Attachment 3B - Process Design Strategy - OREZ · 132005.638.06

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PR25001 Noosa Composting Facility
Process Design Strategy




Process Design Strategy
Revision Schedule

 Date         Revision    Issue                     Prepared By   Approved By

                                                                  S. Murray,
 20/07/2026   01          Final Issue               M. Taylor
                                                                  S. Galdermans

 07/08/2026   02          Draft Issue               M. Taylor

 17/08/2026   03          Response to NSC PDS v01   M. Taylor     S. Galdermans
                          feedback




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PR25001 Noosa Composting Facility
Process Design Strategy




1.       Introduction

1.1.     Purpose of this Document
This Process Design Strategy (PDS) establishes the process basis of design for the Noosa
Composting Facility (Noosa CF), a turnkey in-vessel composting (IVC) facility to be designed
and delivered by OREZ Solutions for Noosa Shire Council (NSC) at the Noosa Resource
Recovery and Recycling Facility (NRRF), Doonan, Queensland.

The purpose of this document is to set the process parameters that the facility will be
designed to, and to provide a single reference that aligns the project team ahead of design
development. It is not the finished design. Its role is to fix the confirmed baseline, separate
confirmed items from open items, and enable the mass balance, process flow diagram
(PFD), spatial planning and infrastructure design to proceed on an agreed baseline.

On confirmation of this PDS, the PFD will be finalised and the balance of facility infrastructure,
spatial planning, water balance and operational logistics will be developed against the
parameters set out here.


1.2.     Project Background
NSC received approximately 17,000 tonnes of green waste across FY25, this was processed
on site by an external contractor into mulch. Under the From Waste to Resource: Waste Plan
2023 to 2028, and the community endorsed goal of 100% diversion of organic waste from
landfill by 2030, thus NSC is procuring a dedicated composting facility within the NRRF.




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PR25001 Noosa Composting Facility
Process Design Strategy




2.       Process Description
An indicative general arrangement of the facility has been included in Appendix D; it should
be viewed in conjunction with this Process Description section.


2.1.     Vehicle Movements
Waste Receivals (Deliveries)

Public (self-haul) and commercial waste deliveries will be managed via two different weigh
bridges to efficiently manage the traffic movements onsite and minimise interactions. Loads
will be weighed with the relevant vehicle type directed to their specific unloading zone.

Public (self-haul) customers will enter and exit via the northern weigh bridge. They will drop
green organic waste at the western side of the facility. A road located off the main arterial
facility road will be used for queuing, reducing burden on the atrial route.

Commercial customers will enter from the southern weighbridge and exist via the northern
weigh bridge. They will drop green organics waste at the southern green organic waste
bunker, additionally they will drop source separated food waste directly into the covered
food waste receival hopper, which incorporates air ducting to the odour management
system. Where a source has not yet been vetted, the delivery is instead directed to the
adjacent push wall bay, enabling quality checks to be completed prior to the material being
loaded into the hopper.

Compost & Oversize Material Dispatch

Compost and oversize material dispatch vehicles will enter the site from the southern
weighbridge and exit via the northern weighbridge. Material will be dispatched via a
dedicated maturation loading zone where trucks will drive forwards into the covered
building and will be loaded perpendicular by a front-end loader.

Air Management System

A dedicated acid unloading zone for sulfuric acid deliveries to the scrubber will be spatially
allowed for, but an acid system is not deemed necessary for the odour produced from the
basis of design feedstock blend. The same zone will be used for the collection and dispatch
of the ammonium sulphate generated if the scrubber doses acid in the future.

Although biofilter media replacement is infrequent, the biofilter has been positioned to allow
efficient media replacement while minimising obstruction of the facility's arterial road.




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PR25001 Noosa Composting Facility
Process Design Strategy




2.2.     Green Organic (GO) Waste & Source Separated Food Organic
         (FO) Waste Pre-treatment
GO Waste Pre-treatment:

Incoming green organic waste feedstock is stockpiled in a dedicated storage bunker and
fed to a shredder for size reduction. The shredded material is then conveyed beneath an
over band ferrous magnet, which removes ferrous metal contamination, and into an
intermediate storage bunker ahead of the IVC tunnels. This intermediate bunker is sized to
hold approximately half of one tunnel volume, providing buffer storage between pre-
treatment and tunnel loading.

