WO2003105987A1 - Water treatment device and water treatment method - Google Patents

Water treatment device and water treatment method Download PDF

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Publication number
WO2003105987A1
WO2003105987A1 PCT/JP2003/006811 JP0306811W WO03105987A1 WO 2003105987 A1 WO2003105987 A1 WO 2003105987A1 JP 0306811 W JP0306811 W JP 0306811W WO 03105987 A1 WO03105987 A1 WO 03105987A1
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WO
WIPO (PCT)
Prior art keywords
water
filter layer
sand filter
raw water
filtered
Prior art date
Application number
PCT/JP2003/006811
Other languages
French (fr)
Inventor
Tadayoshi Nagaoka
Original Assignee
Tadayoshi Nagaoka
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tadayoshi Nagaoka filed Critical Tadayoshi Nagaoka
Priority to AU2003240019A priority Critical patent/AU2003240019A1/en
Publication of WO2003105987A1 publication Critical patent/WO2003105987A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C02F1/004—Processes for the treatment of water whereby the filtration technique is of importance using large scale industrial sized filters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/02—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed stationary during the filtration
    • B01D24/10—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof with the filter bed stationary during the filtration the filtering material being held in a closed container
    • B01D24/14—Downward filtration, the container having distribution or collection headers or pervious conduits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/46—Regenerating the filtering material in the filter
    • B01D24/4605—Regenerating the filtering material in the filter by scrapers, brushes, nozzles or the like placed on the cake-side of the stationary filtering material and only contacting the external layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/46—Regenerating the filtering material in the filter
    • B01D24/4605—Regenerating the filtering material in the filter by scrapers, brushes, nozzles or the like placed on the cake-side of the stationary filtering material and only contacting the external layer
    • B01D24/4621—Regenerating the filtering material in the filter by scrapers, brushes, nozzles or the like placed on the cake-side of the stationary filtering material and only contacting the external layer by nozzles acting on the cake side of the filter material, or by fluids acting in co-current direction with the feed stream
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D24/00—Filters comprising loose filtering material, i.e. filtering material without any binder between the individual particles or fibres thereof
    • B01D24/46—Regenerating the filtering material in the filter
    • B01D24/4631—Counter-current flushing, e.g. by air
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/006—Water distributors either inside a treatment tank or directing the water to several treatment tanks; Water treatment plants incorporating these distributors, with or without chemical or biological tanks
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/74—Treatment of water, waste water, or sewage by oxidation with air
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C02F2101/203—Iron or iron compound
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C02F2101/206—Manganese or manganese compounds

Definitions

  • This invention relates to a water treatment device and a water treatment method and, more particularly, to a water treatment device and method capable of treating suspending materials such as clay, bacteria and algae in raw water such as raw water for tap water by oxidizing them by aeration and thereby turning them to flocks with a relatively compact device without employing an oxidizing agent or flocculant.
  • the low speed filtering is a method employed in a case where quality of raw water for tap water is relatively good and stable.
  • raw water is introduced directly to a sand filter layer and passed slowly through the sand filter layer and insoluble and soluble substances in the raw water are oxidized and dissolved by bacteria which grow on the surface of the sand filter layer and also in the sand filter layer.
  • the filtering speed is very slow (4 to 5m per day), it needs a sand filter layer of a vast area and also requires a laborious work for scraping sand of the surface portion of the sand filter layer when clogging of the sand filter layer has taken place.
  • the quick filtering which uses a high filtering speed of 120m to 150m per day needs only a relatively narrow filtering area and can cope with a case where the quality of raw water is not good.
  • suspending materials such as clay, bacteria and algae in the raw water to flocculate by using a flocculant such as aluminum sulfate and to separate and settle these suspending materials in a settling basin before introducing the raw water to the sand filter layer.
  • the water treatment device using a flocculant In the water treatment device using a flocculant, a large amount of flocculant is required and, as a result, the cost for the flocculant is enormous.
  • the water treatment device using a flocculant consists of an aerating basin, a flocculation tank, a settling basin, a sand filter tower and a flocculant tank and, therefore, it requires a complex and large system and a large space.
  • an object of the present invention to provide a water treatment device which has eliminated the above described disadvantages of the prior art quick filtering water treatment device using a flocculant and is capable of treating water by oxidizing and flocculating suspending materials in raw water by a simple and small-sized device without using a flocculant.
  • a water treatment device comprising: a raw water supply tube; a plurality of jet nozzles, each being at one end portion thereof in communication with the raw water supply tube and having at the other end portion thereof a raw water jetting outlet for blowing out the raw water in a jet stream; a sand filter layer container containing a sand filter layer having an upper surface thereof being provided below the jet nozzles with a predetermined interval from the raw water jetting outlets of the jet nozzles; a filtered water outlet provided in the sand filter layer container for taking out water which has been filtered through the sand filter layer; and means for reciprocating the raw water supply tube in a plane parallel to the surface of the sand filter layer.
  • the jet water stream is blown out of the raw water jetting outlet and is struck against the water surface above the sand filter layer disposed below the raw water jetting outlet and a multiplicity of small air bubbles are produced by involving air by the jet stream.
  • vehement aeration takes place in the water and on the surface of the sand filter layer.
  • suspending materials such as clay, bacteria and algae in the water are oxidized and are either flocculated or settled and caught on the surface of the filtering sand of the sand filter layer.
  • the filtered water which has passed the sand filter layer and removed of flocks and other impurities is taken out of the filtered water outlet.
  • flocculation and settling by using a flocculant as a pretreatment before filtering by the sand filter layer becomes unnecessary.
  • the filtering speed of the device according to the invention for catching flocks of oxidized particles on the surface of the sand filter layer is a high speed of 120m to 150m per day which is equivalent to the filtering speed of the quick filtering and, therefore, only a small filtering space is required.
  • the water treatment device comprises means for reciprocating the raw water supply tube in a plane parallel to the surface of the filter layer and, therefore, by operating this means in a state where the water surface is adjusted to a level which is slightly above the surface of the filter layer to reciprocate the raw water supply tube in a plane parallel to the surface of the filter layer, the jet water strea which is blown out of the raw water jetting outlet is struck vehemently against the surface of the sand filter layer which is closed with the flocks etc. and, as a result, the entire surface portion of the sand filter layer is turned over whereby the closed state of the surface of the sand filter layer with the flocks etc. is eliminated and the filtering function of the sand filter layer is restored.
  • the water treatment device further comprises a plurality of clogging-removing bars each of which is provided between adjacent ones of the jet nozzles in such a manner that a tip end portion of the clogging-removing bar is inserted in a surface portion of the sand filter layer.
  • a water treatment device comprises: an air supply tube; a plurality of jet nozzles, each being at one end portion thereof in communication with the air supply tube and having at the other end portion thereof an air jetting outlet for blowing out air in a jet stream; a sand filter layer container containing a sand filter layer having an upper surface thereof being provided below the jet nozzles with a predetermined interval from the air jetting outlets of the jet nozzles; a filtered water outlet provided in the sand filter layer container for taking out water which has been filtered through the sand filter layer; and means for reciprocating the airf supply tube in a plane parallel to the surface of the sand filter layer.
  • suspending materials in the raw water supplied to the sand filter layer are oxidized and flocculated by aeration caused by the jet air stream blown out of the jet nozzles and thereby are trapped on the surface of the sand filter layer in the same manner as in the device blowing out the jet water stream.
  • the function of the jet air stream during reverse washing is also the same as the jet water stream.
  • a water treatment method employing the water treatment device blowing out the jet water stream, comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the jet water stream.
  • a water treatment device as described above further comprising filtered water circulating means for stopping supply of raw water from the raw water supply tube during stoppage of supply of filtered water and returning the filtered water to the raw water supply tube thereby to circulate the filtered water through the sand filter layer.
