Aquaculture Scoop - March 2016

Aquaculture Scoop is a magazine for aquaculture professionals worldwide

Issue 11 / March 2016 Advanced Extrusion

Growth Promotion

For superior Fish Feed

The best solution

Processing Technology

Issues in Extrusion

Aquafeed Innovation

Gordon Young / Dennis Forte

Expo list

The world’s top events related to milling from around the world, listed on p. 31

Innovation in Aquafeed

14/17 Offshore/Onshore Risks in aquaculture

Clextral’s new systems deliver improved flexibility and control, plus energy savings

PAGE 20

Read more on p.6

FILTRATION OF COLLOIDAL MATTER

In Recirculating Aquaculture Systems Read more on page 19 Published by Nisa Media Ltd www.aquaculturedirectory.co.uk www.facebook.com/nisamedia www.twitter.com/Aquaculturedire

Aerators in ponds

p.25

Advanced Extrusion

p.2

Editorial

Issue 11 / March 2016 Advanced Extrusion

Welcome to the latest issue of Aquaculture Scoop.

In this issue we take a look at Extrusion advances with insight from Andritz, Gordon Young and Dennis Forte. We learn about Processing Technology in Aquafeed production, growth promotion solutions and worms in wastewater management. We also have an Article from Willis Towers Watson on Insurance in Aquaculture with Onshore and Offshore perils. As you will see this is a packed out issue, the news of a major breakthrough in Ammonia/Nitrite control from Bio Industries of Ireland is worth a read too!

As ever, please send us your comments and articles for inclusion, contact details below right.

www.aquaculturedirectory.co.uk

Keeping in touch with Aquaculture Scoop, follow us on: Twitter: www.twitter.com/Aquaculturedire Linkedin: www.linkedin.com/company/nisa-media-ltd Scoop it: www.scoop.it/t/aquaculture-directory Paper.li: www.paper.li/Aquaculturedire/1334242719 Pinterest: www.pinterest.com/aquadirectory/ Facebook: www.facebook.com/pages/Aquaculture-Directory/27260116281734

For superior Fish Feed

Processing Technology Aquafeed Innovation

Issues in Extrusion Gordon Young / Dennis Forte

Growth Promotion The best solution

Events

The world’s top events related to milling from around the world, listed on p. 31

>> Published by: NISA Media Ltd 14 Clarke Way Cheltenham GL50 4AX United Kingdom

www.aquaculturedirectory.co.uk > Editorial Manager Nicky Barnes Tel: +44 117 2306494 Email: nbarnes@aquaculturedirectory.co.uk > International Marketing Manager Sabby Major Tel: +44 117 2306493 Email: smajor@aquaculturedirectory.co.uk > News Editor Martin Little Email: mlittle@aquaculturedirectory.co.uk

Aquaculture Scoop / March Issue 2016

Page 1

The nutritional quality of fish feed can be defined as: • Recovery of essential amino acids and

Advanced extrusion technologies for superior fish feed characteristics

specific vitamins • Digestibility On most newer extruder designs, an optimum screw configuration can be established in order to apply the SME quantity necessary for matching a specific product (for example salmon or trout feed) with a high content of fat/oil, internal oil or similar products with high nutritional value.

A screw configuration can be optimized to apply more SME by implementing the

> Back pressure valve (FLEXTEX ™) and Expansion Control System (ECS™) – Combining two unique process technologies for full feed controllability.

Extruding fish feed is primarily a matter of

the extruder, it is possible (to a certain

following components:

extent) to supply the specific mechanical energy (SME) necessary to produce a given

• Screw design and geometry

product with an optimum degree of cook.

• Shear locks

The degree of cook is decided from both a

• Kneading blocks

nutritional as well as a physical product

• Reverse elements

quality point of view.

cooking the starch. The better starch cook,

An optimum screw configuration is not

the better feed quality. However, it is

The physical quality of fish feed product can

always capable of applying sufficient SME to

equally important to control the expansion

be defined by:

produce a given product. Often it is also

of the feed and thus influencing the density

necessary to optimize other parameters that

which determines the sinking and the

• Density

can be used to increase the SME supply in

floating properties.

• Shape and size

the extruder:

• Uniformity Screw configuration for optimum cook

• Durability

• Screw speed

By making a specific screw configuration on

• Water stability

• Open area of venturi die • Open area of die plate • Extruder capacity

> The ANDRITZ FLEXTEX system – reduced downtime and optimum production flexibility Changes in screw configuration and other

Picture 1: ANDRITZ extruder EX1021. Capacity: 2-12 tph

measures that contribute with either higher or lower SME values are all operations that usually result in down time and increased production costs. These changeover procedures can easily take up to 0.5 - 2 hours to adapt. Therefore, technological advances focusing on both cost savings in the form of reduced down time as well as optimal flexibility in terms of capacity and quality are in high demand by the aquaculture industry.

Aquaculture Scoop / March Issue 2016

Page 2

Picture 2: ANDRITZ extruder EX1250. Capacity: 10-12 tph.

> The FLEXTEX working principle

3000 mm2 to 100 mm2 (4.65 to 0.15 in2)

The mechanical design

depending on throughput.

The FLEXTEX system is able to continuously

The FLEXTEX system consists of 3 parts:

control the SME applied in the extruder

With the FLEXTEX system, the extruder

1. The PLC control system

during operation without changing the

operator can determine how much specific

2. The venturi die and the piston system

extruder configuration or other parameters.

mechanical energy (SME) the product needs.

3. The hydraulic station

By changing only this one parameter, it will

From a control system, for example a separate

have the following advantages in the

control or alternatively a control integrated in

The FLEXTEX system is designed with focus

production of fish feed:

the extruder control, the operator can make a

on simplicity and consists of a few compo-

set-point for example kW/ton (HP/ton) dry

nents. However, the critical part of the

• The starch cook (up to 100%) is

matter. By means of a hydraulically controlled

system is the piston which, besides from

completely controlled during operation

piston, the FLEXTEX system automatically

being used as a restriction for the meal flow,

• The bulk density of the product can be

adjusts in relation to the set-point by

also distributes the meal to the die plate.

reduced by up to 30% and can be controlled

decreasing or increasing restriction of the

When restricting the meal flow, it is

with an accuracy of ±5 g/l (0.3 lbs/ft3)

venturi die by moving a piston.

essential that this takes place synchronically

• Higher addition of oil and less starch in the formula without significant influence to bulk density and product quality The system adjusts the opening area in the venturi die plate, which is placed between the last screw and the die plate in the extruder. The venturi die is used in many extruders in a stationary design to decrease or increase the kneading zone in the extruder in order to control the SME applied. This is done by adjusting the size of the hole and thus the opening area and the pressure against it. Smaller holes increase the pressure and thus more energy consumption from the main motor. With the FLEXTEX system the opening area of the venturi die can typically be adjusted from

Aquaculture Scoop / March Issue 2016

Figure 1: FLEXTEX in neutral position – no additional SME applied

Page 3

> Documented results from the FLEXTEX and ECS systems The FLEXTEX and the ECS systems can be installed individually or as a combined concept. This is simply a question of each producer’s requirements for their production. Documented tests supported by experience from systems in full scale operations have shown significant advantages when using the ANDRITZ FLEXTEX and ECS system. During a series of tests with a shrimp feed formula (70% protein), below tests were conducted.

Figure 2: FLEXTEX in closed position – additional SME applied.

Test A: FLEXTEX effect on starch cook By increasing the SME in the extrusion process by approximately 12%, the cook rate was increased by 11.8%. See Fig. 4 Test B: ECS effect on bulk density

in order not to hinder the flow ability.

knife house results in a reduction of

The ECS can increase the bulk density by

Changes in the meal flow will influence the

flash-off and thus an increase of bulk

25% by adjusting the pressure in the knife

visual quality of the product due to an

density (less expansion). Higher overpres-

house only. See Fig. 5

uneven pressure at the die plate. The piston

sure, higher density (less expansion).

in the FLEXTEX system is moved axially and at the same time it is conical, so that the meal flow is not negatively influenced.

