High Value Resources from High Strength Wastes:Leveraging Food Production Byproducts to Reduce BNR Costs

Chris Wilson, Ph.D., P.E.VWEA 33rd Annual Industrial Waste & Pretreatment ConferenceMarch 7th, 2017

2

If we believe that resource recovery is an important role

for treatment utilities…

…then a focus on the recovery of high value products

that can be beneficially used to support operations

should follow.

3

4

We recognize that there are practical impediments to the recovery of

resources that have the highest values

WRRF

Internal market

• Products well defined, processes understood

• Values may be limited

External market

•Novel processes when applied to wastewater

•Values relative to commercial products

CHALLENGE: Accessing External Markets

5

We recognize that there are practical impediments to the recovery of

resources that have the highest values

WRRF

Internal market

• Products well defined, processes understood

• Values may be limited

External market

•Novel processes when applied to wastewater

•Values relative to commercial products

CHALLENGE: Accessing External Markets CHALLENGE: Accessing External Feedstocks

• Feedstock selection

• Feedstock procurement

•Holistic “cost of service”

6

We recognize that there are practical impediments to the recovery of

resources that have the highest values

WRRF

Internal market

• Products well defined, processes understood

• Values may be limited

External market

•Novel processes when applied to wastewater

•Values relative to commercial products

CHALLENGE: Accessing External Markets CHALLENGE: Accessing External Feedstocks

• Feedstock selection

• Feedstock procurement

•Holistic “cost of service”

7

The CosmosJustified

Today’s Presentation discusses an alternative approach to sourcing,

valuing, and processing carbon in resource recovery facilities

Where’s the beef?

8

The CosmosJustified

Today’s Presentation discusses an alternative approach to sourcing,

valuing, and processing carbon in resource recovery facilities

Where’s the beef?

9

Example:

The potential value of diverse carbon sources…

Primary

Clarifier

Methanol

Dose Point

RAS

Secondary

Clarifier

Deep

Bed

Filters

Methanol

Dose Point

Aeration Tank

NRCY

3,000 gpd MeOH

20-22 mg NOX-N/L

10

3,000 gpd MeOH

20-22 mg NOX-N/L

Example:

The potential value of diverse carbon sources…

Primary

Clarifier

Methanol

Dose Point

RAS

Secondary

Clarifier

Deep

Bed

Filters

Methanol

Dose Point

Aeration Tank

NRCY

Primary

Clarifier

Methanol

Dose Point

RAS

Secondary

Clarifier

Deep

Bed

Filters

Methanol

Dose Point

Aeration Tank

NRCY

6-10 mg NOX-N/L1,400-1,900 gpdOptimization

Recovery?

Stone Brewery

& Restaurant

Development

Site

City of Richmond WWTP

Parameter Unit Wastewater Lauter Tun Waste Spent Yeast Composite Waste

flow gal/barrel 62.9 9.9 8.5 81.2

tCOD mg/L 12,745 190,600 206,750 54,674

sCOD mg/L 8,730 120,300 101,300 31,976

TKN mg/L N 291 585 895 390

TP mg/L P 48 76 450 94

Pepsi Bottling Facility

HRSD James River TP

I-64 Parking Lot

PHF

13

The CosmosJustified

Today’s Presentation discusses an alternative approach to sourcing,

valuing, and processing carbon in resource recovery facilities

Where’s the beef?

14

Carbon Product Recovery Economic /Process Model

HSW Character

Sludge Character

Process Stoichiometry

Energy/Commodity Data

Energy Product

Carbon Product (VFA)

Biosolids Impacts

BNR Impacts

Capital and O&M Req’s

Σ =Descriptive life cycle

economics and external

fee requirements

Understanding holistic process impacts of codigestion and

co-fermentation supports robust business case development

15

Energy Product

Carbon Product (VFA)

Biosolids Impacts

BNR Impacts

Capital and O&M Req’s

In this case, implementation was relatively low cost as it leveraged

existing tanks and prior sludge fermentation upgrades

Existing Sludge Fermenter

Brewery Waste Storage/

Mixing

Additional Lab, Administrative, and

Operational Costs

Brewery Waste Piping and

Control Modifications

Existing Truck Scale

16

Energy Product

Carbon Product (VFA)

