BIOFILTERS IN PENAEUS MONODON HATCHERIES
From: Stuart Livesey stuartlivesey@hotmail.com
Sent: 13 October 2002
Question:
I am currently in the process of stocking a series of
biofilters for a
Penaeus monodon hatchery in S.E. Asia. We have already acquired the media
(the cog forms) and are about to start a recirculating system for a couple
of weeks to allow the system to settle and us to monitor changes in water
quality arising.
Has anyone information on seeding the biofilter? Is there any specific
fertiliser or even bacterial stock that is recommended for this, or an
easier way to start the biofilter going.
Stuart Livesey
e-mail:
stuartlivesey@hotmail.com
***************
comments 1 :
In my hatchery we add NH4Cl and NaNO2 to feed the
different strains of bacteria you need to run your filter. Without seeding
bacteria you need at least two months at 25 °C to get a ready to use
filter. Actually I am trying a new product containing Nitrobacter,
Nitrosomonas and other strain of bacteria and for the first time (with this
kind of product) I have a shorter start-up of the filter. I did this trial
with freshwater and I didn't use it with saltwater but if you are
interested......
Olivier Mueller
e-mail :
omueller@fastnet.ch
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COMMENTS 2:
It depends upon the required level of biosecurity you
are after. If
you are going to bring in wild broodstock and are operating non SPF,
a little local mud near a sewerage outfall will be a great seed.
Usually with low levels of biosecurity, just add some animal urine to
the system and let it start naturally.
You really want a more complex microbiological ecology in a biofilter
that you would get from any of the prepared cultures. Look at
ammonia as only an indicator of water quality problems, not "the
problem".
For SPF class system, startup is a much more complicated issue. If
the system is biosecure enough, it won't start on it's own and you
need a seed source that is pathogen free (guaranteed).
Dallas E. Weaver, Ph.D.
Scientific Hatcheries
5542 Engineer Dr.
Huntington Beach, CA 92649, USA
Tel: 714-890-0138
Fax:
714-890-3778
e-mail:
deweaver@gte.net
***************
COMMENTS 3:
In my hatchery we encountered the same problem with
bad colonization of plastic media by Nitrobacter. We just finished our
production season now and we are bringing some modifications to our
biofilters. At the beginning of our activity we used mineral media in our
biofilters with great success in the point of view of ammonia removal. Two
years ago we decided to change this media and to use plastic media for
maintenance reason. Plastic media are easy to clean and to handle. During
these two years we had to face many problems like poor colonization with
Nitrobacter, destruction of bacteria film after back-washing, performance
instability...
For 2003 we will use again a mineral media called biogrog. This is an high
temperature extruded ceramic which is very resistant to mechanical abrasion
and has a high porosity....You can wash your filter like you want and even
use sanitary products (with moderation) without destroying your biofilter!
Olivier Mueller
e-mail :
omueller@fastnet.ch
**************
COMMENTS
4 :
I have been running a closed recirculating maturation
since 1999 and now recirculating larval rearing for the production of F.
aztecus (Atlantic Brown shrimp) and F. duorarum (Atlantic Pink shrimp). I am
working to develop the clean stocks of these animals for the bait shrimp
industry here in Texas. Therefore, the use of recirculating systems has been
central to my research efforts. This system is a basic recirculating set up
(basically out of published literature with a few modifications) consists of
3 maturation tanks which run with trickling biofilters (plastic Media),
Diatomaceous earth filter, Foam Frac and carbon.
To inoculate this filter I use commercially available Fritz Zyme # 9 Salt
Water (In the US) However, any decent commercial producer of this type of
product with Nitrococcus and Nitrosococcus (The bugs formerly known as
Nitrosomonas and Nitrobacter) to inoculate this filter. Don't dump this in
all at once I generally add 1/4 of the recommended dose of inoculum over the
biofilter every 2 days until the entire dose is finished. Add NH4Cl,
starting day 1, at the rate you expect your animals to produce daily for
about a week and watch the biofilter cycle the nitrogen. Once cycling from
NH4 to NO3 starts you can stop the NH4Cl additions and add in the animals.
