Value Recovery From Solid

Confectionery Waste

Susan T.L. Harrison, Madelyn Johnstone-Robertson, Sharon

Rademeyer, Leslie Murhonyi Mapatana, Carol Ngwenya,

Caryn Horn, Shilpa Rumjeet, Nodumo Zulu and Mariette Smart

____________________________________

March 2019

Prof Susan T. L. Harrison

Director, Project Leader

Dr Madelyn Johnstone-Robertson

(former) Research Officer

Dr Nodumo Zulu

Research OfficerDr Mariette Smart

Research Officer

The Centre for Bioprocess Engineering Research

meet the confectionery waste team: senior researchers

Carol Zethu NgwenyaPhD candidate

Bioenergy

Sharon Rademeyer Researcher, M.Eng. graduate

PGA production

Shilpa RumjeetResearcher

PHA technoeconomics

Leslie Murhonyi MapatanaM.S(Eng) candidate

PHA production

Caryn HornPhD candidate

Pigment production

Literature review on scope and scale of the confectionery industry in South Africa

and its associated waste. Emphasis on the sugar, chocolate and starch

confectioneries.

Review typical treatment approaches to confectionery globally to ascertain

approaches to value creation from similar wastes elsewhere.

RESEARCH

APPROACH

“Start where you are.

Use what you have.

Do what you can.”

- Arthur Ashe -

Explore the waste biorefinery concept to draw together generic approaches from

other wastes for application to the confectionery waste.

Identify appropriate products with potential for market demand.

Propose microbial production systems suited to the bioconversion of confectionery

waste to these products.

Collect productivity and yield data for the production of the selected products.

Develop flowsheets for one product for the integrated utilisation of waste

components while maximising value creation. Compile material and energy

inventories for process assessment. Conduct techno-economic feasibility of the

process of using solid waste confectionery as feedstock to the biorefinery.

Confectionery Manufacture

produces Confectionery

Waste

South Africa’s

confectionery

industry

generates

substantial

organic waste

Confectionery Waste to Landfill:

contaminates water contaminates air

uses space

Currently

South Africa’s

confectionery

waste is

largely sent

to landfill – wasting resources,

polluting ground

water, forming

GHGs, and using

space

Confectionery Waste to Waste Biorefinery:

bioenergynatural soil amelioranteco-friendly “plastics”

natural pigmentclean water

Confectionery

Waste to

Waste

Biorefinery:

bioenergy

natural soil

ameliorant

eco-friendly

“plastics”

natural

pigment

Feedstock ProductsConversion

Processes

Municipal solid waste

Animal waste

Pulp and paper waste

Food waste

Agricultural residues

Timber

Crops

Algal biomass

Bioconversionsfermentation

enzymatic hydrolysis

Chemical Conversions

Thermochemical

Conversionsgasification

pyrolysis

hydrothermal conversion

Physicochemical

Conversions

Bioenergy

biogas

biofuels

Power products

electrical

thermal

Chemical products

polymers

platform chemicals

pigments

surfactants

fertiliser

fatty acids

Biomass products

compost

fibre

Th

e W

ast

e B

iore

fin

ery

Th

e W

aste

Bio

refin

ery

Sele

cti

on

of

bio

pro

cess

op

tio

ns

Complexity & Concentration

Chemically

defined, dilute

Chemically

complex,

concentrated

Chemically

defined, dilute

Physicochemical may be more suitable

Biorefinery units may be more suitable

High C

composition

High solids

content

High N,P

composition

Bacterial bioreactor

may be more suitable

Solids bioreactor

may be more suitable

Concentrated,

and/or high flows

Dilute, low flows,

or sporadic

Algal bioreactor

may be more suitable

Macrophyte bioreactor

may be more suitable

Chemically

defined,

concentrated

Sele

ctio

n o

f bio

pro

cess o

ptio

ns

Fine

Chemicals

Biopolymers

Platform and

Commodity Chemicals

Biomaterials

Bioenergy Products

Biomass Products

Power and Heat

incre

asin

g vo

lum

ein

creasi

ng

valu

e

Product selection criteriaTRL 1 Basic idea

TRL 2 Concept developed

TRL 3Experimental proof

of concept

TRL 4 Lab demonstration

TRL 5 Lab scale validation

TRL 6Prototype

demonstration

TRL 7 Pilot scale

TRL 8 Commercial design

TRL 9Ready for full

deployment

Technology Readiness Levels

ProductProduct

categoryTRL Use Primary feedstock

Poly-γ-glutamic acid (PGA) Biopolymer TRL 6 Soil conditioner

Water retention

C6 sugars

NH4+

Poly--hydroxyalkanoates

(PHA)