The ANDRITZ Expansion Control System (ECS) – for increased bulk density

could be obtained as with original high starch formula, but without FLEXTEX (8

To be able to control the bulk density of

hours).

products in a wide range and at the same time obtain an optimum product quality, the

Insert: Figure 7

ANDRITZ Expansion Control System (ECS) is unique. The ECS concept is based on controlling the expansion in the extruder

Summary

knife house without influencing the product

The FLEXTEX and ECS system provides

quality. Thus all desirable parameters can

significant flexibility in the production of

be used in the extruder without regard to

feed for all fish species. By continuously

expansion. The main focus here is product

controlling the SME during operation, it is

quality.

possible to achieve an optimum physical quality. At the same by using the ECS to

By adding compressed air in the knife house, it is possible to control and adjust the pressure. This is made possible by mounting an airlock under the knife house (see figure 3). An increased pressure in the

Aquaculture Scoop / March Issue 2016

control the density, two unique tools for

Picture 3: Extruder with FLEXTEX installed.

controlling finish product characteristics are present. The advantages of the systems can be summarized into: •

Increase starch cook by 10-15%

Page 4

controlling the SME during operation, it is possible to achieve an optimum physical quality. At the same by using the ECS to control the density, two unique tools for controlling finish product characteristics are present. The advantages of the systems can be summarized into:

Figure 3: FLEXTEX and ECS

• Increase starch cook by 10-15% • Decrease bulk density by 20-30% • Increase bulk density by 0-5% • No change of screw configuration which means reduced down time • Only two parameters needed for control-

Test C: FLEXTEX effect on water stability

ling starch cook, reduced and increased bulk

By increasing the SME it was possible to

density

increase the water stability by additionally 6 hours. See Fig. 6

Figure 4

Figure 5

Figure 6

Figure 7

Test D: Reduced starch contents in formula by means of FLEXTEX By reducing the starch contents by approximately 50%, equal water stability (8 hours) could be obtained as with original high starch formula, but without FLEXTEX (8 hours). See Fig. 7

> Summary The FLEXTEX and ECS system provides significant flexibility in the production of feed for all fish species. By continuously

Picture 3: Extruder with FLEXTEX installed.

Aquaculture Scoop / March Issue 2016

Page 5

Innovation in aquafeed processing technology:

Clextral new Preconditioner + and twin screw extruder EVOLUM+

Clextral’s new systems deliver improved flexibility and control, plus energy savings More information: Mariel Badel Clextral Marketing Department www.clextral.com

World leading aquafeed technology expert,

the finished food products; it enables energy

ports have been optimally positioned to

Clextral has played a pioneering role in the

savings, while providing greater flexibility

enhance absorption and product exposure

innovation and development of twin screw

and reduced maintenance within the global

time during the mixing stage.

extrusion for aquafeed since the 70’s. To

extrusion process, whatever the recipe.

respond to new challenges and increase the

Extensive experimental trials have been

capacity of existing systems, Clextral is

The key innovation of Clextral’s Precondi-

carried out on the Preconditioner+ to verify

introducing major innovations in 2014: a

tioner that improves heat and mass transfer

the process improvements generated by its

combined twinshafts preconditioner and a

to the product is the Advanced Filling Control

AFC system on the twin-screw extrusion

new range of twin screw extruders with on

device (AFC); it interacts directly on the

process. In this case, a standard fish-feed

board advanced control system.

material inside the mixing chamber and

recipe (basic trout feed) was used, not to

enables the filling ratio to be adjusted. The

gauge optimal performance but to set an

AFC system uses an exclusive conveying

objective benchmark compared to traditional

screw inside the tank and adjusts the flow by

preconditioning systems.

New Preconditioner+: process flexibility and improved efficiency

a partial and controlled recycling of the material being processed, from the outlet to

In twin screw extrusion of fish-feed pellets,

the entry point, thus intensifying the specific

preconditioners are recognized by industry

preconditioning functions.

Increase of the filling ratio in the Preconditioner+ during fish feed trials

experts for their production benefits. The new Clextral Preconditioner+ integrates two horizontal, intermeshing, counter-rotating shafts that provide tangible production

Advanced Filling Control (AFC) system: key innovation of Clextral new preconditioning system

Aquaculture Scoop / March Issue 2016

lowering of the SME (Specific Mechanical Energy) required in the extruder mainly due to the increase of preconditioning time. As

benefits : improving the overall mixing and cooking process and therefore the quality of

The first significant observation was a

The adjustable water and steam injection

mentioned previously, this efficient

Page 6

pre-cooking reduces the shear and the

In terms of hygiene and food safety, the

gives processors new levels of throughput,

torque requirements in the extruder, which

Preconditioner+ is designed with minimal

flexibility, and control while ensuring

results in less wear of the screws and

retention areas to facilitate cleaning. This

maximum product quality and process

barrels.

feature is further enhanced by an integrated

stability.

“quick recipe change-over” function through By focusing exclusively on the

the reversible AFC system, used here as an

A major innovation, the Advanced Thermal

Preconditioner+, the experiment also

efficient emptying device. These two larges

Control (ATC) is a self-learning, proprietary

demonstrated that the new filling ratio (up

doors allow the quick access to the shafts

software solution to ensure absolute

to 75%) achieved with AFC made it possible

and screws for a perfect cleaning. Cleaning

precision in temperature control. ATC

to increase residence time by 60% for an

capabilities and hygienic design are

continuously monitors production and

equivalent fish feed flow and therefore to

important advantages for food processing

adjusts to changes in parameters

exceed the average of three minutes. At the

applications.

(characteristics of raw materials, recipes,

same time, the combination filling/steam

throughput, etc.) to ensure process and

distribution made it possible to achieve a

New range of twin screw extruders:

product consistency. ATC is proven to

product temperature between 85°C to 95°C.

EVOLUM+ sets a new standard

enhance process stability up to 70%, with

Following the improvements on the

Clextral’s new EVOLUM + twin-screw

energy savings averaging 20% by eliminating

pre-cooking stage, a significant increase in

extruders offer advanced technology that

excess heating/cooling to maintain process

starch gelatinization before product feed into the extruder was witnessed and measured.

Finally, on the finished product after extrusion, granulation and drying, these upstream modifications resulted in increased hardness of the pellets between 10% up to 30% depending on process conditions.

The strong mechanical design allows the system to start up when fully charged, even after prolonged down time with a full tank, thanks to the new kinematic feature.

Aquaculture Scoop / March Issue 2016

Page 7

Clextral continues to innovate with twin

accurately control pellet density for specific

screw extrusion systems that produce

product attributes, such as sinking and floating

aquatic feed with a precise balance of

properties. With these innovations in

proteins, oils and carbohydrates, processed

preconditioner and extruder technologies,

for optimum digestibility with reduced

Clextral is helping aquafeed processors meet

waste. Clextral’s systems process a wide

the process challenges of today and the future.

selection of recipes and raw materials and

> Improved response time and stability thanks to Advanced Thermal Control (ATC) proprietary innovation.

The EVOLUM+ range has also been specifically built for more hygienic processing and food safety with ergonomic designs and open profiles that allow full machine access.

Aquaculture Scoop / March Issue 2016

Page 8

ISSUES IN EXTRUSION OF AQUAFEEDS Gordon Young, Food Industry Engineering, Australia Dennis Forte, Dennis Forte & Associates, Australia The authors are presenting short courses on “Aquafeed Extrusion Technology” and “Drying Technology” at Centre for Feed Technology, FôrTek, Norway, in May 2016. Also an Extrusion Course in Thailand in July 2016 (www.fie.com.au/events)

Introduction

the technology – the extrusion process

Firstly, realise that starch does not truly

needs to be properly understood. This

“gelatinise” during extrusion – there is not

Extrusion technology provides a number of

paper discusses just a couple of the issues

enough water present for the swelling and

major benefits over the more traditional

relating to successful extrusion of

unravelling of granules that characterise the

pellet milling processes commonly used for

aquafeeds.

gelatinisation reaction. In addition, the

aquaculture feeds. In particular extrusion can provide a much higher degree of control over the “cook” achieved, as well as better

starch is easily damaged by excessive

Extrusion chemistry & aquafeed ingredients

“shear” during extrusion. So we promote conditions that will “cook” the starch – achieving sufficient temperature with

control of the product density (therefore controlling the floating/sinking characteris-

In the area of ingredients, the aquafeeds

sufficient water, and with sufficient time,

tics).

industry faces a series of contradictions.

but without excessive shear – therefore use

Marine meals provide the best nutritional

of a preconditioner can be a major

But extrusion is a very complex process –

basis, but are increasingly difficult to obtain

advantage.

and we only have “indirect” control over that

and are therefore expensive. Selected plant

process. We never have just one parameter

sources of protein can provide required

Another option – if we require starch for

change during extrusion – if ingredients

proteins, but tend to come with fibre and

pellet binding – is to choose a starch that

vary, it doesn’t just change the final product

starch which can interfere with the

cooks and binds more effectively at a lower

composition – it changes the rheology of the

extrusion process and affect digestibility.

temperature – such as use of tuber starches

mix and therefore changes how the melt

We generally require very high fat (energy)

instead of grain starches. Therefore effective

moves through the extruder and the die,

contents in the feeds – but high fat levels

selection of both the source and the amount

which in turn affects the residence time and

are a problem in extrusion. Following are

of starch can be used to optimize the

temperature developed in the melt, which

some basics of “extrusion chemistry” that

processing and nutritional characteristics of

changes degree of cook and expansion –

relate to the way we design aquafeed

the product formulation.

and therefore affects digestibility and

extrusion processes:

floating/sinking characteristics. Within this complex relationship, we need to achieve

Protein Starch During extrusion, the protein denaturation

consistency – of nutrition, of digestibility, of physical characteristics. It is the cumulative

Many fish species do not tolerate starch –

reaction is not unlike that of starch – that is,

effect of these parameters which ultimately

especially uncooked starch. But starch

with respect to good “functional” protein

determine the feed conversion ratio (FCR)

comes with many of the alternative

(here referring to protein functionality from

for the product.

plant-based protein ingredients. Also starch

a physical, rather than nutritional, perspec-

can be an important “binder” to help

tive). The globular proteins unravel and,

achieve pellet durability.

under the right conditions (optimal

So to use extrusion effectively – and take full advantage of the opportunities offered by

Aquaculture Scoop / March Issue 2016

moisture content and temperature), can

Page 9

cross-link. Therefore “functional” protein contributes to binding and pellet durability.

