Recycling Agricultural Film: Dealing With Soil, Sand and Moisture

The material is not the problem

Agricultural film — greenhouse film, silage wrap, mulch film and similar — is generally clean LDPE or LLDPE. There is nothing about the polymer that makes it hard to recycle.

What makes it hard is what comes with it:

• Soil and sand from the field, often a significant proportion of the incoming mass.
• Organic residue — plant matter, roots and soil-bound organic material.
• Moisture, held in folds and layers and not removable by gravity.
• Physical form — thin, torn, irregular, often baled, and with very low bulk density.

The process route is designed around these, not around the polymer.

Why soil and sand drive the design

Sand and grit are abrasive. If they reach pumps, screens, blades or bearings in quantity, they wear them out quickly and the maintenance cost of the whole line rises.

This is why pre-washing comes early and is sized generously in an agricultural film line. Its job is as much protective as it is cleaning: removing the bulk of abrasive material before it reaches the equipment that matters.

It is also why the waste stream is significant. A film washing line processing heavily soiled agricultural film produces a substantial volume of soil-laden water and separated solids, and the water treatment stage has to be sized for that, not for a nominal flow.

Why one washing pass is not enough

Organic residue does not release as readily as loose soil. It clings to the film surface and requires mechanical action to break the bond. In practice this means:

• Pre-washing for bulk soil removal.
• Friction washing to scrub the surface and break down the remaining residue.
• A further washing or rinsing stage where the contamination is heavy.

The number of stages is set by how dirty the material actually is, which varies enormously between crops, regions and collection practices. This is one of the clearest cases where a material trial is worth more than a specification sheet.

Dewatering carries more of the load

Agricultural film arrives and remains in a form that holds water. It folds, it layers, and it does not drain under gravity the way rigid flake does.

The consequence is that mechanical dewatering is more important here than in most other streams. A film squeezer — which compresses the material and forces water out from between the layers — does the bulk of the work, and thermal drying removes what is left.

If the dewatering stage is undersized or bypassed, the problem surfaces as a dryer that cannot keep up, which is much more expensive to fix than correctly sizing the squeezer in the first place.

Hot washing is usually not required

Agricultural film rarely carries the contaminants that justify hot washing:

• No labels, so no adhesive to release.
• No oil or grease in normal agricultural use.
• No printing ink in most applications.

Cold washing with good mechanical action normally reaches the required cleanliness. Hot washing is added where a specific contaminant requires it — for example film that has been stored with chemical residue or mixed with silage wrap that carries a tacky layer.

Form and bulk density

Agricultural film is thin and low in bulk density, which affects two decisions:

• Size reduction must handle material that wraps and tears; shredding before crushing is common.
• Pelletizing, if the route goes that far, requires compaction before extrusion — an extruder

cannot be fed loose film at a stable rate.

Typical route

Bale opening → shredding → pre-washing → friction washing → rinsing → density separation → mechanical dewatering (squeezer) → drying → [optional: compaction and pelletizing]

The bracket is the decision point: whether the output is washed film or regranulate. That is set by the destination, not by the material.

Related: Agricultural Film Solutions · How to Reduce Moisture After Film Washing · Why Film and Fibre Need Compaction