Basic Pretreatment Processes

Control of waterside chemistry starts in the pre-boiler section because the lack of, or inappropriate methods for, water treatment creates significant operational difficulties and impacts the economics of the entire process from start to finish. 

All boiler plants, irrespective of design, size, pressure, or location, need as a minimum to be supplied with RW of a basic good quality that is consistently clean and clear throughout the seasons. Further treatment may be necessary. 

Raw water essentially should be free of suspended matter, natural organics, iron, manganese, and sulfur gases. Ideally, it should also be low in hardness, alkalinity, silica, and bacteria and have a pH level of approximately 7 to 8. 

Pretreatment processes should not be regarded as impurity-specific, stand-alone methodologies because, typically, each form of water impurity may be removed by more than one type of process and individual technologies can be modified to deal with particular RW chemistries. 

In practice, for any specific boiler application, the various pretreatment and purification techniques employed are incorporated in a sequential train to provide the most cost-effective or operationally effective treatment solution. 

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During the ensuing five years, a number of pitches were developed as carbon fiber precursors through use of various pretreatment techniques (4-9). We explored four basic pretreatment processes, sometimes in combination (a) polymerization and/or... 

Processes for the bioproduction of ethanol from cellulosic materials have been studied extensively. Some of the process steps are specialized and beyond the scope of this chapter. However, there are many recent review articles dealing with some specific subjects. Basically, the processes consist of a number of steps. They are availability and collection of raw feedstock [20], size reduction, pretreatment, fractionation of biomass components, enzyme production [21, 22], saccharification, enzyme recycle [23, 24], pentose fermentation, improvement of pentose-fermenting biocatalyst, overcoming of product inhibition, overcoming inhibition by substrate-derived inhibitors, ethanol recovery [25], steam generation and recycling [26], waste treatment, and by-product utilization. 

Will the basic metal be adversely affected by the pretreatment process solutions ... 

Although there have been few changes in the basic anodising practices, and sulphuric acid is the electrolyte used in most plants, there have been many developments in the pretreatment, colouring and sealing processes associated with anodising. 

Although EDI may be used as a process for the production of basic pure water, in practice it suffers from the organic fouling potential of resins and the scale fouling potential of ED when higher TDS water sources are utilized. Appropriate pretreatment is therefore required. As a consequence, EDI is best suited for the production of very pure and ultrapure water by acting as a polisher to follow bulk water deionization by RO. Under these circumstances, it competes with both doublepass RO and MB units. 

The process is basically a rotary kiln design. Waste is first pretreated and then inserted in the rotary kiln, where it is incinerated with air. The chlorinated hydrocarbons are converted into H2O, CO2 and HCl. After that, in a wet scrubber the HCl is recovered as aqueous HCl. If needs be, natural gas or liquid energy carriers can be added in order to reach the necessary high temperatures in the afterburner. 

Phosphorus is manufactured by the reduction of commercial-quality phosphate rock by coke in an electric furnace, with silica used as a flux. Slag, ferrophosphorus (from iron contained in the phosphate rock), and carbon monoxide are reaction byproducts. The standard process, as shown in Figure 2, consists of three basic parts phosphate rock preparation, smelting in an electric furnace, and recovery of the resulting phosphoms. Phosphate rock ores are first blended so that the furnace feed is of uniform composition and then pretreated by heat drying, sizing or agglomerating the particles, and heat treatment. 

The basic process involves three steps a pretreatment solvent application, actual solvent extraction, and a final drying phase. Pretreatment is done to break the emulsions. The drying phase involves steam heating to recover residual solvent. In some cases a biofilter is used to further treat liquid effluents if present. 

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