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The Screw Wash Press is a screenings wash system to bring dissolvable organic content from screenings back to the treatment process. The Screw Wash Press provides a major weight and volume reduction of screenings, achieving a dry solids content of 40-60%.
Applications
The MEVA Screw Wash Press (SWP) is a rotating screw which slowly feeds forward screenings. Wash water is added in the wash/press zone, where dissolved materials and water are pressed out and brought back to the waste water treatment process.
The composition of the screenings can be optimised by adjusting the working cycle via the control system. The retention time in the press can be prolonged by mounting a Counter Pressure Screw (CPS) after the SWP. This will increase the washing efficiency and dry solids content.
The press transports the washed and pressed screenings to a container via a pipe system. The MEVA SWP is designed with double troughs making it very "torque resistant" for heavy operations with screenings of high dry solids content. The high "torque resistance" enables the SWP to be supplied with a large inlet opening. Furthermore, the double trough allows for the inner pipe to be fully perforated, thereby, allowing maximum dewatering.
The screw is a close fit within the inner pipe, which results in high dewatering. A robust axial bearing and gearbox absorb the forces from the press. The press zone is easily and safely accessible through a hatch in the top of the casing.
MEVA Screw Wash Press is mainly manufactured in stainless steel. The screw and wear parts are manufactured in durable carbon steel.
The use of more fine screens in wastewater treatment works is increasing the amount of screenings separated from wastewater. The amount of screenings leads to an increase in odour problems and disposal costs.
When the MEVA SWP is combined with a MEVA Fine Screen, the result is an optimal screenings unit for inlet works or sludge applications. Feeding the MEVA SWP can also be done via coarse screens, sieves or shaftless screw conveyors. MEVA SWP is well suited for both smaller and larger waste water treatment plants. It is a compact and cost efficient unit, which has proven good functionality due to its simple and functional design.
The screw is a close fit within the inner pipe, which results in high dewatering. A robust axial bearing and gearbox absorb the forces from the press. The press zone is easily and safely accessible through a hatch in the top of the casing.
The operating headloss is between 0 and 200 mm, approximately 400 mm should be allowed overall allowing for overflows.
This is site dependent, normally this is a 3 to 4 month period.
Hydrochloric or sulphuric acid is often used, along with an occasional application of sodium hypochlorite.
The SludgeScreen™ is an inline pressurised device that screens sludge in one operation. The enclosed system reduces odour problems and has no washwater requirements.