FO Waste Pre-treatment:

Source separated FO is delivered by the collection vehicle and, where the source is vetted
and proven reliable, is tipped directly into the receival hopper by the delivery vehicle. The
hopper lid is opened for unloading and closed immediately afterwards. This is expected to
be the normal mode of operation for the majority of deliveries.

Where a source is new or not yet proven, the delivery is instead directed to the push wall
bay, which keeps food deliveries isolated so that NSC operational personnel can inspect the
load and confirm contamination is within acceptable limits before the front-end loader
operator transfers the discrete FO into the hopper. Once a source has been vetted over
several deliveries, it reverts to direct tipping into the hopper by the delivery vehicle.

To limit both the time discrete FO is held and its odour potential, the FO is blended with GO
through the shredder, held in an intermediate bunker, and moved into the process as
promptly as practicable.

The food waste bunker is to be sized to minimise the frequency at which it is emptied into the
intermediate bunker, and so to minimise the time that FO mixed with GO is held in the
intermediate bunker awaiting tunnel availability. The design intent is that blended material
moves into the composting process as efficiently as possible and is not left exposed for any
longer than necessary. Bunker sizing is nonetheless to remain practicable, balancing
operability against capital cost, and is to be confirmed with the tunnel filling schedule.

The receival hopper is a sealed vessel fitted with a hydraulic lid that remains closed except
during unloading. Material is transferred from the hopper by an enclosed screw conveyor to
the shredder, where it is fed simultaneously with green organics so that blending occurs
entirely within the shredding step. There is no subsequent mixing of food waste in the open
processing area.

Extracted air from the receival hopper and the enclosed screw conveyor is directed to the
same air handling and biofilter system that serves the IVC tunnels.

During periods with no FO deliveries, the hopper lid remains closed, and air is extracted from
the hopper.




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Process Design Strategy




2.3.    In-vessel Composting (IVC) System
In-Vessel Composting (IVC) is the confirmed composting methodology for this project. The
constrained footprint favours an enclosed process that minimises the space required for both
active composting and maturation.




          Figure 1: Example IVC system render from Noosa CF tender submission (Drawing
                                          No. P0050_1).

Understanding In-Vessel Composting

In-Vessel Composting (IVC) is a fully enclosed, forced-aeration composting method.
Feedstock is loaded into a sealed tunnel, and composting takes place within that contained
envelope for a fixed retention period, rather than in an open pile or windrow exposed to the
weather. Air, temperature, and moisture within the tunnel are actively managed throughout
the cycle, rather than relying on passive airflow or periodic mechanical turning as in open
composting methods. This is the primary distinction between IVC and open windrow
composting, and it is the basis for IVC's suitability to sites, such as the NRRF, where odour
control and a constrained footprint are driving considerations.

A typical tunnel cycle proceeds as follows:

   1. Premixed feedstock is loaded into the tunnel and the entrance sealed.
   2. Air is forced through the base of the pile via a plenum or floor duct system, supplying
      oxygen to the aerobic microorganisms driving decomposition and removing the
      heat, moisture, and carbon dioxide generated by that activity.
   3. Aeration is typically controlled by temperature, meaning airflow is automatically
      increased or decreased to hold the pile within a target range, rather than run at a
      constant rate regardless of process conditions.
   4. At the end of the retention period, the tunnel is unloaded in the same manner it was
      filled.




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Process Design Strategy




   5. The partially composted material is fed into a stationary drum screen where it is
      separated into two fractions, fines and oversize.
   6. The fines fraction is then stored in the maturation building prior to becoming a
      saleable and useable product.

Aeration and Process Control

Forced aeration is what allows a tunnel to reliably reach and hold the temperatures required
for pathogen destruction and weed seed kill, even with the dense, low free-air-space
feedstock mixes typical of green waste and food organics blends. This is a meaningful
advantage over open windrow methods, where uneven pile density and limited turning
frequency can leave cool zones without adequate temperature exposure. The trade-off is
that IVC systems provide limited or no in-vessel agitation. Without periodic turning,
decomposition proceeds somewhat unevenly through the pile, which is why tunnels are
treated as the first stage of a two-stage process rather than a complete solution on their
own, with the partially composted material requiring a further maturation period outside the
tunnel to complete decomposition evenly throughout the batch.

