 Part 3 Part 4 Conclusion Resultaten Stripping/scrubbing Scenario 1 Hot water bath + air flow Quirijnen Energy Farming Digestate Liquid Fraction Digestate Scenario 2 Hot plate + stirring magnet Scenario 3 Hot water bath without mixing Mydibel Bioelectric pocket digester Digestate Liquid Fraction Digestate Digestate

16 6/15 Introduction Objective Part 1 Part 2 Part 3 Part 4 Conclusion Resultaten Stripping/scrubbing Total Ammonia Nitrogen (TAN) removal efficiency Scenario 1 Hot water bath + air flow Anaerobic digestion plant T ( C) Product type TAN Removal (%) Mydibel 40 Digestate 42% Liquid fraction digestate 43% 60 Digestate 69% Liquid fraction digestate 72% Bioelectric 40 Digestate 38% 60 Digestate 68% 40 Digestate 54% Quirijnen Energy Farming Liquid fraction digestate 54% 60 Digestate 85% Liquid fraction digestate 87%

17 7/15 Resultaten Stripping/scrubbing Part 2 Part 3 Part 4 Conclusion Digester volume: m 3 Biogas Feeding rate: 250 m 3 /d Iteration of a group of five steps Feedstock input in digester Biogas production Output from digester Recirculation output Recirculation input Input Digester Output Three variables Stripping efficiency Recirculated fraction Total nitrogen concentration in the input Stripping

18 8/15 Resultaten Stripping/scrubbing Part 2 Part 3 Part 4 Conclusion 3.5 TAN concentration in digester (g N/L) % 50% 60% 70% 80% 90% 100% Stripping efficiency Initial TAN in digester: 4.5 g N/L Stripping efficiency: variable Recirculation fraction: 5 % (fixed) Total nitrogen input: 4.5 g N/L (fixed) Variation of Total Ammonia Nitrogen (TAN) concentration in digester with increasing stripping efficiency

19 9/15 Resultaten Stripping/scrubbing Part 2 Part 3 Part 4 Conclusion TAN concentration in digester (g N/L) % 5% 15% 20% 10% Recirculation fraction Initial TAN in digester: 4.5 g N/L Stripping efficiency: 85 % (fixed) Recirculation fraction: variable Total nitrogen input: 4.5 g N/L (fixed) Variation of Total Ammonia Nitrogen (TAN) concentration in digester with increasing recirculation fraction

20 Resultaten Stripping/scrubbing Part 2 Part 3 Part 4 Conclusion TAN concentration in digester (g N/L) % 5% 15% 20% 10% Recirculation fraction Reduced TAN Increase in biogas Variation of Total Ammonia Nitrogen (TAN) concentration in digester with increasing recirculation fraction

21 Resultaten continue vergisting Case study runderveemest Condities Looptijd: 5.5 maanden Mesofiele T SRT: dagen Actief volume reactor: 50 L Behandeling: ultrasoon Resultaat: >20 % meer biogas geproduceerd in vgl met BAU Geen invloed op ammoniakale N in vergister 21

22 Resultaten continue vergisting Case study aardappelafval Condities Looptijd: 4 maanden Thermofiele T SRT: 30 dagen Actief volume reactor: 50 L Behandeling: ultrasoon Resultaat: ca. 10% meer biogas geproduceerd in vgl met BAU verzuring 22

23 Resultaten continue vergisting Case study gemengd organisch afval Condities Looptijd: 2 maanden Thermofiele T SRT: 30 dagen Actief volume reactor: 50 L Behandeling: stripping/scrubbing Resultaat: geen siginficant effect in vgl met BAU Extreem hoge ph in de vergister leidt tot inhibitie 23

24 Conclusies N-oxidatie Negatief effect van NH 3 -oxidatie op biogasvorming Stripping/scrubbing 60 C > 40 C (haalbaarheid?) Continue vergisting Positief effect van laag-energetische ultrasoonbehandeling op digestaat + recirculatie Effect wordt groter naarmate meer refractair organisch materiaal aanwezig Einde project: 31/01/

25 Bedankt voor uw aandacht Met dank aan Vlaio en al onze partners! Projectuitvoerders Lise Appels: Boudewijn Meesschaert: Erik Meers: EPPT bvba 25