Italiano
Promeco advanced waste technology

Peat-Free Product and Wood Fiber Production Process

sostituto di torba

The PROMECO process is an innovative system for the production of a natural, eco-friendly alternative to harvested peat from materials that are composed of low value biomass, agricultural waste, wood chips and screened compost oversize.
Peatlands are places of natural heritage and the European Union is taking measures to prevent the use of peat as a component of both substrates as well as biomass for energy use. The European Union also denies the Ecolabel to products for substrates containing peat and the full ban on the use of peat has already been put on the agenda, while the British Government has planned the full ban by 2020.

The wood and green waste recycling industry produces a byproduct of the composting process, screened compost oversize material that in most markets has little or no value and in many cases has cost factor as it has to be reprocessed by grinding or sent back through the composting process. Screened compost oversize is very often contaminated with plastics making its reuse in the composting cycle.
Promeco also provides the equipment to remove plastics, stones and other foreign material from compost oversize.

The alternative to peat
The input material is ground biomass material with high specific density.
The process produces a peat replacement product with all the characteristics of natural peat: neutral pH, reduced salinity, high porosity, specific density of approximately 200 to 250 kg/m³. The product can be used as growing media in nursery, horticulture, gardening and landscaping.
Process description
The process consists of two phases:

  1. Pre-treatment: Screen and sort of the feed material to remove contaminants such as metal, stone and plastics.
  2. The process uses a twin screw extruder (BIOEXTRUDER©) rather than a shredder to breakdown and open the material to produce a softer more fibrous material with higher surface area than material shredded in conventional grinders.

The BIOEXTRUDER© process works as follows.

  • Two counter rotating screws exert pressure and friction on the feed material.
  • This generates heat to convert the moisture in the material to steam.
  • The increased volume of the steam causes difibration (separation of the fibers) in the biomass material.
  • The thermo-mechanical breakdown of the material changes its structure and physical characteristics creating a lighter open product with similar characteristics to Peat

Characteristics of the Alternative-to-Peat Product

  • Increased porosity giving it greater oxygen, nutrient and water holding capacity.
  • Mixes easily to produce high quality topsoil or planting mix that is looser and more open mix.  This more open mix encourages root development and makes oxygen, nutrients and water readily available for plant uptake.

An optical post process sort can be added to remove any remaining plastic particles to produce a 100% contaminant free material.

Potential partners:

  • Producers of soil amendments for landscaping, nursery and agricultural uses.
  • Companies involved in peat moss harvesting.
  • Composting operations that produce screened compost oversize product.

References

  • The first industrial-scale plant is in production in the UK since July 2009 (no. 3 lines)
  • The resulting product has been certified for use in green areas to be implemented in conjunction with the London Olympic Games of 2012