A2MA2M Experimental and modeling approaches to optimize an algae-to-methane coupled bioreactor system Ruby An – 2015 SURF Metcalf Student Principal Investigators : Joe Vallino & Zoe Cardon The University of Chicago – Chicago – IL – MA – Woods Hole – Marine Biological Laboratory

Algae-to-methane (A2M) has potential as an efficient and practical renewable energy strategy Algal biomass: minimal land & water usage Methane: efficiently stored & energy on demand

A2M Research Aims 1.Experimental – Develop closed system with 100% nutrient recycling – Maximize methane production 2.Modeling – Develop accurate description of system – Predict system performance to achieve experimental objectives

A2 M Design Temperature: 25 °C

A2 M Design Aerobic Algal Reactor Inputs: Air CO 2 Light – Diel 12h Cycle Temperature: 25 °C

Chlamydomonas rienhardtii CW15 25 μm Green algae mutant lacking a cell wall

A2 M Design Temperature: 25 °C Anaerobic Microbial Digester Output: CO 2 and methane gas Digested algae as nutrients & detritus

Aim 1: Experimental Set-up A2M IRL

Liquid Volume: pH Dissolved oxygen (DO) Headspace: Oxygen (O 2 ) Carbon Dioxide (CO 2 ) Methane (CH 4 ) Data Monitoring in both reactors

Key Features of the Data

Lights onLights off

Lights onLights off CO 2 + H 2 O CH 2 O + O 2 light algae

Key Features of Data Installed spargers Doubled light levels Elevated CO 2 input 0.039% => 2%

Key Features of Data Day 1Yesterday

Aim 2a: Algal Reactor Mass Balance Model rate of change = gain - loss State Variables: 1.C Algae 2.C DIC(aq) 3.C O2(aq) 4.p CO2(g) 5.p O2(g)

Inflow & Outflow

Mass Transfer

Inflow & Outflow Mass Transfer Algal Growth & Respiration

CO 2 + H 2 O CH 2 O + O 2 light algae Algal Growth Equation Light Limitation CO 2 Limitation

Adjustable Parameters

Model & Data Comparison Model fit to days Model Data

Model & Data Comparison Model predictions for days Data Model

In Summary: Experimentally - achieved high algal growth Accurately modeled algal reactor dynamics Establish and maximize methane production Develop the full coupled bioreactor model to simulate methanogenisis Next Steps:

Acknowledgements Joe Vallino Zoe Cardon Suzanne Thomas Anonymous Donor Ken Foreman & Wyntin Goodman Zeiss Microscopy Staff Jim & Joey

Questions/Discussion

Supplementary Info

Anaerobic Microbial Community Inoculated Day 71

Methane

Microscopic analysis of algal cellular disintegration Jumpstart methanogenic pathway : new inoculum Genomic analysis of microbial community? Methane Production Strategies