But many of the traditional fish meals, while good nutritionally, contain denatured protein, and contribute little to the “binding” function.

So while the scarcity of traditional marine proteins (eg fish meals) is an issue for nutritional balance, the substitution of “functional” plant proteins can have the

Effect of Density on Sink / Float Pellet Behaviour

Sea Water (3% Salt)

Fresh Water

Fast Sinking

> 640 g/L

> 600 g/L

Slow Sinking

580 to 600 g/L

540 to 560 g/L

Neutral Buoyancy

520 to 540 g/L

480 to 520 g/L

Floating

< 480 g/L

< 440 g/L

added benefit of assisting pellet durability – as long as the process promotes rather than destroys that functionality (temperature and

Density control

shear not excessive).

Fat

The bulk density is the result of the balance between the expansion (influenced by the

The finished product bulk density is one of

process conditions and the amount and type

the key product quality attributes, directly

of starch) and elastic collapse (influenced by

affecting the sink/float behaviour of the

the amount and type of protein). That is, again

Fat under normal extrusion conditions is

finished product. Note, however, that this

there is a complexity in the extrusion process

stable – it does not itself change and “cook”

does not only relate to the extrusion

which makes it inherently difficult to predict

as starches and proteins do. But it does

process – drying also affects pellet density.

and control. Under the correct conditions:

have a major effect on the extrusion process

In fact, inappropriate drying can result in

– increasing “slip” and effectively lowering

drying and shrinkage of the outside layers,

• Higher amylose starch content makes the

viscosity, and therefore affecting

increasing overall density so the pellet sinks

extrudate puff more at the time of exiting

expansion/density, extruder backfill/degree

(perhaps as required). Then, over time in

the die

of cook, and pellet durability. An increase in

storage, moisture redistributes within the

• Higher “functional” protein makes the melt

fat content of the mix of only 2% (which can

pellet, the outside layers relax and expand,

more elastic, so it recoils after the initial puff

happen due to raw material variations) has

and the feed turns from floating to sinking.

and starts to collapse

a similar effect on the effective viscosity of the melt as a 5% increase in moisture content. Therefore control of fat content can be a major issue.

At the same time, for most species, as high a fat content as possible is required for nutrition. This is where one of the tensions lie – the challenge of achieving good stable pellets at sufficiently high fat content.

Strategies to achieve this balance include the use of appropriate extrusion systems (twin screw extruders can operate in a more stable manner to higher fat levels than single screw extruders), and methods to maximise post-process addition of oil, such as vacuum infusion.

There are of course many other aspects of ingredients that also need to be balanced in successful feed extrusion.

Aquaculture Scoop / March Issue 2016

Page 10

Figure 1.

• Higher amylopectin starch increases the

Formulation + Process

Product

So the final pellet size – and therefore

The ingredient source (and the order of

Extrusion is not a simple process. The

density – is the result of the interaction of all

addition) have a significant impact upon the

interactions that occur in process param-

these effects. This is illustrated in Figure 1.

product nutrition. For example, the effect of

eters, along with variations in raw materials

Conclusion

oil added during the process is not the same

and changes over time due to extruder and

In addition:

as oil added via external coating –

die wear, makes it a difficult process to

Degree of Expansion = f { Melt Temperature

complexes formed during extrusion can

control. And these variations can have

(TM), Die Pressure Drop (ΔPd) },

change the nutritional effect of the oil.

“invisible” effects – because nutritional

with the Melt Rheology and the Die Geometry greatly affecting ΔPd.

content of the formulation does not fully Energy inputs also have a major role in final

define the nutritional performance of the

nutrition of the feed. Energy may be added

feed. Variations in the extrusion process do

The product bulk density is also significantly

via Convective Energy (steam injection),

not only affect physical changes in the

influenced by the Specific Mechanical

Thermal Energy (barrel heating) and

product such as density and size/shape, it

Energy (SME), since the SME directly affects

Mechanical Energy (viscous dissipation or

also affects the way in which the fish will

both temperature and molecular degrada-

SME). The comparative balance of these

digest the ingredients. A good understand-

tion of the starch and protein – which

energy inputs affect nutrition by changing

ing of the extrusion process is required for

changes the viscosity and elasticity of the

the conversion and break-down of proteins

reliable and consistent feed production.

melt. Figure 2 shows some measured results

and starches, changing their nutritional

of bulk density vs SME.

contribution. In extreme cases, it can even form fat complexes that are toxic to fish.

The SME is influenced by process parameters, most significantly the melt moisture content (used to manipulate the melt

Figure 2.

rheology), the screw profile design, and the screw speed.

Aquafeed specifications – not the full story Final product nutrition (and FCR) is not just due to the composition of the formulation ingredients – though that is what feed specifications almost exclusively (along with density) often dictate.

The manufacture of a feed should be considered as:

Aquaculture Scoop / March Issue 2016

Page 11

The best solution for growth promotion in aquaculture Rui Gonçalves, Scientist - Aquaculture, Benedict Standen, Product Manager – Aquaculture, Gonçalo Santos, R&D Manager - Aquaculture

Case 1: Phytogenics to improve digestibility

The aquaculture industry is characterized by

factors, including genetic characteristics of

a large variety of species compared to other

the species, diet quality, environmental

methods of animal production. Conse-

conditions and absence of disease

quently, there is huge diversity in feeding

outbreaks. Add to this industry pressure,

The reliance on less costly protein sources

habits (carnivorous, omnivorous or

such as the need for the efficient use of

and low-nutrient diets to replace costly

herbivorous), physiology, rearing environ-

increasingly expensive raw materials or

fishmeal - whether for economic or

ments (marine, brackish, or freshwater

health management, and the picture

sustainable reasons - will most likely lead to

habitats) and temperature (cold,

becomes more complex. A focus on good

lower protein digestibility, higher amino

sub-tropical or tropical climates) and also in

gut health can help to successfully navigate

acid imbalance and higher carbohydrate

feed formulations. Identifying the correct

this large set of considerations and set the

and fiber content, since plant raw materials

tool to promote growth must take into

foundation for better growth.

are less digestible and negatively impact the

consideration each of these elements along with the value of the species and the specific

Identifying the right solution

challenge affecting the each production system.

Growth performance and gut health It is no secret that optimum animal performance encompasses a number of

gastrointestinal tract. The presence of undigested nitrogenous compounds in the intestine favors the formation of ammonia

Identifying the most promising strategy to

and biogenic amines by the intestinal

achieve the best growth performance can be

microbiota. These toxic compounds cause

a challenge. Here we provide three different

an imbalance of the intestinal microbiota,

scenarios on how to support gut health and

resulting in inflammatory processes and

growth enhancement using distinctly

accelerated turnover of the intestinal tissue,

different tools.

leading to poor performance. In addition, sub-optimal animal performance due to

Figure 1. Feed conversion ratio and specific growth rate of sea bream as affected by diet supplementation with Digestarom® P.E.P. MGE. Source: Biomin trials, 2012

Aquaculture Scoop / March Issue 2016

Page 12

inefficient nutrient use, results in increased feed usage and consequently higher production costs, environmental problems (higher ammonia emissions) and disease vulnerability.

Phytogenic feed additives —consisting of herbs, spices, extracts or other plantderived compounds— have gained considerable attention as a tool to achieve improved growth performance. The active ingredients (e.g. phenols and flavonoids) can exert multiple effects in animals, Figure 2. Nutrient retention of sea bream as affected by supplementation with Digestarom® Source: Biomin trials, 2012

including improvement of feed conversion ratio (FCR), digestibility, growth rate, reduction of nitrogen excretion and improvement of the gut flora and health status. In the case of nutrient sparing or fish meal replacement, phytogenics can stimulate the digestive secretions, increase villi length and density and increase mucous production through an increase in the number of globlet cells. As a result, phytogenics can improve feed digestibility, especially for proteins and amino acids.

