ANAEROBIC DIGESTION –BEYOND THE PARIS AGREEMENTS

WILLY VERSTRAETE

UGENT / AVECOM /KWR

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of all solutions !!

OVERVIEW

• MINDSETS ANNO 2019

• PROGRESS IN BITS AND PIECES

• TWO PLATFORMS OF NEW DEVELOPMENT FOR BIOGASIFICATION

• CONCLUSIONS

The things which are on the mind of theconsumer

• Energy

• Climate

• Food for all

THE ISSUE OF ENERGY

• WE WANT TO CHANGE SOME 85% OF ENERGY USE FROM FOSSIL AND NUCLEAR TO WHAT ???

• RENEWABLE IS STILL MINIMAL ( SOME 10% IN THE EU) BUT GROWING ;YET IT SHOULD NOT BECOME EXPENSIVE (WIND / PV/ …)

• THE HYDROGEN ECONOMY IS COMING / Solar Power to the People -Ad Van Wyck Delft University 2017

TAKE HOME : NOW MINIMUM 50 EURO /MWH

MAYBE COMING 10 EURO/ MWH ?

CLIMATE CHANGE

MOST OF US ARE CONCERNED INDEED

THE CO2 ISSUE : SO FAR NO CONCRETE STEPSTONES ARE IN PREPARATION ….

Under consideration: - CO2 burial in the deep soil eg Rotterdam ….

- CO2 use for shale and oil winning …

- CO2 use to produce chemicals

WHAT ELSE ?

World needs of edible highly nutritious protein

- 1 person needs (and excretes) about 14 g N per day. This corresponds with

an uptake of about 100 g edible protein (plant based and/or animal based)

dw per day

- In 2006, the amount of available highly nutritious protein (dw) is about 25

g (dw) per person per day. There is a need of highly nutritious protein

- In 2050, the population will increase to 10 billion people and the demand

for high quality protein per person per day will at least increase with a

factor 2

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Take Home: The demand for highly nutritive edible protein will, in

the comming decade, rise strongly

PROTEIN GAP

60%

12,5%

TOTAL REACTIVE NITROGEN INPUTS

LOSSES TO ATMOSPHERE ANDAQUATIC ENVIRONMENT

WASTE REACTIVE NITROGEN

THE BIRD’S EYE VIEW:

The anthropogenic N-cycle

40%

URBAN WASTE WATER TREATMENT

PLANT

AGRICULTURE

FEED-FOOD CHAIN

N2

NH3

N2

8

2L/kg N

2L/kg N

Conventional Edible Protein

(dry weight – dw)• The conventional feed/food chain: 2 ha of land → 1 ton of edible animal

protein dw per year (pork, chicken, beef, carp) (FAO, Alexandratus and Bruinsma 2012)

• Related fresh water consumption per 1 KG edible animal protein dw: ca 50 m3

• Related CO2 production per 1 KG of edible animal protein dw produced: ca 100 KG

9

Take Home: Edible protein from conventional Agriculture / but alsofrom Fishing the oceans / has a VERY heavy environmental

footprint; these production lines are under pressure(Sinha et al. Sience 2017)

THE EXTERNALIZED COSTS OF PROTEIN; THE ENVIRONMENTAL BURDENS.

The things which are on the mind of the consumer / CONSEQUENCES

-AD IS NOW MAINLY ‘ALTERNATIVE ENERGY FOR CHP ’

- AD SHOULD SHOULD BY ALL MEANS TRY TO BE MORE EFFECTIVE IN CONVERSION EFFICIENCY

-AD SHOULD DARE TO SPEAK OUT ON ITS ADDITIONAL POTENTIAL OF ‘CLIMATE CHANGE’ ABATEMENT VIA CO2 AND NUTRIENT ISSUES

-AD MUST EXPLORE NEW VALUE CHAINS WHICH RELATE TO NOVEL PRODUCTS , PARTICULARLY PROTEIN PRODUCTION

AD and ‘DARE TO THINK ‘ forward

*PLATFORM 1 : Incremental steps forward

AD for sewage / More biogas / NH3

*PLATFORM 2 : Quantum leaps

Small Steps : Type 1 : Integrate AD directly in sewage

treatment

• Use Forward Osmosis to concentrate the sewage and THEN apply AD to the concentrate

