Maximizing Microorganism-BasedResources

Bruce E. Rittmann

Regents’ Professor of Environmental Engineering

Director of the Swette Center for EnvironmentalBiotechnology

Biodesign Institute at Arizona State University

Rittmann@asu.edu http://environmentalbiotechnology.org

My Context

• We know that many kinds of complexorganic residues – food processingwastes, animal wastes, sludges,microalgae, etc. – can be converted intorenewable, socially useful energy bydifferent anaerobic microbial systems.

• Why aren’t we doing more of it?

– So far, it is not economically valuable enough.

We Want to Improve the ValueProposition

1. Get more energy out of complex organicresidues

2. Produce a higher value energy outputthan methane

3. Capture nutrients into high value “mobile”stream

4. Get high value from the left-over solids

Our PARENS concept

PARENS = Profitable Agriculture through Recovered Energy, Nutrients, andSolids

1. Get more energy out ofcomplex organic residues

Pre-treatment

Sludge pre-treatment technologies

Technology Description/Scale Comments

Thermal •High-temperature treatment (150-220oC)

•Full-scale success

•Achieve solids reduction

•Capital intensive

•Energy neutral/negative

Mechanical(includingultrasound)

•Shear, pressure, homogenization,or ultrasonic physical attack ofmembrane

•Pilot scale success

•Achieve benefits of cell lysis at smallscale

•High energy consumption

•Restricted to WAS only

Chemical •Addition ofacids/bases/enzymes/oxidants toattack membrane

•Lab/pilot scale success

•Achieve benefits of lysis

•High chemical/capital costs

•Chemical removal/neutralization

Electrical •Generation of free radicals byelectrolysis of water

•Pilot scale demonstrations

•High energy consumption

•Discontinued technology

Electrical – PEF •Electroporation of cell membranesresulting in osmotic lysing;disruption and fragmentation

•Lab/pilot/full scale

•Demonstrated in multiple labs and atfull scale

•Energy positive

R&D Issues

• Reproducibility

Electromechanical – OpenCEL® FP• Focused Pulsed (FP) technology

uses pulsed electric fields (PEF) ofhigh voltage to permanently openpores and fragment flocs and cells:

– Voltage of 20 – 30 kV, Pulsingfrequency of > 2000 Hz, Treatmenttime <500 milliseconds

• Full-scale application (Mesa,Arizona) indicated that FP pre-treatment of the input primary andWAS demonstrated a biogasproduction increase of nearly 60%and reduced biosolids requiringdisposal by 30%

• FP treatment caused importantimprovements in the microbialcommunity structure

Up to 200% more CH4 from animal wastes!

2. Produce a higher valueenergy output than methane

Microbial ElectrochemicalCells (MXCs)

e- donor half reaction: - 0.29 V

e- acceptor half reaction: 2 O2 + 8H+ + 8e- → 4 H2O 0.81 V

The reaction potential drives all biological, chemical, and electrochemicalprocesses in MFC => typical recovered potentials are 0.3 - 0.6 V

Membrane

H2O

CH3COO-¼ O2

Air

e-H+ +

CH3COO- + 3 H2O → CO2 + HCO3- + 8H+ + 8e-

1.10 VNet reaction: CH3COO- + 2O2 → CO2 + HCO3- + H2O

Electrical powergeneration

Anode Cathode

Microbial Fuel Cell

Modifying the MXC to an MEC toProduce H2e- donor half reaction: - 0.29 V

e- acceptor half reaction: 8H+ + 8e- → 4 H2 - 0.41 V

In a Microbial Electrolysis Cell (MEC), we exclude O2 and addpower (applied voltage) to have a low enough cathode potential toproduce H2.

Membrane

H2

CH3COO-

e-

H+ +

CH3COO- + 3 H2O → CO2 + HCO3- + 8H+ + 8e-

- 0.12 VNet reaction: CH3COO- + 3H2O → CO2 + HCO3- + 4 H2

H2 gasproduction

CathodeAnode

2H+

H2 from an MEC or CH4?

• H2 can be used to power chemical fuel cells, sayto drive your car of the future.

• H2 is a major feedstock to the chemical industryfor reductions, or hydrogenations.

• H2 can be used for water-pollution control toreduce oxidized contaminants, like nitrate,perchlorate, selenate, and TCE The MBfRtechnology.

• The economic value of H2 is about 5 timesgreater than CH4 on an e- (or BOD) basis!

3. Capture nutrients into highvalue “mobile” stream

Selective Sorption Technology

P-recovery strategy (similar for N)

High P and BOD(animal waste)(40% of mined P)

Convert Org-P toInorg-Psimultaneouslywith anaerobicbioenergyproduction

Separate, concentrate, andrecover Inorg-P by selectiveadsorption or ion exchange

Low P and BOD(runoff)(46% of mined P)

Convert Org-P toInorg-P with anAOP

Recovered P for food crops orother uses

Sources Conversions Recovery and Use

Energy output, e.g., CH4 or H2

Water for reuse

Medium P andBOD (sewage)(16% of mined P)

Hybrid Ion-Exchange (HAIX)

Anion exchange resin beads impregnated with hydrated ferricoxide (HFO) nanoparticles

PhosXnp

4. Get high value from the left-over solids

High-value Soil Amendment

Partnering with Midwest BioAg

• Post anaerobic digestion, they

– Dry residual biomass

– Augment with N and P

– Pelletize

• Creates a high-value soil amendment forregional use.

Where is the Value?

EBT = earnings before taxes

North American Partnership for PhosphorusSustainability

NAPPS

The goal of NAPPS is to work actively with stakeholders to fosterthe implementation of sustainable P solutions in public and

private sectors.

Short introductory presentation anddiscussion today at 5:15pm.

Please join me!

Maximizing Microorganism-BasedResourcesBruce E. Rittmann

Regents’ Professor of Environmental Engineering

Director of the Swette Center for EnvironmentalBiotechnology

Biodesign Institute at Arizona State University

Rittmann@asu.edu http://environmentalbiotechnology.org

P-RCN: Coordinating PhosphorusResearch to Create a Sustainable

Food System

• Five-year effort funded by the US NationalScience Foundation (2012 – 2017)

• ASU as lead institution

– James Elser is PI; Helen Rowe is executive

• Goal: catalyze an international network ofresearchers and practitioners tosynthesize data, perspectives, andunderstanding about phosphorus toidentify and implement solutions for Psustainability.

~45 core participants.

International: USA, Canada, Australia, Japan,United Kingdom, Ireland, Switzerland, India,China, Argentina, Congo

From university, industry, NGO, and governmentagencies.

Includes NAPPS

Who is in the P-RCN?

North American Partnership for PhosphorusSustainability

NAPPS

The goal of NAPPS is to work actively with stakeholders to fosterthe implementation of sustainable P solutions in public and

private sectors.

• Monitor, collect, review and circulateinformation concerning key dimensions of Psustainability.

• Foster implementation of innovativetechnologies and solutions

• Coordinate position statements andcommunication

• NAPPS Stakeholders

Water Quality: governmentagencies, non-profits

Agriculture: producers,consultants, fertilizer industry

P Recycling: companies/startups

P Demand: bioenergy, foodindustry, food and detergentadditives

Phosphorus and WaterQuality

Phosphorus Efficiency inFood Production

PhosphorusRecycling

P DemandDrivers

Stage I Working Groups

It’s not just the P!

Extra Slides