Plastic Collection and Procurement

Collection, Sorting, and Recycling of Industrial PP Plastic Waste

In today’s industrial age, recycling PP (Polypropylene) plastic waste not only brings economic value but also plays a crucial role in protecting the environment. PP is one of the most commonly used plastics in the production of packaging, automotive components, household goods, and medical equipment. However, once its lifecycle ends, a significant amount of PP waste is generated. Therefore, the collection and sorting of industrial PP plastic waste have become the first and most decisive steps in the entire recycling process.

1. Industrial PP Plastic Waste Collection Process

PP plastic waste is mainly collected from manufacturing plants, industrial zones, and plastic packaging or component processing workshops. The collected waste typically includes damaged packaging, defective products, sprues, injection burrs, or spilled pellets. The collection process must ensure:

• Separate by plastic type: PP must not be mixed with PE, PET, or PVC to avoid compromising recycled quality.

• Remove impurities: Dust, oil, metal, or paper labels must be eliminated at the initial stage.

• Sort by color: White, transparent, opaque, or colored PP should be separated to ensure uniformity in recycled pellet color.

After collection, the plastic is transported to recycling facilities using specialized vehicles to prevent spillage or contamination during transit.

2. Importance of the Sorting Stage

Sorting is a critical stage that determines the quality of the recycled PP pellets. Improper sorting can lead to contaminated recycled material with poor flexibility, dull color, and unsuitability for high-tech applications. Modern recycling lines typically apply the following methods:

• Manual sorting: Workers use experience to manually separate different plastic types.

• Automatic sorting: Spectral recognition or magnetic sensors are used to identify plastic types accurately.

Once properly sorted, PP plastic is sent into a closed-loop recycling process to produce industrial-grade recycled pellets.

Sorting – Shredding – Washing – Drying – Pelletizing

After collection and sorting, PP waste undergoes several technological stages to become high-value recycled plastic pellets.

1. Shredding Stage

Sorted PP plastic is fed into shredding machines, which cut it into small flakes (5–20 mm). This step:

• Increases surface area for effective washing and drying.

• Reduces volume, making transportation and feeding easier.

Industrial shredders are equipped with ultra-durable alloy steel blades capable of processing hard materials such as PP, PE, and ABS without wearing out quickly.

2. Washing Stage

Washing is the most important step, aimed at removing dust, oil, adhesives, labels, and organic residues. It typically includes:

• Rough washing: Uses water and mild detergents to remove surface dirt.

• Fine washing: Uses hot water or a dilute alkali solution (NaOH) to remove deep-seated contaminants.

After washing, flakes are separated in a float-sink tank — PP, being lighter than water, floats, while heavier plastics such as PET or PVC sink.

3. Drying Stage

Washed PP flakes are mechanically dewatered and then dried using circulating hot air to reduce moisture to below 0.5%. Insufficient drying can cause bubbles or burning during extrusion. Modern facilities often use centrifugal dryers to save energy and shorten drying time.

4. Pelletizing Stage

This is the final stage, where PP flakes are melted and extruded into recycled pellets through:

• Heating: The flakes are melted in an extruder at 180–250°C.

• Extrusion: The molten plastic is forced through a die to form plastic strands.

• Pellet cutting: The strands are cooled in water and cut into uniform pellets (3–5 mm).

The quality of recycled PP pellets depends on cleanliness, size, and color. Standard pellets are glossy, uniform, and free of impurities — ideal for producing packaging, plastic parts, household goods, and components for motorbikes and electronics.

Quality Standards for Recycled PP Pellets

To ensure safety and usability in production, recycled PP pellets must meet the following criteria:

• Cleanliness ≥ 98%: Free of dust, oil, or metal particles.

• Moisture ≤ 0.5%: Prevents bubbling or voids during molding.

• Uniform particle size: 2–5 mm for stable feeding.

• Stable color: Adjustable with masterbatch if needed.

• High mechanical strength: Can be reused across multiple cycles without significant degradation.

Qualified pellets are packed in 25–50 kg bags and stored in dry warehouses away from sunlight and humidity.

Economic and Environmental Value of PP Recycling

PP recycling not only reduces raw material costs for manufacturers but also significantly decreases plastic waste released into the environment. Statistics show that each ton of recycled plastic can save:

• 1.5 tons of CO₂ emissions

• 3,000 kWh of electricity

• 5,000 liters of water

Additionally, the recycling process provides stable employment, promotes the circular economy, and fosters sustainable industrial growth in Vietnam’s plastic industry.