The Princeton Biodigester Project By: Kevin Griffin

Outline Background Information Background Information Explanation of the Princeton Biodigester Project Explanation of the Princeton Biodigester Project Details of Progress this Summer Details of Progress this Summer Future Plans Future Plans

What Is a Biodigester? Anaerobic Digestion-C 6 H 12 O 6 → 3CO 2 + 3CH 4 Anaerobic Digestion-C 6 H 12 O 6 → 3CO 2 + 3CH 4 Main byproducts are CO2, methane, and compost Main byproducts are CO2, methane, and compost

Motivation Energy Independence Energy Independence Import 45% of transportation and heating fuels in 2011 (EIA) Import 45% of transportation and heating fuels in 2011 (EIA) Waste Management Waste Management 65% increase from % increase from % compostable (MSU) 28% compostable (MSU) Environmental Impact Environmental Impact Methane would otherwise Methane would otherwise escape or be burned escape or be burned CH4 is a 20 times more potent green house gas than CO2 (EPA) CH4 is a 20 times more potent green house gas than CO2 (EPA)

Project Summary Biodigester at the Forbes Garden Biodigester at the Forbes Garden Food waste from the Forbes Dining Hall Food waste from the Forbes Dining Hall Pilot project to determine viability of Mid-Atlantic climate and evaluate quality of compost produced Pilot project to determine viability of Mid-Atlantic climate and evaluate quality of compost produced

Benefits to the University Reduce methane emissions Eliminate emissions from transporting food waste Reduce food waste collection costs Supply the Garden Project with compost Provide nitrogen rich compost to the community, decreasing the community’s need for nitrate fertilizers that pollute the water supply Produce natural gas for heating and cooking

Implementation Construction of the Biodigester Circuit for System Monitoring and Data Logging

Challenges Two stages of digestion. Two stages of digestion. Acidogenic bacteria break sugars and amino acids into organic acids. Acidogenic bacteria break sugars and amino acids into organic acids. Methanogenic bacteria then convert acids into CO2 and CH4 Methanogenic bacteria then convert acids into CO2 and CH4 Methanogenic bacteria are sensitive to pH and temperatures Methanogenic bacteria are sensitive to pH and temperatures The composition of waste stream can greatly affect the balance of these bacteria groups The composition of waste stream can greatly affect the balance of these bacteria groups

Future Research Response to Changes in temperature Changes in pressure The introduction of bacterial cultures The use of different waste materials and how these changes affect the system pH and the health of essential bacteria.

Acknowledgements I would like to thank Dr. Shana Weber from the Office of Sustainability for all of her help and support. I would like to thank Dr. Shana Weber from the Office of Sustainability for all of her help and support. Thank you to Professor Justin Sheffield for technical advice. Thank you to Professor Justin Sheffield for technical advice. Thank you to Sean Gallagher and his team for constructing the biodigester and donating materials. Thank you to Sean Gallagher and his team for constructing the biodigester and donating materials. Thank you to Dean Caddeau and the Forbes College Office for their support and advice. Thank you to Dean Caddeau and the Forbes College Office for their support and advice.

Sources of Data h4.html h4.html ster%20manual.pdf ster%20manual.pdf