Exhaust air drawn from the tunnel headspace is directed to a biofilter or equivalent air
treatment system before release, rather than vented directly. Typically, a portion of this
exhaust air is recirculated back into the incoming aeration supply, which both returns heat
and moisture to the process and reduces the volume of air the biofilter must treat. This
recirculation capability is a key reason enclosed tunnel systems achieve better odour and
emissions control than open composting methods, and is central to why IVC was the
technology nominated for this project given the airshed sensitivity around the NRRF site.




          Figure 2: Example IVC and air management system render from Noosa CF tender
                                 submission (Drawing No. P0052_1).

Leachate Management

Composting feedstock releases moisture as it decomposes, and forced aeration draws
additional moisture out of the pile as vapour in the exhaust air stream. Any moisture that
condenses or drains rather than leaving as vapour is collected as leachate at the tunnel



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Process Design Strategy




floor, typically through a sloped floor or integrated drainage channels running the length of
the tunnel. Because the tunnel is a sealed structure, this leachate is fully contained within the
vessel rather than able to run off into the surrounding site, which is a further point of
environmental control IVC offers relative to open composting methods where run-off must
instead be managed through site-wide stormwater infrastructure.

Collected leachate is returned to the process wherever it can be usefully absorbed, which
recovers moisture and nutrients that would otherwise be lost and reduces the volume
requiring separate management. Moisture control into the tunnels is achieved principally by
adding leachate at the drop point of the intermediate bunker feed conveyor, where the FO
and shredded GO are mixed prior to tunnel filling, so that the blend reaches the target inlet
moisture content before loading. Leachate may also be sprayed onto the pile within the
tunnel where further moisture addition is required during the retention period.

Where leachate volumes exceed what can be usefully returned to the process, for example
during high moisture ramp-up periods or where wetter feedstock streams are introduced, the
surplus requires a dedicated storage and treatment pathway.


2.4.     Refining
On completion of the tunnel cycle, material is transferred from the IVC tunnel to a stationary
drum screen with a feed hopper. The screen splits the material at a 15 mm aperture into a
fines fraction (<15 mm) and an oversize fraction (>15 mm), each conveyed into its own
bunker. The oversize material passes under a vacuum hood located above the drop point in
the bunker, capturing light material such as film plastics to reduce oversize contamination.
The fines fraction is then transferred via a front-end loader to one of eight dedicated
maturation storage bays for the six-week maturation period, the fines are typically turned into
an available bunker weekly or fortnightly to aerate the pile and aide with maturation. The
oversize material is transferred by a front-end loader to one of two dedicated maturation
storage bays prior to offsite dispatch.

Space has been allocated on the eastern side of the maturation building for future
maturation bay expansion, where a crushed concrete slab is being considered to provide
further oversize storage prior to implementing a maturation building extension. This will be
confirmed during detailed design.

2.4.1.   Oversize Fraction Recovery Options

The current basis of design produces a single oversize fraction at the 15 mm screen cut. NSC
has asked whether two oversize fractions of differing particle size could be produced to
increase product recovery and marketability from the oversize stream.

This is an opportunity to be evaluated rather than a change to the basis of design. The single
15 mm cut remains the baseline, and the palm content in the feedstock means the oversize
tonnage may be larger than modelled, which strengthens the case.

Three options are available within the nominated process train:




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Process Design Strategy




   1. Option 1 – Second screening step downstream of the drum screen, splitting the
      oversize into a graded mulch product and a coarse fraction disposed of or returned
      to the process as bulking agent when space is available within a tunnel and
      depended on seasonal fluctuations. This adds a screening step, a further conveyor
      and an additional storage bay / using one of the existing ones.
   2. Option 2 – Secondary screening of the oversize on a campaign basis using mobile
      plant, avoiding fixed capital but adding operating cost and plant hire, and requiring
      additional hardstand for the campaign.
   3. Option 3 – Secondary screening on a campaign basis using NSC-owned mobile
      plant, avoiding both fixed capital and plant hire, subject to NSC holding suitable
      screening plant with available capacity, and still requiring additional hardstand for
      the campaign.

Recovering a graded mulch product from the oversize fraction reduces the tonnage leaving
site as low to no value material. Progressing any option requires a market view of what
graded mulch achieves per tonne in the Noosa catchment against the current oversize
disposition. The achievable product specification and price for each grade, should be
developed by NRC to enable assessment.




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