Waste water treatment generates a great deal of solid matter which must be disposed of. This section of a treatment plant is called Solids Management. Solids come from the initial screening of influent, and from the activated sludge process. Waste activated sludge (WAS) is removed from the treatment process after digestion, usually in an anaerobic digester and occassionally in an aerobic digester.
The solids management portion of the plant is also where the chemical additives (flocculants, coagulants, additives) are stored and distributed.
The anaerobic digester will generate methane gas, which is often used to heat and power the plant, plus inert solids. The solids still contain a large percent of water and must be "dewatered."
Many techniques are available for dewatering. They include: gravity belt filter thickeners, centrifuges, and plate filter presses. The solids, once dewatered, will either be dried and processed for fertilizer, or removed for landfill.
APG instruments appropriate for the digestion and dewatering processes include the ultrasonic level, bulk level vibration, and pressure transmitters. |
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| Amplified Output Pressure Transmitters |
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Available ranges from vacuum
up to 500 psi and 0 up to
10,000 psi |
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Standard outputs: 4-20 mA,
0-5 VDC, 0-10 VDC, 1-5 VDC,
and 1-6 VDC |
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High overpressure capability |
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Single piece stainless steel process fitting and sensor |
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Zero and span adjustments |
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1/4-18 NPTM fitting standard |
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True 0-5 or 0-10 VDC, can transistion from vacuum to positive pressure |
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±0.25% accuracy of full scale
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Unaffected by material build-up |
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Adjustable detection time delay avoids transient signals |
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Withstands high lateral loads |
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Multiple mounting options |
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Class II, Group E, F and G explosion-proof versions |
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Bulk densities as low as
12.5 lb./ft .3 (0.2 g/cm3 )
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