In a trial with gilthead sea bream (Sparus aurata) at the University of Algarve in

Figure 3. Nitrogen budget (gain, fecal losses and metabolic losses) in sea bream with supplementation by Digestarom® Source: Biomin trials (2012)

Portugal, fish were fed a low fishmeal diet (14%), supplemented with a matrixencapsulated phytogenic feed additive (Digestarom® P.E.P.MGE). Dietary supplementation with Digestarom® P.E.P. MGE showed the best results with a significant reduction of FCR from 1.28 up to 1.12 and an improvement of specific growth rates (from 1.76 to 1.82 %.day-1) (Figure 1).

Inclusion of the phytogenic products in the diet significantly enhanced (p < 0.05) protein and fat retention (Figure 2). The results also showed that a significant reduction of total nitrogenous losses, which was clearly associated with lower metabolic losses (Figure 3).

Case 2: Probiotics for pathogen control Figure 4. Feed conversion ratio of trout with diet supplementation using AquaStar® Hatchery Source: Biomin trials, 2010

Aquaculture Scoop / March Issue 2016

The use of beneficial bacteria (probiotics) to

Page 13

control pathogens is well documented in aquaculture, given the richness of microbial life in aquatic environments. Probiotic bacteria can maintain a healthy balance of bacteria in the gut through: competitive exclusion (beneficial bacteria exclude potential pathogenic bacteria through competition for attachment sites and nutrients); antagonism (inhibit the growth of pathogenic bacteria by producing, for example, bacitracin and polymyxin (produced by Bacillus spp.). Probiotics can also promote gut maturation and integrity, modulate and stimulate the immune Figure 5. Lactobacilli count in trout gut fed AquaStar速 Hatchery supplemented diets. Source: Biomin, 2010

system, prevent inflammation, boost the metabolism, increase digestive enzyme activity, decrease bacterial enzyme activity and ammonia production, improve feed intake and digestion, and neutralize enterotoxins. With this in mind, a total of 60 juvenile rainbow trout (Oncorhynchus mykiss) were used in a trial carried out at a commercial trout farm in Karditsa, Thessaly, Greece. Here we tested the effect of dietary incorporation of AquaStar速 Hatchery (multi-strain probiotic) on growth performance and intestinal bacteria count. Here we saw that probiotic, significantly (p < 0.05) increased body weight gain in the test group when compared to the control by an

Figure 6. Specific growth rate Pangasius catfish (Pangasionodon hypophtalmus) fed Biotronic速 supplemented diet or flavomycin, compared to control group. Source: Biomin, 2014

average of 10.8 %, FCR was significantly (p < 0.05) improved by 18.8 % (Figure 4) and Lactobacilli loads were 54.6 % higher in probiotic fed fish compared to fish fed the basal diet only (Figure 5). As their name suggests, lactic acid bacteria, including lactobacilli, produce vast quantities of lactic acid. This lowers the pH of the intestinal environment, which inhibits the growth of some harmful bacteria.

Case 3: Sustainable replacement for AGPs Unlike antibiotic growth promoters, which kill both beneficial and harmful bacteria, organic acids attack Gram-negative Figure 7. Total bacteria count in pangasius catfish gut (Pangasionodon hypophtalmus) fed Biotronic速 supplemented diet or flavomycin, compared to control group.

Source: Biomin, 2014

Aquaculture Scoop / March Issue 2016

(pathogenic) bacteria while leaving the beneficial ones in place. In the undissoci-

Page 14

ated form, organic acids can freely diffuse

Biotronic® supplemented diet had an

to withstand infectious and non-infectious

through the semi-permeable membrane of

improvement of 1.72% in SGR compared to

stressors. Given the wide range of consid-

the bacteria into the cell cytoplasm. Once in

the control group and 0.86% when

erations in aquaculture production, a focus

the cell, where the pH is maintained near 7,

compared with the flavomycin group (Figure

on good gut health can help farmers to

the acid will dissociate and suppress

6). Analyzing the bacteria counts in the gut,

enhance growth. A number of novel feed

bacterial cell enzymes (e.g., decarboxylases

it was evident that animals fed Biotronic®

additives –such as probiotics, phytogenics

and catalases) and nutrient transport

supplemented diets had a considerable

and organic acids– can help support gut

systems. The reduction of pathogenic

reduction in total bacteria count, -76% than

health and growth enhancement. Further-

intestinal bacteria, which can produce toxin

the control group and -43% when compared

more, unlike antibiotics, these natural

causing damage of intestinal villi and crypt

with the flavomycin group (Figure 7).

solutions facilitate consumer perceptions of

structure, is directly associated with the improved gut structure. Furthermore, lower

bio-security and sustainability.

Conclusion

abundance of pathogens in the immediate environment allows the animal to direct

Understanding gut health requires the

more energy into somatic growth, as

elucidation of the complex interactions

opposed to fighting disease. In a trial at the

between many components that will allow

Aquaculture Centre of Applied Nutrition

the gut to perform under normal physiologi-

(ACAN) in Vietnam, Pangasius catfish fed the

cal conditions, thereby supporting its ability

Aquaculture Scoop / March Issue 2016

Page 15

Filtration of colloidal matter in Recirculating Aquaculture Systems (RAS)

More information: Julian A. Mamo Water Engineering, monitoring and control systems AquaBioTech Group Central Complex Naggar Street Targa Gap, Mosta MST 1761 Malta G.C. SKYPE: jam-abtg Main Office: +356 2258 4100 Mobile: +356 9996 7550 Direct Line: +356 2258 4114 Rob J. Davies Senior Aquaculture Consultant AquaBioTech Group Central Complex Naggar Street Targa Gap Mosta MST 1761 Malta G.C. SKYPE: rjd-abtg Main Office: +356 2258 4100 Mobile: +356 9910 2565 Direct Line: +356 2258 4119

Land-based recirculation systems are a

tive methods that are developed and tested

organic matter. The organic matter in

modern alternative to traditional net-pen

at our R&D facility in Malta and applied in

aquaculture water varies with the quality of

and flow through culture systems. They

the construction of our commercial scale

the incoming water, the production on the

offer a strict control and monitoring of the

RAS farms.

farm (species, feed, growth rate, etc.) and

environment that the organisms are grown

whether seawater or freshwater is used.

in, which is bio-secure and non-detrimental

A key component in operating intensive RAS

Colloidal organic compounds, to be

to the surrounding environment. Due to the

is controlling the accumulation of fine

removed, typically include microorganisms

extremely fast growth rates and efficient

particulate matter known as colloids. There

(bacteria, viruses, fungi and algae), faeces

utilization of precious water supplies,

is no strict range of particles that are

and waste feed, while dissolved organic

investment and development of RAS

defined as colloidal matter, but colloids are

material in the RAS water column would be

technology has flourished.

typically particles smaller than one (1)

made up of proteins, amino acids,

this, the Department for Environment, Food

In addition to

micrometre that do not settle and for which

phosphates, urea, humic acids and fatty

& Rural Affairs (DEFRA), Food and Agricul-

mechanical filtration is ineffective. A focus

acids.

ture Organization (FAO) and European

on the control of nitrogenous compounds

Commission have identified that political,

and suspended particulate matter without

Apart from the consumption of dissolved

social and environmental drivers favor

taking a closer look at colloidal matter will

oxygen during the biological degradation of

development of RAS as a sustainable source

have a number of detrimental effects on fish

organic matter, the breakdown of organic

of aquaculture for the future. However,

health and the biological and chemical

wastes by sheer forces and microbial

there are many challenges in a technological

processes controlling the removal of

degradation into other products could both

solution to filtering the metabolites of the

nutrients and particulate wastes from the

increase the total ammonia nitrogen as well

organisms cultured, beyond the removal of

system.

as support the growth of heterotrophic

macro- particulate matter. At AquaBioTech

bacteria affecting nitrification. The concen-

Group, these challenges are being met and

Typically, more than half of the dry weight

tration of both dissolved and colloidal

overcome using new, efficient and innova-

of the total solids in a RAS water column is

organic material also affects the prolifera-

Aquaculture Scoop / March Issue 2016

Page 16

tion Nitrosomonas spp., which is the bacterium in the biofilter, which converts ammonia into nitrite. This bacterium operates more efficiently under high organic loadings than Nitrobacter spp., which coverts nitrite to nitrate, and therefore, if this organic matter is not removed, then the levels of nitrite in the system can increase and be toxic to the cultured organisms.

Studies have also shown that colloidal matter could irritate gill tissues providing preferential surfaces for attachment of detrimental bacteria, reducing fish health and hence immune- susceptibility, putting the stock at risk.

