Pulp Waste: How to Turn It Into Molding Polymers in 2026

by Marco Arezio | Updated: March 2026 | Reading time: ~9 min

European paper mills face a growing production and environmental challenge every year: managing pulper waste, the solid residue generated during the recycling of waste paper. In 2026, thanks to technological advances and a regulatory framework increasingly geared towards a circular economy—particularly the new European Packaging Recycling Regulation (PPWR, which came into force in 2025 )—this waste is no longer considered a burdensome waste, but a resource to be recovered in the form of recycled LDPE polymer granules.

In this updated guide we analyse the industrial process, the technologies available in 2026, the technical critical issues and the main market outlets for the polymer deriving from pulper waste.

What is Pulp Waste?

The pulper is the heart of the paper mill recycling process: a cylindrical tank in which waste paper is immersed in water and subjected to intense mechanical agitation to separate the cellulose fibers from the foreign materials. The solid residue that cannot be reintroduced into the production cycle is called pulper waste (or pulper rejects).

This waste is primarily composed of aluminum and polyethylene (PE) from multi-material food packaging such as Tetra Pak, beverage cartons, and flexible packaging. According to industry data updated to 2025, approximately 8-12% of incoming paper by weight is converted into pulper waste, with higher peaks in paper mills that process mixed fractions from urban waste sorting.

At European level, it is estimated that the paper sector generates over 4 million tonnes of pulp waste every year, with landfill or incineration costs still very high and increasingly less acceptable under regulations.

The Recycling Process in European Paper Mills in 2026

The industrial process that leads to the formation of pulper waste is divided into well-defined phases:

• Maceration in the tank: the waste paper is introduced into the pulper with hot water (40-60°C) and subjected to a rotating mechanical action until the fibres disintegrate.

• Coarse filtration: rotating grids and screens retain large materials (rigid plastics, metals, wood).

• Fine filtration: the suspended cellulose fibre is separated from the light materials through centrifuges and pressurised screens.

• Collection and dehydration: the residue, still with a high humidity content (60-75%), is dehydrated using screw presses or filter presses before being delivered or recycled.

By 2026, many paper mills have integrated automatic pre-separation systems with NIR (Near Infrared) optical sensors that increase the purity of the polymer stream upstream of the pulper, reducing the percentage of residual paper and increasing the yield of the final granule.

Composition and Characteristics of Pulper Waste

The composition of pulper waste varies depending on the type of incoming paper. A typical average composition (dry weight) is as follows:

- Average percentage component (dry)

- Polyethylene (LDPE/LLDPE) 55 – 70%

- Aluminum (flexible foil) 15 – 25%

- Residual cellulose (paper) 5 – 15%

- Other polymers (PP, PS, etc.) 2 – 8%

- Humidity (on the wet mass) 60 – 75%

Energy Enhancement Technologies Available in 2026

2026 marks a technological milestone for pulper waste recycling. The main available supply chains are:

1. Granulation of LDPE polymer (main supply chain)

This is the most widespread and established technology. The process involves mechanical and densimetric separation, shredding, intensive washing with hot water, drying (essential to reduce moisture content to below 2%), filtration of the melt through fine mesh screens, and pelletization using an underwater cutting head (underwater pelletizing). The resulting granules are classified as recycled LDPE with an MFI between 1 and 3 g/10 min at 190°C/2.16 kg.

2. Recovery of aluminum through pyrolysis (co-product)

Advanced Alurec or Thermovac-type systems separate aluminum from PE through low-temperature pyrolysis (approximately 450-500°C) in an inert atmosphere. The aluminum is recovered with a purity greater than 97%; the pyrolysis gas is used as an internal fuel. This technology, already in use in Spain, Portugal, and Brazil, is becoming widespread in Italy and Germany.

3. Compounds and technical materials

In 2026, the production of technical compounds from LDPE pulper granules, mixed with PP, HDPE, or mineral fillers (CaCO3, talc), is growing to obtain materials with customized mechanical properties. Some manufacturers use reactive compatibilizers (e.g., maleic anhydride) to improve the cohesion between the PE and the aluminum residues, increasing the impact resistance of the final product.

Technical-Production Critical Issues and How to Resolve Them in 2026

The critical issues already identified in 2020 remain current, but in 2026 we have more mature and effective technical solutions:

Criticality 1 – High initial humidity (>60%)

Problem: High humidity reduces production yields and causes defects in the granules. Solution 2026: Latest-generation high-pressure screw presses reduce moisture content by up to 30-35%; fluidized bed or hot air drying systems complete the reduction to 1-2% before granulation, eliminating outgassing problems.

Criticality 2 – Gas during molding

Problem: Residual moisture in the pellet causes bubbles and micropores in molded parts. Solution 2026: Degassing twin-screw extruders with multiple venting zones eliminate residual volatility directly during pelletization, eliminating the need for separate pre-drying.

Criticality 3 – Presence of residual paper

Problem: Cellulose microparticles clog filters and form micropores in the granules. Solution 2026: Continuous melt filtration systems with automatic candle or rotating disc screen changers, with mesh sizes up to 80-100 microns, ensure effective filtration without production downtime.