Small steps : Type 2 : Get more biogas from the incoming organics

• C-Redirection / HRAS / A-B systems ( Sancho et al.2019)- Some 60% of the organic C can be upgraded by AD to biogas- From 0.43 tot O,28 kg CO2 per m3 wastewater treated (30% decrease)

Small steps : Type 2 : More biogas by FNA ( free nitrous acid )

Get more biogas from the incoming organics : Use FNA to lyse cells and EPS ( Zhiguo Yuan group / Brisbane )

Secondary settler

Thickener

Effluent

Bioreactor

Anaerobic

digester

To head of the WWTP

or side-stream treatment

Dewatering

Anaerobic digestion liquor

Disposal

Dewatered

sludge

Lodomat - AD for retrofitting

Secondary sludge

CH4

Low N

FNA treatment

of sludge

CH4 production increases by >30%VS destruction increases by >30% AD reactor size reduced by up to 50%

Small Steps : Type 3 : Recover NH3 FROM THE DIGESTATE

Use AD to produce NH3 , then remove the ammonia for re-use

Small Steps : Type 3 : Recover NH3

New ways to capture ammonia• Water splitting electrodialysis and hollow fiber extraction (Yan et al .

2018)

Only 4.5 MJ per kg N

Note: Stripping 50 MJ

per kg N

Small Steps : Type 3 : Recover NH3

A nice combination is to produce biomethane and ammonium fertilizer (Qingyao et al.2017)

Small Steps : Type 3 : Recover NH3

• Strip NH3 and reform it to H2 (Babson et al. 2018)

• Take home: Economically

marginally feasable

at C/N below 16

Small Steps : Type 3 : Recover NH3 because it represents fossil fuel!

Use AD to produce NH3 , then remove the ammonia for re-use

The value of recovered mineral N is max 20% of that of fertilizer mineral N (0.2 x 0.7 = 0.14 Euro per kg N)

The issue is that :Recovery + Re-use as mineral N > Haber Bosch + Dissipation

Take Home :

Upgrade the recovered mineral N to the organic form :Organic N as fertilizer. = 2,5 Euro per kg NOrganic N as feed /food = 6-10 Euro per kg N

AD and ‘DARE TO THINK ‘ forward

PLATFORM 1 : Incremental steps forward

PLATFORM 2 : Quantum leaps

Centralized systems / Go for the GRAS aspect

Quantum leapsExample 1 : Centralized Valorization of BioMethane

• ‘Decentral Biomethane’ combined with ‘Central Petro’ Technology (Verbeeck et al 2018)

• The case :

-Up to 10% of trucks on the road transport organics : deal with the wastes of organics at ‘Decentral Bio Plants ‘

-In the EU , large gas-networks will be used less : re-juvenate them tobring bio-methane to ‘Central Petro Plants ‘

-At such Central Petro Plants , one can implement new technology

* to have very efficient CHP ( 50% to electricity / district heating …)

* to combine CO2 capture and production of chemicals

24

Case C: ‘Super-dry’ reformingProduction of CO from biomethane

𝐶𝐻4 + 3𝐶𝑂2 → 4𝐶𝑂 + 2𝐻2𝑂

Case B: Dry (CO2) reformingProduction of syngas from biomethane

𝐶𝐻4 + 𝐶𝑂2 → 2𝐶𝑂 + 2𝐻2

Case A: Sorption-enhanced Steam reformingProduction of H2 from biomethane

𝐶𝐻4 + 2𝐻2𝑂 → 4𝐻2 + 𝐶𝑂2

Buelens et al,. 2016, Science

CO2 use: 7.33 ton CO2 / ton CH4

CO production: 6.22 ton CO / ton CH4

Biomethane reforming allows CO2 utilization in a chemical looping process In

ten

sifi

cati

on

of

CO

2co

nver

sio

n

25

Importance of CO in chemical synthesis

Quantum leaps : Type 1 : Centralized Valorizationof Biomethane

• Couple biomass digestion to centralized production

By doing this Agriculture en AD can link up with

- Carbon capture in chemicals

- Green fuels for mobility !!!!

