FOGO OR NOT TO

FOGO?

Webinar by Andy Street,

13th February 2017

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WELCOME INTRODUCTION

Andy Street – Director, SLR Consulting

Andy has more than 35 years’ experience as an environmental consultant and is

a founding Director of SLR. He has experience of working on the financing and

procurement of waste infrastructure and projects across the globe, and

specifically across Europe, North America, Australia and New Zealand. He

currently spends much of his time working and supporting clients in Australia

and New Zealand.

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SLR GEOGRAPHY

We deliver global environmental and advisory solutions from a network of offices in five

regions covering Europe, the US, Canada, Asia-Pacific and Africa.

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SLR ASIA-PACIFIC

We deliver global environmental and advisory solutions

from a network of offices across Asia-Pacific.

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• Waste strategy development and review • Business case development

• Sustainability strategies • Procurement and bid support

• Stakeholder / community consultation • Project management

• Waste audits • Lifecycle assessment

• Contracts and procurement and

purchasing strategies

• Advice and support on waste policy at

National, regional and local level

• Feasibility studies • Facility concept and detailed design

SLR has a strong track record of supporting local, regional and

rural councils in developing strategies that are structured to align

with regional and national policies for waste avoidance, recycling

and diversion of waste from landfill

One of SLR’s primary business streams is the provision of

planning and technical support across the full spectrum

of waste management services, including:

1. BACKGROUND

2. ORGANIC WASTE SEGREGATION

3. COLLECTION COSTS

4. TREATMENT COSTS

5. COMBINED ORGANIC WASTE SYSTEM COSTS

6. ORGANICS TREATMENT PROCESSES

7. CARBON PERFORMANCE

8. REGULATORY ISSUES

9. CONSIDERATIONS FOR WASTE STRATEGISTS

10. CONCLUDING COMMENTS

OVERVIEW

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1. BACKGROUND

• In a bid to further improve recycling rates and increase diversion from landfill, many councils

are now evaluating options for collection of organic waste, including food scraps.

• When disposed to landfill, anaerobic decay of organic waste produces the greenhouse gas

methane (even well managed landfill gas capture systems fail to capture a significant

proportion).

• In designing systems for management of organic waste, NZ’s Councils are faced with the

same choices a other municipalities internationally. Specifically, these choices concern:

– organic waste streams to be targeted (specifically garden organics [G0] and/or food

organics [FO]);

– collection methods (separate FO and GO, or combined FOGO); and

– processing/treatment options (principally open windrow composting, in-vessel

composting, or anaerobic digestion).

• Possible operational configurations arising from these options are illustrated schematically

overleaf.

• To inform debate on optimum approaches to management of organic waste, this webinar

develops indicative whole-system costings for contrasting approaches to management of GO

and FO.

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1. BACKGROUND (continued …)

Separate GO

collection

Separate GO

collection

Garden

organics

(GO)

Food

organics

(FO)

Separate FO

collection

Separate FO

collection

Wet AD (low

solids anaerobic

digestion)

Wet AD (low

solids anaerobic

digestion)

Combined

FOGO

collection

Combined

FOGO

collection

OAW

(open-air

windrow)

OAW

(open-air

windrow)

IVC

(in-vessel

composting)

IVC

(in-vessel

composting)

or

or

and/or

• Separately collected garden waste can be

processed relatively simply by open-

windrow composting.

• Separate food scraps collections can

potentially be introduced at a later date.

• From a waste collection operations

perspective, relatively straightforward to

combine FO and GO via a single bin.

• However, it may not always be possible to

treat mixed FOGO by OAW, due to e.g.

vermin, odour, runoff (in the UK OAW

composting of food is prohibited under

animal by-product regulations).

Dry AD (high

solids

anaerobic

digestion)

Dry AD (high

solids

anaerobic

digestion)

or

• Aerobic composting of separate food

scraps alone is generally not feasible

(woody matter required for aeration)

• Hence anaerobic digestion is generally

used where food is collected separately.

