Bottle-to-Bottle PET Solution

Name: Bottle-to-Bottle PET Solution
Brand: AISORT

A purity-first sorting route for PET lines targeting cleaner bottle fractions and stronger downstream reuse readiness.

Solution Overview

Bottle-to-Bottle Recycling: Complete rPET Processing Solution

Bottle-to-bottle (B2B) recycling is the highest-value pathway for post-consumer PET bottles — converting used beverage containers back into food-grade pellet or preform feedstock. Achieving food-contact certification (EFSA, FDA, or equivalent) requires a precisely engineered chain of sorting, washing, decontamination, and extrusion processes. A single weak link in the chain can disqualify the entire output from food-grade use.

This solution covers the complete B2B process from incoming bale to food-grade rPET pellet, with particular focus on the sorting stages that determine whether the downstream purification processes can meet regulatory requirements.

Market Value

$1,200-1,800/t food-grade rPET pellet

Food-grade rPET commands a $300-500/t premium over fiber-grade and $200-400/t over non-food bottle-grade, driven by brand commitments and regulatory mandates.

Regulatory Threshold

EFSA: <50 ppm PVC in flake

The entire downstream process — SSP, extrusion, IV rebuild — cannot compensate for inadequate sorting. Purity must be achieved at the flake level before decontamination begins.

Typical Plant Scale

15,000-50,000 t/year input

Below 10,000 t/year, the fixed costs of EFSA/FDA certification, laboratory equipment, and quality management systems are difficult to amortize.

Critical Success Factor

Integrated process design

B2B is not a set of independent unit operations. Sorting performance affects washing efficiency; washing quality affects SSP effectiveness; SSP parameters affect final IV and color. The process must be designed as an integrated whole.

The Bottle-to-Bottle Process Chain

Stage 1: Bale Receiving and Whole-Bottle Pre-sort

Incoming PET bottle bales typically contain 5-15% non-PET materials (other polymers, metals, glass, trash) and 10-30% colored PET bottles. The pre-sort stage removes these before grinding:

Debaling and tramp removal: Bales are broken, ferrous metals removed by magnet, large non-PET items manually or mechanically removed.
Whole-bottle NIR sort: Bottles pass through NIR sensors that identify polymer type. Non-PET bottles (PVC, HDPE, PP, PS) are ejected. Colored PET bottles (green, amber, blue, opaque white) are separated from clear/light-blue PET.
Target: Post pre-sort, the clear PET stream should contain <2% non-PET and <5% colored PET by count.

Stage 2: Grinding and Washing

Wet grinding: Bottles ground to 2-15mm flake under water to reduce dust, control friction heat, and begin label separation.
Hot caustic wash (80-90°C, 2-4% NaOH): Removes labels, adhesives, residual product, and surface contaminants. Duration: 15-30 minutes.
Friction wash / turbo washer: High-shear washing removes remaining label fragments and adhesive residues from flake surfaces.
Density separation (sink/float tank): PET (SG 1.38) sinks; polyolefin caps and labels (SG 0.90-0.97) float and are skimmed off. Critical for removing PP/PE before optical sorting.
Drying: Mechanical drying (centrifuge) followed by thermal drying to <1% moisture before optical sorting.

Stage 3: Optical Flake Sorting (The Purity Gate)

This is the stage that determines whether the downstream product can achieve food-contact certification. A typical B2B line uses two or three optical sorting passes:

Pass 1 — Polymer sort (NIR): Removes non-PET polymers (PVC, PE, PP, PS, PLA, PA). This is the critical pass for PVC removal. Target: <200 ppm PVC in accept.
Pass 2 — Color sort (RGB): Removes remaining colored flakes (yellow, blue, green, amber) from the clear stream. Target: <50 ppm total color in clear accept.
Pass 3 — Purity polish (NIR + metal detection): Final pass for polymer and metal verification. Target: <50 ppm PVC, <10 ppm metals.

Modern high-performance lines may combine Pass 1 and Pass 2 into a single multi-sensor machine, but the two-pass approach provides higher purity assurance and is preferred for new food-grade installations.

Stage 4: Extrusion and Solid-State Polycondensation (SSP)

After sorting, clean PET flake is extruded into pellets. For food-grade applications, the pellets then undergo SSP — a thermal process under vacuum or inert gas that rebuilds intrinsic viscosity (IV) and removes volatile contaminants. Typical target IV for bottle-grade rPET: 0.75-0.84 dL/g.

Economic Model

A 25,000 t/year B2B plant produces approximately 18,000-20,000 tonnes of food-grade rPET pellet (accounting for process losses of 20-25%). At a $400/t premium over non-food-grade material, the incremental annual revenue is $7.2-8.0 million. Typical B2B plant capital cost: $15-25 million for a complete line including building, utilities, and certification. Payback period: 3-5 years at current rPET premiums, potentially shorter if local regulatory mandates create a supply-constrained market for food-grade rPET.

Regulatory Pathway

Obtaining food-contact approval involves submitting a challenge test dossier to the relevant authority. The dossier must demonstrate that the complete recycling process — from sorting through SSP — reduces surrogate contaminants to levels below the accepted migration threshold (typically 0.1-0.5 ppb dietary concentration, equivalent to <50 ppm in the recycled material). The sorting stage is specifically evaluated for its ability to remove polymer contaminants that could carry or generate harmful substances during the high-temperature SSP and extrusion stages.

Recommended AISORT platforms

These platforms are typically combined when bottle-grade PET recovery depends on both primary bottle purification and deeper refinement logic.

AISORT Hyperspectral Sorter

Supports contamination-sensitive purification and finer discrimination in PET and HDPE preparation workflows.

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AISORT Tower Sorting System

A compact route for multi-output rigid plastic recovery where floor area remains limited.