Flotation is based on the extraction of impurity particles by gas, usually air bubbles(surfacing). Sedimentation-release of impurities from the volume of water being treated under the influence of gravity, Archimedes , and water resistance to the movement of the impurity particle. The resultant of these forces will determine the direction and speed of the impurity particles.

Dear Mrs. Kong Zaleta,

what type of mineral processing is your question aimed at ?

Laboratory or industrial scale (?)

Kind regards

HGD

In diagnosing parasites using concentration methods vary across species of parasite, their morphological form, conditions, size and density. You should also consider the time as some lysis and collapse in a few minutes or seconds making a false-negative result. Flotation method is best used when studying nematodes and large protozoan cysts that needs high specific gravity so it rises in the concentration while debris sinks to the bottom. This method relies on the use of dense solution with appropriate specific gravity, and fewer dense parasite. Sedimentation techniques relies on the use of low density in which parasitic form falls. It used in small parasites that can’t be easily seen in a normal microscope since this method has better sensitivity in determining parasites.

Goal of this sedimentation procedure is the routine recovery of protozoan cysts, helminth larvae, and ova (including operculate and schistosoma eggs). The eggs of hymenolepis nana and the cysts of giardia lamblia and iodamoeba butschii do not show a good recovery ratio.

Reagents and procedure: transfer from ¼ to ½ teaspoon (about 2-4 g) of fresh stool into 10 ml of 5-10% neutral formalin (dissolve in 900 ml dH2O, 4.0 g NaH2PO4 and 6.5 g Na2HPO4, check pH to 7.0, and then add 100 ml of formaldehyde [USP- aqueous solution of 37% formaldehyde with sufficient methanol (5-15%) to prevent polymerization]) placed in adapted container with broad mouth. Close tightly top and mix the stool and formalin thoroughly and let the mixture stand for a minimum of 30 min. for fixation, thus the specimen it's stable for several months. Once that specimen get to laboratory for analysis, 0.3 ml of a 20% Triton X-100, aqueous solution, is added to the slurry, and the mixture it comes before emulsified and after filtered through wet gauze (no more than two layers of nonsterile gauze) directly into a conical 15 ml centrifuge tube to give the desired amount of sediment (0-5 to 1 ml). Add from 3 to 15 ml of ethyl acetate or for the better chemical properties HEMO-DE (Fisher cod. 15-182-507A) at the mixture, stopper the tube, invert and shake vigorously for at least 10-30 sec. Hold the tube so stopper to avoid that the mixture squirts on your face. After from 15 to 30 sec. waiting, carefully removed the stopper. Centrifuge for 10 min. at 500 g or 1200-2500 rpm for 5-10 mins. Four layers will result in the tube after centrifugation: a small amount of sediment containing the parasites (if presents) in the bottom of the tube; a layer of formalin solution; a plug of faecal debris top of the formalin layer, and a layer of ethyl acetate at the top. Free of debris plug with at applicator stick and carefully decant the top three layers, leaving the sediment undisturbed. Use a cotton swab to the clean the remnants of ethyl acetate from inside of the tube, for don't reading disturb. Remix the sediment with an applicator stick, transfer a drop to a clean slide, add a coverslip (22x22 mm) and observe microscopically for parasites.