Farm Intake Water Treatment (FIWT) project FRDC 2017/231 start July - - PowerPoint PPT Presentation

Farm Intake Water Treatment (FIWT) project

FRDC 2017/231 – start July 2018

‘Water treatment to control influent water biosecurity risk on Australian prawn farms. Effectiveness and impacts on production ponds.’

David Mann Co-invest. Paul Palmer Tom Gallagher Stephen Wesche Bribie Island Research Centre DAF

Project context

Enhancing farm biosecurity

• Intake water is a significant potential vector
• 2018/19 farms in the Logan River Region operating in

the white spot control zone Filtration to remove disease vectors is a common biosecurity measure

• alone or in combination with a

following disinfection step

• rotating drum filters – best tech. for

high flow volume

Project context

“From a biosecurity standpoint, WSSV risk decreases with screen size.”

Responsible Aquaculture Foundation / World Bank. 2013.

Case Study…Mozambique and Madagascar: Impacts and Management Recommendations.

Intake water filtration

• Farms now screen pond inflow water
• This project is about the next level of protection
• requires large farm investment
• Need to optimise the cost:benefit
• Fine filtration (sub-100µm) as well as water disinfection

will impact plankton bloom dynamics

• Need to manage adverse impacts

Project results

Part 1. Farm monitoring

• Performance of commercially operated rotating drum

filtration system

• Impact of filtration on downstream plankton composition

Part 2. Filter mesh size tests

• Direct comparison of different filter sizes (20-150µm)

Outcomes

• What do the results mean for farm biosecurity and
• perations

Results: Part 1. Farm monitoring

Gold Coast Marine Aquaculture

Hosted project monitoring activities over the whole 2018/19 production season Operating parameters

• two filters in parallel at

start, third installed later

• nominal 80µm mesh
• estimated 5 ML/h flow rate

Results: Part 1. Farm monitoring

Farm intake water filtration

What it did do…

• 1. removed large quantities of small crustaceans
• in raw water and backwash water - not in filtrate
• amphipods, shrimp, crab and other decapod larvae
• filter feeders, scavengers, predators
• large proportion of these in the 0.3 to 4mm range
• 2. potentially obstructed entry by Penaeid prawns
• very few non-P. monodon prawns within the farm
• different from previous years

Small crustaceans in filter backwash

Results: Part 1. Farm monitoring

Farm intake water filtration

What it didn’t do…

• 1. Did not greatly affect the copepod population
• 2. Did not stop glass shrimp (Acetes sp) from colonising

the farm

• passage of larval stages?
• 3. Did not stop barnacles
• heavy colonisation occurred within first few weeks

Barnacles on pond liner Glass shrimp Copepods

Copepods at different points within the farm

• no statistically significant differences

Results: Part 1. Farm monitoring

number / m3

• Adult copepods of

the four groups present

• Some larger adults

restricted - Calanoids

Results: Part 1. Farm monitoring

Nauplii at different points within the farm

• no statistical differences within water supply system

number / m3

• Nauplii not affected

by filtration

• No difference in body

size pre- and post- filter

Plankton much larger than the 80µm nominal mesh size pass through the filters

• copepods over 200µm width
• almost all nauplii (to 340µm)

HOW?

• 1. Plankton tend to be bendy,

squishy and variably shaped

• 2. Filter mesh actual pore size and

shape

Results: Part 1. Farm monitoring

Acartia sp. copepod Barnacle nauplii

Nominal 80µm mesh – [absolute 125µm]

Results: Part 1. Farm monitoring

Plain weave Weft Warp

167µm

167µm ̴166µm ̴250µm

Location

Results: Part 2. Mesh size tests

Pumicestone Passage Bullock Creek Prawn Farm

Mesh size comparison...

• 1. Tested range (20, 40, 80,150µm), nominal pore size

greatly affects copepod population

• 20µm retains virtually all copepods and nauplii
• 150µm retains around half of copepods and nauplii
• 2. All copepod groups pass through 40µm & above
• 3. Copepods and nauplii passing through 40µm are viable
• 4. Rotifers can pass through 20µm
• small species? ; eggs?

Results: Part 2. Mesh size tests

Testing set-up

• Inshore estuarine water
• prawn farm standard
• Scaled down drum filter
• Reparator Pty. Ltd

(manuf. by Adriyatic)

• Stainless woven mesh
• 20, 40, 80, 150µm, (raw)
• 80µm same weave as GCMA
• 21 tank array
• plankton mesocosms to

assess animal viability

Results: Part 2. Mesh size tests

Results: Part 2. Mesh size tests

Copepod density post-filter Initial

# / m3

Day 14

# / m3

• Comparatively large restriction step from 150 to 80 µm
• Copepod size did not follow same pattern as abundance

Results: Part 2. Mesh size tests

All nauplii density post-filter Initial

# / m3

Day 14

# / m3

• 150µm mesh restricts ̴50% of nauplii, 40µm ̴25%
• Average body size of filtrate nauplii same for all mesh sizes

• 1. Logan River plankton and glass shrimp samples WSSV

negative (intake and in farm; over the season).

• 2. Drum filtration at nominal 80µm effectively excludes higher

WSSV risk organisms at practical flow rates.

• 3. Nominal 80µm stainless filter has a low impact on pond bloom.
• time to peak copepod density delayed but main groups

present to form normal productive pond bloom

• 4. To prohibit barnacle entry need 40µm or less filter mesh.
• larval stages of crustaceans still enter (lower risk?)
• 5. Nominal 40µm stainless filter would allow some copepod entry

but retard pond population development.

• 6. Filtration alone lowers probability of vector intrusion.
• chemical disinfection – high protection

Outcomes

This project

• sampling completed
• final report will have more detailed analyses

What next…

What next…

Future work on water biosecurity…

• 1. Continue farm monitoring and testing
• performance and impacts of the re-developed systems

being implemented on farms this season – ‘Growing together’ theme – sharing information

• 2. Optimise chemical disinfection for high water biosecurity
• options – oxidants, eg ozone, other oxidants; trichlorfon
• conditioning of disinfected water important
• 3. Creating healthy pond systems
• water/pond biome management
• adapting overseas innovations to the Australian context

• FRDC and DAF funded the project
• Gold Coast Marine Aquaculture opened their Logan River

farm to regular sampling and assisted on farm activities

• Frank Coman and Julian Uribe Palomino (CSIRO) assisted

pond sampling method development and conducted training

• f DAF staff in zooplankton identification
• Bullock Creek Prawn Farm allowed use of hatchery and

intake facility and assisted in systems set-up

• Reparator Pty. Ltd supplied the fully equipped drum filter

and different size mesh screen replacements for tests

Acknowledgements

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