Aeration tank of organic waste liquor and aeration apparatus using the tank

Disclosed is an aeration apparatus for the efficient purification of livestock excretory liquid at low cost and in a way that prevents environmental pollution. The organic waste fluid aeration tank consists of an outer tank (1) and an aeration tube (2) installed within the outer tank. This aeration tube (2) has suction holes (3) set in the lower tube wall and scatter holes (4) set in the upper tube wall. An air diffusion head (6) coupled to a blast pipe (5) is built into the base of the tube. The liquid being treated is decomposed biologically within the outer tank (1), and is aerated within the aeration tube (2). It is expelled into a sludge sedimentation tank. A portion of the attached organic substances and generated bubbles is scattered back into the outer tank (1) through the scatter holes (4). In this invention, multiple units of the above-mentioned tanks are employed in series. Purified water is obtained through the purification of supernatant liquid delivered to the sludge sedimentation tank from the first aeration tank by aeration in the remaining tank. The purified water may be used as wash water for pig houses and liquefied fertilizer.

FIELD OF THE INVENTION
 This invention is related to organic waste fluid aeration tanks and
 aeration apparatuses, with special regard to the liquid waste, excreta,
 etc., of livestock.
 BACKGROUND OF THE INVENTION
 Environmental pollution due to livestock excreta has become an increasingly
 large problem in recent years. In the past, various activated sludge
 apparatuses for organic waste fluid processing, including livestock
 wastes, have been proposed. The high cost of activated sludge apparatuses,
 however, makes it difficult for livestock raisers to employ them. Further,
 the handling of reactors used in the treatment process, the nutrition
 source/microorganism loading ratio, and selection of the mean residence
 time within the tank are difficult. The most difficult problem is an
 interference with sludge sedimentation due to increases of fibrous
 microorganisms. The maintenance of dissolved oxygen levels in the aeration
 tanks, the regulation of the cycling volume of activated sludge and the
 control of waste activated sludge are difficult. Fine bubbles are thought
 to be better in promoting the conveyance efficiency of oxygen. The
 distinction between fine and coarse is, however, ambiguous, making
 appropriate control impossible. Further, not only is the treatment time
 from the introduction of raw liquid to discharge lengthy; it also takes an
 inordinate amount of time to produce a non-offensive smelling and
 biochemically stable quality nutritious source. The establishment of an
 economical and structurally simple excretory liquid treatment system for
 livestock is still some time off; therefore, a dependence upon such
 primitive methods as natural decomposition using trench holes or aeration
 continues to be necessary.
 Natural decomposition utilizing trench holes, however, causes ground water
 contamination, and forced aeration utilizing concrete frames requires an
 extended period of time to purify excretory liquid to effluent quality,
 making it an inefficient method due to the lengthy digestive time required
 by microorganisms.
 The present invention alleviates the above mentioned problems by being
 non-polluting and by providing inexpensive organic liquid through an
 efficient purification system.
 SUMMARY OF THE INVENTION
 The aeration tank of this invention returns a portion of adhered organic
 substances and bubbles to its outer tank after treatment in its aeration
 tube. The aeration tube is installed within the outer tank. Suction holes
 are set at the base of the aeration tube wall and scatter holes are
 positioned at the upper end of the tube wall. An air diffusion head,
 coupled to a blast pipe, is inserted into the base of the tube. A further
 tube, designed to carry away bubbles expelled upward from the aeration
 tube, is fitted to the top end of the tube. The organic waste fluid
 aeration apparatus employed in the above mentioned aeration tank
 constitutes a quick and continuous automatic system for the removal of
 solid organic substances suspended in waste fluid.
 The system functions in the following manner: At least two of the above
 mentioned aeration tanks are utilized in tandem or series. One unit
 functions as the collected bubble mixture aeration tank. Liquid to be
 treated is received into the outer tank from the raw liquid adjusted tank.