Criticality 4 – Presence of aluminum and aesthetic appearance

Problem: Aluminum flakes create heterogeneous surfaces in the final product.

Characteristics of LDPE Granules from Pulper in 2026

In 2026, the granule resulting from the valorization of pulper waste has the following standard technical characteristics:

• Base polymer: LDPE with content above 90%

• MFI (Melt Flow Index): 1-3 g/10 min at 190°C / 2.16 kg (ASTM D1238)

• DSC: regular profile, melting temperature 108-115°C

• Residual aluminum content: 2-8% by weight (flexible strips)

• Residual cellulose content: <1% after fine filtration

• Humidity: <0.5% post-drying

• Color: dark grey / black (with added masterbatch)

• EWC classification: 19 12 04 (plastic and rubber) or 15 01 02 depending on the regime

The granule is normally marketed with a technical data sheet and, in some cases, with a declaration of compliance with the RecyClass guidelines or with an EPD (Environmental Product Declaration), which are increasingly requested by European industrial buyers.

Pulp Granules Market and Applications in 2026

LDPE granules from pulper waste are suitable for applications where functional performance takes precedence over aesthetics. In 2026, the main market outlets are:

• Industrial pallets made from recycled plastic: a rapidly growing market thanks to PPWR, which requires a minimum recycled content in industrial packaging

• Vases, tubs and containers for industrial and agricultural use

• Accessories and components for construction (profiles, spacers, supports)

• Non-drive-over draining gratings and permeable paving

• Corrugated pipes for drainage and cable protection

• Compounds with PP, HDPE or polyolefins for specific mechanical applications

• Sound-absorbing and anti-vibration panels (emerging application 2024-2026)

The market price of LDPE pulper granules in 2026 is between €200 and €400/t depending on the quality (LDPE percentage, moisture, residual paper), with higher peaks for material certified with EPD or according to the RecyClass guidelines.

European Regulations and Incentives 2025-2026

The European regulatory context has undergone a profound transformation between 2020 and 2026:

• Regulation (EU) 2025/40 – PPWR: sets minimum recycled content targets in packaging (e.g. 35% for rigid plastic packaging by 2030), creating direct demand for recycled pulp granules.

• SUP Directive and 2024 updates: restrictions on single-use plastics favor durable recycled materials.

• CEAP 2.0 of the European Commission: the paper sector is among the priority sectors for industrial symbiosis.

• National Plastic Tax (MACSI): makes the use of recycled granules more competitive compared to virgin ones.

• PNRR calls for advanced recycling plants: some Italian regions co-finance pulper waste recovery lines.

Paper mills that implement internal recovery plants can achieve End of Waste (EoW) qualification for the granules produced—according to Legislative Decree 116/2020 and subsequent MASE circulars—transforming the waste into a fully marketable product.

FAQ – Frequently Asked Questions

How much pulper waste does an average paper mill produce?

A paper mill that processes 100,000 t/year of recycled paper generates on average between 8,000 and 12,000 t/year of wet pulp waste, equivalent to approximately 3,000-5,000 t/year of recoverable dry waste.

Is the pulper granule food-grade?

No, in almost all cases. The presence of aluminum, cellulose, and the variability of its composition make pulper granules unsuitable for direct contact with food. Applications remain primarily in the industrial, agricultural, and construction sectors.

Is it possible to add mineral fillers to the pulper granules?

Yes. The regular DSC profile makes it compatible with the addition of mineral fillers such as calcium carbonate (CaCO3), which reduces LDPE's inherent flexibility and improves the stiffness of the final product. Talc and silica are also common for specific applications.

What is the payback of a pulper recovery plant?

Based on industry analyses available in 2026, a medium-sized plant (5,000-10,000 t/year) has a payback period of between 3 and 6 years, depending on the current disposal cost, the market price of the granules, and available public incentives.

What is the difference between virgin LDPE and pulped LDPE?

Pulper-grade LDPE has a MFI similar to virgin, but with residual aluminum (2-8%) and a color that cannot be standardized without additives. It is suitable for all non-aesthetic applications where virgin purity or food-contact compatibility are not required.

Conclusions

By 2026, pulper waste recovery is no longer a technological gamble but a consolidated industrial reality. Paper mills that choose to invest in recovery facilities—or rely on specialized operators—reduce disposal costs, generate additional revenue, and improve their sustainability profile in an increasingly demanding regulatory environment.

Technical challenges (humidity, aluminum, aesthetic quality) still exist, but they are largely manageable with available technologies today. The key to success lies in the quality of the drying and filtering process, the correct characterization of the granules, and the identification of suitable end markets.

Need advice on pulp recycling or paper mill waste recovery? Contact our team of circular economy and plastics recycling experts .

Tags: pulper waste, paper recycling, recycled LDPE, paper mill polymers, circular economy, polymer granules, Tetra Pak recycling, pulper waste, multi-material packaging, PPWR 2025 regulation, End of Waste paper mill

Category: Technology | Paper | Recycling | Circular Economy | European Regulations