Suction scrapers

Another example for a possible aeration cell occurs with suction scrapers made of unalloyed steel in the clarification basin. In this case, the difference in aeration arises from the oxygen deficiency in the bottom deposit and the relatively high oxygen content in the waste water [17]. 

A static leaf filter is used for cleaning machine tool coolants. These are used on the suction side of a pump circulating system, with the same pump employed for withdrawal of the filtrate as for backdushing the filter elements. SoHds in this case are removed from the sump by a scraper conveyor. 

In order to obtain the degree of vacuum required, the manufacture of the de-airing bell must be very accurately accomplished and it must be provided with suitable seals and scrapers to prevent soiling. Moreover the suction point in the receiver must be suitably protected against penetrahon of contaminating material. 

The means of preventing this kind of trouble (and the less often the sludge is pumped out, the more frequent it is) is to install a scraper screw across the whole width of a single concentration pit or to have a number of square truncated pyramid shaped concentration pits all across the width of the basin with an equal number of suction devices. 

Flotation is the process by which dispersed solid or liquid particles, colloidal species, and solutes are floated to the solution surface with the aid of a rising stream of air bubbles. In general, the substance to be floated should be hydrophobic and therefore attachable to the bubbles. The bubbles deliver surface-active material to solution surface and leave it there when they break. This stipulates a concentration gradient up the solution phase. As a result, the SAS concentration inside the surface layer is increased. Different devices, such as scrapers, ventilation suction, and air-blowers, remove this layer. The disadvantage of bubble flotation in the classic version is the significant hydrodynamic circulation. As a result, concentrated surface solution is redispersed back to the water bulk. 

Saturator n A machine designed to impregnate paper, fabrics, and the like with resins. The web to be saturated is conveyed by rollers through a pan containing a solution of the resin, then through metering devices such as squeeze rolls, scraper blades, or suction elements that control the amount of resin retained. 

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