Dryden Aqua produces a range of products for Aquaculture, providing clean water to ensure optimal fish health and growth rates, while saving on operational costs. Our philosophy is to rapidly remove and eject as many organic particulates as possible, with the resultant effect of reduced oxygen demand, pH adjustments, sludge reduction and overall reduction in risks of pathogen related problems.
Organics load
Dissolved oxygen
demand
Mortalities
Deformities
Sludge
Viral and
parasite problems
Biosecurity
Fish growth rates
Fish health
Stock yield
Aquaculture facilities often face virus and parasite issues due to anaerobic zones in biofilters that emerge due to high sludge generation and poor particle removal protocols. This excess sludge is formed because the biofilter acts primarily as an organics filter (capturing particles not removed by the drum filters) instead of their designed purpose, which is the nitrification process to remove toxic ammonia.
Pathogen
Bacterial community for breaking down particles
Bacterial community for nitrification of ammonia
Heavy organic load in the biofilter
Bacterial community primarily occupied with breaking-down particles rather than nitrification of ammonia
Overall increase of sludge content
Vicious cycle of:
• Larger fluctuations in alkalinity
• Higher DO demands & pH drop
• Ideal conditions for pathogens to breed
• Excess of biofilm formation
• Increase in turbidity
• Increased concentration of toxic ammonia
Consequences:
• Stress of the fish in system
○ Reduced growth rates
○ Increase in deformities
○ Disease or parasite outbreaks
• Frequent water exchanges
• High chemical post treatment
Pathogen
Bacterial community for breaking down particles
Bacterial community for nitrification of ammonia
Reduces organic load in the biofilter
Bacterial community focused on nitrification of ammonia
Reduces load on bio filters and thus reduced sludge production
Consequences:
• More efficient biological filters
• Reduced DO required
• Increased pH stability
• Reduced alkalinity buffering required
• Parasite reduction
• Improved growth rates
• Overall healthier fish population
Full cycle filtration through media filters is useful where sensitive/vital livestock are kept, and stocking densities are relatively low. This makes AFM® ideally suited for hatcheries, nurseries and brood stock systems.
Due to the sensitivity of these animals to poor water quality, pathogens, parasites and growth deformities we recommend::
Water quality
feeding/growth
reduced mortalities and growth deformities
The organics load in hatchery systems increases over the growth cycle, therefore recommendations are given for expected water quality variables at the end of that cycle.
AFM® media filtration in a 20 to 100% side loop of the skid sump (depending on application). This would be (directly after the drum filter and before the biological filtration). This will reduce the load on the biofilter, making it more efficient with reduced pH and dissolved oxygen variability.
Water quality
DO demand & pH correction
Manual maintenance requirements
pathogenic & parasitic problems
Stable water quality is crucial for brood stock viability and consistency in spawning events when stimulated/required. We therefore, recommend the following:
Results
Due to the high turnover rates, media filters are generally not suited to treat 100% of the volume, but partial filtration can be used between the drum filtration and biological component as described above. Our recommendation is:
Many governments are tightening wastewater regulations, requiring far better outlet water quality. AFM®s 1 micron filtration performance is part of the process to ensure parasites are not being transmitted to the environment (providing biosecurity), while also reducing TSS to ensure the regulations are adhered too.
When AFM® is used with prefiltration flocculation/coagulation the resultant 0.1 micron filtered water can be treated with UV and be re-used as backwash water for drum filters or media filters inside the system, drastically reducing water consumption. High phosphate values often pose a problem in outlet water. As most phosphate is bound in organic matter, removal of fine particles allows for removing large amounts of phosphates before it can become a problem. and dissolved phosphates can be removed with our NoPhos product, to further reduce environmental contamination that often leads to eutrophication of local waters.
In combination with coagulation/flocculation, AFM® ng filters down to 0.1 micron. This allows the mechanical removal of pathogenic bacteria from the waters.
WATER AERATION, OXIDATION & MIXING
Aeration is crucial in a range of applications in Aquaculture. Dryden Aqua air diffusers can be used for heavy metal precipitation, degassing, airlift and of course oxygenation through aeration. The self-weighted tubes allow for easy maintenance and can be removed and cleaned while the system continues to run.
To filter heavy metals from intake water, they need to be precipitated. Aerating intake water for 30 minutes, in a tank/sump, will oxidize typical metals, such as iron and manganese, allowing them to be removed by AFM®.
Dryden air diffusers are engineered to provide a bubble size between nanobubbles and coarse bubbles. They are small enough (1 to 3mm) to facilitate good gas exchange through a good surface/volume ratio, but still large enough to provide substantial airlift. Because of this they can be used for aeration, as well as keeping organic material suspended in the water column, allowing it to be removed by the filters. The sheer forces can also help to keep net cages free of fouling and/or providing water movement in and out the cages.
Phosphate management in water systems involves efficient removal of organics, as most phosphates in water systems are bound in organic, algal and bacterial cell biomass. Organic particulate reduction, oxidation or UV lysis of cell membranes will release the bound phosphates into the water. Less organics means less phosphates.
The Zeta potential mixer is a static mixer, stabilizing zeta potential, allowing for rapid and fine mixing inside a pipe. At high enough pressures, gas bubbles cavitate inside the mixer allowing gases to be very finely dispersed, but more importantly, provide for sterilisation of pathogens moving through the pipes.
In Aquaculture, the ZPM is mainly used for dosing low amounts of ozone before filtration. In this case, ozone is not used as a disinfectant, but rather in low doses for coagulation/flocculation. Used before an AFM® filter, this allows for 0.1micron filtration performance.
With UV light after the 0.1 micron filtered water, any surviving pathogens can be eliminated providing safe, disease-free water for even the most delicate life stages.
No. 16 Heqing Road
Tsuihang New District, Zhongshan City,
+86 189 3870 1176
