Floating Treatment Wetlands FAQ
What is the Blue Frog System?
The Blue Frog System is a lagoon based wastewater treatment technology based on high efficiency 3 horsepower floating water circulators called Blue Frogs. The frogs are used to create a type of granular sludge bed reactor approach at the very beginning of a tank or lagoon. Typical BOD and TSS removal rates are 80-90% in as little as 12-18 hours of HRT making Blue Frog one of the most efficient treatment options available. Blue Frog System is a hybrid approach that makes use of mainly anaerobic processes in the initial granular sludge bed step and aerobic sludge digestion in the remaining steps.
What is granular sludge?
When wastewater treatment bacteria are exposed to flowing water and hydrodynamic shear forces created by the Blue Frog System, they tend to form a kind of an anchor called a granule or granular sludge. The granules are most often made of calcium carbonate crystals that help the bacteria to hold their place in the moving wastewater. The granules can be as large as several millimeters in size and are typically porous. Millions of bacteria can live on each individual granule which greatly enhances the number of treatment bacteria in a Blue Frog Lagoon. The unique biological structure of the granule puts all of the different anaerobic treatment bacteria together in close proximity to one another which helps to
How does granular sludge improve the treatment performance of my lagoon?
Each granule acts like a tiny pump fueled by the nutrients that come into the lagoon in the raw wastewater. Specialized anaerobic bacteria called methanogens that live on the inside of the granules produce methane and carbon dioxide gas that collects in bubbles and leaves the granule. As each gas bubble leaves the granule, fluid is drawn into the center of the granule creating a simple natural pump. The pump ensures that the anaerobic digestion process proceeds as efficiently as possible and allows the digestion process to increase in response to increased loads.
When organic loading of the granular sludge bed is lower bacteria, living on the granular sludge simply go dormant and wait for conditions to improve. This high concentration of granules present in a typical Blue Frog System a huge reservoir of treatment bacteria that are available to respond when the nutrient levels increase. In essence, the granular sludge created by the Blue Frog Technology gives your lagoon an automatic biologically controlled throttle that allows the bacteria to grow up and down in response to variations in organic loading.
What is a CSTR?
CSTR stands for Continuously Stirred Tank Reactor. In the context of the Blue Frog System, a CSTR is a patented floating tank that is created using a Blue Frog. The tank is formed by water leaving the circulator and piling up against a floating curtain of material that hangs down into the water to a depth of about 1 meter. The curtain directs the horizontally flowing water down to the bottom of the lagoon where it ricochets off the bottom and back up to the intake of the circulator. The only way that water can enter or exit a CSTR is at the bottom of the lagoon, this helps protect our anaerobic processes and also concentrates solids at the bottom of the lagoon. The CSTR approach is always used at the very beginning of a lagoon over top of the raw water inflow using a Blue Frog. Insert picture of markdale CSTR
What is Anaerobic Digestion?
Simply put, anaerobic digestion is the process of breaking down complex organic compounds such as fats, sugars and proteins into simpler and simpler molecules in the absence of oxygen. The end step of the process is methane and carbon dioxide. The process is carried out by a large number of different types of bacteria that are already naturally present in any sewage lagoon. Anaerobic digestion proceeds as a series of chain-linked reactions whereby the end product of one bacteria’s breakdown becomes the food for the next bacteria in the process and so on and so forth. Anaerobic digestion is occurs naturally in areas like the deep ocean and natural wetland sediments.
Won’t my lagoon go septic and smell bad if the dissolved oxygen drops below 2mg/L?
Not necessarily. Anaerobic processes definitely do generate bad smells such as hydrogen sulphide and volatile fatty acids however, these smells can only create problems if they are allowed to leave the lagoon. The trick is to keep the anaerobic processes and the associated smells where they belong at the bottom of the lagoon. Keeping a lid on the lagoon through active horizontal circulation and settling of solids allows the Blue Frog System to contain odours even when the surface DO drops below 2mg/L.
I spray irrigate my lagoon effluent how will the Blue Frog System affect this process?
Because Blue Frog System is so efficient at knocking down TSS and BOD quickly (typically 80-90% after 12-18hour HRT)
How can Blue Frog System add capacity to my lagoon?
Cost is based on the number of modules required and the location of the work. However, a good ballpark number to use for initial project budgeting purposes for PhytoLinks FTW is $X/ square foot. This price is inclusive of plants, installation, anchoring and fencing.
How deep do my lagoons have to be to use the Blue Frog System?
The minimum depth required to run the Blue Frog circulators is 36 inches or .91 meters. In most cases deeper lagoons are better since a large fraction of the wastewater treatment in a Blue Frog lagoon is accomplished in the anaerobic zone near the bottom.
Does Blue Frog System work with both seasonal continuous discharge lagoons?
Yes, as long as the level of the first lagoon is held constant, subsequent lagoons can be completely drained seasonally to accommodate permit requirements. Because the system is modular and non-permanent in nature, the circulators can also be easily moved around to accommodate almost any type of discharge strategy.
How much does the Blue Frog System cost?
Cost is based on the number of circulators required and the location of the work. However a good ballpark number to use for initial project budgeting purposes for is about $dollars per cubic meters or $ per USG. This price is inclusive of system design, delivery and installation.
How does the Blue Frog System save me money versus other systems?
The Blue Frog system saves money in several ways. First, and most importantly it digests both existing and newly formed sludge which gives you back lost treatment capacity and eliminates the need to dredge on an ongoing basis. Sludge removal gets more expensive every year and currently ranges from $35-$55 per m3 to remove depending on the removal and disposal method. That means for a municipality with a 2,500m3/day average flow Blue Frog System could save you between $44,000 and $69,000 per year on sludge removal alone (based on an accumulation rate of 0.5. m3 sludge per year).
Blue Frog System also requires less electricity to operate than a traditional aerated lagoon strategy. Adding oxygen is expensive so we limit it to only the top portion of the lagoon. The anaerobic processes that Blue Frog Systems employs essentially work for free.
The third way that Blue Frog System saves money is through no requirements to build new infrastructure. Upgrading from a lagoon to a mechanical treatment plant can cost 6-10 million dollars. Blue Frog system can offer similar treatment performance at about 1/10 the cost because there’s no need to build new infrastructure. The circulators are simply retrofit into your existing lagoon.
How are the Blue Frog circulators anchored in the lagoon?
The Blue Frog circulators must be tethered in two directions to keep them in place and prevent them from rotating. This can be accomplished using ropes or cables that run back to shore depending on the number of circulators required and the size of the lagoon.
How does the system handle the winter?
The Blue Frog circulators are designed to be run continuously regardless of the outside temperature. At temperatures around -40 Celius, the water in a lagoon will freeze right up to the circulator, however, because the intake is situated below the surface, the circulator will still be moving water under the ice. AT temperatures from -20 to -30 Celsius, there will still be 10-15 of open water around the circulators. The Blue Frog System has demonstrated trouble free operation in multiple sites through the harshest Canadian winter conditions. (Insert Winter Picture)
Can I use Blue Frog in my sludge wasting lagoon?
Yes, Blue Frog System can be used to help digest wasted sludge however we strongly recommend that at least a small flow of raw wastewater be mixed in with the wasted sludge as it feeds into the Blue Frog System to accommodate a higher sludge digestion rate.
How does the system handle larger flows?
The size of the CSTR can be increased by adding additional circula