  • Iron bacteria and other microorganisms five naturally and form their colonies in the sand filter layer. These microorganisms have a function of removing impurities such as iron and manganese in the raw water by oxidizing and absorbing them. According to the invention, it is assumed that, as a result of significant increase in the concentration of dissolved oxygen in the raw water by aeration, activities of these microorganisms also increase and thereby enhance removal of iron and manganese.
  • the filtered water circulating means the filtered water is returned to the raw water supply tube and circulated through the sand filter layer thereby continuing aeration during stoppage of supply of the filtered water when it is unnecessary.
  • the filtered water circulating means comprises ⁇ a filtered water circulating tube for connecting the filtered water outlet with the raw water supply tube; a water supply pump connected to the filtered water circulating tube; a changeover valve provided in the filtered water circulating tube for passing filtered water and stopping supply of water to the filtered water circulating tube during supply of the filtered water and stopping supply of the filtered water and returning the filtered water to the raw water supply tube through the filtered water circulating tube during stoppage of supply of the filtered water; and valve means provided in a raw water supply channel for passing raw water and stopping passage of the filtered water from the filtered water circulating tube during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube during stopping of supply of the filtered water.
  • the filtered water circulating means comprises: a filtered water circulation outlet provided separately from the filtered water outlet; a filtered water circulating tube for connecting the filtered water outlet with the raw water supply tube; a water supply pump connected to the filtered water circulating tube; a valve provided in a tube provided on the side of the filtered water outlet for opening during supply of the filtered water and closing during stoppage of supply of the filtered water; and valve means provided in a raw water supply channel for passing raw water and stopping passage of the filtered water from the filtered water circulating tube during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube during stoppage of supply of the filtered water.
  • the above described water treatment device may further comprise a reverse washing tube disposed in the sand filter layer at a depth which is sufficient for removing foreign matters which have been accumulated in the upper portion of the sand filter layer by reverse washing and also is sufficient for allowing a substantially thick portion of the sand filter layer to exist under the reverse washing tube.
  • a water treatment method employing the water treatment device blowing out the jet water stream and comprising the clogging-removing bars, comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the jet water stream and by the clogging-removing bars.
  • a water treatment method employing the water treatment device blowing out the jet air stream comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while blowing out the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the air jet stream.
  • a water treatment method employing the water treatment device blowing out the jet air stream and comprising the clogging-removing bars, comprising the steps of: generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while blowing out the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the air jet stream and by the clogging-removing bars.
  • a water treatment method employing the water treatment device blowing out the jet water stream and comprising the clogging-removing bars, comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while stopping blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the clogging-removing bars only.
  • a water treatment method employing the water treatment blowing out the air and comprising the clogging-removing bars, comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while stopping blowing out of the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the clogging-removing bars only.
  • a water treatment method further comprising the step of stopping supply of the raw water from the raw water supply tube during stoppage of supply of the filtered water, circulating the filtered water through the sand filter layer by returning the filtered water to the raw water supply tube, and continuing aeration to maintain concentration of dissolved oxygen in the filtered water at a predetermined level.
  • FIG. 1 is a perspective view schematically showing an embodiment of the water treatment device according to the invention
  • FIG. 2 is a sectional view showing positions of the jet nozzles of the embodiment during filtering and during reverse washing;
  • FIG. 3 is a perspective view schematically showing another embodiment of the water treatment device according to the invention.
  • FIG. 4 is a side elevation showing another embodiment of the water treatment device according to the invention
  • FIG. 5 is a perspective view showing another embodiment of the water treatment device according to the invention
  • FIG. 6 is a sectional view showing positions of the jet nozzles during filtering and during reverse washing.
  • FIG. 7 is a perspective view showing a modified example of this embodiment.
  • FIG. 1 schematically shows an embodiment of the invention with a part of the side wall being removed and
  • FIG. 2 shows positions of the jet nozzles of the embodiment during filtering and reverse washing.
  • a water treatment device 1 comprises, as its principal elements, a filter container 3 containing a sand filter layer 2, a raw water supply tube 4, jet nozzles 5 and a raw water supply tube reciprocating mechanism 20.
  • the raw water supply tube 4 made of, e.g., a steel pipe, for supplying raw water to be filtered such as river water to the filter container 3 is connected to an uni-lustrated raw water supply source by means of a hose 27.
  • the raw water is supphed to the raw water supply tube 4 at a predetermined flow rate.
  • the raw water supply tube 4 is disposed above the filter container 3 in such a manner that the raw water supply tube 4 extends in a plane parallel to the surface of the sand filter layer 2 and is reciprocable in a plane parallel to the upper surface of the sand filter layer 2.
  • FIG, 1 shows a state of the raw water supply tube 4 in the reciprocating motion in the central portion of the filter container 3 during reverse washing.
  • a plurality of jet nozzles 5 are provided in a manner to branch off downward from the raw water supply tube 4.
  • the upstream side end portion 5a of each jet nozzle 5 is fitted in the -raw water supply tube 4 in such a manner that the inside of the jet nozzle 5 communicates with the raw water supply tube 4.
  • a raw water jetting outlet 5b which blows out raw water in a jet water stream.
  • a preferable inner diameter of the jet nozzle 5 is 3mm to 6mm.
  • the sand filter layer 2 is provided with its upper surface being disposed below the jet nozzles 5 with a predetermined interval (e.g., about 35cm) from the raw water jetting outlets 5b.
  • the sand filter layer 2 is made of filtering sand of a uniform grain size and functions to filter the raw water by catching flocks of oxidized substances and other foreign matters in the raw water supphed as a jet stream from the jet nozzles 5.
  • Flow rate of the raw water in the filter container 3, i.e., the filtering speed differs depending upon the degree of filtration of object foreign matter (i.e., permissible concentration of the foreign matters in the filtered water).
  • a filtering speed equivalent to the filtering speed of quick filtering i.e., 120m to 150m per day, is preferable.
  • the sand filter layer 3 is supported by a supporting gravel layer 6 made of gravel of a small grain diameter and a supporting gravel layer 7 made of gravel of a larger grain diameter.
  • the supporting gravel layer 7 in turn is supported by a supporting gravel support plate 8 made of wedge -wires which are arranged in parallel to one another.
  • Under the supporting gravel support plate 8 is provided a lower space 16 to which the filtered water flows from the sand filter layer 2.
  • a filtered water outlet 9 for taking out water which has been filtered through the sand filter layer 2 is provided in a side wall of the filter container 3 facing the lower space 16 of the filter container 3.
  • a reverse washing tube 15 for reverse washing the sand filter layer 2.
  • the reverse washing tube 15 is formed in its upper portion with a plurality of upward opening reverse washing water jetting holes 15a.
  • the reverse washing tube 15 is connected to an unillustrated reverse washing water supply source.
  • a baffle plate 13 made of, e.g., a steel plate, is provided between the raw water jetting outlets 5b of the jet nozzles 5 and the surface of the sand filter layer 2 in one end portion 3d of the filter container 3 in which the raw water supply tube 4 is located during filtering in such a manner that the baffle plate 13 extends in parallel to the raw water supply tube 4 and is disposed beneath the raw water jetting outlets 5b.
  • the baffle plate 13 has its end portions in the longitudinal direction fixed to the inside wall surfaces of side walls 3a and 3b by means of, e.g., welding.
  • a preferable depth of the baffle plate 13 from the surface of the water is about 5cm (i.e., distance from the raw water jetting outlet 5b to the baffle plate is about 10cm).
  • Reverse washing water overflow troughs 18 are provided on the side walls 3a and 3b in such a manner that their upper edges are located above the surface of the raw water on the sand filter layer 2. One end 18a of each trough 18 is closed and the other end 18b is opened to drain out soiled reverse washing water. .