Two key elements in the complete conversion to Nitrate in this system are
flow rate over the filter about 2.2 gpm per top 1ft2 top SA of filter and
using Sodium Bicarbonate (Baking Soda) to adjust pH not Sodium Carbonate
(Light Soda Ash). Whenever I used Light soda ash the conversion from nitrite
to nitrate was severely reduced and huge nitrite spikes occurred. With the
use of sodium Bicarbonate (Baking Soda) for pH adjustment the systems
conversion of nitrite to nitrate came back in line and Nitrite stabilized to
<1 mg/l. This has to do with stabilizing the pH and alkalinity as the
Nitrococcus (Nitrobacter) are very sensitive to these changes. For further
system reference see the article published in World Aquaculture Magazine
September 2001 Vol. 32 NO. 3.
Ryan Gandy
e-mail: rgandy@earthlink.net
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COMMENTS 5:
It would be recommendable you calculate your needs
before establishing your biofilter as other device in a water treatment
process or engineering system, you have to respect sizing and a number of
physical rules. Your production of nitrogen is in relation with the organism
you raise, its feeding, the type of feed and the other filtration devices
such as mechanical filters (MES).
On internet you will be able to find several valuable publications as well
as in aquaculture press, books and magazines.
Several companies are available to help you design and build your system, I
would suggest:
www.aquaneering.com
www.r2ksystems.com
www.aquanetics.com
www.aquaticeco.com ( you will find
tips in their catalogue)
One reference very theoretical I have for
"Adults crustaceans" is reporting a production of 300-600 mg
N(NH4) / kg biomass / day.
The balance of nitrification and nitratation is:
To metabolize1 mg of N (NH4) you will require: 4.25 mg O2
and grow: 0.15 mg of nitrifying bacteria and 0.025 mg of nitrating
bacteria.
Suspended matter (MES) goes against nitrification so you may want to
implement your particle filter before your biofilter. This could be because
of competition effect between autotrophic and heterotrophic bacteria or
competition for the O2.
Typically, I would suggest a minimum of 3 minutes residence time in the
biofilter (check your flow and size of your biofilter).
You need about 20 days to start the nitrites (NH4 -> NO2);
You will need about 35 days to start the nitrates (NO2 -> NO3).
In the past I have started several seawater biofilters with filtered water
but I am sure today there are good inocula.
Initiating your water system and biofilter with ammonium cloride (NH4Cl) and
sodium nitrite (NaNO2) can be achieved in about 35 days altogether.
Starting dosis: 4 mg/l NH4Cl & 2 mg/l NaNO2
Following, you will need to test every day your water and maintain the
following concentration: 4 mg/l NH4 & 2 mg/l NO2
If your concentration reduces for loss of water or digestion, complement
with NH4CL and NaNO2.
When the biofilter will be taking off, it will be digesting all these
nutrients in less than 24 hours. When you are sure your system can take the
load of your shrimp, you are ready.
Eric Pinon
e-mail:
epinon@ecua.net.ec
***************
COMMENTS
6 :
It seems that many facilities are adding buffers such
as sodium bicarbonate to their system to resist pH changes; a more cost
effective and low maintenance system would be to use a calcium reactor.
This was originally designed to add calcium to coral reef aquariums, but I
am using a scaled up model to keep the pH and alkalinity levels up in a
30,000 litre display tank that is heavily stocked with rays and sharks and
is filtered by sand filters, protein skimming and trickle filtration.
Has any one started to use such a system on shrimp farms yet?
Paul Hale
Curator
Underwater World Aquarium UK
e-mail:
paul@paulhale.fsnet.co.uk
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COMMENTS
7 :
A 30 ton display tank will only be consuming a few kg
dry wt of feed
per day. Commercial production aquaculture operates at 10X those
feed rates per unit volume. At these higher rates, the calcium
reactors are worthless. You just used lime or hydrated lime to get
the same chemistry and it's smaller, cheaper and faster (however, you
do have to engineer the solution -- you can't just play engineer).
The other half of the problem is CO2 mass transfer capacity in the
system. More than one public aquarium hasn't thought through this
issue and has a totally inadequate design.
For shrimp maturation facilities where the load is low (relative to
growout operations), the alkalinity problem is not as much of a
problem. Relative to fish systems, this problem is very minor
for
shrimp systems (the feed rates per m3 on shrimp is much less than
fish systems). When you get up around 0.5 kg of feed / m3 of
recycle system, now you have a pH, alkalinity and CO2 problem that
must be formally addressed.
Dallas E. Weaver, Ph.D.
e-mail:
deweaver@gte.net