Quantum leaps :Type 2 : Go for the GRAS approach

Generally Regarded As Safe = The regulators points of view !

*Biogas is generally OK : methane , CO2 , NH3 , H2 ,H2S …

Consequence : Use the latter to grow microbial based biomass with acceptedgood quality

*Digestates : wake up to the reality ; the concerns for pharma , personal care products , chlorinated compounds , antibiotics , bacteria … will never go away

Consequence : Go for the Digestates for a technology which breaks the organicsreductively and produces gases which are CLEAN AND FERMENTABLE

g28

Ghent: 260 000

inhabitants

>20 ton/day

CLEAN

Feed resp

Slow Release

Fertilizer

contributing to

CCS

MICROBIAL BIOMAS PROTEIN

O2

H2

Water electrolysis

STEP ONE / THE GAS PART / AEROBIC FERMENTATION

Upgrade fecal ammonia and CO2 to CLEAN ORGANIC FERTILIIZER

AVECOM NV - Bioproducts & Apps

The economics of the Autotrophic Route

Sensitivity analysis

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YearH2 price

(Euro/kg)

Other costs(Euro/kg

Micr Prot)

PROMICfinal cost (Euro/kg)

% of cost due to H2

2016 (high) 5 0,85 2,85 70%

2016 (low) 3,5 0,85 2,25 62%

2020 2 0,85 1,65 48%

>2020 1 0,85 1,25 32%

Not profitable

Profitable (depending on the final quality of the product)

THE SLUDGE PART High tech : Reductive gasification of sludge

*Thermphos in the Netherlands : P fully recovered / yet factory closed

for reasons of environmental concerns and low value of mineral P

* Staged gasification can deliver energy rich producer gases ( Hernandez et al . 2013)

Quantum leaps :High tech : Reductive gasification of sludge

*The “re-invent the toilet challenge” by the Bill and Melinda Gates Foundation stimulates developments of the thermochemical conversion of fecal matter (Fidalgo et al. 2019)

*Existing small scale systems to deal with chemical wastes (rates of 10 tons per hr ) can possibly be optimized in a new context :

The N and P recovery products can be NH3 and also H3PO4 respectively

Link: https://www.nap.edu/read/5274/chapter/8

Aerobic Fermentation to MICROBIAL BIOMASS

Autotrophic route

• Oxygen

• CO2

• Reactive Nitrogen

• Hydrogen / CO/CH4

Food /Animal Feed

OR

Carbon captured in the form Microbial Based

Biomass = Slow Release Organic

Fertilizer This in case the

Quality of Product is low

ORMaterial

Composites

Microbial ProteinPROMIC

In-reactor Microbial Based Biomass production

Organotrophic route• Oxygen• Organic Carbon• Reactive Nitrogen

The challenge : link AD via these gases withwith BIOTECH PRODUCTS OF VALUE

*We need a sequence of Processes :

-First step : Anaerobic digestion and biogas / NH3

-Second step: Harvesting of the Solids

-Third step : Reductive gasification of the solids to yield more gasesGenerally Regarded as Safe (GRAS)

-Fourth step : Aerobic fermentation to upgrade these “GRAS” gases , particularly biogas CO2 , to Microbial Biomass

Preliminary estimation of Cost /Benefit

1. Harvesting sewage sludge biomass and drying : the costs are of the order of 250 Euro ton DW ; Hence : ca 250 Euro per ton COD dry sludge produced

2. The latter , if properly gassed and re-synthesized by aerobic fermentation will have an aeration const of 50 Euro and generate 0.4 ton Microbial Protein DW

3. Balance: Costs 250 + 50 = 300 Euro costs /// Potential sales as feed: 0,4 x 1000 Euro per ton protein

rich feed = 400 Euro .

