Oil/grease removal

Air flotation is one of the oldest methods for the removal of solids, oil grease and fibrous materials from wastewater. Suspended solids and oil grease removals as high as 99%+ can be attained with these processes. 

Abstract The aim of this work was to study the simultaneous effect of amount of clay, activation temperature, contact time, pH, and size of the adsorbent on the retention of oil-grease thermally activated illite by adsorption. The values obtained for the percentage of oil-grease removed ranged from 93.87% for 110°C up to 66.73% for 900°C. The adsorption experiment showed surface that the stronger heat treatment the most effective adsorption of oil-grease. 

Methylcyclohexanol 2-Nitropropane PPG-2 methyl ether PPG-3 methyl ether Propylene glycol methyl ether acetate Propylene glycol phenyl ether Tetradecene-1 1,1,1-Trichloroethane Tripropylene glycol ethyl ether solvent, oils/fats Decahydronaphthalene solvent, oils/greases removal Perfluoroheptane Perfluorohexane Perfluoropentane solvent, ointments... 

F2 gasoline, diesel, fuel oils C4 - CIS degassing, oil grease removal by detergents... 

F3 motor oils, greases, bunker C, crude oil, etc. oil grease removal followed by alkalis zdetergents... 

Chemical cleaning implies the removal of material from the surface of the specimen by dissolution in an appropriate chemical agent. Solvents such as acetone, carbon tetrachloride, and alcohol are used to remove oil, grease, or resin and are usually apphed prior to other methods of cleaning. Various chemicals are chosen for appheation to specific materials some of these treatments in general use are outlined in the NACE standard. 

Degreasing is a process to remove oil, grease, dirt and swarf (file dust) etc. from a surface. 

The main function of most lubricants is to reduce friction and wear between moving surfaces and to abstract heat. They also have to remove debris from the contact area, e.g. combustion products in an engine cylinder, swarf in metal-cutting operations. Sometimes they have to protect the lubricated or adjacent parts against corrosion, but this is not a prime function of most lubricants. On the other hand, many lubricants do contain corrosion inhibitors and some lubricating oils, greases, mineral fluids and compounds are specially formulated to prevent the corrosion of machinery or machine parts, particularly when these components are in storage or transit. These temporary protectives are described in Section 17.3. 

In general, there are two types of surface contamination (1) organic contamination—such as oils, greases, paint coatings etc. and (2) inorganic contamination —such as rust, oxide films, corrosion products, scale, anodic films etc. Although these two types of contaminant can be removed simultaneously, it is simpler to consider the cases separately. 

The practice of corrosion inhibition requires that the inhibitive species should have easy access to the metal surface. Surfaces should therefore be clean and not contaminated by oil, grease, corrosion products, water hardness scales, etc. Furthermore, care should be taken to avoid the presence of deposited solid particles, e.g. stones, swarf, building materials, etc. This ideal state of affairs is often difficult to achieve but there are many cases where less than adequate consideration has been given to the preparation of systems to receive inhibitive treatment. Acid treatments, notably with 3-5% citric acid, with or without associated detergent washes, are often recommended and adopted for cleaning systems prior to inhibition. However, it is not always appreciated that these treatments will not remove particulate material particularly when, as is often the case, the material is insoluble in acids. 

All metal surfaces such as mild steel should be grit blasted, normally to SA 2-5 as defined in Swedish Standard SIS 055900. If the surfaces are contaminated with oil, grease or a chemical from previously used items, the contamination is usually removed by sweating in steam prior to grit blasting. Concrete surfaces must be clean and dry and any laitence must be removed as it will affect the bond of the lining. Preferably the surface should be grit blasted. 

So far, the discussion has primarily centered around the contamination of condensate due to iron and copper. However, large process industries often produce condensate containing oil, grease, and other contaminants, and these must also be removed because they are not only damaging to the boiler plant waterside, but may can adversely affect condensate polisher components. 

A variety of formulations exist for cleaning organics from burners and other fireside areas. Soot, oil, and grease removers are widely available the formulations are often very specific and can be produced in both aqueous and nonaqueous solvent bases. Nonaqueous solvents commonly include petroleum spirit, naphtha, or odorless kerosene. 

New boilers, heat exchangers, and other equipment must be provided with a PCC program to remove oil, grease, mill scale, pipe-threading compounds, drawing compounds, and other detritus that otherwise prevent the formation of clean, passivated metal surfaces and encourage... 

Cleaning involves the removal of oil, grease, and dirt from the surface of the basis material using water with or without a detergent or other dispersing material. 

Pollutant parameters and their concentrations found in the oily waste subcategory streams are shown in Table 9.9. The oily waste subcategory for the metal finishing industry is characterized by both concentrated and dilute oily waste streams that consist of a mixture of free oils, emulsified oils, greases, and other assorted organics. Applicable treatment of oily waste streams is dependent on the concentration levels of the wastes, but oily wastes normally receive specific treatment for oil removal prior to solids removal waste treatment. 

Metals, especially the more common iron and steel types, come from the foundry coated with oil, grease and most often a generous layer of oxide formed on the exposed surfaces. All these materials must be removed from the surfaces and from the pores of the metal to ensure that the oils and greases cannot exude under the increased temperature of vulcanisation, when they become more mobile or volatile. Surface oxides also must be removed for they are often only loosely attached to the metal substrate and will detach themselves under duress in service, after bonding. 

Having disguised each particle of oil or grease, it can readily enter solution while sheathed in its water-attracting overcoat of surfactant. And if the oil particles enter the solution, then the oil is removed from the plate, and is cleaned. 

Brazing fluxes shall be applied to remove oxides and contaminants from base materials to ensure good-quality brazed joints. They remove only surface oxides and tarnish other contaminants (oil, grease, lubricants, and protective coating) must be removed either mechanically or chemically before brazing. 

Adsorption techniques have been successful in removing oil-grease. Clay minerals have been the most widely used absorbent because its cost is low and they can be reached easily. Oil-grease adsorption on various sorbents has been studied by many researchers [1-6]. 

Figure 20.5 shows the effect of contact time and percentage adsorption oil-grease on the removal by thermally activated illite. 

The removal of fiber/yarn preparation during the pretreatment of knitted material can be identified as an important source of oil, grease, and silicones in wastewater. A general treatment can be performed by means of precipitation, flocculation, membrane filtration, and evaporation. 

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