  • a raw water supply tube reciprocating mechanism 20 for reciprocating the raw water supply tube 4 in a plane parallel to the surface of the sand filter layer 2 is comprised of a running box 22 which is fixed to the end portion of the raw water supply tube 4 and has a running wheel 21 on its bottom, a drive device 23 including an electric motor for driving the running wheel 21 and a reduction gear, a running plate 25 which is fixed to the other end portion of the raw water supply tube 4 and has a running wheel 24 on its bottom, and a pair of rails 26 which are fixed to a frame 3e of the filter container 3 in a manner to engage with the running wheels 21 and 24.
  • the reciprocating mechanism is not limited to the above described mechanism but other mechanism such as one using a feed screw and one using a chain drive may be used.
  • raw water is supphed from to the jet nozzles 5 through the raw water supply tube 4 while the depth of water above the surface of the sand filter layer 2 is maintained, e.g., at 30cm. .
  • the raw water is caused to flow in a jet water stream by setting the flow rate of water in the jet nozzles 5 at, e.g., 1.5 1/min. to 3 1/min.
  • the jet water stream is blown out of the raw water jetting outlets 5b of the jet nozzles 5 and is struck against the water surface of the sand filter layer 2 and a multiplicity of air bubbles are generated thereby causing vehement aeration on the water surface and on the sand filter layer 2.
  • the baffle plate 13 enhances this aeration.
  • suspending materials such as clay, bacteria and algae are oxidized and thereby are flocculated or precipitates and are caught on the surfaces of the grains of the filtering sand which constitutes the sand filter layer 2.
  • the filtered water from which the flocks and other foreign matters have been removed by the sand filter layer 2 is taken out of the filtered water outlet 9.
  • the raw water supply tube reciprocating mechanism 20 is actuated to reciprocate the raw water supply tube 4 in a plane parallel to the surface of the sand filter layer 2. Since, by this operation, a jet water stream which is blown out of the raw water jetting outlets 5b is struck vehemently against the closed surface of the sand filter layer 2, the entire surface of the sand filter layer 2 is turned over and clogging of the surface of the sand filter layer 2 by foreign matters is removed whereby the closed state of the surface of the sand filter layer 2 is eliminated and the sand filter layer 2 restores its filtering function.
  • reverse washing water is supphed from the reverse washing tube 15 through the supporting gravel support plate 8 toward the upper surface of the sand filter layer 2 thereby to drain soiled reverse washing water to outside from the reverse washing water overflow troughs 18.
  • FIG. 3 is a perspective view similar to FIG. 1 schematically showing another embodiment of the invention in which aeration is made by a jet air stream.
  • FIG. 3 the same components as those in FIG.
  • a water treatment device 30 comprises, as its principal elements, a filter container 3 containing a sand filter layer 2, a raw water supply tube 38, an air supply tube 34, jet nozzles 35 and an air supply tube reciprocating mechanism 20.
  • the raw water supply tube 38 made of, e.g., a steel pipe, for supplying raw water to be filtered such as river water to the filter container 3 is connected to an unillustrated raw water supply source.
  • the raw water is supphed to the sand filter layer 2 through the raw water supply tube 38 at a predetermined flow rate.
  • the air supply tube 34 is disposed above the filter container 3 in such a manner that the air supply tube 34 extends in a plane parallel to the surface of the sand filter layer 2 and is reciprocable in a plane parallel to the upper surface of the sand filter layer 2.
  • FIG, 3 shows a state of the air supply tube 34 in the reciprocating motion in the central portion of the filter container 3 during reverse washing.
  • the air supply tube 34 is connected to an unillustrated compressed air source such as an air compressor through a hose 39.
  • a plurality of jet nozzles 35 are provided in a manner to branch off downward from the air supply tube 34.
  • the upstream side end portion 35a of each jet nozzle 35 is fitted in the air supply tube 34 in such a manner that the inside of the jet nozzle 35 communicates with the air supply tube 34.
  • an air jetting outlet 35b which blows out air in a jet air stream.
  • a preferable inner diameter of the jet nozzle 35 is 3mm to 6mm.
  • raw water is supphed from the raw water supply tube 38 to the sand filter layer 2 and a jet air stream is blown out of the jet nozzles 35 connected to the air supply tube 34 thereby causing aeration in the water on the sand filter layer 2 and on the surface of the sand filter layer 2.
  • the air supply tube reciprocating mechanism 20 is actuated while jetting out the jet air stream from the jet nozzles 35 thereby ehminating clogging on the surface of the sand filter layer 2 by the jet air stream.
  • FIG. 4 is a view schematically showing an embodiment of the invention which comprises clogging-removing bars each of which is provided between adjacent one of the jet nozzles with a front side wall being removed as viewed in the direction in which the raw water supply tube reciprocates.
  • the same components as those in FIG. 1 are designated by the same reference characters and description thereof is omitted.
  • this embodiment is a modification which is common to the embodiment of FIG. 1 in which aeration is performed by jetting out raw water as a jet water stream and the embodiment of FIG. 2 in which aeration is performed by jetting out air in a jet air stream, reference characters of the components of both FIG. 1 and FIG. 2 are shown side by side.
  • the water treatment device 40 comprises a plurality of clogging-removing bars 42 each of which is provided between adjacent ones of jet nozzles 5 or 35.
  • Each ogging-removing bar 42 is made of a rigid material such as steel. Its base portion 42a is fixed by, e.g., welding, to the bottom wall of a raw water supply tube housing 28 or air supply tube housing 37 and its tip end portion 42b is inserted in a surface portion of the sand filter layer 2.
  • the clogging-removing bars 42 are caused to reciprocate with their tip end portion inserted in the surface portion of the sand filter layer 2.
  • the surface portion of the sand filter layer 2 is turned over by the clogging-removing bars 42 and the clogging in the surface portion of the sand filter layer 2 is effectively removed.
  • aeration is performed in water over the sand filter layer 2 and on the surface of the sand filter layer 2 by blowing out the jet water stream or jet air stream from the jet nozzles 5 or 35 during filtering of the raw water.
  • the raw water supply tube 4 or the air supply tube 34 is moved in reciprocating motion while blowing out the jet water stream or jet air stream from the jet nozzles 5 or 35 during reverse washing of the sand filter layer 2 thereby to remove clogging of the surface portion of the sand filter layer 2 by the jet water stream or jet air stream and by the clogging-removing bars 42.
  • FIG. 5 is a perspective view similar to FIG. 1 showing another embodiment of the invention and FIG. 6 is a sectional view similar to FIG. 2 of the same embodiment.
  • the same components as those in FIG. 1 are designated by the same reference characters and description thereof will be omitted.
  • one or more reverse washing tubes 48 (three in the illustrated example) having upward opening reverse washing water jetting holes 48a (FIG. 6)) are disposed in the sand filter layer 2 at a depth which is sufficient for removing foreign matters which have been accumulated in the upper portion of the sand filter layer 2 by reverse washing and also is sufficient for allowing a substantially thick portion of the sand filter layer 2 to exist under the reverse washing tubes 48.
  • This depth is determined having regard to factors including the types and amount of foreign matters which close the surface of the sand filter layer 2, grain diameter of filtering sand which forms the sand filter layer 2, flow speed of reverse washing water and frequency of reverse washing during a predetermined period of time.
  • This embodiment of the water treatment further comprises filtered water circulating means 50 for stopping supply of raw water from the raw water supply tube 4 during stoppage of supply of filtered water, i.e., when supply of the filtered water is not needed, and returning the filtered water to the raw water supply tube 4 thereby to circulate the filtered water through the sand filter layer 2.
  • the filtered water circulating means 50 includes a filtered water circulating tube 52 made of a flexible tube such as a hose for connecting the filtered water outlet 9 with a hose 27 connected to the raw water supply tube 4, a water supply pump 58 connected to the filtered water circulating tube 52, a changeover valve 54 provided in the filtered water circulating tube 52 for passing filtered water and stopping supply of water to the filtered water circulating tube 52 during supply of the filtered water and stopping supply of the filtered water and returning the filtered water to the raw water supply tube 4 through the filtered water circulating tube 52 during stoppage of supply of the filtered water, and a changeover valve 56 which is a valve means provided in a connecting portion of the hose 27 and the filtered water circulating tube 52 for passing raw water and stopping passage of the filtered water from the filtered water circulating tube 52 during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube 52 during stopping of supply of the filtered water.