Biosolids Impacts

BNR Impacts

Capital and O&M Req’s

Digester gas is a relatively small driver for Richmond due to low cost of

natural gas and current mono-fuel plant heating systems

$0K

$5K

$10K

$15K

$20K

$25K

$30K

$35K

$40K

Average Monthly NG Cost without

Digester Gas Recovery

Average Monthly NG Cost

after Digester Gas Recovery

With Current Biogas Production

With 10% Reduction in Biogas Production for Fermentation

17

Energy Product

Carbon Product (VFA)

Biosolids Impacts

BNR Impacts

Capital and O&M Req’s

Carbon recovery relies on a combination of two-stage fermentation and

elutriation of sCOD through gravity thickeners

LTD LTDLTD Brewery Byproduct Discharge Point Alternate Brewery Byproduct Discharge Point

LEGEND

Primary

Clarifier

Fermenter

Gravity

Thickener

tPS

rbCOD

(GTO)

LTD

LTD

LTD

Alternate

Alternate

FS

12-20% Conversion of

pCOD in fermenter

85% Recovery of sCOD

in Gravity Thickener

Total VFA production as

a function of loading

and sCOD content

18

Energy Product

Carbon Product (VFA)

Biosolids Impacts

BNR Impacts

Capital and O&M Req’s

Biosolids hauling cost is increased by additional heterotrophic biomass

production (from VFA) and residual brewery waste solids

LTD LTDLTD Brewery Byproduct Discharge Point Alternate Brewery Byproduct Discharge Point

LEGEND

Primary

Clarifier

Fermenter

Gravity

Thickener

tPS

rbCOD

(GTO)

LTD

LTD

LTD

Alternate

Alternate

FS

12-20% Conversion of

pCOD in fermenter

85% Recovery of sCOD

in Gravity Thickener

Total VFA production as

a function of loading

and sCOD content

To Land Application

Dewatering

Side Stream

Treatment

Anaerobic

Digesters

tWAS

HS

HMS DS

Extra tWAS due to OHO

growth on VFA

19

Energy Product

Carbon Product (VFA)

Biosolids Impacts

BNR Impacts

Capital and O&M Req’s

Nutrient impacts include imported soluble nutrients that are elutriated

with VFA and digester-released nutrients subject to sidestream treatment

1

2

3

Tier 1: Soluble nutrients imported

with brewery waste

Tier 2: Nutrients released from brewery

waste in fermenter and digester

Tier 3: Nutrient uptake by OHO growth

due to VFA usage for denitrification

20

Relative magnitude of costs by category: Unique distribution driven by

waste character, recovery strategy and availability of existing facilities

($200,000)

($100,000)

$0

$100,000

$200,000

$300,000

$400,000

$500,000

MeOH offset Digester Gas Biosolids AmmoniaRemoval

Storage TankEAC

Laboratory &Admin Cost

Quirk of high recovery of sCOD (85%)

and high solubility of brewery waste

$234k net

annual value

($0.067/lb COD

Delivered)

Example condition: Year 6 projected brewery build-out (2022), 100% of LTD to Fermenter

Scalable with HSW

Loading

Level Annualized

Costs

21

Process/Cost model output guides practical decision-making:

Compare codigestion and co-fermentation strategies (sensitivity analysis)

-0.060

-0.040

-0.020

0.000

0.020

0.040

0.060

0.080

0.100

0 5,000 10,000 15,000 20,000 25,000 30,000

Daily Brewery Waste Received (Gallons)

Net Value of

Brewery Waste

($US/lb COD)

Brewery Waste

directed to

Fermenter

Brewery Waste

directed to

Digester

22

Process/Cost model output guides practical decision-making:

Brewery waste value as a function of sCOD content (sensitivity analysis)

-$0.10

-$0.05

$0.00

$0.05

$0.10

$0.15

0.00 0.20 0.40 0.60 0.80 1.00

Net Value of

Brewery Waste

($US/lb COD)

The

“No gate fee,

no value”

point

Increasing potential

for “gain share”

Example condition: Year 3 projected brewery build-out (2019), 100% of LTD to Fermenter