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1. BACKGROUND (continued …)

Possible option permutations:

• Separate GO (no FO collection)

• Separate FO (no GO collection)

• Mixed FOGO – to IVC

• Mixed FOGO – to OAW

• Separate FO in parallel with separate GO

(Dry AD less proven, and not included in this analysis)

Illustrative costings are developed for these options in the following slides

[NOTE: indicative only, and intended to highlight the issues that Councils should consider in

developing waste management systems for organics]

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2. ORGANIC WASTE SEGREGATION

• International experience shows that quantities of GO and FO yielded by kerbside schemes

vary with the mode of collection.

Garden waste

capture rates

high (~95%)

Garden waste

capture rates

high (~95%)

Relatively low

capture of

food for mixed

FOGO (~30%*)

Relatively low

capture of

food for mixed

FOGO (~30%*)

Improved capture

where food is

collected separately

(50%+*)

Improved capture

where food is

collected separately

(50%+*)

* Please note that capture rate varies significantly by scheme.* Please note that capture rate varies significantly by scheme.

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2. ORGANIC WASTE SEGREGATION

• In modelling costing systems, it is important to remember that unsegregated residual waste

continues to be disposed to the residual waste stream.

Reduced

tonnage

under FOGO

due to poor

food capture

Reduced

tonnage

under FOGO

due to poor

food capture

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3. COLLECTION COSTS

• Collection costs are highly dependent on local specifics – for instance urban vs. rural, housing

type, collection method (e.g. dedication vs. collection with recyclables).

• Demonstrated below by the spread in data for UK, converted to $NZD (with relatively few

organic schemes in place in NZ, an equivalent NZ dataset does not yet exist):

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3. COLLECTION COSTS

(Unsurprisingly) mixed FOGO may allow

more cost effective collection than the

separate case

(Unsurprisingly) mixed FOGO may allow

more cost effective collection than the

separate case

• Illustrative collection cost by modelled option:

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3. COLLECTION COSTS

• On the basis of the above …

– Separate collection of garden waste only is the cheapest case

– Separate collection of food scraps is relatively expensive

– Mixed garden/food scraps collections show a cost per household significantly higher

than that for garden waste alone

• This is likely because where garden waste is collected in isolation, collections can

cease over the winter period.

• In contrast, under a mixed FOGO approach, collections must continue year-round to

continue to capture food scraps.

– The combination of separate food, in parallel to separate garden waste, is the most

costly option in terms of collection.

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4. TREATMENT COSTS

• Illustrative treatment gate fees for the purpose of scenario modelling:

Assumed $50/t

landfill

operating cost,

combined with

a $60/t levy as

an intermediate

case (assume

for purpose of

this analysis)

Assumed $50/t

landfill

operating cost,

combined with

a $60/t levy as

an intermediate

case (assume

for purpose of

this analysis)

AD requires

renewables

subsidy to

achieve lower

gate fee

AD requires

renewables

subsidy to

achieve lower

gate fee

If mixed FOGO cannot be

composted by OAW, treatment

costs are much higher than

separate collection (i.e.

‘contaminating’ garden with

food may double the

composting cost)

If mixed FOGO cannot be

composted by OAW, treatment

costs are much higher than

separate collection (i.e.

‘contaminating’ garden with

food may double the

composting cost)

(Please note the error values – i.e. dotted lines)(Please note the error values – i.e. dotted lines)

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• Treatment costs by option, applying the above gate fees to tonnages collected:

4. TREATMENT COSTS

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5. COMBINED ORGANIC WASTE SYSTEM COSTS

• Overall system cost per household by option, combining collection and treatment costs

above:

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5. COMBINED ORGANIC WASTE SYSTEM COSTS

• The above measure ignores the performance of options … a more useful metric is perhaps

the whole system cost per tonne of waste diverted from landfill:

• Comparable performance across

all options on whole system costs

per tonne diverted.

• Important to evaluable all options,

accounting for local conditions.

* Higher organics diversion under the separate case may facilitate a shift to less

frequent residual collection – though these savings are not quantified here.

* Higher organics diversion under the separate case may facilitate a shift to less

frequent residual collection – though these savings are not quantified here.