 It is then received into the aeration tube where it is aerated by a
 mixture of collecting bubbles. The generated bubbles are then expelled
 into a sludge sedimentation tank. The second unit receives supernatant
 liquid from the sludge sedimentation tank directly into its aeration tube
 via an initial return tube. Subsequent units receive liquid directly into
 their aeration tubes from the outer tank of the aeration tanks directly
 preceding the receiving units. A portion of the organic substances
 attached to bubbles generated by each aeration tube is scattered back into
 its respective outer tank and a portion is conducted to the collected
 bubble mixture tank. The overflow from the final aeration tank is
 collected in the treated liquid reservoir tank.
 If only one aeration treatment unit is employed in conjunction with a
 collected bubble mixture tank, liquid expelled into the outer tank is
 delivered directly into the treated liquid reservoir tank. When two units
 are employed, expelled liquid is delivered into the treated liquid
 reservoir tank only from the outer tank of the second aeration tank. The
 more aeration tanks utilized, the more the waste fluid is purified. From
 an economic perspective, however, the optimum number of units is from two
 to four. Three units should provide an acceptable level of purity.

DETAILED DESCRIPTION
 FIG. 1 shows an example of the aeration tank or unit of the invention. The
 outer tank (1) is a cone shaped anti-corrosion tank with its apex at the
 bottom. The lower end is closed at the center of the outer tank (1). The
 aeration tube (2) is installed within the outer tank and is connected at
 its upper end opening port to a transfer tube. Anti-corrosion vinyl pipes
 are used in the aeration tube (2). The liquid being treated (9) is
 received into the aeration tube (2) from the outer tank (1) through
 multiple suction holes (3) set at the base of the aeration tube (2) wall.
 Multiple scatter holes (4) are positioned at the upper end of the aeration
 tube (2).
 In this invention, concentrated aeration is performed in the aeration tube
 (2), and solid substances are removed automatically by generated bubbles
 to which they adhere. A portion of the bubbles generated by aeration are
 cycled into the outer tank (1) through the scatter holes (4), and the
 remaining bubbles are expelled to the sludge sedimentation tank (described
 later) via pipes fitted to the upper end opening port. Biological
 decomposition is effected in the outer tank (1) by the reproductive
 activity of oxygenated microorganisms. The aeration tube (2) contains a
 built-in air diffusion head (6) coupled to a blast pipe (5) positioned at
 the base of the tube. The diffusion head (6) aerates and froths the liquid
 being treated in the outer tube (1) as it is introduced into the aeration
 tube (2). Liquid being treated is pumped (8) into the outer tank (1) via a
 raw liquid supply tube (7). The liquid being treated (9) can be, for
 example waste fluid and livestock excretory liquid containing pre-adjusted
 organic substances.
 FIG. 2 shows the organic waste fluid aeration apparatus with four of the
 aeration units described in FIG. 1 installed in series. The first of the
 four units serves as the collected bubble mixture aeration tank (10). The
 remaining three tanks serve as pure liquid aeration tanks and consist of
 the first aeration tank (11), the secondary aeration tank (12), and the
 tertiary aeration tank (13). The outer tank (10a) of the collected bubble
 mixture aeration tank (10) is connected to the raw liquid adjusted tank
 (14) via the raw liquid supply tube (7). Number eight (8) is a pump. The
 adjusted raw liquid is supplied to the upper part of the outer tank (10a)
 through the raw liquid supply tube (7). The upper end of the aeration tube
 is connected to the sludge sedimentation tank (16) via the secondary
 bubble transfer tube. Bubbles generated in the aeration tube (10b) are
 expelled to the sludge sedimentation tank (16) via the bubble transfer
 tube (15). Number seventeen (17) is a sludge pullout valve.
 The first aeration tank (11), the secondary aeration tank (12), and the
 tertiary aeration tank (13) are connected in series in the direction of
 flow of the liquid being treated. The first aeration tank (11) is
 connected to the sludge sedimentation tank (16) via the first return tube
 (18). The first return tube (18) is connected at one end to the
 supernatant section of the sludge sedimentation tank (16). The other end
 is connected to the aeration tube (11b) of the first aeration tank (11).
