Leopold® Clari-DAF® dissolved air flotation systems create millions of microbubbles to float solid particles to the surface of the water where they are removed as floating sludge, usually by mechanical skimming.

Normal Clarification Cycle

Chemical coagulants are introduced to improve flocculation efficiency.

The water is stirred to distribute the chemical coagulant among the solid particles and cause the particles to collide and flocculate.

Air under pressure is dissolved into water according to Henry's Law of Dissolution. Reducing the pressure back to atmospheric via a special device creates millions of "microbubbles" approximately 20 to 60 microns in diameter. The microbubbles attach to floc in the water and float it to the surface for removal.

The process starts with the addition of chemicals and rapidly mixing the raw water with coagulants. Good coagulation is one of the most important factors affecting flotation. Two-stage tapered flocculation is used to cause the particles to collide and form flow particles using low tip speed to prevent floc from being sheared.

A saturator is used to take a fraction of the throughput and recycle it back to a pressure vessel. A compressor provides air to the tank and mixes with the water to collect in the tank reservoir as saturated air.

The aerated water is delivered to a distribution header that spans the width of the DAF cell. The header has a series of specially designed nozzles. The pressure drop through the nozzle produces a cloud of microbubbles approximately 20 to 60 microns in diameter.

The tiny bubbles rise through the coagulated water, capturing floc as they ascend to the surface. The tiny bubbles rise under laminar flow at a rate following a modified Stokes equation.

A blanket of sludge forms on the surface of the flotation cell. The blanket is supported from beneath by tiny air bubbles and periodically removed.

The Solution for Reducing Nitrogen in Wastewater Effluent

The Leopold^® elimi-NITE^® 2.0 denitrification system is an attached growth, microbiologicol process. It is ideal for removing nitrogen from wastewater when the nitrogen is predominantly in the form of nitrate.

Product Description

The Leopold elimi-NITE 2.0 denitrification system consists of a gravity downflow packed-bed filter with a carbon source (methanol, acetic acid, molasses, etc.) located upstream. The media in the packed-bed filter—a coarse, hard, predominantly siliceous material—provides the support system to which the denitrifying microorganisms attach. The carbon source supplements the nitrified influent, providing the microorganisms in the filter media with a degradable carbonaceous material to metabolize nitrogen.

The packed-bed filter is well-suited for denitrification because it provides the necessary hydraulic detention time for the biological reaction to take place. It also filters out solids, eliminating the need for downstream filtration or clarification units required of other denitrification systems.

The Leopold® Clari-DAF® LT (Lagoon Treatment) system is a clarification technology

for the removal of algae, colloidal and suspended solids, precipitated dissolved solids,

and BOD (Biochemical Oxygen Demand) associated with suspended solids from

wastewater lagoon treatment systems. It is a proven, highly effective technology for

providing consistent effluent water quality and lowering your total cost of operation.

Thirty Years of Reliable, Proven Performance

The concept of using a floating siphon to remove sludge—The Leopold^® Clari-Vac^® floating sludge collector—was developed in 1970. Since then is has established a proven record of exceptional performance in installations throughout the world. It removes material faster, produces a higher solids content, lowers sludge disposal costs, drastically reduces power costs, and virtually eliminates maintenance. Its exceptional performance is another example of how Leopold engineered simplicity continues to deliver powerful and reliable solutions for the wastewater treatment industry.

Engineered Simplicity

The Leopold Clari-Vac floating sludge collector owes its outstanding and reliable performance to its engineered simplicity. It operates on the basic principles of buoyancy and siphon. Collection headers attached to siphon pipes supported from floats travel one inch above the tank floor "vacuuming" the solids that have naturally settled and compacted there. The sludge is then siphoned into a separate trough where is returned to secondaries in activated sludge applications or wasted to the dewatering process.

The vacuuming action of the Clari-Vac submerged sludge collector produces a more dense sludge because there is no stirring action involved. There are no plows or scrapers that can disperse light sludges. A more dense return sludge can result in decreased return rates, decreased power consumption, lower power costs, and lower sludge disposal costs.

Leopold® tertiary granular media filter systems with Leopold® FilterWorx® controls remove suspended solids from water by flowing the water downward via gravity through granular media at a high rate.

Normal Filter Cycle

Suspended particulates are removed from water by flowing the water via gravity through granular filter media at a high rate.

The solids are removed within the depth of the granular material.

Filtered water is removed from the filter through an underdrain system.

Normal Backwash Cycle

Cleaning the filter media is accomplished with an upflow water wash with either full bed fluidization or sub-fluidization depending upon the media.

Air scour ensures thorough cleaning resulting from higher shear forces in the media bed and abrasion between grains.

The volume of water above the filter bed increases to just above the edge of the waste gullet.

Dirt is dislodged and flushed out of the media, pushed to the surface of the water by the upward flow, and captured via water overflow into the waste gullet.

Dirty backwash water is evacuated from the filter for recovery.