Co digestión anaerobia de estiércol de ganado con paja de arroz

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  • 1. ainiaAnaerobic co-digestion of cattle manure with rice straw.Gracia Silvestre, Paz Gómez, Andrés Pascual and Begoña Ruiz ADSW&EC 2011 Vienna 29.08.2011
  • 2. CONTENTS• Introduction• Objectives• Materials and Methods• Results and Discussion• Conclusions
  • 3. INTRODUCTIONSome figures about rice in Region Valencia… 15000 Ha rice cultivation (part in a natural park). 30% of national production. Rice Straw production Around 100.000 t/year
  • 4. INTRODUCTIONTraditional management of rice strawOpen-air burning Air pollution NATURAL PARK Reincorporation to fields Water pollution
  • 5. INTRODUCTION Rice fields 2005
  • 6. OBJECTIVES Rice straw management Traditional Alternative Burn Anaerobic Bury (“fanguejat”) digestion Atmopshere and Sustainable water pollution management
  • 7. OBJECTIVESThe aim of this research is to define a sustainable system forusing the rice straw as substrate for anaerobic digestion in theconditions of the region of Valencia (Spain).PARTICULAR OBJECTIVES • Assessment of thermal pre-treatment of the rice straw to increase the biogas potential (fibres difficult to digest) • Study the rice straw co-digestion with cow manure in semi-continuous plug flow pilot-scale reactor. • Evaluation of the economic and energy balance of the process.
  • 8. MATERIALS AND METHODS. SubstratesRice straw samples Origin: rice field in Valencia (Spain) Grinded to 2-3 cm with agricultural chopper.Cow manure samples Origin: cow farm in Valencia.Inoculum Origin: biogas plant in Valencia (co- digestion of cow manure and vegetal co-substrates at 38ºC and 3 kgVS·m-3·d-1.
  • 9. MATERIALS AND METHODS. Pre-treatmentsRice 1 w.u. Thermal 1h BMP teststraw pretreatment A Oven 105ºC 2h ThermalWater 6 w.u. pretreatment B
  • 10. MATERIALS AND METHODS. BMP tests • VDI Standard 4630 “Fermentation of organic materials” • Digester volume: 2L • Runs in triplicates • Incubator at 38ºC ± 2ºC • Manual mixing • Biogas production: counter 1 mL resolution • Gas analysis. CH4, CO2, O2, H2, H2S
  • 11. MATERIALS AND METHODS. Co-digestionPlug-flow digester with a working volume of 900 LOperation temperature 38ºCControl parameters: TS, VS, pH, NH4+-N and VFABiogas production was measured by gas counter Kromschröder BK-2,5CH4 and H2S content was measured by Dräger MultiwarnThree different mixtures of cow manure and rice straw were analyzed (1%,2% and 5% rice straw)
  • 12. RESULTS AND DISCUSSION. PretreatmentsMaceration of rice straw sample at 105ºC (1 h and 2 h) Biogas Biogas Methane Substrates (NL/KgVS) (NL/Kg) (%) RS untreated 547 ± 45 399 ± 33 58 ± 2 RS thermal pretreat (1h) 616 ± 38 62 ± 4 55 ± 4 RS thermal pretreat (2h) 616 ± 43 68 ± 5 58 ± 4 • The pre-treatment increased the biogas potential in 13%. • The different maceration time did not show differences in the biogas potential. • Taking into account the methane concentration, the improvement achieved by maceration 1 and 2 h was 6% and 13% respectively. • Maceration pre-treatment implies water addition and the biogas potential (on wet weigh basis) is lower than the untreated RS.
  • 13. RESULTS AND DISCUSSION Parameters* PI PII PIII PIV Rice straw (%) 0 1 2 5 3 OLR (KgVS/m d) 2.3 3.6 3.9 4.9 HRT (days) 34 26 25 24 3 3 Biogas (m /m d) 0.54 0.56 0.68 0.83 Methane (% biogas) 65 66 67 72 Methane (m3/t) 12 13 18 22 Methane (m3/tvs) 153 156 117 122 VFA (mg/L) <100 <100 <100 <100 pH 7.6 7.9 7.9 8.0 *Average values. SD are available in the proceedings. Biogas productivity was insignificantly increased in the period II in comparison with the period I. Biogas productivity increased 28% and 54% in period III and IV respectively. VFA and pH indicated that the process was developed in stable manner. In period IV accumulation of the rice straw was observed inside the digester.
  • 14. CONCLUSIONS Maceration pre-treatment slightly improves biogas production per kgVS, but due to the high water requirement, the biogas production per kg is lower than untreated straw. Anaerobic rice straw co-digestion with a cow manure was technically feasible. Biogas productivity increased in 4%, 28% and 54% when addition of rice straw was 1%, 2% and 5% (on weight basis). The mixture 5% of rice straw showed problems of solids accumulation in the digester.
  • 15. ACKNOWLEDGEMENTS This study is supported by the project “Evaluation of technic, economic and environmental feasibility of the valorization of rice straw through biogas production for sustainability improvement” (nº04/10) financed by the Agroalimed Foundation.
  • 16. Thank you for your attention!