Clarification processes

Water Clarification. Process water that aeeds to be clarified comes from several differeat sources ia the recycling mill rejects from screeas and mechanical cleaners rejects from washers, thickeners, and flotation cells water that drains from the pulp as it is converted iato paper oa the paper machine (white water) and water from felt washers. These waters contain different dissolved chemicals and suspended soflds and are usually processed separately. 

Coagulation involves neutralizing charged particles to destabilize suspended soflds. In most clarification processes, a flocculation step then follows. Flocculation starts when neutralized or entrapped particles begin to colUde and fuse to form larger particles. This process can occur naturally or can be enhanced by the addition of polymeric flocculant aids. 

In most water clarification or softening processes in which coagulation and precipitation occur, at least a portion of the clarified water is filtered. Clarifier effluents of 2—10 NTU may be improved to 0.1—1.0 NTU by conventional sand filtration. Filtration ensures acceptable suspended sohds concentrations in the finished water even when upsets occur in the clarification processes. 

A CLOSER LOOK AT THE MECHANICAL CLARIFICATION PROCESS AND THE CHEMISTRY OF CLARIFICATION... 

KUtrung,/. clarification, clarifying, clearing. Klkrungs-fass, n. — Klarfass. -mittel, n. = Klarmittel. -prozess, m. clarification process. -salz, n. clearing salt. 

Flocculation or clarification processes are solids-liquid separation techniques used to remove suspended solids and colloidal particles such as clays and organic debris from water, leaving it clear and bright. Certain chemicals used (such as alums) also exhibit partial dealkaliz-ing properties, which can be important given that the principal alkaline impurity removed is calcium bicarbonate—the major contributory cause of boiler and heat exchanger scales (present in scales as carbonate), although closely followed by phosphate. 

PHOSPHATATION A clarification process where phosphoric acid or a soluble phosphate is used with lime and heat. The impurities are removed by flocculation, flotation, and surface scraping. 

Removal of Total Suspended Solids and Oil and Grease from Coil Coating Wastewater by Emulsion Breaking and Clarification Process... 

Sedimentation and dissolved air flotation are the most common clarification processes for removal of precipitates. Either sedimentation or flotation is often preceded by chemical coagulation or precipitation, which converts dissolved pollutants to a suspended form, and by flocculation, which enhances clarification by flocculating suspended solids into larger, more easily separating particles. Simple sedimentation normally requires a long retention time to adequately reduce the solids content. The detention time of dissolved air flotation, however, is much shorter. When chemicals are used, retention times are reduced and clarification removal efficiency of either sedimentation or flotation is increased. A properly operated clarification system is capable of efficient removal of suspended solids, metal hydroxides, and other wastewater impurities.10-12... 

Wong, J.M. and Chang, F.Y., Application of High-Rate Clarification Processes (DAF, AquaDAF and Actiflo), Technical paper presented at the California AWWA Fall Conference, San Diego, CA, October 6-9, 2003. 

Clarification is the process of agglomerating the solids in a stream and separating them by settling. Chemicals that are commonly added to the clarification process do not contain any of the listed priority pollutants. 

In most Interior Valley winery operations, the wines are racked once. After this racking, the wines are fined. This is a clarification process carried out by use of certain fining agents that cause flocculation and settling out of any cloudiness in wine. In addition, certain colloidal and proteinaceous soluble solids are absorbed by the fining agent. If not removed by fining, these soluble materials may later precipitate out in the bottle and cloud the wine. 

Clarification. All clarification treatments include the addition of lime. Lime increases the pH, stabilizing the sucrose against hydrolysis at high temperatures, and the calcium forms insoluble precipitates with many of the impurities in the raw liquor. Simple liming is rarely used in refining. The important clarification processes are phosphatation and carbonatation, which include combinations of lime with either phosphoric acid or carbon dioxide. 

Cane Sugar Handbook, 12th ed. (Section 5.77) Raw Syrup Clarification Processes, J. C. P. Chen and... 

Although pectic enzymes are used universally by the apple juice industry, the actual clarification mechanism has not been completely elucidated. Endo showed 186, 187) that hydrolysis of pectin, accompanied by a decrease in viscosity of the juice, is the principal step during clarification. Endo separated the clarification process into three phases a pectin fraction is solubilized viscosity decreases and previously col-... 

The clarification process divides the whole juice into two portions (1) the clarified juice and (2) the precipitated settlings, which are the... 

The use of sulfur dioxide in addition to lime makes a better clarification. In this method (sulfitation process), lime is added as usual, but then sulfur dioxide from a sulfur burner is bubbled through the juice. The precipitate is settled as in the ordinary clarification process. The bleaching effect of sulfur makes a lighter-colored sugar. The extra cost of sulfitation, increased sealing in heaters and evaporators, and higher ash in raw sugars are reasons for the discontinuance of this process. 

Filtration is the most straightforward, probably the oldest form of sugar liquor clarification process. Filtration is effected with plate and frame pressure-filters or some type of leaf pressure-filter such as Sweetland filters with stationary suspended circular leaves covered on both sides with filter cloth. A filter aid of some sort (diatomaceous earth, paper pulp, or kieselghur) is essential to the operation. The precipitated calcium carbonate serves as a filter aid in the carbonation process. The liquor is mixed with the filter aid and forced under pump pressure through the fabric, which retains the cake and allows the clear liquor to flow through. The retained sugar in the cake can be washed out with hot water. Filtration is no longer used as the sole means of clarification. The process is used for further clarification of the liquor from a carbonation or phosphatation process. 

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