Sludge Removal

All hydrocarbon oils react with oxygen upon exposure to air at sufficiently elevated temperatures for long periods of time. Over the range of temperatures developed in engine crankcase, the rate of oil oxidation has been found to double for every 20°F rise in temperature. Although all lubricating oil hydrocarbons are susceptible to oxidation, of more importance to engine performance are the oxidation products. Paraffinic hydrocarbons 

TABLE 2 EFFECT OF REACTION TEMPERATURE ON LEAD REDUCTION 

REACTION TEMP. °C LEAD CONTENT (ppm) % LEAD REDUCTION 

oxidation of paraffins yields alcohols, aldehydes, ketones and acids. The acids formed are vigorously corrosive to copper, lead and cadmium engine bearings. 

Naphtenic hydrocarbons yield products similar to paraffins upon oxidation. Aromatic hydrocarbons are che most readily oxidized constituents of lubricating oils. The end products are very complex condensation and polymerization products and tend to be Insoluble in oil. These products constitute the sludges, resins and varnishes which allegedly cause piston ring sticking in the engine. 

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For wet ESPs, consideration must be given to handling wastewaters. For simple systems with innocuous dusts, water with particles collected by the ESP may be discharged from the ESP system to a solids-removing clarifier (either dedicated to the ESP or part of the plant wastewater treatment system) and then to final disposal. More complicated systems may require skimming and sludge removal, clarification in dedicated equipment, pH adjustment, and/or treatment to remove dissolved solids. Spray water from an ESP preconditioner may be treated separately from the water used to wash the ESP collecting pipes so that the cleaner of the two treated water streams may be returned to the ESP. Recirculation of treated water to the ESP may approach 100 percent (AWMA, 1992). 

Figure 4-63. Tray-type scrubber with continuous sludge removal. Courtesy of National Dust Collector Corp.

Higher rates of sludging also take place in the boiler vessel. In turn, this potential fouling problem requires additional maintenance time because more frequent internal surface cleaning, wash-down, and boiler vessel sludge removal usually is required. Carryover of contaminants into the steam also is more likely. 

The boiler should have been previously drained and all sludge removed with a pressure jet. It should be filled with fresh water, then checked for pressure and vacuum and the integrity of the circulation rig and hoses. 

In pollution control in treatment of sewerage and sludge, removal of SOjc and NO from flue gases. 

The inlet, outlet, and sludge removal mechanisms are contained in the central rotating section. This central rotating section and the spiral scoop rotate around the tank at a speed synchronized with the flow (Figures 27.1 and 27.2). 

Water-scrubbing devices are often used to control emission to the air. Most of these devices generate wastewater streams that are potentially contaminated with pesticide ingredients. Although the quantity of water in the system is high - about 20 gallons per 1000 cfm - water consumption is kept low by a recycle-sludge removal system. 

Sludge Removal. Metal fines can catalyze reactions that lead to decomposition of the solution, and sludge buildup. Paint chips can absorb solution and swell, forming a viscous sludge. Routine maintenance should be performed to remove sludge. Continuous filtering is often helpful. 

Oil and sludge removal from such shallow basins would be difficult however, bv lilting the basins at 45° to 50 from horizontal, separation of the oil and sludge can be achieved... 

Landfill leachate Non-hazardous wastec Sewage/sewage treatment Sewage-Mixed industrial, commercial, and domestic -No sludge removal - With sludge removal Sludge-Mixed industrial, commercial, and domestic -CEPT... 

Lagoons are often preceded by septic tanks or aerobic units in order to provide a more acceptable influent to and minimize sludge removal from the lagoon (5). 

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