Mandy Pyke (2011)

The Introduction of Ozone and
Intensive Water Treatment Systems for
Purification into the UK

Mandy Pyke

The authority on seafood

Ozone (O ) is:

A colourless, unstable, toxic gas with a
pungent odour and powerful oxidizing
properties
Formed from oxygen by electrical
discharges or ultraviolet light.
It differs from normal oxygen (O2) in
having three atoms in its molecule (O3).


O Used for purification in:
Italy
Spain
France
Japan
UK Crustacea
FAO Bivalve
hatchery +
Purification Plants


Depuration is
The removal of low level
bacteria( 4,600 cfu
E.coli)
Animals purge
themselves
Optimum metabolism
Control environment in
tank
UV is meant to keep the
water clean during
process


From 1995
most systems
based on 6 x
Seafish designs
42 Hours
minimum
immersion time
for all species
Using UV only
No attempt to
remove ammonia
or introduced
suspended solids
and contaminants


Effiacy of UV can be
reduced

Suspended solids
Discolouration of Quartz
tube
Age of lamp
Operating Temperature
Inappropriate flow rates


Cross- contamination in tanks
When clean seawater is
introduced into a tank of
shellfish, the animals inoculate
that water, with material from
the harvesting grounds and
continue to do so
Faecal material from one
animal and its by-products may
be ingested by other animals
in the tank.
O could reduce this cross
contamination


Ozone (O )
Is a powerful oxidising agent
Used for disinfection of water
and air
inactivates pathogens, oxidize
organic wastes (including
colour) and nitrite, or
supplement the effectiveness
of other water treatment units.
Very unstable, half life in
seawater reported as = 5.3s
Oxygen is produced as a
reaction end product

Source: Steven T. Summerfelt 2002.Ozonation and UV irradiation*/an introduction and examples of
current applications. Aquacultural Engineering 28 (2003) 21/36


O O = Release of Energy = Breaks Cell Wall

http://understanddolphins.tripod.com/dolphincaptivehabitat.html


Production of ozone
By electricity
Also by U.V.
Produced at UV < 200 (nm)
nanometer
Destroyed at 254 (nm)
UV used for purification =
254nm as biocidal optimum
Therefore insert O before UV


Application of ozone into a
purification tank
Via venturi
Bubble diffuser
integrating a micro-
bubble generating a
gas-liquid dispersion
device ensuring
maximised mass
transfer


How much O should be applied
FAO state... Ozone at a Difficult to measure
concentration not exceeding
0.5 mg/l (in order to minimize O directly
bromate production see Advise use
below) can be used to treat
seawater in batches for Oxidation/ Reduction
periods up to 10 minutes. Potential (ORP)
CEFAS ...or suitable
Measured in mV using
time/dose equivalent has Redox meter
been added.
FAO. Fisheries Technical Paper 511. Bivalve Depuration : Fundamental and Practical Aspects.

A. Younger. CEFAS. Ozone Potential Application in Depuration Systems in England & Wales.
Discussion Document . June 2010.


Setting an O dose
Ozone Redox E.coli / Comment
concentra Pot 100ml
tion
Mg/l
mV Untreated Seawater
(approx)
~200mV (remember,
0.0 50 - Below 50mv, anaerobic
100 sediment, bacterial sludge. pH and t c variability)
0.1 200 300 Poor quality natural water FAO: ~600mV
0.2 300 30 Good quality natural water FSA: no un-reacted
desired minimum level for
aquaculture O to reach animals
0.3 400 3 Upper limit for aquaculture
and aquariums Seafish: 10%
0.4 500 2 Damage to the epithelial
tissues if aquatic life above, untreated
0.5 600 1 Severe damage to aquatic
life, near 100% disinfection
starting point mV
Control = Use to
much and the animals
0.6 700 0 Above 700mv complete
die.
Source:
disinfection. Swimming pools,
(http://media.live.harnesslink.com/files/f1038953 potable water treatment.
750.pdf


Degassing un-reacted O
Protein skimmer by itself adds nothing,
will remove suspended solids and
proteins
Apply the O into protein skimmer
Any un-reacted O is degassed to
atmosphere


Bromate formation
Potential for brominated
organic by-products
Potential carcinogen
No evidence take up by
shellfish
Requires bromide salts (are
present in natural seawater )
Bromate level allowed in tap
water = 10µg/l
Not high risk in artificial
seawater(Bromide not in the
salts)
Granulated activated carbon
filter will remove from
seawater.


Live Biological filter

a substrate is
provided for the
growth of a biofilm
that utilizes oxygen to
convert ammonia and
nitrites to nitrates, and
oxidize organic matter
It cleans the water
Maria Teresa Gutierrez-Wing, Ronald F. Malone. 2006. Biological filters in aquaculture: Trends and research
directions for freshwater and marine applications. Aquacultural Engineering 34 (2006) 163 171


All operations can be incorporated

No firm Seafish Bio- O
advice on design filtration

It depends
CEFAS discussion Activated Protein
document on web Carbon Skimmer

Challenge your
supplier
UV
Speak to your EHO

All unit operations incorporated
together The authority on seafood


Norovirus Can it be
in Oysters removed by O ??
Gills 14.71% should be eliminated
Cilia of mantle from water
Labial palps May be eliminated from
surface organs
Stomach 13.97%
Unlikely to be
Digestive diverticula
eliminated from
13.24%
Wang et al. 2008. New target tissue for food-borne virus detection in oysters.
Letters in Applied Microbiology ISSN 0266-8254
intestinal tract


No apparent evidence to date o will guarantee total virus
inactivation

SOLUTION ISTO STOP CONTAMINATING FOOD GROWING AREAS


Richard Emans
Gerardo Saggiomo
Adriatic Sea
Group Azzurra Pesca
FSA
CEFAS

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Mandy Pyke (2011)

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