Take home: There is as YET a narrow financial perspective for the reductive gasificatio/

HOWEVER the overall process might become cost neutral /and be fully fitting to the cyclic economy!!

End of ‘digestate dispair’ !

Quoi de neuf with respect toMicrobial Protein ?

*Old : Microbial protein from methane gas ( = pruteen ) already at 50 000 tons per year in the 70’s ; the idea was to valorize the excess of fossil fuel*Now : Environmental cost of conventional protein are very high

+ There is a need to design meaningfull processes in terms of CO2

avoidance and carbon capture and storage

New :We use ‘teams’ (microbiomes ) of microorganisms which ‘take-it-all’

+ We can use HYDROGEN as the energy driver to FULLY capture CO2

The market potentials for Microbial ProteinFood : 100 g higly nutritious protein dry matter per person per day / the demands willdouble in the next decade / Say a total market potential of some

1 000 000 tons of Top quality protein for food per year .

Feed :The current world market for animal feed has a size of

~ 200 000 000 ton Medium quality Protein/year - it is massive

Organic Fertilizer : demand is on the rise since chemical fertilizer becomes less reliable in case of climate change , say 5% of the total fertilizer demand ie some

10 000 000 ton microbial protein in the form

of New MBB Slow release organic fertilizer per year

Biobased biodegradable plastics : use protein as a component of biodedable plastics , at 2% biodegradables of total of a total of all plastics , this still represents

6 000 0000 ton microbial protein /year

AVECOM NV - Bioproducts & Apps

The Life Cycle Analysis for the Autotrophic Route

37

Beef Chicken Salmon Algae Crickets Soybeans PROMIC

Electricity kWhel 4,7 1,7 25 13 15 0,3 25

Water m3 6,2 1,7 2,5 1,0 0,3 0,3 0,01

Natural gas

MJ 87 30 73 62 40 3,2 8**

Net CO2

emissionskg CO2-eq 106 13 16 9,4 9,0 0,6* -0,85

Nitrogen run-off

kg N 4,5 0,4 0,3 0,1 0,02 0,002 0

Total primary energy

MJ 452 375 265 178 124 26 98

Main requirements for conventional and alternative protein (per kg protein dry weight):

Source: LuxResearch Inc.*Does not account for LUC =land use change

**Energy for drying from 10% to 85% DW

GENERAL CONCLUSIONS ABOUT ANAEROBIC DIGESTION & CLIMATE CHANGE • THE CONSUMER IS CONCERNED ABOUT ALTERNATIVE ENERGY , CO2

ABATEMENT AND FOOD /FEED / BIODEGRADABLE COMMODITIES

• ANAEROBIC DIGESTION HAS A MAGNIFICIENT OPPORTUNITY TO PLAY A KEY ROLE IN RELATION TO ALL OF THESE ISSUES

FOCUSS ON BETTER BIOGAS YIELDS AND UPGRADING TO BIOMETHANE

THIS CAN REVITALIZE THE AGRO-CROP SECTOR

AND PROVIDE ROADS TO

BULK ORGANIC CHEMICALS

AND TO GREEN MOBILITY

DEAL WITH THE POTENTIALS OF THE GRAS STATUS

AD CAN LINK UP WITH NEW PROCESS AND VALUE CHAINS TO GENERATE BIOTECH PRODUCTS OF INTEREST TO THE SUSTAINABLE ECONOMY SUCH AS

FOOD & FEED

SLOW RELEASE ORGANIC FERTILIZER

VARIOUS ORGANIC BIOMOLECULES