Industrial multi-stage PET bottle washing and recycling line at SLS PVT LTD facility in Bangladesh

Sorting is the foundation of high-purity PET reprocessing. Baled post-consumer containers arriving at our facility are debaled and distributed across illuminated manual and mechanical inspection conveyors.

Bottles are classified into dedicated color streams:

• Hot-washed clear (pure white transparent)

• Emerald and light green

• Amber brown

• Lemon-lime tint

During this stage, operators identify and remove non-PET plastics—such as PVC containers, HDPE bottles, and multi-layer packaging—alongside debris and metal caps. Segregating polymers before granulating prevents cross-contamination and ensures color consistency for downstream fiber spinning and sheet extrusion.

Surface contaminants and external packaging elements must be removed before granulating. Whole bottles pass through an industrial mechanical de-labeling system where angled rotor blades peel away oriented polypropylene (BOPP) shrink sleeves and paper labels without damaging the underlying PET containers.

The materials then undergo multi-stage friction washing and high-temperature caustic cleaning:

• Friction Agitation: Dislodges surface dirt, dust, and beverage residues.

• Caustic Hot Wash: High-temperature alkaline cleaning dissolves label glues, hot-melt adhesives, and oily films.

• Continuous Rinse: Counter-current fresh water rinsing neutralizes the wash solution, leaving the polymer chemically clean.

Once de-labeled and surface-cleaned, whole PET bottles are fed into heavy-duty rotary knife granulators equipped with continuous water injection.Wet milling provides distinct manufacturing advantages:Injected water cools the rotary cutting blades, reducing friction and preventing thermal degradation on flake edges.Continuous water flushing carries away residual surface particles, preventing airborne dust from adhering to the polymer.Bottles pass through calibrated sorting screens to produce a uniform 3–10 mm flake profile ($\ge$ 95%) with dust and fine particles controlled under 1.0%.

Granulated flakes enter continuous sink-float flotation tanks. Because Polyethylene Terephthalate has a specific gravity of approximately $1.38\text{ g/cm}^3$, the clean PET flakes sink directly to the discharge screw at the bottom of the tank. Lightweight polyolefin contaminants—specifically polypropylene (PP) and high-density polyethylene (HDPE) caps and neck rings with a density under $1.0\text{ g/cm}^3$—float to the surface and are skimmed away, driving polyolefin levels below 50 ppm.Every production lot undergoes rigorous laboratory testing before export approval:PVC Contamination Analysis: Thermal baking oven tests to detect and isolate PVC particles below 50 ppm.Moisture Testing: Halogen moisture analysis ensuring levels remain below 1.0% after passing through centrifugal dewatering and hot-air pipeline drying.Sieve Sizing Analysis: Verifying consistent particle distribution and fines extraction.

Finished, dried, and tested PET flakes pass through zig-zag air classifiers where upward air streams extract residual lightweight film particles and micro-fines.

The clean rPET flakes are discharged directly into heavy-duty, UV-stabilized woven polypropylene jumbo bags (big bags). Each bulk sack is sealed, weighed, and tagged with an individual lot number for complete batch traceability. Palletized or floor-loaded into 40ft High Cube containers, our flakes are staged for prompt overland transit and ocean export dispatch via Chattogram (Chittagong) Sea Port, Bangladesh.