Faeces followed by uneaten feed typically form the largest portion of suspended solids in the water column. The size distribution of the two sources of suspended solids together with their specific gravity differ greatly, with the majority of uneaten feed remaining larger than zero point five (0.5) mm despite being recirculated a number of times. The size distribution of both feed and faeces is determined by the feed composition as well as the species and size of the organism. A review of studies where particle size analysis was carried out in RAS showed that the vast majority of suspended particulate matter was smaller than twenty (20) micrometres and that there was a low degree of removal by the installed processes.

A common removal method for colloidal

depends on a number of factors but the size

oxygen and poorer in double bonds due to

material in RAS is to pass a portion of the

of the particle is particularly important. The

increased hydroxyl, carbonyl and carboxyl

water from the biofilter through a saturation

minimum size for attachment typically

functional groups. Creation of the more

cone into which ozone is injected before

occurs for particles around one (1) micro-

polar functional groups can cause dissolved

flowing through a foam fractionation

metre. For this reason, methods for

organics to precipitate and can also produce

process. Foam fractionation works on the

agglomeration and flocculation are typically

polyelectrolyte characteristics among

principle that dissolved organic compounds

used to increase the size of colloids to

suspended particles that increase enmesh-

as proteins in the water have bipolar

increase the removal efficiency.

ment, adsorption and cross linking between

properties. These compounds attach to the

the solids, which in combination are

gas/liquid interface of air bubbles in water.

Through the process of oxidation, ozone

referred to as â&#x20AC;&#x153;micro-flocculationâ&#x20AC;?. Studies

When sufficient dissolved organic material is

precipitates dissolved organic matter and

have shown that the optimum dosage for

skimmed from the water, a stable foam is

acts as a micro-flocculent of colloidal

the flocculation of organic solids was

created and can be then removed from the

organic matter. Oxidized organic

primarily dependant on the Total Organic

system. The mechanisms involved in the

compounds are usually smaller and contain

Carbon (TOC) concentration and to a lesser

attachment of a particle to a bubble

more polar compounds that are richer in

extent the ratio of hardness to TOC. In

Aquaculture Scoop / March Issue 2016

Page 17

seawater systems, the addition of very small doses of ozone changes the charge on some particles so that they are more hydrophobic and therefore attach to the bubble surface.

As the ozone concentration is increased, the surfactants attached to the bubble may instead break down into smaller hydrophilic parts. This makes for easier removal of the colloidal matter in the form of foam, which exudes from the water column.

Development of new technology to make this process more energy efficient such as low pressure microfiltration membranes, having pores of between zero point one and one

such as this at AquaBioTechâ&#x20AC;&#x2122;s facility may

decrease and knowledge increases, further

(0.1â&#x20AC;&#x201C; 1) micrometres in pressurised or

change this, by designing a membrane

developments and progress will increase the

submerged configurations have still not been

process that is adapted for intensive RAS

effectiveness and efficiency of our systems.

proved to be an effective economic alterna-

systems by optimizing membrane configura-

Hence promoting the advancement of the

tive to traditional micro-screens, foam

tion, flux and fouling control mechanisms to

RAS filtration system design and the

fractionation and other technology. However,

minimize energy use. In addition, as the

long-term environmental sustainability of the

research and development into technology

price of membranes and other technologies

aquaculture industry.

Aquaculture Scoop / March Issue 2016

Page 18

Aquaculture Insurance: Is your most important asset covered?

Aquaculture is high risk. As well as the risks

Financial (credit, liquidity & cash flow, etc.),

A number of new insurance products are

associated with animal production (disease,

Strategic (competition, industry changes,

available to farmers, and insurance solutions

reduced growth rates, natural mortality) fish

etc.), Operational (supply chain, regulation,

can be developed to suit individual needs

farms are often located in environments that

etc.) and Hazard (natural catastrophe, stock,

and budgets.

test equipment to their limits, and where

equipment and properties).

Insurance covers available

human error can have disastrous results.

Some of these risks are insurable, but many Not all risks are insurable, but some of the

arenâ&#x20AC;&#x2122;t.

Biomass insurance

considering the cost of risk over time,

By using tried and tested techniques you can

This insurance covers the risks of mortality

insurance, very often, is a very efficient way

quickly get a broad sense of how much risk

of stock held on the farm site. This insurance

of transferring risk, and gives peace of mind

could be costing your company, even if you

covers the costs of production, and does not

to managers and investors.

have never had a loss.

insure against loss of profits, market price or

biggest risks facing an operation are. When

business interruption.

Calculating the Cost of Risk

Insurance is a valuable tool in the risk management tool box, and operational and

Live fish transits

The first step in Risk Management is to

natural hazard risks should be regularly

identify the risks facing your company.

assessed to ensure adequate protection is in

Biomass insurance can be extended to cover

Risk comes in many forms, and can be

place.

the risk of stock mortality while in transit

Aquaculture Scoop / March Issue 2016

Page 20

Biomass insurance can be extended to cover

Typical perils:

the risk of stock mortality while in transit between farm sites, or from hatcheries.

Transit cover is typically only offered as an extension of the biomass policy.

Offshore equipment

OFFSHORE

ONSHORE

1.

2.

3.

4.

5.

1.

2.

Offshore floating equipment, cages and feed barges can be covered, however usually only for larger operations as minimum premiums tend to make this uneconomic for smaller farms.

Wordings – Biomass insurance

6.

7.

8.

9.

10.

11.

12.

• ‘All Risks’ Wording 13.

An ‘All Risks’ policy protects against all risk of stock mortality unless specifically excluded within the wording. With these wordings the

14.

Pollution.

Plankton bloom / red tide.

Jellyfish attack / bloom.

Theft and Malicious Acts.

Predation, or physical damage caused by predators or other aquatic organisms (not sealice or other ectoparasites).

Storm.

Lightning.

Tidal wave.

Collision.

Sudden and unforeseen structural failure of equipment.

Freezing, Supercooling, Ice damage.

Deoxygenation due to competing biological activity or to changes in the physical or chemical condition of the water, including upwelling and High water temperature.

Any other change in concentration of the normal chemical constituents of the water, including change in pH or salinity.

Disease.

onus is on the underwriter to demonstrate

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

losses are not covered under the policy, whereas in the case of a Named Perils 17.

wording the onus is on the policy holder to

Theft and Malicious Acts.

Predation, or physical damage caused by predators or other aquatic organisms (not ectoparasites).

Flood.

Tidal Wave.

Storm Damage.

Subsidence, Landslip, Structural Failure, Breakage or blockage of any part of the water supply system.

Drought.

Fire.

Lightning.

Explosion.

Earthquake.

Freezing, Frost damage, Frazil ice.

Mechanical breakdown or Accidental damage to machinery and other installations.

Electrical breakdown, Failure or interruption of the electricity supply, Electrocution.

Deoxygenation due to vegetation, microbiological activity or high water temperature.

Any other change in concentration of the normal chemical constituents of the water, including supersaturation with dissolved gases and change in pH or salinity.

Disease.

demonstrate that the loss was a result of a peril named in the policy (see below).

‘All Risks’ policies are not always available,

Submission requirements

with underwriters reluctant to offer these

assessing how much premium to charge to transfer this risk. Most underwriters have

where species, locations, or farming risks

To enable an underwriter to accurately

significant experience in assessing aquacul-

are not fully understood by the underwriter.

assess the risks of a farming operation, the

ture risks, and some have come from the

following are required:

aquaculture industry so are generally

Depending on the operation, an ‘All Risks’ wording is typically around 5 – 10% more

knowledgeable about most species and 1. Proposal Form

systems in use.

A fully completed and signed proposal form

Please note this information will be part of a

will be needed (there are separate forms for

legally binding submission to insurers, and

offshore and onshore operations). The

as such the accuracy and truthfulness of the

expensive than a Named Perils policy (with all perils covered).

• Named Perils Wording

information contained within the proposal

information supplied is critical. Any

Named Perils policies cover only those perils

form will provide underwriters with details

incorrect or fraudulent information may

chosen by the policy holder (or offered by

of the applicants farming ability, experience

prejudice a claim in the event of a loss.

the underwriter), and do not cover losses

and what monitoring and controls are in

falling outside of these.

place on which to base their risk assessment

Changes to the risk

on. The more information and detail that In Named Perils policies the onus is on the

can be supplied the better.

policy holder to prove that a loss falls within

Should there be significant and material changes to the operation (and therefore the

the scope of the policy, as a result of the

It should be remembered that the applicant

risk) during the period of the policy then this

perils covered.

is in effect asking insurers to accept their

should be declared to underwriters. Failure

production risk, and insurers will be

to do so may prejudice a claim following a

Aquaculture Scoop / March Issue 2016

Page 21

loss. If in doubt, declare any changes to your broker.

Sums insured and valuation of stock

exposure. The average biomass value is used to avoid any large premium adjustments at the end of a policy.

2. Deductible

Sums insured will be determined by the stock projection and basis of indemnity.

