Chemical flotation-filtration system

Flotation-Filtration System Using Conventional Chemicals. 249... 

Flotation-Filtration System Using Innovative Chemicals... 

Another innovative flotation-filtration wastewater treatment system adopts the innovative use of the chemical ferrous sulfide (FeS), which reduces the hexavalent chromium and allows separation of chromium hydroxide, nickel hydroxide, and ferric hydroxide in one single step at pH 8.5. Figure 6.7 illustrates the entire system. Again, a DAF-filtration clarifier plays the most important role in this wastewater treatment system. 

FIGURE 6.6 Innovative flotation-filtration wastewater treatment system using conventional chemicals. 

A combined flotation-filtration unit, shown in Figure 6.8, is an advanced water clarification system, using a combination of chemical flocculation, DAF, and rapid sand filtration in one unit. The average processing time from start to finish is less than 15 min.15-57-58... 

The innovative flotation-filtration wastewater treatment system (Figure 6.6) using conventional chemicals has the highest flexibility and best performance. When desirable, the innovative chemical FeS or equivalent can also be used. 

An innovative potable filtration plant with a design capacity of 1.2 MGD has been reliably serving 10,000 residents and tourists in the town of Lenox, Massachusetts, USA, since July 1982. Its process system consists of chemical flocculation, dissolved air flotation, and automatic backwash and sand filtration. It substantially improves upon the conventional flocculation, sedimentation, and filtration system in performance, capability, operation, maintenance, and energy use (19 2). 

Like all unit chemical processes, the RO is usually not capable of standing entirely by Itself. The important thing to remember is that a system must be developed to give a complete product. In the case of Cummins, the complete system includes dissolved air flotation, anthracite/sand filtration, activated carbon filtration and RO. In the case of Whitestone Chemical, the complete system includes RO and a cleaning regimen to maintain the RO at the required permeate flow rate. Time will tell which of these alternatives has the best economics. The economics and the proper system using RO are both dependent on the problem that requi res a solution. 

With a chapter on particle-particle interaction (coagulation) the characteristics of particles and colloids as chemical reactants are discussed. Since charge, and in turn the surface potential of the colloids is important in coagulation, it is illustrated how in simple cases the modelling of surface complex formation permits the calculation of surface charge and potential. The role of particle-particle interaction in natural water and soil systems and in water technology (coagulation, filtration, flotation) is exemplified. 

L. K. Wang, Reduction of Color, Odor, Humic Acid and Toxic Substances by Adsorption, Flotation and Filtration. Annual Meeting of American Institute of Chemical Engineers, Symposium on Design of Adsorption Systems for Pohuhon Control. Philadelphia, PA, 1989. 

TREATABILITY/REMOVABILITY Process, Removable Range (%), Avg. Achievable Cone. (pg/L)) Coal flotation with chemical addition (calcium chloride polymer), 76, 260 Filtration, 50->94, 3.8 Sedimentation with chemical addition (alum, lime), >99, <0.05 Sedimentation with chemical addition (alum), 25->50, <12 Aerated lagoons, >96, <10 Granular activated carbon adsorption, >99, <0.05 in a continuous flow activated sludge system, about 100% removal (78% biodegradation, 22% stripping) was reported... 

Bubbles are formed in the sintered glass as air, or other suitable gas (Nj, CO2, etc.) is bubbled through the solution containing the solid suspension. A flotation agent (a suitable surface-active agent) is added and the air is bubbled. Surface-active pollutants in wastewater have been removed by bubble film separation methods. Especially very minute concentrations are easily removed by this method, which is more economical than more complicated methods (such as active eharcoal, filtration, and other chemical methods). This method is now commercially available for such small systems as fish tanks, etc. (Birdi, 2009, 2010a). The principle in this procedure is to create bubbles in wastewater tank and to collect the bubble foam at the top. Figure 1.56. 

But due to flotation (bubble-film extraction), the products of bacterial metabolism and the products of bacterial degradation together with other water contaminants are ranoved continuously from recirculation flow through the bubble-film extractor. As a result, another positive feedback is realized in filtration-flotation system. The essence of this effect lies in the inhibition of vital functions of bacteria with increasing microbial metabolite concentration according to the law of chemical kinetics. And in accordance with the same law, bacterial activity is increased as the products of bacterial metabolism are removed from treated water [20]. Thus, we are able to add one more component, namely, AK, to the magnitude (/fj + AK2). The component AK represents the increase in biofiltration efficiency due to bacterial inhibitors removed by means of bubble-film extraction. In such a way, the resulting rate constant of the process takes the form ( fi + AK2 + AKi). 

Stock usually the best dewatering stock component used at the paper machine is selected in order to Hmit the size of the disc filter. In addition to cloudy and clear filtrate, disc filter save-aU applications also produce a superclear filtrate with very low solids content This superclear filtrate is used as a fresh water substitute for spray apphcations in the paper machine. The clear filtrate is stored in a buffer tank. The cloudy filtrate is usually fed directly back to the inlet of the disc filter, the used sweetener, including the recovered stock, is fed back to the thick stock in the approach flow system. DAF (dissolved air flotation) type save-alls are used in older machines and nowadays when a certain degree of ash and fines removal from the process is demanded. In this case, the sludge of the DAF is rejected. The advantages of a disc filter save-all compared to a DAF save-all are higher filtrate quahty, no chemical consumption and less space requirements (see Sections 4.2.62 and 4.2.9). 

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