  • the changeover valve 56 is changed over to stop passing of the raw water to the raw water supply tube 4 and allows the filtered water from the filtered water circulating tube 52 to pass whereas the changeover valve 54 is changed over to stop supply of the filtered water and allows passing of the filtered water to the filtered water circulating tube 52.
  • the water supply pump 58 By actuating the water supply pump 58 in this state, the filtered water is returned from the filtered water outlet 9 to the raw water supply tube 4 through the filtered water circulating tube 52 and falls from the jet nozzles 5 to the sand filter layer 2 while performing aeration.
  • the filtered water is returned to the raw water supply tube 4 and circulated through the sand filter layer 2 thereby continuing aeration during stoppage of supply of the filtered water when it is unnecessary.
  • dissolved oxygen is sufficiently supphed to iron bacteria and other microorganisms in the sand filter layer 2 even during stoppage of supply of the filtered water and, as a result, extinction or reduction of the microorganisms due to shortage of oxygen can be prevented whereby, when supply of the filtered water is resumed, reduction in the effect of removing iron and manganese in the sand filter layer 2 can be prevented.
  • FIG. 7 is a perspective view similar to FIG. 5 showing a modified - example of the filtered water circulating means.
  • a filtered water circulating means 60 comprises a filtered water circulation outlet 61 provided separately from the filtered water outlet 9, a filtered water circulating tube 62 made of a flexible material such as a hose for connecting the filtered water outlet 61 with a hose 27 connected to the raw water supply tube 4, a water supply pump 68 connected to the filtered water circulating tube 62, a valve 64 provided in a tube provided on the side of the filtered water outlet 9 for opening during supply of the filtered water and closing during stoppage of supply of the filtered water, and a changeover valve 66 which is valve means provided in a connecting portion of the hose 27 and the filtered water circulating tube 62 for passing raw water and stopping passage of the filtered water from the filtered water circulating tube 62 during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube 62 during stoppage
  • a water treatment device having a filter container 3 containing a sand filter layer 2 is provided.
  • the invention is not hmited to these embodiments but it is also apphcable to a water purification plant where a sand filter layer is contained in a filtering basin.
  • the water treatment device and method of the present invention can be utihzed for filtering various kinds of foreign matters and impurities in raw water such as underground water, river water, lake water, water flowing from farm and mountain, including treating foreign matters including water soluble substance such as iron and manganese in such raw water by oxidizing them and flocculating them and thereupon filtering them.
  • the water treatment device and method can also be utilized for treating turbid water such as water containing red soil and various types of dirty water without using chemicals.

Abstract

A water treatment device comprises a raw water supply tube (4). a plurality of jet nozzles (5), each being at one end portion thereof in communication with the raw water supply tube (4) and having at the other end portion thereof a raw water jetting outlet (5a) for blowing out the raw water in a jet stream, a sand filter layer container (3) containing a sand filter layer (2) having an upper surface thereof being provided below the jet nozzles (5) with a predetermined interval from the raw water jetting outlets (5a) of the jet nozzles (5). a filtered water outlet (9) provided in the sand filter layer container (3) for taking out water which has been filtered through the sand filter layer (2) and means (20) for reciprocating the raw water supply tube (4) in a plane parallel to the surface of the sand filter layer (2).

Description

DESCRIPTION
Water Treatment Device and Water Treatment Method
Technical Field
This invention relates to a water treatment device and a water treatment method and, more particularly, to a water treatment device and method capable of treating suspending materials such as clay, bacteria and algae in raw water such as raw water for tap water by oxidizing them by aeration and thereby turning them to flocks with a relatively compact device without employing an oxidizing agent or flocculant.
Background Art
According to the guide line published by the Japanese Tap Water Association, there are two types of tap water filtering methods, namely a low-speed filtering and a quick filtering.
The low speed filtering is a method employed in a case where quality of raw water for tap water is relatively good and stable. According to this method, raw water is introduced directly to a sand filter layer and passed slowly through the sand filter layer and insoluble and soluble substances in the raw water are oxidized and dissolved by bacteria which grow on the surface of the sand filter layer and also in the sand filter layer. Since the filtering speed is very slow (4 to 5m per day), it needs a sand filter layer of a vast area and also requires a laborious work for scraping sand of the surface portion of the sand filter layer when clogging of the sand filter layer has taken place. Further, when the quality of raw water has deteriorated, it is obligatory to use a flocculant as a pre-treatment for generating flocks and treating raw water in a settling basin before introducing it to the sand filter layer. In contrast, the quick filtering which uses a high filtering speed of 120m to 150m per day needs only a relatively narrow filtering area and can cope with a case where the quality of raw water is not good. It is obligatory in the quick filtering, however, to cause, as a pre-treatment, suspending materials such as clay, bacteria and algae in the raw water to flocculate by using a flocculant such as aluminum sulfate and to separate and settle these suspending materials in a settling basin before introducing the raw water to the sand filter layer.
In the water treatment device using a flocculant, a large amount of flocculant is required and, as a result, the cost for the flocculant is enormous. Besides, the water treatment device using a flocculant consists of an aerating basin, a flocculation tank, a settling basin, a sand filter tower and a flocculant tank and, therefore, it requires a complex and large system and a large space. Further, when filtering sand used in this water treatment device using a flocculant needs to be replaced due to clogging caused by accumulation of impurities, the sand must be treated as an industrial waste because it contains the flocculant which is a chemical preparation and, therefore, a place for disposing of the waste sand is restricted.
In reverse washing of the sand filter layer, a manner of reverse washing affects the filtering efficiency significantly. In the prior art water treatment device, a very complex and large structure is required in a water collecting section in the lower stage for improving the reverse washing effect and the reverse washing operation requires a long time. This results in an output of a large amount of waste reverse washed water which requires a large system for disposing of the waste reverse washed water.
It is, therefore, an object of the present invention to provide a water treatment device which has eliminated the above described disadvantages of the prior art quick filtering water treatment device using a flocculant and is capable of treating water by oxidizing and flocculating suspending materials in raw water by a simple and small-sized device without using a flocculant.
The applicant has already filed a patent application in the same field of art which has been published as Japanese Patent Application Laid-open Publication No. 2002-125768.
Disclosure of the Invention
For achieving the above described object of the invention, there is provided a water treatment device comprising: a raw water supply tube; a plurality of jet nozzles, each being at one end portion thereof in communication with the raw water supply tube and having at the other end portion thereof a raw water jetting outlet for blowing out the raw water in a jet stream; a sand filter layer container containing a sand filter layer having an upper surface thereof being provided below the jet nozzles with a predetermined interval from the raw water jetting outlets of the jet nozzles; a filtered water outlet provided in the sand filter layer container for taking out water which has been filtered through the sand filter layer; and means for reciprocating the raw water supply tube in a plane parallel to the surface of the sand filter layer.
According to the invention, the jet water stream is blown out of the raw water jetting outlet and is struck against the water surface above the sand filter layer disposed below the raw water jetting outlet and a multiplicity of small air bubbles are produced by involving air by the jet stream. Thus, vehement aeration takes place in the water and on the surface of the sand filter layer. By this aeration, suspending materials such as clay, bacteria and algae in the water are oxidized and are either flocculated or settled and caught on the surface of the filtering sand of the sand filter layer. The filtered water which has passed the sand filter layer and removed of flocks and other impurities is taken out of the filtered water outlet.
Accordingly, according to the invention, flocculation and settling by using a flocculant as a pretreatment before filtering by the sand filter layer becomes unnecessary.
The filtering speed of the device according to the invention for catching flocks of oxidized particles on the surface of the sand filter layer is a high speed of 120m to 150m per day which is equivalent to the filtering speed of the quick filtering and, therefore, only a small filtering space is required.
