PET bottle washing line: how to configure it for bottle-to-bottle, fiber, strapping or sheet

Two PET washing lines with the same output can differ by a factor of two in price, and both can be the right answer. What decides the configuration is not the capacity but two questions: what will the flakes be used for, and how dirty are the bottles. This guide walks through both, explains each stage of the process, and lists what to check when you compare quotations. Lines are available from 1,000 to 7,000 kg/h of finished flakes.

Start from the end use

A fiber mill and a bottle-grade recycler need lines that are a whole sorting and hot-wash section apart. If you sell flakes, ask who buys them before you ask for a quote.

One rule holds even on the simplest line: PVC must be controlled. PET is processed above the temperature where PVC degrades, so a few PVC bottles cause black specks, yellowing and filament breaks. Keep at least one PVC removal step, manual or NIR.

Then look at the bottles

The best way to settle this is a sample wash test: send a bale, or 20–50 kg of bottles, and get the washed flakes and a video back. It is also the strongest protection against disputes about output and flake quality later.

The process, stage by stage

1. Bale opening and feeding. A four-shaft bale breaker loosens compressed bales and feeds bottles at a steady rate.
2. Trommel screen. Removes stones, sand, loose caps and small metal dry, before anything gets wet: less dirt in the water, longer knife life.
3. Metal removal. A magnet removes ferrous metal; an eddy current separator removes aluminium caps and rings.
4. Dry label remover. Strips sleeve and wrap labels from whole bottles without water and without flake loss.
5. Whole-bottle pre-wash. Removes surface dirt and sugar so that the sorters see clean bottles. Hot for very dirty bottles, cold otherwise.
6. Whole-bottle sorting. An NIR sorter rejects PVC, PETG, PS and coloured bottles; a manual sorting belt catches what it misses.
7. Wet crushing. Bottles are cut into 12–14 mm flakes with water, which pre-cleans the flakes and cools the knives.
8. Float-sink. PP/PE caps and labels float, PET sinks.
9. Hot wash. 80–90 °C water with 1–2 % caustic soda dissolves label glue, oil and residue. A continuous hot wash suits most bales; a batch hot wash with a buffer silo gives a controlled residence time and the most consistent glue removal.
10. Friction washing and rinsing. High-speed friction scrubs off softened glue; several rinsing stages bring the flakes back to neutral pH.
11. Drying. Centrifugal dewatering, then hot-air pipe drying to below 1 % moisture.
12. Label and fines removal. A zig-zag air classifier removes label fragments and dust.
13. Flake sorting. A colour sorter removes off-colour flakes; a material sorter removes PVC and other polymers at flake level.
14. Packing and control. Big-bag station and PLC line control.

Reference flake specification

For the 2,000 kg/h reference line running typical post-consumer bales. Final values depend on your bottles and are confirmed by the sample wash test.

Bottle-to-bottle: what the washing line does and does not do

A washing line produces bottle-grade flakes. It does not by itself make food-grade rPET. Food contact needs a decontamination step downstream, such as solid-state polycondensation or melt decontamination, approved in the target market:

• Brazil: ANVISA RDC 20/2008. PET-PCR must come from an approved, registered decontamination technology validated by a challenge test.
• USA: FDA letter of no objection.
• European Union: EFSA opinion under Regulation (EU) 2022/1616.

Be careful with any supplier that calls a washing line "food grade".

How to compare quotations

A cheaper quotation usually leaves something out. Check item by item:

• Is there an eddy current separator for aluminium caps and rings?
• Hot wash: continuous or batch? Volume and residence time?
• Flake sorting: colour sorter only, or also a material sorter?
• Is the whole-bottle NIR sorter included, or listed as customer-supplied?
• Are water treatment and the steam boiler included or excluded?
• Installed power, water and steam per tonne of flakes, not only the machine price.

Compare cost per tonne of flakes and the price those flakes will sell for, not just the price of the line.

What to send for a quotation

• Photos of your bales, and where they come from
• What the flakes will be used for, or who buys them
• Output in kg/h of finished flakes, or tonnes of bales per day
• Voltage and frequency at your plant (for example 380 V / 60 Hz)
• Whether you already have steam, water treatment or an NIR sorter

To pelletize the washed flakes, see the PET flakes pelletizing line with pre-drying.

See also: PE/PP bottle washing line · PET bottle washing line specifications