1. Anaerobic Treatment of HTC Waste Water B. Wirth a,b, J. Mumme a, B. Erlach b a ) Leibniz Institute for Agricultural Engineering, APECS Junior Research Group b ) Technische Universität Berlin, Institute for Energy Engineering Supported by

2. The APECS Concept Introducing APECS Anaerobic Pathways to Renewable Energies and Carbon Sinks Member of IBI Junior research group focusing on the combination of anaerobic digestion (AD) and carbonization technologies Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/20122

3. Aim of this Study Investigation of anaerobic digestion as a treatment for waste water from hydrothermal carbonization (HTC): General feasibility Process performance COD (chemical oxygen demand) and TOC (total organic carbon) removal efficiency Comparison of two reactor types Economic impact on an industrial-scale HTC plant Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/20123

4. State-of-the-Art I Hydrothermal Carbonization Products of HTC: Solid phase – hydrochar Gaseous phase – 90 % CO 2 Liquid phase HTC liquor: Contains volatile fatty acids, phenols, sugars, etc. Contains up to 20 % of initial carbon Needs treatment before released to the environment -> An anaerobic treatment of waste water yields methane and can gain further energy! Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/20124

5. State-of-the-Art II Anaerobic Digestion Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/20125 Flow Diagram of Anaerobic Digestion 4 major steps Hydrolysis is the speed-limiting step AD of HTC liquor should be dominated by immediate methanogenesis

6. Materials & Methods I Experimental Set-Up Experimental Set-up @ ATB Biofilm Carriers Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/20126

7. Materials & Methods II Substrate Properties and Reactor Operation HTC liquor HTC of corn silage 220 °C – 6 hrs Reactor operation 37 °C – mesophilic Daily feeding of HTC liquor Organic loading rate (OLR) of 1 g COD L -1 d -1 Weekly removal of (liquid) digestate 13 weeks continuous operation Monitoring of pH, reactor temperature, gas production rate, and gas composition Regular analysis of the chemical properties of the digestate Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/20127

8. Experimental Results Gas Production during Continuous Operation Methane fraction: 50-65 % Methane yield: ~ 0.25 L g COD -1 and ~ 0.65 L g TOC -1 Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/20128

9. Experimental Results COD and TOC Removal Efficiency Maximum COD removal as high as 80 % TOC removal always ~ 20 percentage points lower Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/20129

10. Economic Assessment Basic Parameters Based on previous HTC plant design (Erlach et al., 2010) and previous economic assessment (Wirth et al., 2011) HTC of SRF wood chips and municipal organic waste 11.15 MW HHV biomass input @ 7000 h a -1 Amounts of waste water and demand of natural gas (for raising steam for the HTC process) extracted as referring values ParameterUnit HTC Plant Design Wood ChipsOrganic Waste Waste Waterkg h -1 21416706 TOCg L -1 20.410.0 CODg L -1 54.026.4 Natural Gas Demand kW9651272 m 3 h -1 45.059.4 kJ MJ char -1 69.092.9 Produced Hydrochart TS a -1 979712947 Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/201210

11. Economic Assessment Results ParameterUnitWood Chips COD Degradation%80100 Natural Gas Replaced%58.274.4 Share on the Feedstock%2.63.3 Share on the Char%2.93.7 Organic Waste COD Degradation%80100 Natural Gas Replaced%75.294.0 Share on the Feedstock%4.45.6 Share on the Char%5.06.3 Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/201211

12. Conclusions HTC liquor can be treated anaerobically Methane yield of up to 0.65 L g TOC -1 COD removal as high as 80 % AF was more stable compared to the CSTR Lasting inhibition by process intermediates was not observed Further experiments (higher OLRs, thermophilic conditions, etc.) are in preparation 60-75 % of natural gas could be replaced at 80 % COD degradation Higher OLRs increase economics Savings for the aerobic treatment may further improve economics Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/201212

13. Thank you for your attention! Wirth et al. – Anaerobic Treatment of HTC Waste Water8/1/201213