As the above described filtering operation is continued, flocks of oxidized substances and other foreign matters are accumulated on the surface of the sand filter layer as time elapses with the result that the surface of the sand filter layer is clogged and closed with the flocks and other foreign matters and the filtering function of the sand filter layer thereby is reduced. In another aspect of the invention, the water treatment device comprises means for reciprocating the raw water supply tube in a plane parallel to the surface of the filter layer and, therefore, by operating this means in a state where the water surface is adjusted to a level which is slightly above the surface of the filter layer to reciprocate the raw water supply tube in a plane parallel to the surface of the filter layer, the jet water strea which is blown out of the raw water jetting outlet is struck vehemently against the surface of the sand filter layer which is closed with the flocks etc. and, as a result, the entire surface portion of the sand filter layer is turned over whereby the closed state of the surface of the sand filter layer with the flocks etc. is eliminated and the filtering function of the sand filter layer is restored.
In another aspect of the invention, the water treatment device further comprises a plurality of clogging-removing bars each of which is provided between adjacent ones of the jet nozzles in such a manner that a tip end portion of the clogging-removing bar is inserted in a surface portion of the sand filter layer.
By this arrangement, by moving the raw water supply tube in reciprocating motion in a plane parallel to the surface of the sand filter layer, the clogging-removing bars are caused to reciprocate with their tip end portion inserted in the surface portion of the sand filter layer. As a result, the surface portion of the sand filter layer is turned over by the clogging-removing bars and the clogging in the surface portion of the sand filter layer is effectively removed.
In another aspect of the invention, a water treatment device comprises: an air supply tube; a plurality of jet nozzles, each being at one end portion thereof in communication with the air supply tube and having at the other end portion thereof an air jetting outlet for blowing out air in a jet stream; a sand filter layer container containing a sand filter layer having an upper surface thereof being provided below the jet nozzles with a predetermined interval from the air jetting outlets of the jet nozzles; a filtered water outlet provided in the sand filter layer container for taking out water which has been filtered through the sand filter layer; and means for reciprocating the airf supply tube in a plane parallel to the surface of the sand filter layer.
According to this aspect of the invention, suspending materials in the raw water supplied to the sand filter layer are oxidized and flocculated by aeration caused by the jet air stream blown out of the jet nozzles and thereby are trapped on the surface of the sand filter layer in the same manner as in the device blowing out the jet water stream. The function of the jet air stream during reverse washing is also the same as the jet water stream.
In another aspect of the invention, there is provided a water treatment method employing the water treatment device blowing out the jet water stream, comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the jet water stream.
In another aspect of the invention, there is provided a water treatment device as described above further comprising filtered water circulating means for stopping supply of raw water from the raw water supply tube during stoppage of supply of filtered water and returning the filtered water to the raw water supply tube thereby to circulate the filtered water through the sand filter layer.
Iron bacteria and other microorganisms five naturally and form their colonies in the sand filter layer. These microorganisms have a function of removing impurities such as iron and manganese in the raw water by oxidizing and absorbing them. According to the invention, it is assumed that, as a result of significant increase in the concentration of dissolved oxygen in the raw water by aeration, activities of these microorganisms also increase and thereby enhance removal of iron and manganese. By the provision of the filtered water circulating means, the filtered water is returned to the raw water supply tube and circulated through the sand filter layer thereby continuing aeration during stoppage of supply of the filtered water when it is unnecessary. By this arrangement, dissolved oxygen is sufficiently supplied to iron bacteria and other microorganisms in the sand filter layer even during stoppage of supply of the filtered water and, as a result, extinction or reduction of the microorganisms due to shortage of oxygen can be prevented whereby, when supply of the filtered water is resumed, reduction in the effect of removing iron and manganese in the sand filter layer can be prevented. In another aspect of the invention, the filtered water circulating means comprises^ a filtered water circulating tube for connecting the filtered water outlet with the raw water supply tube; a water supply pump connected to the filtered water circulating tube; a changeover valve provided in the filtered water circulating tube for passing filtered water and stopping supply of water to the filtered water circulating tube during supply of the filtered water and stopping supply of the filtered water and returning the filtered water to the raw water supply tube through the filtered water circulating tube during stoppage of supply of the filtered water; and valve means provided in a raw water supply channel for passing raw water and stopping passage of the filtered water from the filtered water circulating tube during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube during stopping of supply of the filtered water. In another aspect of the invention, the filtered water circulating means comprises: a filtered water circulation outlet provided separately from the filtered water outlet; a filtered water circulating tube for connecting the filtered water outlet with the raw water supply tube; a water supply pump connected to the filtered water circulating tube; a valve provided in a tube provided on the side of the filtered water outlet for opening during supply of the filtered water and closing during stoppage of supply of the filtered water; and valve means provided in a raw water supply channel for passing raw water and stopping passage of the filtered water from the filtered water circulating tube during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube during stoppage of supply of the filtered water.
In another aspect of the invention, the above described water treatment device may further comprise a reverse washing tube disposed in the sand filter layer at a depth which is sufficient for removing foreign matters which have been accumulated in the upper portion of the sand filter layer by reverse washing and also is sufficient for allowing a substantially thick portion of the sand filter layer to exist under the reverse washing tube.
By this arrangement, foreign matters which have been accumulated in the upper portion of the sand filter layer are washed away by reverse washing whereas, in the portion of the sand filter layer under the reverse washing tube where influence of the reverse washing does not reach, the colonies of iron bacteria and other microorganisms are not destroyed whereby, when operation of the device is resumed after completion of reverse washing, the effect of removing iron and manganese by the microorganisms surviving in this portion of the sand filter layer is maintained continuously and, therefore, the effect of removing iron and manganese of the device as a whole is improved.
In another aspect of the invention, there is provided a water treatment method employing the water treatment device blowing out the jet water stream and comprising the clogging-removing bars, comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the jet water stream and by the clogging-removing bars.
In another aspect of the invention, there is provided a water treatment method employing the water treatment device blowing out the jet air stream comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while blowing out the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the air jet stream.
In another aspect of the invention, there is provided a water treatment method employing the water treatment device blowing out the jet air stream and comprising the clogging-removing bars, comprising the steps of: generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while blowing out the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the air jet stream and by the clogging-removing bars.
In another aspect of the invention, there is provided a water treatment method employing the water treatment device blowing out the jet water stream and comprising the clogging-removing bars, comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while stopping blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the clogging-removing bars only.
In another aspect of the invention, there is provided a water treatment method employing the water treatment blowing out the air and comprising the clogging-removing bars, comprising the steps of generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while stopping blowing out of the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the clogging-removing bars only.
In still another aspect of the invention, there is provided a water treatment method further comprising the step of stopping supply of the raw water from the raw water supply tube during stoppage of supply of the filtered water, circulating the filtered water through the sand filter layer by returning the filtered water to the raw water supply tube, and continuing aeration to maintain concentration of dissolved oxygen in the filtered water at a predetermined level.
Brief Description of the Drawings
In the accompanying drawings,
FIG. 1 is a perspective view schematically showing an embodiment of the water treatment device according to the invention;
FIG. 2 is a sectional view showing positions of the jet nozzles of the embodiment during filtering and during reverse washing;
FIG. 3 is a perspective view schematically showing another embodiment of the water treatment device according to the invention;
FIG. 4 is a side elevation showing another embodiment of the water treatment device according to the invention; FIG. 5 is a perspective view showing another embodiment of the water treatment device according to the invention;
FIG. 6 is a sectional view showing positions of the jet nozzles during filtering and during reverse washing; and
FIG. 7 is a perspective view showing a modified example of this embodiment.
Best Mode for Carrying Out the Invention
Referring now to the accompanying drawings, embodiments of the invention will be described. FIG. 1 schematically shows an embodiment of the invention with a part of the side wall being removed and FIG. 2 shows positions of the jet nozzles of the embodiment during filtering and reverse washing.