Biopolymer TRL 9 Biodegradable plastic for

healthcare products, packaging

and one-use plastic products

C6 sugars

Organic acids

CO2 & H2

Citric acid Organic

acid

TRL 9 Acidulant C6 sugars

Purple Monascus pigment Biopigment TRL 4 Colorant C6 sugars

Bioethanol Alcohol TRL 9 Biofuel, platform chemical,

precursor to polymer

C6 sugars

Biogas Biomethane TRL 9 Bioenergy C6 & C5 sugars,

organic acids etc

Products selected for study

Four products

Four student projects

Purple

pigment

PGA

Bioenergy

PHA

Renewable energy production

Confectionery waste carbohydrate

content = ideal bioprocess feedstock

for renewable energy production.

Here, confectionery waste was used

as a substrate to convert to

bioenergy as:

• Bioethanol by microbial

fermentation using Zymomonasmobilis

• Biogas using anaerobic digestion

(AD).

Valorisation of waste streams results

in increased resource efficiency

producing commodity products and

reducing their environmental

footprint.

Bio

en

erg

y

Bioethanol

0.0

0.2

0.4

0.6

0.8

1.0

Synthetic Mix Candy Mashmallows Chocolate

Yie

ld (

g/g

)

Yx/s Yp/s Max. EtOH ( x10 g/L)

Biogas

0

200

400

600

800

1000

1200

0 10 20 30 40

Cum

ula

tive

bio

gas

pro

duce

d (

mL)

Days

Flour confectionery Mixed confectionery waste

Bio

en

erg

y

Polyhydroxyalkanoate (PHA) production

confectionery

wastePHA

What is it?

Landfill

Why PHA?• Biodegradability

• Biocompatibility

• Renewable feedstock

• Physical and mechanical properties

• Application versatility (packaging,

agriculture, pharmaceuticals etc.)

Intracellular carbon

storage compound

produced by some

microorganisms under

controlled condition

microorganisms

PH

A

Waste characterisation

carbon source

composition

Microorganism selection

Alcaligenes latusCupriavidus necator

Growth of the species

on confectionary waste

0.00E+00

1.00E+08

2.00E+08

3.00E+08

4.00E+08

5.00E+08

6.00E+08

7.00E+08

0 2 4 6 8 10 12 14

Cells

/ml

Time (hours)

candy chocolat

0

5

10

15

20

25

0 5 10 15

To

tal c

arb

ohyd

rate

(g

/l)

Time (hours)

candy chocolate

Experimental growth

and sugar utilisation of

Alcaligenes latus

Optimisation and PHB

production continuing

for A.latus (oils) and

C. necator (sugars)

PH

A

RESOURCE RATHER

THAN WASTE

Bacillus sp

Bioflocculant

Fertiliser/soil

enhancer

Poly(γ-glutamic) acid

(PGA) production

Attractive as a soil conditioner or bioflocculant

• Biodegradable

• Non-toxic

• Hygroscopic

• Can be used as a nitrogen source

• Has many flocculation applications

PGA is produced by Bacillus species that are able

to use confectionery waste as a carbon source

PG

A

1. Identify a Bacillus species that is able to produce PGA

2. Characterise the confectionery waste from an identified factory in SA

3. Identify key nutrients needed to supplement the waste to produce PGA

4. Determine the sugar concentration range needed to produce PGA

5. Commission and operate a bioreactor set-up that will produce PGA

1. Bacillus licheniformis JCM 2505 selected as it can use inorganic nitrogen

2. Waste characterisation showed that hard candy waste consists mostly of sucrose

3. Hard candy waste with “basal medium” can be utilised by B. licheniformis 4. Growth kinetics on candy and sucrose are comparable

