Pretreatment grease removal

The pretreatment unit operations wluch may be necessary for various types of treatment processes are slmwn in Table 14. In addition to screening and free-floating grease removal, various in-plant control practices, such as blood recovery, and separate handling of paunch manure as solid waste would greatly reduce the waste constituents in process wastewaters. When meat product wastewater is combined widi domestic wastewater, pretreatment should include equalization to reduce organic and hydraulic fluctuaticHis. The equalization basin should be aerated to prevent septic conditions. 

Pretreatment is a series of physical and chemical processes to precondition the wastewater and remove some wastes. The treatment is usually arranged in the following sequence screening flow equalization and neutralization optional fat, oil, and grease (FOG) separator optional acidification ... 

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. 

Pretreatment is the removal of stones, sand, grit, fat/grease, rags, plastics, etc. using mechanical processes such as screening, settling, or flotation. 

Following the surface preparation, it is the task of surface pretreatment to generate the adhesive forces on the adherend surfaces required for the development of a strong bonded joint. Since almost all materials interesting for bonding have the property to cover the surfaces with impurity layers (oxides, rust, dust, greases), those layers have to be completely removed prior to adhesive application, since otherwise failures in the development of the adhesive forces will occur (Figure 7.5). 

Ultrafiltration is currently used as a pretreatment technique for the removal of greases, oils and colloids before effluent is passed through an ion-exchange column for final clean-up. Otherwise, there are no other uses in industry for the direct use of ultrafiltration as a single clean-up step for metals. 

Iron passivity and Iranspassivily were investigated in aqueous solutions of either sodium sulfate (Na2S04) or potassium nitrate (KNO3) after different pretreatments. In all cases, ti first treatmmit consisted of an alkaline rinsing in order to remove grease fi om the sur ce. Then, we conqiared the effect of treatm t in various aqi us n dia ... 

The simplest type of surface pretreatment for aluminum or any metal is to solvent-wipe or vapor-degrease the as received metal. This will obviously remove most kinds of loosely adhering dust or dirt or other atmospheric deposits as well as organic greases, lubricants, and... 

Before any pretreatment is performed, the surface should be washed with an alkali surfactant and rinsed with clean water to remove oils and greases that may have accumulated. Regardless of which pretreatment is used, testing for chlorides (and indeed for all contaminants) is essential after pretreatment and before application of the new paint. 

The technological implications of the above points are basically that, to attain good initial joint strengths, in many instances no surface treatment is necessary and even when the state of the incoming substrate material is such that relatively thick layers of protective greases, mill scale, etc. need to be removed then a simple degreasing and, possibly, mechanical abrasion, pretreatment are all that is required. 

The combination of sodium gluconate with sodium carbonate or with sodium hydroxide solutions are useful for removing grease and corrosion from aluminum and rust from steel. Gluconate is also useful in the pretreatment of certain surfaces, e.g., in the galvanic deposition of nickel-cobalt brazing surfaces onto aluminum. Concrete manufacturers... 

---