Filter ripening

Filter Ripening In water filtration, the process in which deposition of an initial layer of particles causes the filter surface to take on a nature more similar to the particles to be removed. This process enhances the filtering (hence, removal) of the particles. 

Particle concentration and size distribution in raw water have extensive and complex effects on the performance of individual treatment units (flocculator, sedimentation tank, and filter) and on the overall performance of water treatment plants. Mathematical models of each treatment unit were developed to evaluate the effects of various raw water characteristics and design parameters on plant performance. The flocculation and sedimentation models allow wide particle size distributions to be considered. The filtration model is restricted to homogeneous suspensions but does permit evaluation of filter ripening. The flocculation model is formulated to include simultaneous flocculation by Brownian diffusion and fluid shear, and the sedimentation model is constructed to consider simultaneous contacts by Brownian diffusion and differential settling. The predictions of the model are consistent with results in water treatment practice. 

The Standard Plant. The results presented in Figure 9 for the standard treatment plant indicate that effective removal (85% ) of suspended solids is produced by the flocculation-sedimentation process. Filter run length, as indicated by the time it takes to reach a head loss of 250 cm, is 28 hr. Filter ripening is rapid, and essentially complete removal of suspended solids is accomplished by the Alter throughout the run. The settling eflBciency, head loss development, and filtrate quality predicted by the model are consistent with typical water treatment plant performance. 

Ripened Ume fruit (P. mume) was taken and the fleshy cover was removed to obtain the seeds. The upper layer of the seeds was cracked with a hammer to give the soft kernels inside. Those kernels were collected and crushed in the process homogenizer at 4 °C, with 10 mM potassium phosphate buffer, pH 6.0, to give a milky suspension. The suspension was filtered through four layers of cheesecloth to remove the insoluble part. The HNL activity shown by P. mume extract was 6.9 U mg in the milky suspension. ... 

Fig. 12.9. Flow diagram for manufacture of cellulose acetate yarn (1) wood pulp (2) attrition mill (3) cyclone (4) 35% acetic acid (5) pretreater (6) magnesium acetate solution (7) precooled acetylation mix (8) sulfuric acid (9) acetylator (10) ripener (11) steam (12) blender (13) precipitator (14) dilute acetic acid (15) hammer mill (16) water (17) rotary screen washer (18) squeeze rolls (19) drying oven (20) blender (21) storage bins (22) silos (23) weight bins (24) acetone (25) wood pulp (26) pigment (27) mixers (28) hold tanks (29) filter press (30) pump (31) filter (32) air (33) jet (34) acetone recovery (35) oiling wheel (36) feed roll (37) bobbin (38) inspection.

Documented oil extraction dates back to 1650 b.c. when ripened olives were pressed by hand in Egypt using wooden pestles and stone mortars. The extracted ohve oil was hltered through goat hair filters and used as a lubricant. Sesame, hnseed, and castor oils were recovered in Egypt by hand pressing as far back as 259 b.c. (1). 

Consideration of this ripening process provides an explanation for the apparent delay in the travel of the 0.23- and 0.91 -pm particles relative to the 1.35-pm particles and the chloride tracer. The largest particles act as collectors or filter media for the smaller ones. Although not stated in the paper by Harvey et al. (1989), these large particles were present in substantially lower number... 

Ghee is a solid fat-based product made in India from cow- or buffalo-ripened milk. It is less perishable than butter and, therefore, more suitable for a tropical climate. Milk is curdled. The curd is then manually churned until it precipitates butter and leaves behind some whey. The butter is then heated on a low flame until a layer of white froth covers the surface. This state indicates the end of the process, and the liquid obtained on filtering the suspension is pure ghee. Ghee is made by simmering unsalted butter in a large pot until all water has boiled off and protein... 

Figure 22.10 Reprinted from Giuliano Gregori, G., Kleebe. H.-J., Readey, D.W, and Soraru, G.D. (2006) Energy-filtered TEM study of Ostwald ripening of Si nanocrystals in a SiOC glass .) J. Am. Ceram. Soc. 89,...

The pulp is first steeped in an aqueous solution of sodium hydroxide (17 18%), which causes the fibers to swell and converts the cellulose to sodium cellulosate, commonly called alkali cellulose or white crumb. After steeping, the swollen mass is pressed to obtain a precise ratio of alkali to cellulose and then shredded to provide adequate surface area for uniform reaction in subsequent process steps. The alkali cellulose is aged under controlled conditions of time and temperature to depolymerize the cellulose by oxidation to the desired DP prior to reacting with carbon disulfide to form sodium cellulose xanthate. The xanthate, which is a yellow to orange crumb, is dissolved in dilute sodium hydroxide to yield a viscous orange-colored solution called viscose. The solution is filtered, deaerated, and ripened to the desired coagulation point (called salt index) appropriate for spinning. 

Figure 10.69. These are automatic filters and are normally used for the first filtration to remove objectionable particles in such a way that the backwash is recycled, thereby reducing waste and extending the life of second stage and other filtration steps used to pohsh the viscose. Because these filters are automatic, there is a significant reduction in the labor required to change and dress filter presses. The filtered viscose is next pumped to a ripening tank.

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