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Biological filter media and the biological filtration system they are used in is the heart of any filtration system for aquaculture or wastewater. Pure Aquatics in Port Macquarie can size a variety of biological filters, including:
Not all filter media is created equally and there are many very important key design and operational parameters that need to be met—for both the media and the biological filter reactor vessel. For instance, are you looking to boost your MBBR’s filtration capacity? Have a look at the Hel-X flake.
HEL-X FLAKE:
Hel-X medias are a powerhouse in MBBR carrier design, from conventional style carrier elements to trickle filter media and the incredibly high surface area flake, there is a media for every application. The Hel-X flake boasts an improved surface area of over 5,500m2/m3, with higher TAN removal than ever before. The Hel-X company was the first company to develop this type of media carrier and has invested significant time and resources into research of their flake product, resulting in a cost effective but equally impressive removal performance compared to other high surface area biomedia types.
Pore size, circulation, biofilter design and overall substrate concentration and diffusion across the biofilms determine the removal rates in the system, and this goes hand in hand with surface area. The volume of surface area and pore distribution within is only one part of the equation—too much porosity, size of pores and not enough cleaning of the media can negatively impact waste removal in some cases. Hel-X flake can be used solely in a biofilter, or, as we prefer to use the media, as a mix in certain ratios to boost biofilter removals and result in lower effluent concentrations. As most MBBR’s in aquaculture are only filled to 50% void volume, Hel-X flake can be deployed to fill the further 10% of the reactor volume (totalling 60%) to boost biofilter TAN removal. Hel-X flake is available in either a black re-granulate (recycled) product, or a virgin (white) HDPE. Pure Aquatics represent Hel-X in Australia and New Zealand and distribute on demand other carrier element types from Hel-X should you have a specific requirement.
MBBR MEDIA:
The design of MBBR biofilter media elements is only one part of the story in an MBBR filter, or any biofilter for that matter. Other factors, such as dwell time, hydraulic loading rate, air and water distribution, media velocity and oxygen transfer, all determine overall effectiveness and removal rate of nitrogenous waste. There is a lot more involved in designing any biofilter than just throwing in media and aerating it, and this is especially true of an MBBR. Pure Aquatics have identified specific removal rates for the K+ and Hel-X flake and have optimised its performance through identifying design parameters in biofilter design. Although surface area plays a role in removal rates in MBBR’s, it isn’t all that is involved. Please do not hesitate to contact us with your MBBR or other biofilter requirements.
Plastic media, for use in biological pond filters – specifically in moving bed bio reactors, was pioneered by Evolution Aqua, some 20 years ago. In recent years, other plastic media have come onto the market, usually with the aim of trying to get more and more surface area. However, one drawback to using plastic media has always been the time it takes to establish a stable biofilm, which is essential for good filtration. After many years of research, Evolution Aqua have now developed a new media that not only gives class-leading surface area, but also overcomes the problem of long maturation times.
K+Media is designed and manufactured in the UK by Evolution Aqua. This advanced media, with its innovative design and class-leading surface area, provides enhanced biological and mechanical filtration. As Evolution Aqua extrude the K+Media, minerals and enzymes are added to the raw material. The result of this process, unique to Evolution Aqua, is a filtration media that not only outperforms most of its competitors due to its large, protected surface area, but also answers the problem of how to speed up the time taken to mature your filter.
Benefits of K+:
To boost your MBBR’s performance, why not also consider the addition of Hel-X flake?
Biological filters are the heart of a life support system for closed aquaculture systems. There are many types of biological filters available that Pure Aquatics have experience in using, designing, building and implementing. Pure Aquatics both manufacture and import a variety of biological filters and filter media suitable for a wide variety of biological loads and applications.
MBBR FILTERS
Moving bed biological reactors (MBBR) have become the standard in biological filtration in recirculating aquaculture systems and for good reason. They are robust, easy to build, inexpensive to operate, require low pumping heads and control biofilm thickness, ensuring optimum biological performance. They also simultaneously oxygenate the filter and strip a percentage of CO2 for the system. Through extensive and ongoing research, experience and development, Pure Aquatics have optimised our MBBR design for high removal, high oxygenation, superior mixing and easy maintenance.
TRICKLE FILTERS/DEGASSING UNITS
Trickle filters were a very widely used biological filter in the past and still have their place in aquaculture today. Trickle filters are flexible—they have a wide hydraulic loading range, oxygenate and degauss the water as a function of their operation, and have a very high ammonia and nitrite consumption rate per m2. Just like all filters, the higher the ammonia and nitrite levels the more the biological filter removes (however effluent concentrations go up), however, trickle filters really excel at high ammonia concentrations.
The one thing they do not do is self-clean, so clogging can be an issue. Ways to negate this are to filter the water to a fine degree and/or increase the void space of the media, which also decreases surface area. They can also be more expensive to operate due to having to pump to elevated heights for operation. When employed as degassing units under gravity or on low-head pumping loops they are very effective, especially for high-density culture systems. Trickle filters are worth considering for biological filters in certain applications and should not be discounted.
FLUID BED FILTERS
Fluid bed filters, also called fluid sand filters, fluidised bed filters or fluidised sand filters, pack a huge surface area into a compact area. Depending on the sand choice, surface areas can range from 8,000m2/m3 up to and sometimes exceeding 20,000m2/m3. They operate well in recirculating aquaculture systems but require the water to be quite clean prior to entering the filter due to their susceptibility to blocking or producing thick biofilms that result in excess sand loss.
Fluid bed filters lose sand over time as the sand is colonised by bacteria and becomes lighter and floats out of the system. This can be managed by siphoning the top layer and increasing the velocity at the top of the vessel, but it is generally done by a higher maintenance filter than an MBBR. They may have a high surface area, but removal rates are generally lower per m2 as a fluid bed is a very abrasive environment. The pumping and energy requirements are higher compared to some other biological filter options, but they do have their place in biological filtration.
