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Crab shell

biosorbents to

recover metals

from

manufacturing

effluent

Globally the food industry discards

>750 ktonnes of crab shells annu-

ally with 4 ktonnes per annum dis-

carded in the UK.

Crab shells are comprised of:

20 — 30 % chitin (polysaccharide)

30 — 50 % calcium carbonate

30 — 40 % protein

< 1 % lipids

Chitosan is a non-

commercially synthesiz-

able derivative of chitin,

produced by deacetylation.

The natural polymer char-

acteristics are:

~ biodegradability

~ non-toxicity

~ adsorptive

~ chelating abilities

~ regenerative/reusable

~ anti-fungal

Crushed Shell Chitosan Flake Crushed Shell

SEM Image SEM Image

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The STOWURC project is develop-

ing a method for producing crab-

based chitosans. This biosor-

bent will be used primarily in

printed circuit board (PCB)

manufacturing effluent treat-

ment for metal recovery. The chi-

tosan can be regenerated and

the process will be demon-

strated at a UK PCB facility.

ca. 4,000 tonnes of crab shells discarded in UK per annuma

Stabilization:

Crab shells free of

flesh

Demineralisation:

Removal of CaCO3

Deprotenization:

Alkaline treatment

Granulation of Chitosan

Parameter

optimization:

efficiency &

metal ions

Metal adsorption:

> 95 %

obtainable from

effluent

Metal recovery:

electroplating

Chitosan

regeneration:

washing & return

to neutral pH

UK crab landings of

30,000 tonnes per annuma

a UK Sea Fisheries

Statistics, 2012

Introduction to

effluent Deprotenization:

Alkaline treatment

The use of chitosan aligns

with the UK’s efforts to

achieve a circular econ-

omy, by diverting a food by

-product from landfill to-

wards reuse with added-

value, involving material

recovery over multiple cy-

cles through biosorbent re-

generation

Project Co-funded by the Technology Strategy Board, project #: 101692