Dr Ashley J. Wilson
Technical Director
Carafiltration Ltd.
CARASOLS
– Developed for a Cleaner, Greener
Environment
WHAT ARE CARASOLS?
CARASOLS are a range of natural, innovative,
harmless – but potent – bio-adsorbents for the removal of
contaminants from both aqueous and gaseous industrial and
agricultural effluent.
Carasols are: Derived from specific waste materials from food
processing which currently attract a cost for disposal

Low-cost (capital and recurrent) compared with
alternatives
 In the form of a range of non-hazardous, safe/pleasant-touse powdered media
 Extremely versatile with respect to the wide range of
molecules and ions they will trap
 Able to be used when wet or dry for waste-water or
gas/odour applications
 Very strong binding of the contaminant to Carasol
Difficult to de-sorb what is trapped
 Completely biodegradable in landfill and safe to
incinerate.
CARASOLS are the result of: Six years R & D at the University of York
 Ten European and DTI - sponsored* investigations into:
 How best to ‘contact’ the bioadsorbent with the contaminant i.e.
in a packed or fluidised bed scrubber
 How the adsorbents work (physical and biochemical trapping
mechanisms)
 What contaminants they will trap (i.e. range of molecules and
ions)
 How to source the raw material and prepare it as an adsorbent
 How to add value to the raw materials by the addition of
functionalised groups and biocides etc.
 How to detect when the bioadsorbent is saturated with
contaminant
 How best to dispose of the bioadsorbent/contaminant.
*
SMART (X2), EU LIFE-Environmental, Bio-Wise, RECRAFT,
KTP, TIDE etc.
RAW MATERIAL
Carasols are manufactured from a food
waste (so they are obviously derived from
natural materials) which currently attracts a
cost for disposal. The food waste is the
carapace or shell of a range of marine
crustacea such as:




Crab
Prawn
Lobster
Langoustine
The Seafish Industries Authority is currently
very concerned about the volume of shellfish
waste illegally dumped at sea and also the
major odour problems arising from
putrefying shellfish waste dumped in landfill.
It was important to find a use for this waste.
HOW ARE CARASOLS MADE?

Dirty carapace is sourced and cleaned with mild caustic
to remove residual soft tissue.

Rinsed and dried to <5% water content.


Fragmented into 10 mm pieces.
Rinsed with a biocide solution (Amolden or Cetrimide)
to extend the shelf-life and increase binding efficiency.
 Treated with a ‘mordant’ or functionalised group to
increase binding capacity or improve specificity.

Gently milled to a powder using a pin-mill or high shear
to retain structure.

Screened (sieved) to a particle size between 250 mm and
720 mm. (Mean 480 mm)

Bagged as Carasol 480 (waste-water cleaning) or
Carasol 120 (gas and odour scrubbing).
HOW DO CARASOLS BIND/TRAP?
I Physisorption
 Micro-pores similar to those in activated carbon
provide a large surface-area-to-volume ratio.
 1g of Carasol 480 typically has a surface area of
approx. 15 m2.
HOW DO THEY BIND/TRAP?
Synergistically with:
II Chemisorption
(amines, hydroxyl, carboxyl groups, ionexchange and neutralisation)
• Chitin and the chitosan family of molecules
+
• Fibrous proteins
+
• Calcium carbonate
WHAT WILL THEY TRAP?
Original Application
Carasols were initially developed for removal
of Textile Dyehouse Effluent
Herbert Roberts Ltd. – Worsted dyer in
Keighley, West Yorkshire.
Problems with a variety of dyestuffs and metal
ions in their effluent stream.
 Dyestuffs
 Metal ions (cobalt, chromium etc.)

Textile ‘finishes’ (insecticides, flameretardants, anti-dust mite finishes).
WHAT WILL THEY TRAP?
Versatility
Carasols are extremely versatile in their application and will
trap a very wide range of contaminating molecules from both
wastewater and air. This is because they provide trapping by
both physisorption and chemisorption. Typical contaminants
they will bind include:

Metal ions (both anionic, cationic and chelated)

Pesticide residues (herbicides and insecticides)




Biocides
Dyes and pigments (printing and graphics)
Phenols and polyphenolics (e.g. humic acid)
Oils from stable oil-in-water and water-in-oil emulsion
(e.g. metal cutting fluids)




Antibiotics
Detergents / surfactants
Acid gases inc. oxides of sulphur
Odours inc. mercaptans, various organic sulphides

Dioxins and furans

PCB’s
Others, as yet undiscovered!
INDUSTRIAL APPLICATIONS
Carasols have application to the cleanup of a
broad range of industrial and agricultural
processes including:


Textile dyeing and finishing
Metal plating and finishing (Ni, Cr)
 Galvanizing industry (Zn/Pb gas emissions and run-off)
 Printed circuit board manufacture (Cu)
 Photographic processing (Ag)

Printing press fount solution cleaning

Metal cutting and turning (oil)
 Tanning industry (Cr)
 Screen printing

Printing ink pigment manufacture

Composting (Odour)
 Antibiotic manufacture
 Food processing
Carafiltration Ltd.
In order to commercialise the product there
was a need to establish a Limited company.
The Company facilitated:

Licensing of patents (X4) on the
technology
 Eligibility to apply as an SME for EU &
Government research funding
 Setting up trading agreements with
intermediary companies selling into
specialist niches
CONCLUSIONS
Carasols are:
• a good example of valuable, novel product,
which can be derived from FOOD WASTE
• a low cost bio-adsorbent clean-up process
• extremely versatile in their breadth of
application
• leave only a biodegradable residue
• safe, clean user-friendly products
• a simple to use process