IL28626A

IL28626A - Process and apparatus for clarifying contaminated liquids

Info

Publication number: IL28626A
Application number: IL28626A
Authority: IL
Original assignee: Traitement Et Utilisation Eaux
Priority date: 1966-09-28
Filing date: 1967-09-12
Publication date: 1971-08-25
Also published as: NL6713173A; DE1642878C3; GB1200364A; IT1009006B; LU54479A1; FR1501912A; BE702558A; DE1642878B2; ES344259A1; DE1642878A1

Description

Process and apparatus for clarifying contaminated liquids SOCIE E POUR LE DBS Gi27187 This invention relates to the purification and clarification of contaminated in although not of water containing suspended contaminating in make the water suitable for industrial agricultural and in particular are as a rule purified by treatment various liquid or gaseous Since these are generally used in small by volume or in relation to the liquid to be it is important to ensure as rapid and complete a contact as possible between the liquid and the In order to achieve suspended particles of solid matter have to be removed from the treated These particles may have been contained in the liquid before the purifying or they may have been introduced by the The invention has the object to provide a process and an apparatus for purifying and clarifying by which a very rapid action of the purifying if such reagents are and an at least partial separation of suspended particle from the liquid is The consists in a process for the clarification of liquids contaminated with impurities in wherein the contaminated liquid is passed in an narrower upward flow through a vessel containing in part a bed of granular material herein with a speed such as to maintain the bed in a fluidiaed the speed of flow of the wider liquid is reduced in the part of the vessel above the bed so as to allow entrained particles of the granular material to As used in this specification and the the term denotes a solid material chemically inert to the impurities of the liquid to be and of greater specific gravity than this and having a particle size such that it can readily be stirred up by the more rapid flow of the liquid in the narrower part of the vessel so as to form a fluidized be but is not entrained by the liquid at its lower speed of flow in the wider upper part of the Suitable granular especially for the clarification of for hard sand of various filings of iron and of other synthetic Suitable particle sizes for in the range from about 5 to about 500 but this may vary with the nature of both the granular material and the liquid to be The use of purifying reagents is optional but and they may be used primarily for producing or promoting the agglomeration of suspended impurities in order to make the liquid and also for chemical or biological action on the Suitable reagents for coagulants or aluminium ferric ferric ferrous sodium sodium adjuvants such as organic from algae and potato and rice flour paste the nature of an unleavened bread sodium active ben and cationic or synthetic In the nature of the granular the nature of the the degree its the of a practical nature have a bearing on the and maintenance of the fluidized The most appropriate conditions cannot be specified in advance every case as between these different and this will have to be done by She invention also consists in an apparatus fo carrying out the process which apparatus comprises a vessel with conically tapering for containing a bed of granular a pipe for introducing contaminated liquid connected to the bottom end of the and a pipe for removing clarified liquid to the upper end part of the Two embodiments of the its application to the clarification of contaminated are described below by way of example with reference to the accompanying drawings in which Figure 1 is a representation of a first apparatus according to the Figure 2 shows similarly a second apparatus according to the shown The Figure 1 comprises a vessel 1 conically taperin towards its to lowest point of which a pipe 2 for the feed of contaminated water is A pipe for the overflow of the treated water is connected to upper part of the A feed pump 4 the introduction of a reagent into the contaminated water is connected to the pipe In this the reagent is a ferric chloride containing of She contains a bed of granular material 5 up to about half its which in this is magnetite with an average grain size of about The vessel 1 has a retaining grate or the like at its for preventing the granular material 5 from entering the pipe The contaminated water is fed to the bottom part of the vessel 1 in the direction of the arrow F with a speed higher than that necessary to maintai the material 5 in the the pressure required for this purpose being in each For with a vessel 1 having a capacity of 1000 litres and containing tons of granular material speed at the outlet of the pipe 2 is 500 The bed in the state then occupies a volume of about 850 litres and the output of treated water is 20 m She of flow of the water becomes the the higher the water rises in the vessel and its speed of flow drops At a certain indicated at 6 well below the level of the speed of flow has become so slow that the water no longer entrains the material The reagent is injected by the pump 4 into the contaminated before this enters in the vessel at a rate of 12 in the case of this of to admix the water with two or more different reagents which may be added simultaneously or in During the passage of the contaminated water through the fluidized bed any impurities originally contained in the water in a finely divided state are agglomerated to form particlei of much larger This is due on the one hand to the chemical action of the on the other hand to mechanical of the impurities are made to collide with each The water discharged through the pipe 3 then contains the impurities agglomerated into large particles which can be a removed filtering The effect of treatment of the water in the vessel 1 can be verified as The water treated as described in this Example contained initially impurities in suspension and in the form of colloidal organic matter which give it a turbidity corresponding to 60 drops of mastic and a coloration of measured on the At the outlet of the pipe the turbidity remained the but the impurities had agglomerated into flakes and the water carrying these flakes with it had become t After filtration through a sand filter with a grain size of 1 at a speed 10 the water had a turbidity corresponding to 1 drop of and coloration of on the the same contaminated water was directly filtered through the same sand filter without having passed through the vessel the turbidity of the filtered water corresponded to 45 drops of mastic and its coloration was Sometimes the conditions of treatment in the vessel 1 can be so chosen that the agglomeration of the impurities becomes so pronounced that the bed of granular material can retain the impurities and no subsequent filtration is For this purpose the volume of the fluidized bed in the vessel 1 should be that up to a somewhat higher The apparatus shown in Figure 2 comprises a pump 4a for the supply of the same reagent as in Example ferric The water is assumed to have a turbidity corresponding to 600 drops of The vessel la is cylindrical in its upper part and conical in its bottom and it volume per a larger quantity of granular material 5 than in the case of Example The material in this case is anthracite of a mean grain size of 500 microns and a specific surface of 92 Under the impact of the inflowing water a fluidized bed of 100 height and a volume of about 1800 is formed in the vessel The mean vertical speed of the water in the region of the fluidized bed is about 12 but at about 1 meter above the level the speed is about In the water drained through the pipe the turbidity corresponds to 60 drops of mastic In the same apparatus but magnetite of 8 microns grain size and a specific surface of 1500 cm as the granular the turbidity of the purified water corresponded to 55 drops of In order to free the fluidized bed 5 from the agglomerated impurities accumulated therein below the level a pipe 7 is This pipe has a horizontal extension within the vessel la and opens at 8 into a central part of the fluidized bed preferably closer to level 6 than to the The outer branch of the pipe includes a pump 9 which aspirates a part of the mixture of water and of bed particles in the direction of the arrow and delivers it to a cyclone In the latter the impurities separate from the granular material and are removed by a pipe while the entrained grains of material 5 are distance from the mouth 8 of the pipe with the apparatus of Figure 2 the process can also performed similarly as in the case of the apparatus Figure in that only a partial clari ication is carried out in the vessel la and the water is thereafter subjected to a conventional 9 1 insufficientOCRQuality