23

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

0.080

0.090

0.100

0 5,000 10,000 15,000 20,000 25,000 30,000

Daily Brewery Waste Received (Gallons)

Net Value of

Brewery Waste

($US/lb COD)

12% pCOD

Conversion to VFA

Sensitivity analysis using Process/Cost model:

Relative importance of pCOD conversion rate in fermenter

24

Sensitivity analysis using Process/Cost model:

Relative importance of pCOD conversion rate in fermenter

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

0.080

0.090

0.100

0 5,000 10,000 15,000 20,000 25,000 30,000

Daily Brewery Waste Received (Gallons)

Net Value of

Brewery Waste

($US/lb COD)

20% pCOD

Conversion to VFA

12% pCOD

Conversion to VFA

About $25k/year

increase in value

for this example

25

Carbon Product Recovery Economic /Process Model

HSW Character

Sludge Character

Process Stoichiometry

Energy/Commodity Data

Energy Product

Carbon Product (VFA)

Biosolids Impacts

BNR Impacts

Capital and O&M Req’s

Σ =Descriptive life cycle

economics and external

fee requirements

Understanding holistic process impacts of codigestion and

co-fermentation supports robust business case development

26

The CosmosJustified

Today’s Presentation discusses an alternative approach to sourcing,

valuing, and processing carbon in resource recovery facilities

Where’s the beef?

27

Eirene A. Pavlakis

28

We commonly use anaerobic digestion to mineralize complex substrates, producing byproduct methane

≥ 15 days HRT

▪ Wastewater sludge

▪ Manure

▪ Food and animal waste

▪ Industrial wastes

▪ Methane

▪ Carbon Dioxide

▪ Hydrogen Sulfide

▪ Water, Residue

WERF OWSO11C10 - Barriers to Biogas Use for

Renewable Energy

“Inadequate payback and lack

of available capital remain the

dominant barriers to

recovering power through

anaerobic digestion with

combined heat and power

production.”

29

Others (e.g. chemical and food manufacturing) view feedstocks as a source for numerous chemical intermediates

▪ Wastewater sludge

▪ Manure

▪ Food and animal waste

▪ Industrial wastes

2-3 day HRT

▪ VFA and other low molecular

weight compounds

30

31

(g-CODVFA/g-CODsCOD) (gPHA/gVSS)

Morgan-Sagastume et al., 2010 Wastewater sludge 60% 21%

Reddy and Mohan, 2012 Food waste 53% 40%

SubstrateSource

VFA

Enrichmentreactor

PHA accumulators

PHA accumulation

reactor

Biomass

Wastewater biosolids

Food waste

AcidogenicCo-Fermentation

We are interested in understanding the operational levers associated with both VFA and PHA generation steps within relatively conventional processes

Pavlakis E. et al. 2016 (unpublished)

Wastewater sludge + Food waste

35%

Pavlakis E. et al. 2015 (unpublished)

Food waste 44%

25%

32

• VFA-rich fermentate derived from food waste is a suitable substrate for

PHA production

• VFA production from sludge and food waste are limited by different

mechansms

• Uptake of COD into PHA accumulating organisms is not terribly hard to

accomplish – producing the right quantity and quality of VFA it the art

Lessons learned so far through research into converting food wastes to raw polyhydroxyalkanoate:

33

• The higher the VFA content in the soluble COD the higher the PHA

accumulation and the higher the rate of substrate consumption.

• Value in investigating relief of hydrolysis and thermodynamic limitations

on VFA fermentation from specific feed stocks.

• Next steps:

– External modification of reaction energetics

– Optimization of PHA accumulation from mixed waste fermentate

– Microbial ecology

– Conceptual process flow schematic and lifecycle cost model development of

full scale mixed fermentation to PHA systems

Lessons learned so far through research into converting food wastes to raw polyhydroxyalkanoate:

34

If we believe that resource recovery is an important role for treatment

utilities…

…then a focus on the recovery of high value products that can be

beneficially used to support operations should follow.

The CosmosJustifiedWhere’s the beef?

High Value Resources from High Strength Wastes:Leveraging Food Production Byproducts to Reduce BNR Costs

Chris Wilson, Ph.D., P.E.WaterJAM 2016 YP WorkshopSeptember 13th, 2016