Significance Coagulation

The pathogenic mechanism that affects factor VIII/ vWF complex has not been elucidated. There may be accelerated elimination after attachment of factor VIII/ vWF complex to starch molecules. The significant fall in factor XI and factor XII shows that impairment of the intrinsic system of coagulation is not limited to factor VII/ vWF complex (14). Even a small volume of 6% etherified starches (average molecular weight 450 kDa 2.5 litres in 3 days) can cause a significant coagulation disorder (15). 

Products prepared in this manner typically contain significant quantities of coagulation Factors II, VII, and X and other proteins as well as Factor... 

Table 1 Hsts a number of common inorganic coagulants. Typical iron and aluminum coagulants are acid salts that lower the pH of the treated water by hydrolysis. Depending on initial raw water alkalinity and pH, an alkah such as lime or caustic must be added to counteract the pH depression of the primary coagulant. Iron and aluminum hydrolysis products play a significant role in the coagulation process, especially in cases in which low turbidity influent waters benefit from the presence of additional colHsion surface areas.

Polymeric coagulants do not affect pH therefore, the need for supplemental alkalinity, such as lime, caustic, or soda ash, is reduced or eliminated. Polymeric coagulants do not add to the total dissolved soHds concentration, eg, 1 ppm of alum adds 0.45 ppm of sulfate ion (expressed as CaCO ) the reduction ia sulfate can significantly extend the capacity of anion-exchange systems. 

For color removal, ozonization has achieved the greatest practical importance as seen by the plethora of articles and patents on this method (147—163). Ozonization in combination with treatments such as coagulation, flocculation, carbon adsorption, uv irradiation, gamma radiation, and biodegradation significantly and successfully remove dye wastes and reduce costs (156,164—170). 

The choice of coagulant for breaking of the emulsion at the start of the finishing process is dependent on many factors. Salts such as calcium chloride, aluminum sulfate, and sodium chloride are often used. Frequentiy, pH and temperature must be controlled to ensure efficient coagulation. The objectives are to leave no uncoagulated latex, to produce a cmmb that can easily be dewatered, to avoid fines that could be lost, and to control the residual materials left in the product so that damage to properties is kept at a minimum. For example, if a significant amount of a hydrophilic emulsifier residue is left in the polymer, water resistance of final product suffers, and if the residue left is acidic in nature, it usually contributes to slow cure rate. 

Fiuoride F- Not usually significant industrially Adsorption with magnesium hydroxide, calcium phosphate, or bone black Alum coagulation reverse osmosis electrodialysis... 

Prechlorination (before the clarifier) significantly improves the removal of organics as well as reducing the coagulant demand. 

The proper selection of polymers for coagulation has a significant impact on organic removal. 

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