Plastic Washing Line – Comprehensive Guide & Solutions

What Is a Plastic Washing Line?

A plastic washing line is an industrial system specifically designed for the recycling of post-consumer and post-industrial plastic waste. It removes various contaminants from plastics — such as solid impurities (e.g., sand, metals, glass) and surface residues (e.g., labels, oils, adhesives) — through a series of mechanical processing and physical separation techniques. The end result is high-purity, low-moisture recycled plastic flakes or regrind suitable for reuse.

A standard washing line typically includes core processing stages such as shredding, pre-washing, density separation, friction washing, hot washing, rinsing, and drying. Each step is precisely engineered to ensure the effective removal of both surface and embedded contaminants. In addition, advanced sorting technologies such as optical sorting and eddy current separation can be integrated to further improve the consistency and purity of the recycled output.

As a critical part of the plastic recycling process, washing lines are suitable for single-type materials such as PET, PE, PP, HDPE, and ABS. Without efficient washing and separation, plastic waste cannot meet the quality requirements for downstream processes like extrusion, pelletizing, injection molding, or film blowing. Therefore, a well-designed plastic washing line not only enhances the quality of recycled plastic but also directly affects the stability of production and performance of final products in the next stages.

Process Flow of a Plastic Washing Line

Note: The washing and recycling process for PET bottles is more complex. This flowchart applies only to basic single-type soft or hard plastic recycling.

Crushing and Pre-washing

Crushing Process: Waste plastics are conveyed by a belt into the crusher and cut into sizes suitable for washing.

Pre-washing: The ground plastic enters the pre-washing system, where hydraulic washing, friction washing, or flotation separation removes large contaminants, reducing wear on downstream equipment and improving washing efficiency.

Main Washing Processes (Density Separation, Hot Washing, Friction Washing)

Density Separation (Flotation): Using water buoyancy separation technology, plastics with different densities are separated from non-plastic impurities (such as bottle caps, labels, metal particles) to improve purity.

Hot Washing Process: For plastics with heavy oil contamination and adhesive residues (such as PET flakes), high-temperature alkaline washing and steam treatment are applied to remove stubborn stains and odors.

Friction Washing: Plastics enter a friction washing machine where high-speed rotating blades further remove surface oils, adhesives, and fine particulate impurities to improve cleanliness.

Drying and Storage

Centrifugal Dehydration: Plastics pass through a high-speed centrifugal dehydrator to remove surface moisture, typically reducing moisture content to ≤5%.

Hot Air Drying: Further reduces moisture to 3%; some plastics (like PE/PP soft plastics) can use an extruder dryer directly to ensure moisture control meets optimal recycling standards.

Finished Product Storage: Processed products can be directly bagged for storage or connected to pelletizing systems for further processing (such as melt extrusion or injection molding).

Main Components of Plastic Washing Line

The equipment configuration of a plastic washing line depends on the type of materials processed, contamination levels, and final recycling requirements.

	Shredder: Tear large plastic items into smaller pieces suitable for subsequent processing (100 mm~200 mm).
	Crusher: Crushes plastic items into uniformly sized, finer flakes (8mm~20mm).
	Bale Opener (Horizontal / Vertical): Used for bundled materials to separate compressed recyclables.
	Metal Separator (Metal Detector / Metal Roller Separator / Fully Automatic Pneumatic Flap): Extracts any metal contaminants.
	Sink-Float Tank: (Sink tank / Float tank) Uses immersion and flotation to differentiate materials by density.
	Friction Washer: (High-speed / Low-speed) Uses blades driven by a spindle to impact plastic surfaces, providing initial strong cleaning.
	Hot Washing: Removes stubborn stains such as oil films and adhesives.
	Centrifugal Dryer: Removes excess moisture from plastics using centrifugal force.
	Eddy Current Separator: Mainly removes aluminum metals.
	Label Extractor: (Serrated Separator / Fine Particle Separator) Further optimizes material separation by removing fine particles, label fragments, dust, etc.
	Optical Sorting: (Material sorting, Color sorting, Aged flake sorting) Used for high-grade PET flakes.
	Squeezer: Removes moisture from soft plastics and partially plasticizes them.
	Vibrating Screen: Commonly used for hard plastics to remove materials smaller than 10mm by vibration.

Benefits of Using Plastic Washing Lines

The global plastic recycling market is projected to grow to $1.2 trillion by 2040 (Global Plastics Outlook)This growth reflects the impetus given to the plastics recycling industry by government policies, environmental regulations and corporate sustainability needs.

Plastic Recycling’s Impact on Carbon Emissions

According to a 2023 study by the European Environment Agency (EEA 2023), the plastic recycling industry reduces CO₂ emissions by 250 million tons annually, equivalent to taking 53 million cars off the road for one year.

Plastic Washing Lines Improve Recycling Efficiency

According to a 2023 study by Plastics Recyclers Europe (PRE 2023), optimizing plastic washing lines can increase the recycling rate of HDPE and PP soft plastics by 30%, reduce raw material waste, and improve the quality of recycled pellets.

How to Choose the Right Plastic Washing Line For You

The recycling processes vary for different types of waste plastics, and the terminology differs accordingly. Based on material properties, plastic washing lines are generally categorized into three main types: PET bottle washing lines, soft plastic washing lines, and hard plastic washing lines.

PET Bottle Washing Lines can be further divided by the final product type:

(Fiber-grade flake washing line; Filament-grade flake washing line; Food-grade flake washing line)

Soft Plastic Washing Lines are classified according to the recycled materials:

(Film washing line, Woven bag washing line, Jumbo bag washing line, etc.)

Hard Plastic Washing Lines are divided by material type:

(HDPE milk bottle washing line, Single-material washing line, Mixed-material washing line, Household plastic washing line, etc.)