Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Floes formation

To improve magnesium reduction, which also improves siHca reduction in cold process softening, sodium aluminate may be used. The sodium aluminate provides hydroxyl ion (OH ) needed for improved magnesium reduction, without increasing calcium hardness in the treated water. In addition, the hydrolysis of sodium aluminate results in the formation of aluminum hydroxide, which aids in floe formation, sludge blanket conditioning, and siHca reduction. [Pg.259]

At higher pH values the amide groups are unproton-ated [106], while the carboxylate groups [7,11] and quaternary ammonium groups [61] are ionized. Alternatively, the interaction can occur between these cations of the solution and the active groups of the polymer chains for floe formation. [Pg.130]

Zinc also may be produced by electrolysis of zinc sulfate solution. The zinc oxide in the roasted concentrate is leached with sulfuric acid. The oxide is converted to soluble zinc sulfate. Impurity metals, such as iron, copper, cadmium, arsenic, tin, and cobalt are removed by precipitation, floe formation, and other methods. The purified zinc sulfate solution is electrolyzed using aluminum cathodes and lead anodes. Zinc is deposited on the cathode. [Pg.982]

The most common cause of floe formation in a clear soft drink is microbiological growth (yeasts). If this occurs the yeasts can be identified by... [Pg.238]

Figure 2. Distribution curves of aggregates of AS HPP by their size at different time of floes formation. Time, min 1 (1) 3 (2) 10 (3) and 20 (4). Figure 2. Distribution curves of aggregates of AS HPP by their size at different time of floes formation. Time, min 1 (1) 3 (2) 10 (3) and 20 (4).
Two other fining proteins must be mentioned, namely egg albumin and casein (more precisely egg proteins and cow milk proteins). However, in both cases the floe formation is due to the insolubility of the fining protein at pHs below their pis, hence the fining aefion is nol fhe same as in the case of gelatin which is soluble at all pHs, even at its isoelectric pH. [Pg.135]

In phosphatation, the high-density liquor is heated to 60 to 70°C and treated with small amounts of phosphoric acid and sufficient milk of lime to bring the pH to 7.2 to 7.8. After the addition of lime, the temperature of the liquor is raised to 90°C and time is allowed for floe formation. Some air is injected (blown) into the system for entrapping air bubbles into the floe. The precipitate then floats to the surface as a scum and is scraped off without any filtration. The phosphate clarifiers have many sizes and shapes. Essentially all the present-day systems are based on the Williamson patents of 1918 in which the liquor is impregnated with air, then heated in a suitable vessel so that the insoluble material floats and does not depend on filtration. Some of the best-known clarifiers are Williamsons, Bulkley-Dunton, Sveen-Pederson, and Talo clarification systems. [Pg.182]

Tables 3 and 4 (column 4) give the influence of the different mixing parameters and of the water conditions on the total floe build-up time. From the results it is clear that a more intense mixing during coagulation (Gpapy) and during flocculation accelerates floe formation. The choice of the duration of... Tables 3 and 4 (column 4) give the influence of the different mixing parameters and of the water conditions on the total floe build-up time. From the results it is clear that a more intense mixing during coagulation (Gpapy) and during flocculation accelerates floe formation. The choice of the duration of...
Use of PAC helps to stabilize sludge, improve floe formation... [Pg.459]

For reactors in which the dispersion number varies significantly with changing hydraulic loading (i.e., less stable hydraulics) the effectiveness of the floe formation process is more significant than for other reactor types. [Pg.391]

Sedimentation tanks that are characterized by more stable hydraulic regimes are more independent of the effectiveness of the preceding floe formation stage. The slight reduction in removal efficiency of tank C with increasing values on the y-axis does not fit too well into this picture. Characteristics other than those described by collision efficiency factors may be responsible for these effects. [Pg.391]

Two series of observations are recorded in Figure 5 for A/S ratios of 2.8 and 4.6%, respectively. They are shown with data on sedimentation of the same suspensions in a sedimentation tank of a geometry that closely resembles that of the flotation tank. The y-axis, depicting the independent variable floe formation, is quantified again in terms of the calculated coagulation efficiency factor. [Pg.392]

The less rapidly coagulating Al3+ floe system (a = 0.35) is separated in flotation nearly as effectively as the better coagulating Fe3+ floe system (a = 0.59). In fact, this system appears more suitable for flotation than the quite effective polymer floe formation system (a= 0.47), which has been removed to a more satisfying degree in sedimentation. The Fe3+ plus polymer floe system (a = 0.84) shows the best removal efficiency, as it does also in sedimentation units. [Pg.392]

The investigations reported here were aimed at clarifying the interaction between floe formation tendency or floe properties (y-axis ), differently designed and operated separation units (x-axis), and separation efficiency (z-axis). These interactions can be tentatively described in quantitative terms. They can also be illustrated by comparing the efficacy of different separation units for specified suspensions, thus developing rules of thumb for practice. [Pg.393]

Comparing the sedimentation or flotation behavior of differently formed floes, as shown in Figure 5, indicates that the efficiency of a flotation unit of a geometry similar to that of the design D sedimentation tank is noticeably higher for the not so readily coagulating suspension (Al3+). Upgrading inefficient sedimentation seems possible when Al3+ salts are used for floe formation. [Pg.393]

Suspensions treated under conditions in which good floe formation exist are separated with higher efficiency in flotation units. For intermediary conditions of floe formation, sedimentation in well-designed tanks B and C and flotation tank D show comparable overall efficiency in liquid-solid separation. Flotation appears to be less favored than sedimentation if floe formation is accomplished by lower chemical dosages. [Pg.393]

Other authors (7) reported that the Al-type floe is removed better in flotation than in sedimentation. Furthermore, the specific density of aluminum, which is lower than that of iron, is responsible for the better flotation effect. It appears that floe formation in the aluminum system does not provide sufficiently high sedimentation rates, although enough chemicals are available for solid-bubble enmeshment (i.e., good flotation). [Pg.393]

The use of flotation for liquid-solid separation may compensate for some of these limitations of the sedimentation process for suspensions with less optimal floe formation. This effect was observed in particular if suspensions were coagulated with Al3+. [Pg.394]

The better the hydraulic performance of the tank (expressed as dispersion number) and the better the floe formation (expressed as collision efficiency factor), the smaller are the differences in efficiency between the sedimentation and flotation processes. [Pg.394]


See other pages where Floes formation is mentioned: [Pg.35]    [Pg.35]    [Pg.36]    [Pg.183]    [Pg.85]    [Pg.246]    [Pg.11]    [Pg.70]    [Pg.653]    [Pg.150]    [Pg.5]    [Pg.363]    [Pg.171]    [Pg.174]    [Pg.145]    [Pg.246]    [Pg.278]    [Pg.1840]    [Pg.629]    [Pg.183]    [Pg.3604]    [Pg.3606]    [Pg.290]    [Pg.291]    [Pg.291]    [Pg.1165]    [Pg.540]    [Pg.385]    [Pg.387]   
See also in sourсe #XX -- [ Pg.130 ]

See also in sourсe #XX -- [ Pg.137 ]




SEARCH



Aluminum, floe formation

Floes

© 2024 chempedia.info