A water treatment device 1 comprises, as its principal elements, a filter container 3 containing a sand filter layer 2, a raw water supply tube 4, jet nozzles 5 and a raw water supply tube reciprocating mechanism 20.
The raw water supply tube 4 made of, e.g., a steel pipe, for supplying raw water to be filtered such as river water to the filter container 3 is connected to an uni-lustrated raw water supply source by means of a hose 27. The raw water is supphed to the raw water supply tube 4 at a predetermined flow rate.
The raw water supply tube 4 is disposed above the filter container 3 in such a manner that the raw water supply tube 4 extends in a plane parallel to the surface of the sand filter layer 2 and is reciprocable in a plane parallel to the upper surface of the sand filter layer 2. FIG, 1 shows a state of the raw water supply tube 4 in the reciprocating motion in the central portion of the filter container 3 during reverse washing.
A plurality of jet nozzles 5 are provided in a manner to branch off downward from the raw water supply tube 4. The upstream side end portion 5a of each jet nozzle 5 is fitted in the -raw water supply tube 4 in such a manner that the inside of the jet nozzle 5 communicates with the raw water supply tube 4. In the downstream side end portion of the jet nozzle 5 is formed a raw water jetting outlet 5b which blows out raw water in a jet water stream. A preferable inner diameter of the jet nozzle 5 is 3mm to 6mm. In the filter container 3, the sand filter layer 2 is provided with its upper surface being disposed below the jet nozzles 5 with a predetermined interval (e.g., about 35cm) from the raw water jetting outlets 5b. The sand filter layer 2 is made of filtering sand of a uniform grain size and functions to filter the raw water by catching flocks of oxidized substances and other foreign matters in the raw water supphed as a jet stream from the jet nozzles 5. Flow rate of the raw water in the filter container 3, i.e., the filtering speed, differs depending upon the degree of filtration of object foreign matter (i.e., permissible concentration of the foreign matters in the filtered water). For normal filtering of iron and manganese, a filtering speed equivalent to the filtering speed of quick filtering, i.e., 120m to 150m per day, is preferable.
In the filter container 3, the sand filter layer 3 is supported by a supporting gravel layer 6 made of gravel of a small grain diameter and a supporting gravel layer 7 made of gravel of a larger grain diameter. The supporting gravel layer 7 in turn is supported by a supporting gravel support plate 8 made of wedge -wires which are arranged in parallel to one another. Under the supporting gravel support plate 8 is provided a lower space 16 to which the filtered water flows from the sand filter layer 2. A filtered water outlet 9 for taking out water which has been filtered through the sand filter layer 2 is provided in a side wall of the filter container 3 facing the lower space 16 of the filter container 3.
In the lower space 16 of the filter container 3, there is provided a reverse washing tube 15 for reverse washing the sand filter layer 2. The reverse washing tube 15 is formed in its upper portion with a plurality of upward opening reverse washing water jetting holes 15a. The reverse washing tube 15 is connected to an unillustrated reverse washing water supply source.
As shown in FIG. 2, a baffle plate 13 made of, e.g., a steel plate, is provided between the raw water jetting outlets 5b of the jet nozzles 5 and the surface of the sand filter layer 2 in one end portion 3d of the filter container 3 in which the raw water supply tube 4 is located during filtering in such a manner that the baffle plate 13 extends in parallel to the raw water supply tube 4 and is disposed beneath the raw water jetting outlets 5b. The baffle plate 13 has its end portions in the longitudinal direction fixed to the inside wall surfaces of side walls 3a and 3b by means of, e.g., welding. By way of example, if the depth of water from the surface of water of the filter container 3 to the surface of the sand filter layer 2 is 30cm and distance between the raw water jetting outlet 5b of the jet nozzle 5 to the surface of the water is 5cm, a preferable depth of the baffle plate 13 from the surface of the water is about 5cm (i.e., distance from the raw water jetting outlet 5b to the baffle plate is about 10cm).
Reverse washing water overflow troughs 18 are provided on the side walls 3a and 3b in such a manner that their upper edges are located above the surface of the raw water on the sand filter layer 2. One end 18a of each trough 18 is closed and the other end 18b is opened to drain out soiled reverse washing water. .
In the present embodiment, a raw water supply tube reciprocating mechanism 20 for reciprocating the raw water supply tube 4 in a plane parallel to the surface of the sand filter layer 2 is comprised of a running box 22 which is fixed to the end portion of the raw water supply tube 4 and has a running wheel 21 on its bottom, a drive device 23 including an electric motor for driving the running wheel 21 and a reduction gear, a running plate 25 which is fixed to the other end portion of the raw water supply tube 4 and has a running wheel 24 on its bottom, and a pair of rails 26 which are fixed to a frame 3e of the filter container 3 in a manner to engage with the running wheels 21 and 24. By rotating the electric motor in the drive device 23 in one direction, the raw water supply tube 4 is moved in one direction and, by rotating the electric motor in the reverse direction, the raw water supply tube 4 is moved in the reverse direction.
The reciprocating mechanism is not limited to the above described mechanism but other mechanism such as one using a feed screw and one using a chain drive may be used.
The operation of the water treatment device of the above described embodiment will now be described.
During filtering of raw water, raw water is supphed from to the jet nozzles 5 through the raw water supply tube 4 while the depth of water above the surface of the sand filter layer 2 is maintained, e.g., at 30cm. .The raw water is caused to flow in a jet water stream by setting the flow rate of water in the jet nozzles 5 at, e.g., 1.5 1/min. to 3 1/min. The jet water stream is blown out of the raw water jetting outlets 5b of the jet nozzles 5 and is struck against the water surface of the sand filter layer 2 and a multiplicity of air bubbles are generated thereby causing vehement aeration on the water surface and on the sand filter layer 2. The baffle plate 13 enhances this aeration. By virtue of this aeration, suspending materials such as clay, bacteria and algae are oxidized and thereby are flocculated or precipitates and are caught on the surfaces of the grains of the filtering sand which constitutes the sand filter layer 2. The filtered water from which the flocks and other foreign matters have been removed by the sand filter layer 2 is taken out of the filtered water outlet 9.
As the above described filtering operation is continued, flocks of oxidized substances and other foreign matters are accumulated on the surface of the sand filter layer 2 as time elapses. The surface of the sand filter layer 2 is covered and closed with these flocks and foreign matters and, as a result, the filtering function of the sand filter layer 2 is reduced.
In this case, while the raw water is supplied with the water level being adjusted at a level of, e.g., 10cm above the surface of the sand filter layer 2, the raw water supply tube reciprocating mechanism 20 is actuated to reciprocate the raw water supply tube 4 in a plane parallel to the surface of the sand filter layer 2. Since, by this operation, a jet water stream which is blown out of the raw water jetting outlets 5b is struck vehemently against the closed surface of the sand filter layer 2, the entire surface of the sand filter layer 2 is turned over and clogging of the surface of the sand filter layer 2 by foreign matters is removed whereby the closed state of the surface of the sand filter layer 2 is eliminated and the sand filter layer 2 restores its filtering function.
After removing clogging of the surface of the sand filter layer 2, reverse washing water is supphed from the reverse washing tube 15 through the supporting gravel support plate 8 toward the upper surface of the sand filter layer 2 thereby to drain soiled reverse washing water to outside from the reverse washing water overflow troughs 18.
FIG. 3 is a perspective view similar to FIG. 1 schematically showing another embodiment of the invention in which aeration is made by a jet air stream. In the embodiment of FIG. 3, the same components as those in FIG.
1 are designated by the same reference characters and description thereof will be omitted.
A water treatment device 30 comprises, as its principal elements, a filter container 3 containing a sand filter layer 2, a raw water supply tube 38, an air supply tube 34, jet nozzles 35 and an air supply tube reciprocating mechanism 20.
