TRIALS : GROWING BENEFITS OF WOOL-RICH CARPET SHRED Philip Putwain Philip Putwain Ecological Restoration Consultants + Liverpool University
POTENTIAL ALTERNATIVES TO LANDFILL FOR WOOL-RICH CARPET RESOURCES Wool, nylon, polypropylene, polyester Each year 420,000 tonnes of carpet waste are buried in UK landfill sites 100,00 tonnes woolrich carpet available Ultimate aim of Carpet Recycling UK is to find end-markets for woolrich carpet shred 25mm screen size
GREEN APPLICATIONS LAND RECLAMATION Agriculture (food-crops) and commercial horticulture (pot plants) were ruled out Brownfield land restoration, subsoil improvement, woodland planting, amenity grassland Soil manufacture green roofs slope stabilisation quarry wastes biomass energy crops
TESTING THE POTENTIAL OF WRCS AS A SOIL IMPROVER There was no previous experience of blending WRCS with subsoils or other organic materials (e.g. green compost) AIM OF TRIAL : to test efficacy of WRCS as an improver of poor subsoils Nitrogen content 10% (m/m) Sulphur content 1.4% (m/m) Organic carbon 70% (m/m) ph 6.4 7.4 ERC commissioned by Envirolink Northwest on behalf of CRUK to undertake pot trial at Liverpool University s Ness Botanic Gardens
DESIGN OF THE TRIAL (1) WRCS blended with sandy subsoil subsoil rich in clay and silt Composition of blends Sandy subsoil or clay-rich subsoil 100 WRCS 90 10 75 25 60 40
DESIGN OF THE TRIAL (2) Two cultivars of amenity grass Perennial Ryegrass (cv. Aber sprite) Browntop bent (cv. Aber royal ) Two tree species Silver birch White willow Three herbaceous perennials Fuchsia Scabious Yarrow
MANUFACTURING THE WRCS /SUBSOIL BLENDS Minimum mixing time 7 minutes Dust problem De-compaction issue 18 pots per blend for each test plant species Start dates 1350 pots Grasses trial 11 th March 2010 Trees 16 th March 2010 Herbaceous perennials 19 th March 2010
PLANT GROWTH AND SOIL PROPERTIES PERENNIAL RYEGRASS Fresh biomass yield after 10 weeks growth cut at 15mm above soil Further 6.5 weeks 1 Subsoil A 2 Subsoil B 3 Topsoil 4 90% Soil A/10% Carpet 5 90% Soil B/10% Carpet 6 75% Soil A/25% Carpet 7 75% Soil B/25% Carpet 8 60% Soil A/40% Carpet 9 60% Soil B/40% Carpet 10 60% Soil A/20% 11 60% Soil B/20% Fresh weight (g) 0 100 200 re-growth almost identical pattern of response
NITROGEN CONTENT OF WRCS/SUBSOIL BLENDS Available nitrate-nitrogen (mg/kg) measured after 12 weeks (1 st June 2010) and 19 weeks growth (22 nd July 2010) WRCS/ Subsoil blend Sandy subsoil Clay/silt subsoil Nitrogen content of foliage 01/06/10 22/07/10 01/06/10 22/07/10 15/06/10 Subsoil 0.11 0.5 0.7 0.1 2.29 10% WRCS 4.2 0.1 10.4 0.7 3.1 25% WRCS 14.1 2.2 9.1 1.8 3.6 40% WRCS 31.9 5.2 77.3 15.6 4.21
PERENNIAL RYEGRASS Foliage growth root density
SILVER BIRCH Similar fresh biomass yield response as perennial ryegrass
HERBACEOUS PERENNIALS FUCHSIA DOLLAR PRINCESS
POTENTIAL MARKET OPPORTUNITIES Barriers FOR WRCS The nylon, polypropylene and polyester components of WRCS fall outside BSI PAS 100 and QPC guideline limits Legislative and regulatory control require resolution with the Environment Agency Solution through Environmental Permitting or Product Status? Cost associated with the de-compaction of WRCS transported in baled form Transport of low bulk density un-compacted WRCS = prohibitive haulage cost
POTENTIAL MARKET OPPORTUNITIES Innovative landscaping applications Niche markets Green roofs Lower bulk density Higher available water capacity Urban park naturalistic landscapes
CONCLUSIONS - QUESTIONS Large-scale landscape regeneration: WRCS cannot compete against established recycled organics such as compost or digestates Is there a low-cost processing technology that would remove plastic content and thus allow product status to be achieved? Is it possible to demonstrate a benefit from the inert (plastic) component of WRCS (Environment Agency requirement)?
ACKNOWLEDGEMENTS Gill Haynes Technical Associate (ERC) Helen Rawlinson Envirolink Northwest Carpet Recycling UK Paul Cook (Curator) Ness Botanic Gardens