**

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Windrow Composting : Windrow Composting : Windrow Composting : Windrow Composting : simplest and lowest

cost form of composting. May be carried out

outdoor or indoors

• Open Air Windrow (OAW) preferably

carried out on a concrete yard with

runoff drainage control:

• Limited odour control therefore

must be carried out in non-

residential areas

• Exposed to elements, so longer

process (c.2-3 months), requiring

more land

• Indoor Windrow: requires higher capital

infrastructure, therefore viable only at

high throughput

6. ORGANICS TREATMENT PROCESSES – Windrow Composting

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IVC / Tunnel Composting : IVC / Tunnel Composting : IVC / Tunnel Composting : IVC / Tunnel Composting : Significantly more

technologically complex and expensive than

windrow

• Typically includes pasteurisation to

meet government biosecurity

standards

• Typically used for mixed (FOGO)

waste, rather than green waste only

• Much shorter retention time (several

hours to 3 weeks, depending on

process)

• Smaller footprint and greater control

of emissions makes process suitable

for installation in urban areas

6. ORGANICS TREATMENT PROCESSES – In-vessel / tunnel composting

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Dry Fermentation AD: Dry Fermentation AD: Dry Fermentation AD: Dry Fermentation AD: Least technologically

complex type of AD, with minimal pre-

treatment of feedstocks and addition of

process water

• Relies on mechanical handling of

feedstocks into tunnels, with a process

retention time of 2-4 weeks

• Suitable for solid feedstocks including

FOGO

• Process not overly sensitive to feedstock

contamination (e.g. plastics) – however

post-process aerobic

stabilisation/screening required to

generate high-quality digestate compost

end-product

• May also require a dedicated

pasteurisation step

6. ORGANICS TREATMENT PROCESSES – AD (dry fermentation)

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HighHighHighHigh----solids ‘dry’ AD: solids ‘dry’ AD: solids ‘dry’ AD: solids ‘dry’ AD: Uses horizontal

‘plug flow’ of substrate at 15-25%

Dry Matter, typically in horizontal

reactor(s)

• Requires minimal process water

addition; incomplete substrate

mixing occurs; retention time

typically up to 1 month

• Suitable for solid feedstocks,

including FOGO

6. ORGANICS TREATMENT PROCESSES – AD (high-solids ‘dry’ digestion)

• Feedstock pre-treatment required to eliminate physical

contaminants; post-process aerobic stabilisation and

screening required to generate high quality digestate

compost

• May also require a dedicated pasteurisation step

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LowLowLowLow----solids ‘wet’ AD: solids ‘wet’ AD: solids ‘wet’ AD: solids ‘wet’ AD: Uses vertical reactors

with liquid substrate (DM<10%) and

complete mixing; retention time typically

14-28 days)

• Suitable for liquid feedstocks and

some solid feedstocks - with pre-

treatment (i.e. maceration, water

addition and premixing)

• Highest efficiency biogas generation

process but is sensitive to presence

of contaminants

6. ORGANICS TREATMENT PROCESSES – AD (low-solids ‘wet’ digestion)

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Compost: Compost: Compost: Compost: Aerobically decomposed and

stabilised organic matter rich in nutrients

and beneficial as a soil conditioner and

fertiliser for range of end-use land

applications

• Technical / quality standards to ensure high

quality products and provide end-user market

confidence

• BSI PAS:100 standard applies in UK and is

recognised as ‘end of waste’ criteria

• Requires separate collection of source biowaste

materials and compliance with UK biosecurity

ABPR requirements

• Sets limits on presence in final compost of:

physical contaminants (glass, plastics, stones);

pathogens (E-coli & Salmonella); weed seeds;

heavy metals

6. ORGANICS TREATMENT PROCESSES – compost process outputs (UK approach)

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Digestate: Digestate: Digestate: Digestate: has similar attributes to compost

and is typically used for land application as

either (a) whole digestate as slurry or (b)

dewatered fibre with aerobic stabilisation

into digestate compost

• Technical standards apply to ensure high

quality digestate products and provide

end-user market confidence

• BSI PAS:110 standard applies in UK and is

recognised as ‘end of waste’ criteria

• Defines similar standards to those in

PAS:100 but includes additional criteria -

pH, Ammoniacal Nitrogen and N, P, K

nutrients content

6. ORGANICS TREATMENT PROCESSES – digestion process outputs

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7. REGULATORY ISSUES

• It is understood that at present, open air windrow

composting of food scraps is not explicitly prohibited in NZ.

