Mandy Pyke (2011)

Mandy Pyke

The Introduction of Ozone and Intensive Water Treatment Systems for

Purification into the UK

The authority on seafood

Ozone (O ) is:

A colourless, unstable, toxic gas with a pungent odour and powerful oxidizing propertiesFormed 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:

ItalySpainFranceJapan

UK Crustacea FAO Bivalve hatchery + Purification Plants


Depuration is

The removal of low level bacteria( 4,600 cfu E.coli)Animals purge themselvesOptimum metabolismControl environment in tankUV is meant to keep the water clean during process


From 1995

most systems based on 6 x Seafish designs42 Hours minimum immersion time for all speciesUsing UV onlyNo attempt to remove ammonia or introduced suspended solids and contaminants


Effiacy of UV can be reduced

Suspended solidsDiscolouration of Quartz

tubeAge of lampOperating TemperatureInappropriate flow rates


Cross- contamination in tanksWhen clean seawater is introduced into a tank of shellfish, the animals inoculate that water, with material from the harvesting grounds and continue to do soFaecal 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 agentUsed for disinfection of water and airinactivates 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 = 5.3sOxygen 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

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


Production of ozone

By electricityAlso by U.V.Produced at UV < 200 (nm) nanometerDestroyed at 254 (nm)UV used for purification = 254nm as biocidal optimumTherefore insert O before UV


Application of ozone into a purification tank

Via venturiBubble diffuserintegrating a micro-bubble generating a gas-liquid dispersion device ensuring maximised mass transfer


How much O should be applied

FAO state... Ozone at a concentration not exceeding 0.5 mg/l (in order to minimize bromate production see below) can be used to treat seawater in batches for periods up to 10 minutes.

CEFAS ...or suitable time/dose equivalent has been added.

Difficult to measure O directlyAdvise use Oxidation/Reduction Potential (ORP)Measured in mV using Redox meter

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 doseOzone concentrationMg/l (approx)

Redox PotmV

E.coli / 100ml

Comment

0.0 50 -100

Below 50mv, anaerobicsediment, bacterial sludge.

0.1 200 300 Poor quality natural water

0.2 300 30 Good quality natural waterdesired minimum level foraquaculture

0.3 400 3 Upper limit for aquacultureand aquariums

0.4 500 2 Damage to the epithelialtissues if aquatic life

0.5 600 1 Severe damage to aquaticlife, near 100% disinfection

0.6 700 0 Above 700mv completedisinfection. Swimming pools,potable water treatment.

Untreated Seawater ~200mV (remember, pH and t c variability)FAO: ~600mVFSA: no un-reacted O to reach animalsSeafish: 10% above, untreated starting point mVControl = Use to much and the animals die.

Source: (http://media.live.harnesslink.com/files/f1038953750.pdf

http://media.live.harnesslink.com/files/f1038953


Degassing un-reacted OProtein 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 formationPotential for brominated organic by-productsPotential carcinogenNo evidence take up by shellfishRequires 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 matterIt 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 advice on designIt dependsCEFAS discussion document on webChallenge your supplierSpeak to your EHO

Bio-filtration O

Protein Skimmer

Activated Carbon

UV


All unit operations incorporated together


Norovirus in Oysters

Gills 14.71%Cilia of mantle Labial palpsStomach 13.97%Digestive diverticula 13.24%

should be eliminated from waterMay be eliminated from surface organsUnlikely to be eliminated from intestinal tract

Can it be removed by O ??

Wang et al. 2008. New target tissue for food-borne virus detection in oysters. Letters in Applied Microbiology ISSN 0266-8254


SOLUTION IS TO STOP CONTAMINATING FOOD GROWING AREAS

No apparent evidence to date o will guarantee total virus inactivation


Richard EmansGerardo SaggiomoAdriatic SeaGroup Azzurra PescaFSACEFAS

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Mandy Pyke (2011)