1. METHODS FOR INCREASING THE BIOGAS YIELD IN MANURE BASED BIOGAS PLANTS P. KAPARAJU, N. CHRISTENSEN AND I. ANGELIDAKI ENVIRONMENT & RESOURCES - DTU TECHNICAL UNIVERSITY OF DENMARK BIOGAS FORUM 10 DEC 2004

2. BACKGROUND Manure - major substrate resource Manure - major substrate resource Large fraction of TS - Particulate matter Large fraction of TS - Particulate matter One-step CSTR digestion One-step CSTR digestion –Methane yields of 0.2-0.25 m 3 /kgVS < theoretical yield of 0.4-0.45 m 3 /kgVS. BMP Test – Digested material BMP Test – Digested material –5-10% additional methane

3. RESEARCH APPROACH Focus EFP-04 project on : Focus EFP-04 project on : 1. Reactor configurations Serial digestion Serial digestion 2. Operational procedures Retain degradable material Retain degradable material 3. Methods for degradation of undegraded material Post-treatment Post-treatment Lab-scale and pilot-scale studies Lab-scale and pilot-scale studies

4. 1. Reactor configuration Serial digestion 1. Reactor configuration Serial digestion Conversion eff: Conversion eff: –low - single step digestion Split total reactor vol between two CSTR connected in series Split total reactor vol between two CSTR connected in series Two separate methanogenic reactors Two separate methanogenic reactors On-going projects: On-going projects: a. Effect of different reactor configuration 90:10, 80:20 & 70:30 Vol. b. Effect of temperature 15 d HRT 12 + 3 d HRT

5. 1. Reactor configuration a. Effect of different reactor configuration 80:20 & 90:10 1-10% HIGHER METHANE PRODUCTION COMPARED TO ONE- STEP PROCESS 1-10% HIGHER METHANE PRODUCTION COMPARED TO ONE- STEP PROCESS HIGHER (20-40%) METHANE PRODUCTION DURING VARIOUS PULSES. HIGHER (20-40%) METHANE PRODUCTION DURING VARIOUS PULSES. PROCESS MORE ROBUST TO DISTURBANCES PROCESS MORE ROBUST TO DISTURBANCES

6. a. Effect of different reactor configuration (contd) Fig. Daily biogas production from reactor R1 operated in parallel and reactors R2 and R3 operated in series

7. 1. Reactor configuration b. Effect of temp. on 2-step of serial digestion Methanogenesis in second-step of serial digestion is dependent on temp. and chemical characteristics of the incoming digestate. Methanogenesis in second-step of serial digestion is dependent on temp. and chemical characteristics of the incoming digestate. 55°C 20 ° C 37 ° C 55 ° C

8. b. Effect of temperature (contd): Fig. The effect of temperature (20-55C) on daily biogas production from reactor R3 operated in series with reactor R2.

9. 2. Operational procedures Passive solids separation 10°C Top60 cm97 cm Top 55°C 60 cm97 cm After 1 d

10. 2. Operational procedures Passive solids separation Fig. Changes in TS and VS of digested cow manure samples over time from top, middle (60 cm) and bottom (97 cm) of column

11. 3. Methods for degradation of undegraded material Post-treatment Short-term aerobic/composting as post-treatment Short-term aerobic/composting as post-treatmentAcknowledgements: Chao Pan Chao Pan Kanokwan Kanokwan Tore & Jacob Tore & Jacob Henar Henar Hector Hector