Coagulation value

Coagulation value, is the concentration of a coagulant that effects a given amount of coagulation of a colloidal, or other dispersed system. 

Laboratory parameters Like in the upper GIB, certain parameters are initially important, such as haemogram, haematocrit, blood group, coagulation values, electrolytes, plasma urea, creatinine, Allgower-Burri index, (s. 

N05. Milliii(ranis of HCl per liter of milk. Time for coagulation. Value of the xennK. 

The inverse phenomenon of coagulation is peptization. It occurs when the precipitate passes into a colloidal solution. (Recall that the colloidal state of matter is characterized, among other properties, by a certain range of particule sizes 1 nm-0.1 p.m.) This may occur if the electrolyte concentration in the supernatant liquid goes below the coagulation value. These considerations may be summarized by the scheme... 

Note Some of Grahame s values for and included in this table. For a common cation, the sequence of anions in order of increasing adsorption is similar to that of the Hofmeister series in coagulation studies, and it is evident that specific adsorption properties are involved. 

Color can be removed effectively and economically with either alum or ferric sulfate at pH values of 5—6 and 3—4, respectively. The reaction is stoichiometric and is a specific reaction of the coagulant with the color to form an insoluble compound (17). The dosage required may be as high as 100—150 mg/L (380—570 mg/gal). Raw-water colors may be as high as 450—500 units on the APHA color scale. The secondary MCL (maximum contaminant level) for color in the finished water is 15 units, although most municipal treatment plants produce water that seldom exceeds 5 units. 

Both ions can be removed by oxidation and subsequent filtration. Aeration is adequate for iron(II) oxidation at above pH 6, but the oxidation of manganese(II) is much too slow, even at higher pH values, for effective removal. Potassium permanganate or chlorine dioxide is frequently used for the oxidation of manganese however, their use must be foHowed by coagulation prior to filtration because of the formation of coHoidal Mn02. 

Elocculants and coagulants are sometimes used as pretreatments before dewatering. The market for flocculants and coagulants for water and wastewater treatment in the United States for 1989 was about 250 million, or 68,000 t, provided by 18 companies. In Europe, 22,000 t of flocculants and coagulants, made by 15 companies, had a market value of 115 million. In Japan, 12 companies made 23,000 t, valued at 184 million (150). 

Fest-werden, n. solidification coagulation, -wert, m. fixed value, constant, -zahl, /. fixed number, constant. 

Coagulant aids may be used to improve the filtration of floes, but these are generally only of value if sufficient residence time is available for coagulation to occur before the water enters the filter. 

Filter alum (aluminum sulfate) A12(S04)3 18H20 was widely used as an external coagulant (at pH values of 5.8-6.8) and continues to be available today. It was generally supplied as alum bricks, but usually is supplied today in granular or concentrated liquid form. 

Copperas [green vitriol or ferrous sulfate (FeS04 7H20)] was also employed as an external coagulant (at pH values of approximately 7.7). It forms a turbid precipitate, and when oxygen is present (as is usual), a slimy precipitate of ferrous hydroxide also may form in addition to ferric hydroxide ... 

Blood coagulation tests are usually ordered before and during heparin tiierapy, and die dose of heparin is adjusted to die test results. Optimal results of therapy are obtained when the APTT is 1.5 to 2.5 times the control value The LMWHs do not require close monitoring of blood coagulation tests. 

While Fe- and Mn-oxides certainly are important in the binding and transport of the trace metals in the estuarine system, organic matter appears to play a dominant role in the coagulation step. For instance, adjustment of the solution pH to values where humics normally precipitate (pH = l to 3) causes all the components (Fe and Mn, organics, and trace metals) to coagulate into filterable particles. By contrast, adjustment of the pH upward, which would normally favor precipitation of Fe- and Mn-oxides, has no effect. In view of this it is not... 

---