Premium instalments

the policy holder retains for each and every

The basis of indemnity is the value you

It is recognised that cash flow can be a

loss. Deductibles tend to be a percentage of

would like to be indemnified (paid) following

problem for companies involved in primary

the sum insured, rather than a fixed amount

a recoverable loss (after the application of

food production, with money often only

(excess). Excesses are very rarely used in

the deductible). Values should be based on

becoming available when product is sold. As

biomass policies due to the variation in

costs of production and not sale price. Many

a consequence insurers are willing to offer

exposure (stock levels) across the policy

policies have a provision within them to

premium instalments, however this results

period.

replace the fish with the same or similar

in them carrying a credit risk in doing so.

The deductible is the amount of the risk that

stock, so if values are inflated you may find

Insurers will sometimes consider premium

Due to the high risk nature of aquaculture,

that you will be charged more premium than

discounts, or may amend the policy in other

deductibles tend to be high when compared

necessary, with underwriters simply

ways, to favour policy holders paying

to less risky classes of insurance. Typically

replacing lost stock.

premiums up front.

deductibles per unit, per group, or even per

Basis of indemnity can be a value per kg

Premium instalments also come with

cage or tank are possible. Lower deductibles

(weight), a price per fish (or unit) or a

increased risks to the policy holder, as most

however come at higher premium cost as

mixture of the two (for example a fixed price

insurance policies have warranties in them

insurers are much closer to the risk of paying

per fish, to cover purchase price, plus a value

that could result in a claim being prejudiced

a claim, therefore charging more premium

per kg to reflect input costs over time).

if premium payments are not paid on time.

these tend to be applied on a site basis, but

to transfer the risk.

3. Stock Projections

In extreme cases cover automatically lapses Sums insured can be adjusted up or down

for non-payment of premium, so a policy

during the policy period with agreement

holderâ&#x20AC;&#x2122;s ability to pay the correct premium

from insurers, which might result in

on a given date is crucial.

Stock projections detail how much stock will

additional premium, or a return of premium

be on site during the policy period and

(depending on the minimum premium

should be calculated as a function of

charged on the policy).

biomass (usually kgâ&#x20AC;&#x2122;s or numbers) and the

5. Pre-risk surveys Increasingly pre-risk surveys are being used

basis of indemnity (valuation). Stock should

All stock on site needs to be insured. Under

to confirm the quality of an operation before

be detailed on a monthly basis.

insurance will lead to the application of

committing to an insurance policy. If the

average in the event of a claim if stock

operation is unknown to insurers then it may

cannot be identified as insured.

be that a pre-risk survey will be required

Having stock projections for the period of the policy is essential in determining an insurerâ&#x20AC;&#x2122;s financial exposure, and is used to

before quoting.

Natural mortality rate

calculate the premium charged. Most

The cost of any survey will usually be paid

operations will have stock information in one

Any farming system will have natural

for by the applicant in the first instance, with

form or another as part of their stocking

mortality. The natural mortality rate declared

the cost discounted from the premium if a

plan.

in the proposal form will have an impact on

policy is taken out.

any loss adjustment, as these will be During the policy stock declarations will need

removed from any claim payment.

to be sent in each month to monitor the sums insured on site and to make sure that

4. Rates and Premium

sufficient cover is in place to protect the policyholder.

Premiums are generally calculated on applying the insurance rate to the average sum insured on the policy, with insurers aiming to charge a fair premium for their

Aquaculture Scoop / March Issue 2016

More information: Dan Fairweather - BSc, MSc (Dist) Director - Aquaculture and Fisheries Willis Towers Watson, Willis Limited, UK Email: Dan.Fairweather@WillisTowersWatson.com Web: www.willistowerswatson.com

Page 23

Aquaculture will supply two-thirds of global fish consumption by 2030 Sign up to our FREE weekly newsletter Email us at seafood@nisamedia.com Source: World bank report

Aquaculture Scoop / March Issue 2016

Page 32

Major Breakthrough in Ammonia/Nitrite Control for Aquaculture No More Waiting for Nitrification . . .

New Product controls Ammonia-Nitrite until Nitrification begins . . .

Dublin, Ireland – 15th February 2016 They say you can’t teach an “old dog new tricks” ... but a small Bio-Tech company in Dublin, Ireland is about to change all that!

For more information contact:

Bio-Industries Ltd. has created FirstBIO, an

previously commercially available. These

extraordinary new natural biological

microorganisms can operate in a wide range

product that immediately starts to control

of normal and hostile water conditions and

J Strauss

Ammonia-Nitrite by using a novel method of

are bio-synergistic having the ability to

Bio-Industries Ltd

removal which no longer requires adding

significantly improve the biological action of

Unit 66D Heather Road

nitrifiers and waiting for nitrification.

other bacteria operating within the

Sandyford Business Park

processes.

Dublin 18

Ammonia/Nitrite removal is no longer

Ireland.

dependent on stabilizing water conditions to

The result of more than 3 years of intensive

Tel: + 41 79 301 9791

establish nitrifying populations to start the

manufacturing development, Bio-Industries

Email: joss@bio.ie

Nitrification Cycle. At the same time FirstBIO

Ltd. started field testing of FirstBIO in

improves overall water conditions by

mid-2014 and immediately realized that the

stabilizing pH which leads to healthier

product was superior to just adding

aquatic life and less stress. It can even

nitrifying bacteria and waiting for nitrifica-

control Ammonia-Nitrite levels in extreme

tion to begin. So now aquaculture operators

water conditions.

can get faster control of their water

ISO 14001:2004 & 9001:2008

conditions. FirstBIO is a very cost effective In test after test, FirstBIO continues to

ultra-concentrate and usage rates are based

astound users as to its unique capabilities. It

on water volume or filter capacity. It is

cannot only reduce high levels of

simply added to the water or filter as

Ammonia-Nitrite in as little as 24 to 96

required and during restocking.

hours but also stop them from occurring in a wide range of operating conditions. It has

Worldwide Distributor enquiries welcomed.

been shown to significantly reduce the lag time normally associated with establishing nitrifying populations to start the Nitrification Cycle.

FirstBIO is like NO other product available because it is the only product to have been developed with a group of Class I microorganisms called “extremophiles” not

Aquaculture Scoop / March Issue 2016

Page 25

HOW TO USE AN AERATOR IN A POND Kajal Kumar Roy Singha Research and Development Engineer Sagar Aquaculture Pvt. Ltd. Rajkot, Gujarat

India is growing in the field of fresh water

more during the night following cloudy than

into the entire volume of water. Aerators

and brackish water aquaculture through

clear days. The rate of photosynthesis and

can be used exclusively for emergencies,

extensive and semi intensive cultivation

the rate of oxygen production vary with

continuously at night or throughout the

techniques. The production of fish, shrimp

light intensity, amount of algae present in

day and night. Aerators work by increas-

and other aquatic species in semi-intensive

pond system and duration of exposure to

ing the area of contact between air and

and intensive aquaculture operations

sunlight. In a culture pond more oxygen

water. Aerators also circulate water so that

depends on various water quality

must be produced in water than that is used

fish can locate the areas with higher oxygen

parameters; dissolved oxygen (DO)

by organisms, otherwise depletion of

concentrations. Various types of aerators

concentration is one of them. Dissolved

oxygen will occur. Rise in atmospheric

have been developed over the years to

oxygen is a very essential component for

temperature, causes increased rate of

maintain desired level of DO concentration

culture of aquatic animals and other

biological degradation of organic maters

in the pond and wastewater in an effort to

organisms in water body. Oxygen is

and subsequent depletion in DO concentra-

improve the energy efficiency of the

required respiration purpose. Naturally

tion in water.

oxygen mass transfer process. In

water receives oxygen through photosynthe-

aquaculture, propeller-aspirator- pump

sis process of aquatic plants and diffusion

The supply of oxygen to the water body is

aerators, diffused-air aeration system,

from the atmosphere through the surface

essential to increase the DO concentration.

paddle wheel aerators and spiral aerators

of water. In general, most fish species will

Aeration is the process of bringing water

are most widely used. These aeration

grow within a DO range of 5-12 mg/L (ppm).

and air in contact for diffusion of oxygen

systems can be broadly classified into three

If DO levels drop below 4 mg/L they may

into water required for aquaculture and

groups: mechanical surface aerators,

stop feeding, feel stressed and result reduce

biological wastewater treatment. However,

diffused-air aeration systems and

growth rate. Low dissolved oxygen does not

it is not uniform and gets affected by

subsurface mechanical aerators. Pond

cause mortality directly to the fish life in

various factors. Now a day, demand of

aeration systems have become very popular

the culture system, but leads to the

aquatic product is very high all over the

in the field of aquaculture during the past

deterioration of water quality, which

world. So for increase in the aquacultural

two decades. Paddle wheel aerators and

imparts stresses in fish body and in turn

production, additional aeration through

propeller-aspirator-pumps are probably

causes mortality. Ponds generally reach the

artificial aeration system is very much

most widely used aerators in the field of

minimum dissolved oxygen level during the

essential. A properly designed aeration

aquaculture. Most effective mechanical

mid-night or early morning. However, on

system is essential to maintain adequate

surface aerators are the paddle wheel and

cloudy days the dissolved oxygen concentra-

and continuous supply of DO to meet the

spiral aerators.

tion may reach the alarming level even

demand of the aquatic species. The aeration

during the daytime due to lack of photosyn-

system must also provide sufficient bulk

It is very important to know the dynamics of

thesis. The DO concentration will decline

liquid mixing to ensure proper mixing of DO

dissolved oxygen in an aquaculture system.