The raw water supply tube 38 made of, e.g., a steel pipe, for supplying raw water to be filtered such as river water to the filter container 3 is connected to an unillustrated raw water supply source. The raw water is supphed to the sand filter layer 2 through the raw water supply tube 38 at a predetermined flow rate.
The air supply tube 34 is disposed above the filter container 3 in such a manner that the air supply tube 34 extends in a plane parallel to the surface of the sand filter layer 2 and is reciprocable in a plane parallel to the upper surface of the sand filter layer 2. FIG, 3 shows a state of the air supply tube 34 in the reciprocating motion in the central portion of the filter container 3 during reverse washing. The air supply tube 34 is connected to an unillustrated compressed air source such as an air compressor through a hose 39.
A plurality of jet nozzles 35 are provided in a manner to branch off downward from the air supply tube 34. The upstream side end portion 35a of each jet nozzle 35 is fitted in the air supply tube 34 in such a manner that the inside of the jet nozzle 35 communicates with the air supply tube 34. In the downstream side end portion of the jet nozzle 35 is formed an air jetting outlet 35b which blows out air in a jet air stream. A preferable inner diameter of the jet nozzle 35 is 3mm to 6mm.
In this embodiment, during filtering of raw water, raw water is supphed from the raw water supply tube 38 to the sand filter layer 2 and a jet air stream is blown out of the jet nozzles 35 connected to the air supply tube 34 thereby causing aeration in the water on the sand filter layer 2 and on the surface of the sand filter layer 2. During reverse washing of the sand filter layer 2, the air supply tube reciprocating mechanism 20 is actuated while jetting out the jet air stream from the jet nozzles 35 thereby ehminating clogging on the surface of the sand filter layer 2 by the jet air stream.
FIG. 4 is a view schematically showing an embodiment of the invention which comprises clogging-removing bars each of which is provided between adjacent one of the jet nozzles with a front side wall being removed as viewed in the direction in which the raw water supply tube reciprocates. In FIG. 4, the same components as those in FIG. 1 are designated by the same reference characters and description thereof is omitted.
Since this embodiment is a modification which is common to the embodiment of FIG. 1 in which aeration is performed by jetting out raw water as a jet water stream and the embodiment of FIG. 2 in which aeration is performed by jetting out air in a jet air stream, reference characters of the components of both FIG. 1 and FIG. 2 are shown side by side.
In this embodiment, the water treatment device 40 comprises a plurality of clogging-removing bars 42 each of which is provided between adjacent ones of jet nozzles 5 or 35. Each ogging-removing bar 42 is made of a rigid material such as steel. Its base portion 42a is fixed by, e.g., welding, to the bottom wall of a raw water supply tube housing 28 or air supply tube housing 37 and its tip end portion 42b is inserted in a surface portion of the sand filter layer 2.
By this arrangement, by moving the raw water supply tube4 or the air supply tube 34 in reciprocating motion in a plane parallel to the surface of the sand filter layer 2, the clogging-removing bars 42 are caused to reciprocate with their tip end portion inserted in the surface portion of the sand filter layer 2. As a result, the surface portion of the sand filter layer 2 is turned over by the clogging-removing bars 42 and the clogging in the surface portion of the sand filter layer 2 is effectively removed.
In this embodiment, aeration is performed in water over the sand filter layer 2 and on the surface of the sand filter layer 2 by blowing out the jet water stream or jet air stream from the jet nozzles 5 or 35 during filtering of the raw water. The raw water supply tube 4 or the air supply tube 34 is moved in reciprocating motion while blowing out the jet water stream or jet air stream from the jet nozzles 5 or 35 during reverse washing of the sand filter layer 2 thereby to remove clogging of the surface portion of the sand filter layer 2 by the jet water stream or jet air stream and by the clogging-removing bars 42.
Alternatively, aeration may be made in water over the sand filter layer 2 and on the surface of the sand filter layer 2 by blowing out the jet water stream or jet air stream from the jet nozzles 5 or 35 during filtering of the raw water and the raw water supply tube 4 or air supply tube 34 is moved in reciprocating motion while stopping blowing out the jet water stream or jet air stream from the jet nozzles 5 or 35 during reverse washing of the sand filter layer 2 thereby to remove clogging of the surface portion of the sand filter layer 2 by the clogging-removing bars 42 only. FIG. 5 is a perspective view similar to FIG. 1 showing another embodiment of the invention and FIG. 6 is a sectional view similar to FIG. 2 of the same embodiment. In this embodiment, the same components as those in FIG. 1 are designated by the same reference characters and description thereof will be omitted.
In the embodiment of FIG. 5, one or more reverse washing tubes 48 (three in the illustrated example) having upward opening reverse washing water jetting holes 48a (FIG. 6)) are disposed in the sand filter layer 2 at a depth which is sufficient for removing foreign matters which have been accumulated in the upper portion of the sand filter layer 2 by reverse washing and also is sufficient for allowing a substantially thick portion of the sand filter layer 2 to exist under the reverse washing tubes 48. This depth is determined having regard to factors including the types and amount of foreign matters which close the surface of the sand filter layer 2, grain diameter of filtering sand which forms the sand filter layer 2, flow speed of reverse washing water and frequency of reverse washing during a predetermined period of time.
In the sand filter layer 2, colonies of iron bacteria and other microorganisms are naturally formed as time elapses. As a result of experiments, it has been found that these colonies of microorganisms are formed not only in the surface portion of the sand filter layer 2 but also in the middle portion and lower portion of the sand filter layer 2 and these colonies of microorganisms in the middle and lower portions of the sand filter layer 2 perform the function of removing iron and manganese significantly, though the effect of the removal of iron and manganese is not so great as that in the surface portion of the sand filter layer 2. Accordingly, by disposing the reverse washing tubes 48 at such depth in the sand filter layer 2, foreign matters which have been accumulated in the upper portion of the sand filter layer 2 are washed away by reverse washing whereas, in the portion of the sand filter layer 2 under the reverse washing tubes 48 where influence of the reverse washing does not reach, the colonies of iron bacteria and other microorganisms are not destroyed whereby, when operation of the device is resumed after completion of reverse washing, the effect of removing iron and manganese by the microorganisms surviving in this portion of the sand filter layer 2 is maintained continuously and, therefore, the effect of removing iron and manganese of the device as a whole is improved.
This embodiment of the water treatment further comprises filtered water circulating means 50 for stopping supply of raw water from the raw water supply tube 4 during stoppage of supply of filtered water, i.e., when supply of the filtered water is not needed, and returning the filtered water to the raw water supply tube 4 thereby to circulate the filtered water through the sand filter layer 2.
The filtered water circulating means 50 includes a filtered water circulating tube 52 made of a flexible tube such as a hose for connecting the filtered water outlet 9 with a hose 27 connected to the raw water supply tube 4, a water supply pump 58 connected to the filtered water circulating tube 52, a changeover valve 54 provided in the filtered water circulating tube 52 for passing filtered water and stopping supply of water to the filtered water circulating tube 52 during supply of the filtered water and stopping supply of the filtered water and returning the filtered water to the raw water supply tube 4 through the filtered water circulating tube 52 during stoppage of supply of the filtered water, and a changeover valve 56 which is a valve means provided in a connecting portion of the hose 27 and the filtered water circulating tube 52 for passing raw water and stopping passage of the filtered water from the filtered water circulating tube 52 during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube 52 during stopping of supply of the filtered water. During stoppage of supply of the filtered water, the changeover valve 56 is changed over to stop passing of the raw water to the raw water supply tube 4 and allows the filtered water from the filtered water circulating tube 52 to pass whereas the changeover valve 54 is changed over to stop supply of the filtered water and allows passing of the filtered water to the filtered water circulating tube 52. By actuating the water supply pump 58 in this state, the filtered water is returned from the filtered water outlet 9 to the raw water supply tube 4 through the filtered water circulating tube 52 and falls from the jet nozzles 5 to the sand filter layer 2 while performing aeration. Accordingly, the filtered water is returned to the raw water supply tube 4 and circulated through the sand filter layer 2 thereby continuing aeration during stoppage of supply of the filtered water when it is unnecessary. By this arrangement, dissolved oxygen is sufficiently supphed to iron bacteria and other microorganisms in the sand filter layer 2 even during stoppage of supply of the filtered water and, as a result, extinction or reduction of the microorganisms due to shortage of oxygen can be prevented whereby, when supply of the filtered water is resumed, reduction in the effect of removing iron and manganese in the sand filter layer 2 can be prevented.
