Alum coagulant

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

Fluoride F Few major industrial water problems Reduces dental decay Alum coagulation Magnesium Hydroxide reaction Anion exchange Membrane separation... 

Reverse osmosis plants also are not immune from silica fouling, and where the raw water source naturally contains relatively high levels of silica, good pretreatment of the RO FW is a prerequisite. To reduce fouling of RO membranes by silica, pretreatment by acid adjustment, alum coagulation, and filtration usually is provided. 

Bose, P., and Reckhow, D. A. (2007). The effect of ozonation on natural organic matter removal by alum coagulation. Water Res. 41,1516-1524. 

Carry-over and overfed of alum (aluminum sulfate) coagulants, post-precipitation of alum coagulants due to poor pH control, and naturally-occurring aluminum silicates are responsible for aluminum fouling of RO membranes. Alum feed is usually employed on surface waters where clarification is the first pretreatment step. The overfed of alum occurs when the raw water turbidity increases. Many operators will continue to add alum past the point called for by stoichiometry. Carry over occurs when the clarifier is not operated properly. 

Example 6.2 By considering the criterion for effective mixing, the volume of a rapid-mix tank used to rapidly mix an alum coagulant in a water treatment plant was found to be 6.28 m with a power dissipation of 3.24 hp. Assume air is being provided at a rate of 1.12 m per m of water treated and that the detention time of the tank is 2.2 min. Calculate the pressure at which air is forced into the diffuser. Assume barometric pressure as 101,300 nW, the depth from the surface to the diffuser as 2 m, and the temperature of water as 25°C. 

Upon satisfaction of the natural alkalinity, other alkalinity sources may be used such as lime, caustic soda, and soda ash. Also, as in the case of alum coagulation, alkalinity requirements are usually expressed in terms of CaC03. Therefore, we also express the reactions of the ferric salts in terms of calcium carbonate. The respective chemical reactions are ... 

FIGURE 34.16 Visual comparison of recovered alum coagulant from the AWTP residuals by acid digestion process (a) and DMP (b). 

Coagulants may be either organic such as polyelectrolytes or inorganic such as alum. Coagulants can be used alone or in conjunction with flocculants to improve the performance of the flocculant or reduce the quantity oF the flocculant required. In some systems, where a flocculant has been used in an upstream process, a coagulant may be needed to allow additional flocculant to be effective. 

We did not expect that the removal of dioxin from well and runoff water by alum coagulation and flocculation would be effective, as there is little or no suspended organic phase to act as a carrier for dioxin. This problem was solved by adding a high molecular weight polymer that would be adsorbed to and carried down with the floe. Partition of dioxin into the polymer is so favored that parts per million levels of polymer should remove most of the dioxin. The results of jar tests to find the optimum level of polymer, at a fixed 100 ppm level of aluminum are given in Table III. 

An interesting example of the application of the isotherm model comes from a case study of two coagulation utilities that utilize the same river as their water source, with the plant intakes only a few miles apart. One utility practices alum coagulation while the other uses ferric chloride. These utilities participated in a year-long project where once a week they reported raw water quality (pH and temperature) and treatment conditions (coagulant dose and pH) and collected influent and treated water samples for arsenic analysis. 

Pre-treatment ACH coagulation, Kme, CO2 30 pm drum screen CIO2, coagulation-flocculation w/ alum PAC, KMnOa, alum, Ume, FeCls, CI2. NH3 PAC. H2SO4, FeS04 CI2, alum coagulation, polymer, sand filter... 

Gorezyea, B. and Ganezarezyk, J. (2001). Fractal analysis of pore distributions in alum coagulation and activated sludge floes. Water Pollut. Res. J. Can., 36, 687-700. 

Microwave-assisted Ag-g-PAM grades show better flocculation efficacy than conventional and microwave-initiated technique. Flocculation curves of comparative grades (Ag- -PAM 2 (C), Ag-g-PAM 2 (M.I), and Ag-g-PAM (M.A)) in wastewater with respect to agar and alum (coagulant) are graphically represented as in Figure 3.11. 

Common chemicals are available more efficient than alum coagulation on weight basis Chemicals are available commercially Komgoldm, et al. (2001) Mohan et al. (2007) Tunaeia/. (2013)... 

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