Claims

CLAIMS lo A process for the clarification of liquids, wherein the contaminated liquid is passed in an upward flow through a narrower vessel containing in itsAowez* part a bed of granular material (as herein defined) with a speed such as to maintain the bed in a fluidized state, the speed of flow of the liquid is wider reduced in the /upper part of the vessel above the bed so as to allow entrained particles of the granular material to settle back to the bed, and the liquid is drained from the upper part of the bed.
2. A process as claimed in Claim 1, wherein one or more reagents, i.e., coagulants, flocculants, adjuvants used for the clarification of liquids, is or are added to the contaminated liquid to be clarified.
3 A process as claimed in Claim 2, wherein the reagent is introduced into the contaminated liquid prior to its entry into the vessel.
4. A process as claimed in Claims 1, 2 or 3> wherein a mixture of the liquid in the course of treatment and of the granular material is tapped off from the fluidized bed, subjected to a treatment for the removal of impurities, e.g., by means of a cyclone, and returned to the vessel.
5. A process as claimed in any one of the preceding Claims, in which the treated liquid is recovered from the vessel while containing the impurities in an agglomerated condition, and is thereafter submitted to a conventional filtering operation.
6. An apparatus for carrying out the process set forth in any of the preceding Claims, comprising a vessel with conically tapering bottom, for containing a bed of granular 28626/2' - 10 - to the bottom end of the vessel, and a pipe for removing clarified liquid connected to the upper end part of the vessel.
7. An apparatus as claimed in Claim 6, including means for injecting a reagent into the feed pipe for the contaminated liquid.
8. An apparatus as claimed in Claims 6 or 7» including mei for cleaning the granular material, which means comprise a pipe extending into the vessel at a level within the fluidized bed into which the pipe opens; a pump in the pipe outside the vessel a cyclone to which the pipe is connected; and a conduit for the return of the cleaned material to the vessel at an appropriate distance from the opening of the pipe extension.
9. Apparatus for the clarification of liquid contaminated with impurities in suspension substantially as described herein and illustrated in Figure 1 and Figure 2, respectively, of the accompanying drawings. RC:CB