5. PGA formation in a fed-batch culture favours a specific C:N ratio

PG

A

Fungal pigment production

Filamentous fungus, produces deep red pigmentation

• Monascus-like polyketide pigments

• Confectionery waste as a potential source of sugars,

but requires a nitrogen source

Penicillium purpurogenum

Shown to be suitable substrate for growth and pigment production

• Culture pH maintained using citrate buffer

• Supplemented with soya peptone

Marshmallow confectionery waste

Shift from chemical to natural colourants

• Health and environmental benefits

Microbial sources gaining interest over plant and insect sources

• Fast growth and consistent, controllable production

Overview

Agar plate

Multiwell plate

Shake flask

7 L Bioreactor

Natu

ral p

urp

le p

igm

en

t

Anaerobic

Digestion

tech-ready

not complex

on site use as CHP

ORpolishing step in

the WBR

Technoeconomics

PGA

production

Technoeconomics

inoculum

preparation

bioprocessing

for PGA

PGA

recovery

Tech

no

eco

no

mic

s: PG

A

cell

culture

@ 26 h

4 g/L cells

40 g/L PGA

Upstream: Inoculum Preparation

Capital cost 2018 (3 chains):

US$ 440 000 * 4.74 = US$ 2 085 600

Main process: PGA Production

Capital cost 2018 (3 chains):

US$ 1 200 000 * 4.74 = US$ 5 688

000

Downstream:

Capital cost 2018:

US$ 168 600 * 4.74 = US$ 799 000

US$ 14 600

US$ 73 000

US$ 50 000

US$ 31 000

PG

A p

rod

uctio

n c

ap

ital c

osts

PG

A p

rod

uctio

n o

pera

ting

co

sts

Inoculum preparation and main process

Operating costs 2018 (3 chains):

US$ 1 285 000 per year

Downstream:

Operating costs

2018:

US$ 133 700

PGA

production

details of

process

economics

TechnoeconomicsUSD (2018)

Revenue: 83810 kg/year PGA

sold at $100/kg$ 8 381 000 / year

Total Operating Cost $ 1 418 700 / year

Fixed Capital Cost $24 702 700

Working Capital (15% of fixed) $3 705 400

Total Capital Cost $28 408 100

Taxation (%) 28,0

Escalation (%) 6,2

Years of depreciation 10

Scrap value (%) 5,0

WACC (discount rate, %) 15,0

ROI (%) 33,8

Payback Period (Years) 4,6

NPV ($ 2018 after 15 years) $12 022 000

IRR (%) 23,0

PGA

production

profitable for

food-grade PGA

less profitable for

agricultural PGA

but opportunity to

improve using low

cost reactors and

offsetting disposal

costs

Technoeconomics

optimise

bioreactors

define

purification

PGA grade

vs

costs

Conclusions waste bio-

refinery

green-

house

gases

load on

landfill

produce

bioenergy

lost bio-

resource

toxic

ground-

water

CONCLUSIONS

Conclusions

Bioenergy

Demonstrated

Biogas – CHP

implemented industrially

Polyglutamic Acid

Demonstrated

Low cost reactors under

evaluation

Scale-up studies and

evaluation planned

Polyhydroxyalkanoates

Demonstrated

Currently being

assessed for industry

Purple MonascusPigment

DemonstratedScale-up studies

planned

CONCLUSIONS

Conclusions waste

bio-

refinery

sugar

chocolate

starch

confe

ctio

nery

ind

ust

ry

CONCLUSIONS

reimagining

confectionery

waste as a

resource

Confectionery waste can be valorised

selecting possible

bioproducts and

bioprocesses for

valorisation

proof of concept

for four selected

products in four

student projects

assessing

economic &

environmental

potential

Contact us

www.CeBER.uct.ac.za

Chemical Engineering Building, UCT

CeBER@uct.ac.za

Acknowledgements

Linda Godfrey and team for

project advice and management

DST – CSIR Waste RDI for funding

DST NRF for SARChI chair funding