 |
|
 |
Flotation
Advanced treatment: waste water treatment, material recovery and recycling of used water by flotation with micro bubbles
Informationen:
flotation pressure treatment wastewater cleaning wwt stainless steel
|
|
|
Huber Technology Inc., USA
|
|
Huber Technology Inc., USA
|
|
Member of the Huber group
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
HUBER Dissolved Air Flotation Plant HDF |
|
|
| for industrial wastewater treatment for removal of solids for removal of fat, oil and grease for product recovery for process water recycling We have a mobile DAF unit for on-site testing and demonstration |
|
|
Dissolved air flotation is used for the separation of particles, fat, oil and grease from water or wastewater. Micro-bubbles are generated and attached to the surface of such matter. Due to their increased buoyancy, the aggregates of solids and air bubbles float to the water surface where they form a scum (or flotate) layer that is skimmed off.
Mechanical and chemical pre-treatment
The influent should be well screened to prevent clogging, e.g. with our Rotary Drum Fine Screen Ro 2 or our Micro Strainer Ro 2. Chemical pre-treatment of the influent may be necessary to achieve good separation. pH adjustment, coagulation and flocculation may be required to form well separable flocs.
Generation of micro-bubbles and influent feeding
The inluent to be treated is blended with so-called "milky water", an emulsion of millions of micro-bubbles per gallon of water, having a diameter of 20 to 40 microns. Such micro-bubbles are generated when the pressure of air-saturated water is suddenly released. Up to 30% of the effluent is re-circulated for the generation of "milky water". A multi-stage centrifugal pump (10) generates a pressure of about 90 psi (0.6 bar). A compressor (11) feeds compressed air to the pump rotor that generates small bubbles with a large surface for quick water saturation within a tubular saturation reactor (12). The saturated water flows through a single pressure release valve (13). By using a single valve we avoid the problems that are typical for systems employing a multitude of small valves, i.e. uneven distribution of the milky water, and the need for frequent cleaning and difficult re-adjustment of many valves. The milky water flows into the inner tube of a coaxial tube feeder (14), while the influent to be treated enters the outer tube at the opposite end. The milky water flows through slots from the inner into the outer tube where it thoroughly blends with the influent so that all solids come into close contact with a sufficient number of micro-bubbles. The coaxial tube feeder thus ensures optimal blending. The well blended influent flows upwards through slots (1) in the outer tube into the tank of the DAF unit.
Solid / liquid separation
A lamella separator (5) is submerged in the tank to achieve effective solids/liquid separation on a small footprint. The effective clarifier area is the sum of the horizontal areas of alllamellae, and is about ten times the horizontal area of the lamella packet. While the water flows down through the gaps between the inclined lamella plates, buoying flocs rise a short distance and attach at the lower surface of the upper lamella, and dense particles sink a short distance to upper surface of the lower lamella. These lamellae have a special honey-comb surface to retain thin layers until they are grown into thick and compact layers that finally detach from the surface and slide quickly up or down along the lamella surface. Detached light aggregates slide up and rise to the water surface where they form a floating scum layer. Heavy sludge aggregates slide and sink down to the bottom of the tank. The water, after it has passed down through the lamella separator, rises up again through a channel (7) to an overflow box (8). The water level in the tank and the immersion depth of the scraper is adjusted by the position of an overflow weir (9). Recirculated effluent flows from the effluent box down into the pump (10).
Scum and sludge thickening and removal
A grate is installed just below the water surface. As the scum layer within the grate becomes thicker and thicker, it is compressed and partially lifted out of the water by its buoyancy. The scum is thus drained and thickened. A chain scraper (2) travels over the grating and skims off the top of the scum. It drives it over a small ramp and drops it into a scum hopper (3). The scum flows into a sludge tank. Sediment is gravity thickened in the conical sediment hopper (6). From time to time an automatic valve (15) is opened and desiment flows into the sludge tank where it is blended with the scum. The removed sludge is usually dewatered with our Rotamat Screw Press RoS 3.
|
|
|
|
Huber Technology Inc., 9805 North Cross Center Court; Suite H, Huntersville, NC 28078
Phone: (704) 949-1010, Fax: (704) 949-1020, email: huber@hhusa.net |
|
|
|
|
|
|
|