• Nonetheless, where mixed food scraps and garden waste

are composted via OAW on a large scale, potential for local

impacts (including odour, vermin and leachate production)

may be significant.

• Should large scale composting of mixed food scraps and

garden waste expand in coming years, negative issues

associated with OAW of mixed organics may become

evident.

…. In this event it is possible that regulators may in time

opt to prohibit OAW or post consumer food scraps.

• Even under the present regulatory approach, resource

consents may include conditions which are challenging to

achieve via an OAW process – for example if a requirement

exists for no odour impact outside the site boundary.

Source: The Availability

of New Zealand

Compost Facilities to

Process Compostable

Coffee Cups and

Food Packaging, (Beyond the Bin,

2017)

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8. CARBON PERFORMANCE

• In considering the relative strengths of

organic waste management

approaches, it should be noted that

treatment options differ in respect of

carbon performance.

• Focussing on the global warming

potential associated with treatment of

one tonne of food scraps (as expressed

in carbon dioxide equivalent), the

chart opposite compares landfill, IVC

and AD.

• By avoiding fugitive methane

emissions associated with landfill, IVC

achieves a dramatic reduction in CO2e

emissions.

• AD improves significantly on this

position by achieving a net reduction

in carbon emissions, associated with

renewable electricity generation.

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9. CONSIDERATIONS FOR WASTE STRATEGISTS

Option Waste minimisation Collection Treatment Output marketability

Separate GO (no FO

collection)

�(GO collections can

‘create waste’)

�(cheapest in terms of

collection costs)

�(OAW gives lowest

treatment cost)

�(cheapest in terms of

collection costs)

Separate FO (no GO

collection)

�(no GO may mean lower

overall waste arisings)

����(relatively high cost for

separate food)

–

(Uncertain – low AD

costs typically require

energy subsidies.)����

(potentially reluctance

to accept compost from

post consumer food,

particularly for

agricultural users)

Mixed FOGO

– to IVC � –(intermediate between

GO only, and separate

FO / GO)

�(IVC relatively expensive;

potential for large scale

OAW of FOGO currently

unclear)

Mixed FOGO

– to OAW�

Separate FO in parallel

with separate GO�

–(Relatively high cost for

separate food; may

however facilitate less

frequent residual

collection)

�(Continued low cost

treatment of GO via

OAW)

�(Maintains value of

garden waste-derived

compost)

• Option strengths and weaknesses:

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9. CONSIDERATIONS FOR WASTE STRATEGISTS

• Each organics option has its own strengths and weaknesses on waste prevention, collection

costs, treatment costs, and process output marketability.

• Current discourse seems to be biased towards FOGO – but this is not the only show in town,

and has downsides:

• low food capture rates;

• potential higher treatment gate fees compared to GO alone;

• may compromise the quality and marketability of compost outputs; and

• Does not realise the energy potential in FO

• Choice of organics system should be informed by a full options assessment – ensuring the

optimum approach for a given jurisdiction.

• For all systems, capture rates for food scraps are generally found to be low (e.g. ~30% for

mixed FOGO, 50%+ for separate food)

– Collection of food scraps does not fully solve the problem of organic waste disposal

– Underlines need to consider residual treatment technologies

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10. CONCLUDING COMMENTS

• If the aim is not necessarily to maximise food scraps capture going forward, and to

accept that a lower quality (and possibly therefore, a lower value) compost product is

generated, then a FOGO approach is likely to be a relatively low cost option.

• However, if there is a desire to maximise the capture of food scraps, and to maintain

as high a quality as possible of the resultant process outputs (compost from GO and

digestate / compost from FO) then a separate GO / FO approach may be more

attractive.

• The added benefit of GO / FO is the ability to derive energy from the FO through use

of AD technology. This significantly increases the overall carbon performance of this

approach

CONTACT

Andy Street

Director – Waste & Resource Management

+44 117 906 4280

astreet@slrconsulting.com

www.slrconsulting.com