Aquaculture Scoop / March Issue 2016

Page 27

The actual quantity of oxygen that can be present in solution is governed by the solubility of the oxygen as defined by the

Average body weight (g) O2 demand (mg O2/h)

10 3.703

20 6.819

30

40

50

9.747

12.558

15.287

Henry’s law, partial pressure of the oxygen in the atmosphere, the temperature and the

Form the calculation of this equation it is

concentration of the impurities in the water

apparent that oxygen demand increase with

(e.g. salinity, suspended solids etc.). When air

increasing body weight of shrimp. Plankton

is in contact with water, oxygen enters the

takes oxygen from pond 1.34 kg O2/h at

water from the air until the tension of

night for their respiration requirement and

oxygen in the water equals the partial

produce CO2. Benthos required 0.61 kg O2/h

pressure of oxygen in the air. Even though

during night and day for their respiration in 1

the atmosphere contains nearly 21% oxygen,

hector pond with 1 m water depth.

oxygen gas is slightly soluble in water.

Increase in temperature and salinity causes

Calculation of requirement of HP for culture

a corresponding decrease in oxygen

pond:

concentration. Oxygen solubility is also influenced by the atmospheric pressure.

Oxygen saturation decreases as elevation

Example 1:

makes the surface rough and thereby

Calculation Table Length x Width water depth (m) Depth of pond (L X W X D) m Stocking density No of shrimp/ m3 Salinity (ppt) Average body weight (g) Total density of shrimp water salinity Body weight of shrimp Water volume x density Values from table HP requirement for shrimp Value from table HP/one lakh shrimp Extra HP requirement for day Value from table HP/10000 m Extra HP requirement for night Value from table HP/10000 m Aeration Requirement for culture pond (HP requirement for shrimp X total density of HP requirement for fish HP shrimp) ÷1,00,000

increases surface area. Mixing also causes

HP requirement for day

above mean sea level (MSL) increases, due to corresponding decreases in pressure. The pressure of oxygen in air drives oxygen into water until the pressure of oxygen in water is equal to the pressure of oxygen in the atmosphere. The importance of water mixing (turbulence) on oxygen transfer between the atmosphere and water is apparent. Mixing

mass transfer (convection) of water and dissolved oxygen from the surface to different locations within the water body.

Presently farmers are using aerator blindly.

Pond area (m x m) Volume of water (m ) Temperature (ºC) water temperature

(Extra HP requirement for day X pond water volume) ÷ 10,000 (Extra HP requirement for night X pond water volume) ÷ 10,000 HP requirement for aeration in the culture pond HP requirement for shrimp + HP requirement for day HP requirement for shrimp + HP requirement for night

HP requirement for Night Day Night

HP HP

They don’t bother regarding function of aerator in pond water and how much

Example 2:

artificial DO required for culture pond. For that reason we have calculated for 1 ha (100 m X 100 m) pond with 100000 seeds in a farm for 1 m depth of water. Now let us discuss DO requirement for shrimp: Oxygen requirement per unit body weight should be found out. For example, for shrimp respiration, the empirical equation is: Od (mg O2/h) = 0.487 W0.881.

Where, Od = oxygen demand of shrimp in mg/h, and W = average body weight of one shrimp in gram. This requirement multiplied by the number of total shrimps will give the respiration requirement.

Aquaculture Scoop / March Issue 2016

Calculation Table 100 80 water depth (m) 1.5 100X80X1.5 = 12000 Stocking density Average body weight Total density of Temperature (ºC) Salinity (ppt) (g) shrimp 28 25 20 350000 Values from table HP requirement for shrimp 2.2 HP/one lakh shrimp HP requirement for day 1.95 HP/10000 m HP requirement for night 6.25 HP/10000 m Aeration Requirement for culture pond HP requirement for fish 7.7 HP (2.2 X 350000)/ 100000 HP requirement for day (1.95 X 12000)/10000 2.34 HP HP requirement for Night (6.25 X 12000)/ 10000 7.5 HP HP requirement for aeration in the culture pond 7.7 + 2.34 = 10.04 (take 10 HP) Day Night 7.7 + 7.5 = 15.2 (take 15 HP) Pond area (m x m) Volume of water (m )

Page 28

This contribution helps to save electricity

Example 3:

Calculation Table Pond area (m x m) 90 90 water depth (m) 1.5 Volume of water (m ) 90X90X1.5 = 12150 Stocking density Average body weight Total density of Temperature (ยบC) Salinity (ppt) (g) shrimp 32 20 29 250000 Value found from table HP requirement for shrimp 3 HP/one lakh shrimp HP requirement for day 1.86 HP/10000 m HP requirement for night 5.94 HP/10000 m Aeration Requirement for culture pond HP requirement for fish (3 X 250000)/ 100000 HP requirement for day (1.86 X 12000)/ 10000 HP requirement for Night (5.94 X 12000)/ 10000 HP requirement for aeration in the culture pond Day 7.5 + 2.23 = 9.73 (take 10 HP) Night 7.5 + 7.13 = 14.63 (take 15 HP)

7.5 2.23 7.13

HP HP HP

consumption. Our electric motor can work in voltage fluctuation also. Single mould impeller gives more oxygen and good water current. Heavy weight L angle stainless steel frame holds the aerator firmly so that performance will be higher. All UV resistance plastic parts get minimum 5 years life in sunlight. This way, we serve quality product to aquaculture industry.

Spiral aerator: Spiral aerator (Fig. 2) is specially designed for high dissolve oxygen in aquaculture. Spiral RPM is more than paddle wheel aerator in

Example 4:

the air with small droplets to increase air water surface contact. Spiral is the best

Calculation Table 100 100 water depth (m) 1.5 100X100X1.5=15000 Stocking density 250000 Average body weight Total density of Temperature (ยบC) Salinity (ppt) (g) shrimp 28 35 35 250000 Value found from table 3.47+(4.47-3.47)X5/10=3.97 *For 35 g average body weight of HP requirement for shrimp shrimp we can take HP requirement HP/one lakh shrimp value for 40 g of fish (4.47). Else we have to calculate above this method.

HP requirement for day 2.17 HP/10000 m HP requirement for night 6.94 HP/10000 m Aeration Requirement for culture pond HP requirement for fish (4.47X 250000)/ 100000 11.17 HP HP requirement for day (2.17 X 15000)/10000 3.255 HP HP requirement for Night (6.94 X 15000)/10000 10.41 HP HP requirement for aeration in the culture pond Day 11.17 + 3.255 = 14.42 (take 15 HP) 11.17 10.41 = 21.58 (take 22 HP) Night Pond area (m x m) Volume of water (m )

option for improving dissolve oxygen level in water column. Semi intensive and intensive culture spiral should use with paddle wheel aerator to get more profit. We developed 2 and 3 HP spiral.

Long arm aerator: We require good soil quality that can hold the water, available and plenty of water and electricity for develop aquaculture farm. The place we select is may be suitable for our aquaculture. But their electricity availability may be fluctuated. For solving this problem we developed long arm paddle wheel and spiral aerator that can run with diesel engine is shown in the Fig. 3.

Sagar aquaculture Pvt. Ltd. developed new equipment to contribute aquaculture

Fig. 1 Pictorial view of paddle wheel aerator: (a) 1 HP, (b) 2 HP and (c) 3 HP

industry. And successfully we are helping farmers and aquaculture industry. Now we give information of aeration equipment from our contribution.

Paddle wheel aerator:

(a)

Paddle wheel aerator is specially design for extensive and semi intensive culture systems is shown in the Fig. 1. We developed high efficiency electric motor and bevel type gear

(b)

box for 1, 2 and 3HP paddle wheel aerator.

Aquaculture Scoop / March Issue 2016

Page 29

Submersible aerator: Submersible aerator (Fig. 4) is help full to dissolve more oxygen and produce less water current. It can suck more air from nature and throw in the water and create micro fine bubble to dissolve more oxygen.

(c)

Roots blower: Now a day roots blower is widely used in aquaculture purpose. Roots blower produced high pressure with large volume of air. Aqua animal can get enough oxygen with less electric power. Roots blower and aero tube, oxygen will maintain from bottom to surface of the pond. Roots blower mainly use in feeding time. It is very easy to install and maintain cost also less.