FIG. 7 is a perspective view similar to FIG. 5 showing a modified - example of the filtered water circulating means. In this embodiment, a filtered water circulating means 60 comprises a filtered water circulation outlet 61 provided separately from the filtered water outlet 9, a filtered water circulating tube 62 made of a flexible material such as a hose for connecting the filtered water outlet 61 with a hose 27 connected to the raw water supply tube 4, a water supply pump 68 connected to the filtered water circulating tube 62, a valve 64 provided in a tube provided on the side of the filtered water outlet 9 for opening during supply of the filtered water and closing during stoppage of supply of the filtered water, and a changeover valve 66 which is valve means provided in a connecting portion of the hose 27 and the filtered water circulating tube 62 for passing raw water and stopping passage of the filtered water from the filtered water circulating tube 62 during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube 62 during stoppage of supply of the filtered water.
Various other modifications can be made for the filtered water circulating means.
In the above described embodiments, a water treatment device having a filter container 3 containing a sand filter layer 2 is provided. The invention is not hmited to these embodiments but it is also apphcable to a water purification plant where a sand filter layer is contained in a filtering basin.
Industrial Applicability
The water treatment device and method of the present invention can be utihzed for filtering various kinds of foreign matters and impurities in raw water such as underground water, river water, lake water, water flowing from farm and mountain, including treating foreign matters including water soluble substance such as iron and manganese in such raw water by oxidizing them and flocculating them and thereupon filtering them. The water treatment device and method can also be utilized for treating turbid water such as water containing red soil and various types of dirty water without using chemicals.

Claims

1. A water treatment device comprising: a raw water supply tube; a plurality of jet nozzles, each being at one end portion thereof in communication with the raw water supply tube and having at the other end portion thereof a raw water jetting outlet for blowing out the raw water in a jet stream; a sand filter layer container containing a sand filter layer having an upper surface thereof being provided below the jet nozzles with a predetermined interval from the raw water jetting outlets of the jet nozzles; a filtered water outlet provided in the sand filter layer container for taking out water which has been filtered through the sand filter layer; and; means for reciprocating the raw water supply tube in a plane parallel to the surface of the sand filter layer.
2. A water treatment device as defined in claim 1 further comprising a plurality of clogging-removing bars each of which is provided between adjacent ones of the jet nozzles in such a manner that a tip end portion of the clogging-removing bar is inserted in a surface portion of the sand filter layer.
3. A water treatment device comprising: an air supply tube; a plurality of jet nozzles, each being at one end portion thereof in communication with the air supply tube and having at the other end portion thereof an air jetting outlet for blowing out air in a jet stream; a sand filter layer container cont- ning a sand filter layer having an upper surface thereof being provided below the jet nozzles with a predetermined interval from the air jetting outlets of the jet nozzles! a filtered water outlet provided in the sand filter layer container for taking out water which has been filtered through the sand filter layer; and; means for reciprocating the airf supply tube in a plane parallel to the surface of the sand filter layer.
4. A water treatment device as defined in claim 3 further comprising a plurality of clogging-removing bars each of which is provided between adjacent ones of the jet nozzles in such a manner that a tip end portion of the clogging-removing bar is inserted in a surface portion of the sand filter layer.
5. A water treatment device as defined in any of claims 1 - 4 further comprising filtered water circulating means for stopping supply of raw water from the raw water supply tube during stoppage of supply of filtered water and returning the filtered water to the raw water supply tube thereby to circulate the filtered water through the sand filter layer.
6. A water treatment device as defined in claim 5 wherein the filtered water circulating means comprises: a filtered water circulating tube for connecting the filtered water outlet with the raw water supply tube; a water supply pump connected to the filtered water circulating tube; a changeover valve provided in the filtered water circulating tube for passing filtered water and stopping supply of water to the filtered water circulating tube during supply of the filtered water and stopping supply of the filtered water and returning the filtered water to the raw water supply tube through the filtered water circulating tube during stoppage of supply of the filtered water; and valve means provided in a raw water supply channel for passing raw water and stopping passage of the filtered water from the filtered water circulating tube during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube during stopping of supply of the filtered water.
7. A water treatment device as defined in claim 5 wherein wherein the filtered water circulating means comprises: a filtered water circulation outlet provided separately from the filtered water outlet; a filtered water circulating tube for connecting the filtered water outlet with the raw water supply tube; a water supply pump connected to the filtered water circulating tube; a valve provided in a tube provided on the side of the filtered water outlet for opening during supply of the filtered water and closing during stoppage of supply of the filtered water; and valve means provided in a raw water supply channel for passing raw water and stopping passage of the filtered water from the filtered water circulating tube during supply of the filtered water and stopping passage of the raw water and passing the filtered water from the filtered water circulating tube during stoppage of supply of the filtered water.
8. A water treatment device as defined in any of claims 1 - 7 further comprising a reverse washing tube disposed in the sand filter layer at a depth which is sufficient for removing foreign matters which have been accumulated in the upper portion of the sand filter layer by reverse washing and also is sufficient for allowing a substantially thick portion of the sand filter layer to exist under the reverse washing tube.
9. A water treatment method employing the water treatment device as defined in claim 1 comprising the steps of: generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the jet water stream.
10. A water treatment method employing the water treatment device as defined in claim 2 comprising the steps of: generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the jet water stream and by the clogging-removing bars.
11. A water treatment method employing the water treatment device as defined in claim 3 comprising the steps of: generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while blowing out the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the air jet stream.
12. A water treatment method employing the water treatment device as defined in claim 4 comprising the steps of: generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while blowing out the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the air jet stream and by the clogging-removing bars.
13. A water treatment method employing the water treatment device as defined in claim 2 comprising the steps of: generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the jet water stream from the jet nozzles during filtering of the raw water; and moving the raw water supply tube in reciprocating motion while stopping blowing out the jet water stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the clogging-removing bars only.
14. A water treatment method employing the water treatment device as defined in claim 4 comprising the steps of- generating aeration in water over the sand filter layer and on the surface of the sand filter layer by blowing out the air jet stream from the jet nozzles while supplying the raw water from the raw water supply tube to the sand filter layer during filtering of the raw water; and moving the air supply tube in reciprocating motion while stopping blowing out of the air jet stream from the jet nozzles during reverse washing of the sand filter layer thereby to remove clogging of the surface portion of the sand filter layer by the clogging-removing bars only.
15. A water treatment method as defined in any of claims 9 - 14 further comprising the step of stopping supply of the raw water from the raw water supply tube during stoppage of supply of the filtered water, circulating the filtered water through the sand filter layer by returning the filtered water to the raw water supply tube, and continuing aeration to maintain concentration of dissolved oxygen in the filtered water at a predetermined level.
PCT/JP2003/006811 2002-06-14 2003-05-30 Water treatment device and water treatment method WO2003105987A1 (en)

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WO2007140744A1 (en) 2006-06-08 2007-12-13 Johan Verink Apparatus for wastewater treatment and a plant equipped with such an apparatus
CN101934162A (en) * 2009-06-30 2011-01-05 日本那贺株式会社 Water treatment device and method for cleaning filtration material layer for water treatment device
CN101934162B (en) * 2009-06-30 2015-03-11 日本那贺株式会社 Water treatment device and method for cleaning filtration material layer for water treatment device
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