Fig. 2 Pictorial view of spiral aerator

(a) !

Fig. 4 Pictorial view of Submersible propeller aerator

(b) Fig. 3 Pictorial view of long arm (a) paddle wheel aerator and (b) spiral aerator

Aquaculture Scoop / March Issue 2016

Page 30

Worms transforming wastewater treatment practices

Environmental compliance is one fact of life

companies could afford on site treatment of

Company (Wastewater Wizard) has refined

all facets of the aquaculture industry must

the foul smelling soup that is sludge. Most

their Wizard range of technology to treat

comply with. More so for the on shore fish

companies settle for the waste management

sludge. For the first time this development

farms, hatcheries and food processing

option which involves tankering it off site for

allows on shore operations the option to

facilities, where dilution rates from the

processing elsewhere. If the installation is

treat sludge on site in a cost effective

surrounding water body play no part.

near agricultural land then spreading it as a

manner.

Leaving aside the complex low load/high

low grade fertiliser is an option. For a few

flow conundrum there are many technolo-

large scale operators, investment in

The first thing you notice about vermifiltra-

gies available to treat the vast quantities of

anaerobic digestion can provide a return by

tion technology is its compact size. The

wastewater. These fall into three categories

generating energy from biogas, it stills

Wizard system is no different in this respect

and are either biological, chemical or

leaves a residual sludge.

as it is a single stage treatment process with

physical processes. Companies will pick the

a bed depth ~1m deep. The bed or to be

most suitable technology balancing cost,

In recent years a new innovative technology

more accurate the vermifilter is made up of

energy requirement and the availability of

has come to market, treating sludge which

several layers containing various grades of

land.

has an unlikely organism at its heart – the

aggregate which supports the media above.

lowly worm. Vermifiltration in simple terms

The media or to be more precise is coir, a

Once the wastewater treatment box has

is a worm filtration technology; the term

waste product derived from coconut husks.

been ticked, it then follows that the next

“vermi” is derived from the Latin name for

It is in the upper most layers of the coir

issue faced by the operator is what to do

worm. Though the origins of this technol-

where the worms live. The sludge is

with (what seems like) endless volumes of

ogy is unclear it was pioneered in the UK,

distributed over the surface and it perco-

sludge the treatment process generates.

Chile and Australia. Today we find that the

lates down filtering out the solids and

Although on a much smaller scale that that

largest installations are found in South

organic component. This material becomes

generated by the industry, it does however

America, with 100’s of plants mainly treating

the worm’s food source.

come at a cost. Up until now very few

industry wastewater. In the UK one

Aquaculture Scoop / March Issue 2016

Page 31

WASTEWATER

COCONUT FIBRE (inc. worms, micro ecosystem & vermicast)

Wastewater percolates down, trapping the solids and organics

UNDER DRAIN/MEDIA SUPPORT

FINAL EFFLUENT

Worms thrive in this environment and the

of the distribution arm motor and a small

area there are ~10,000 worms, coupled with

sludge is an ideal food source. After a single

pump station to lift the sludge onto the

a high reproductive cycle with a high protein

pass up to 95% of contaminates (suspended

distribution arm. The capital spend profile

content of up to 60% of body weight, they

solids and BOD) are removed. The resulting

is low compared to the conventional sludge

could lend themselves to reduce the burden

treated effluent has similar make up of that

treatment technologies.

of fish derived protein used in fish food.

of domestic sewage, and is easily treated by

Academics studies have already started

on-site wastewater treatment plant with

As you would expect ongoing maintenance

looking at this solution, but Wastewater

little impact.

is simple. Routine tasks are carried out

Wizard for now is taking it one step at a

using pitch forks, so there is no need to

time. Yesterday was developing wastewater

Unlike the conventional tanker lead

spend time upskilling the workforce. There

treatments systems, they have now adapted

operation, sludge treatment can be

is a by-product produced by the worms.

the system to treat sludge. Solving the fish

achieved on site. The type of worm used

Worm casts are excreted by the worms as

food protein problem will be left for another

within the Wizard system is a key compo-

they feed. This solid material is trapped

day.

nent to its success. Using the worm species

within the media, and over time builds up

Eisenia fotida, they can digest up to its

causing an ever increasing surface level.

entire body weight in sludge each day. This

Removal is carried out by using the same

means that these systems have a low

pitch fork for the routine maintenance. The

footprint due to the relatively high loading

worm casts are high in nutrients, (nitrogen,

rates achieved. In relative terms they can

phosphorus and potassium) and could lead

treat 6 â&#x20AC;&#x201C; 10 times the wastewater load

to an additional revenue stream selling to

achieved by the traditional constructed

agriculture. There is an abundant scientific

wetland.

literature relating to the additional value

More information: Kevin Jeffrey Wastewater Wizard Ltd., Tel: +44 1381 620 413 Web: www.wastewaterwizard.co.uk

these bring to farmers in increased crop Simplicity is a by word for this technology.

yield coupled with a lower requirement to

The natural burrowing action by the worms

buy in manmade fertiliser.

ensure an aerobic environment throughout

One avenue that Wastewater Wizard is

as they need air to breath. Energy consump-

aware of but not yet exploited are the

tion is low as the only power required is that

worms themselves. For every m2 of bed

Aquaculture Scoop / March Issue 2016

Page 32

AQUACULTURE EQUIPMENT Sagar Aquculture Pvt.Ltd. has been established in Year 2001, with the manufacturing of Fishing Floats and Long Arm Impeller only. When we find out that in imported Paddle Wheel Aerator there are so many problems about parts avilability & services, so we decide to solve those problems by manufacturing complete Aerator in India.

Since 2012 we start to manufacturing of Paddle Wheel Aerator.

Day by day, we find that Aquaculture industries require many othermodified products which can help them as an auto solution. So as per their demand we developed many others products like Spiral Aerator, Six Paddle Aerator, Mud Lifting Machine (Sludge Pump), Auto Feeding Machine, Long Arm Aerator, Long Arm Spiral, Submersible Aerator etc.

Events in detail January 20th Edition India International Seafood Show 22-24th January Chennai, India www.indianseafoodexpo.com/ MVC Cereals-Mixed Feed Veterinary 2016 26-28 January Moscow Russia www.mvc-expohleb.ru/ Practical Short Course on Feeds & Pet Food Extrusion 31st January – 5th February Texas, USA http://foodprotein.tamu.edu/extrusion February SeaWeb Seafood Summit 1-3rd February St Julian’s, Malta www.seafoodsummit.org/ Fish International 14-16th February Bremen, Germany www.fishinternational.com/en/ Aquaculture 2016 22-26th February Las Vegas, USA www.was.org March Seafood Expo North America 6-8th March Boston, USA www.seafoodexpo.com/north-america/ AquaMe 13-15th March Dubai, UAE www.agramiddleeast.com/en/Aqua/ Seafood Istanbul 23-26th March Istabul, Turkey http://cnrseafoodistanbul.com

Aquaculture Scoop / March Issue 2016

Aquafeed Horizons Asia Conference 29th March Bangkok, Thailand http://feedconferences.com/ Victam Asia 29-31st March Bangkok, Thailand www.Victam.com April Offshore Mariculture Conference 6-8th April Barcelona, Spain www.offshoremariculture.com/europe Seafood Expo Global 26-28th April Brussels, Belgium www.seafoodexpo.com/global/

June Future Fish 2016/Middle East Aquaculture Forum (MEAF) 2-4th June Izmir, Turkey www.eurasiafairs.com AquaVision 13-15th June Stavanger, Norway www.aquavision.org/ July 2nd Global Summit on Aquaculture & Fisheries 11-13th July Malaysia http://aquaculture.global-summit.com/ August

Asia Pacific Aquaculture 2016 26-29th April Surabaya, Indonesia www.was.org

Asean FishExpo 2016 4-6th August Bangkok, Thailand www.aseanfishexpo2016.com/

May Aquafeed Extrusion Technology Short Course 9-11th May Norway www.fie.com.au Food & Feed Drying Technology Short Course 12-13th May Norway www.fie.com.au 7th World Fisheries Congress 23-27th May Busan, South Korea www.fisheries.org Aquaculture UK 25-26th May Aviemore, Scotland www.aquacultureuk.com/

Nor-Fishing 16-19 August Trondheim, Norway www.nor-fishing.no/?lang=en 11th International Conference on Recirculating Aquaculture & 2016 Aquaculture Innovation Workshop 19-21st August Roanoke, USA www.recircaqua.com Shanghai International Fisheries & seafood Exhibition 2016 (SIFSE) 25-27th August Shanghai, China www.sifse.com China International (Guangzhou) Aquaculture Exhibition 2016 26-28 August Guangzhou, China www.aquaexpochina.com

Page 35

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