 The aeration tube (12a) of the secondary aeration tank (12) is connected
 to the outer tank (11a) of the first aeration tank (11) via the secondary
 return tube (19). The aeration tube (13b) of the tertiary aeration tank
 (13) is connected to the outer tank (12a) of the secondary aeration tube
 (12) via the tertiary return tube (20) in the same manner. The overflow
 liquid from the outer tank (13a) of the tertiary aeration tank (13) is
 introduced into the treated water reservoir tank (21). Each aeration tube
 (11b, 12b, and 13b) in the series of aeration tanks (11, 12, 13) contains
 suction holes (11c, 12c, and 13c) at its base, and scatter holes (11d,
 12d, and 13d) at its upper end. The scatter holes are connected to the
 outer tank (10a) of the collected bubble mixture tank (10) via the
 secondary bubble transfer tube (22). Air diffusion heads (10e, 11e, 12e,
 and 13e) which are connected to a blast pipe (5) are built-in to the base
 of each aeration tube (10b, 11b, 12b, 13b) of all four aeration tanks (10,
 11, 12, 13). Number twenty-three (23) is a blower connected to the blast
 pipe (5).
 The organic waste fluid aeration apparatus shown in FIG. 2 functions as
 follows to purify livestock as well as other organic waste fluid. The
 excreta mixture from pig houses, feed dropping substances, etc., for
 example, are cleansed with water and deposited into a catchment tank (not
 indicated in drawing). The organic waste is then treated by a solid liquid
 separator (not indicated in drawing) where bulky refuse, sediment, etc.
 are removed. It is then introduced into a raw liquid tank (not indicated
 in drawing) through a cushion tank (not indicated in drawing) via waste
 fluid tubes. It is desirable to incubate and produce heterotrophic
 bacteria aerobically after adding microorganisms into the raw liquid tank;
 however, good results are obtainable without adding microorganisms.
 Important microorganisms employed in waste fluid treatment are common
 bacillus sp (Bacillus. sp), lactic acid bacillus, lactic acid coccus,
 Gram-negative bacillus, obligate aerobe, yeast, mold, etc.
 The waste fluid pumped up from the raw liquid tank is loaded from the upper
 section of the outer tank (10a) into the collected bubble mixture aeration
 tank (10) through the raw liquid supply tube (7) by the pump (8),
 maintaining an aerobic condition in the raw liquid adjusted tank (14). The
 waste fluid is decomposed biologically by microorganisms within the outer
 tank (10a) of the collected bubble aeration tank (10). The biologically
 decomposed waste fluid is introduced via the suction holes (10c) into the
 aeration tube (10b) through the action of the air diffusion head (10e). It
 is then aerated. Aeration causes the organic waste to adhere to the bubble
 surface. These bubbles are expelled into the sludge sedimentation tank via
 the secondary bubble transfer tube (15) from the upper end of the aeration
 tube (10b). During this process, a portion of the bubbles is scattered
 back into the outer tank (10a) from the scatter hole (10d) of the aeration
 tube (10b). The organic sludge froth discharged with the bubbles settles
 in the sludge sedimentation tank. The sludge is removed via the sludge
 pullout valve (17), and is transferred to the sludge thickener (not
 indicated in drawing) as necessary by the airlift pump (not indicated in
 drawing). The thickened sludge is utilized as water adjusted materials in
 a compost shed.
 The supernatant liquid in the sludge sedimentation tank (16) is further
 purified, as above, in the first aeration tank (11), the secondary tank
 (12) and the tertiary aeration tank (13). The supernatant liquid in the
 sludge sedimentation tank (16) may be supplied to the aeration tube (11b)
 of the first aeration tank (11) via the first return tube (18). The
 bubbles aerated in the aeration tube (11b) are circulated into the outer
 tank (10a) of the collected bubble tank (10) via the first bubble transfer
 tube (22). A portion of the bubbles is scattered back to the outer tank
 (11a) from the scatter hole (11d) of the aeration tube (11b) where it is
 biologically decomposed in the outer tank (11a). This portion is then
 recycled through the aeration tube (11b) from the suction hole (11c) to
 the aeration tube (11b). A portion is supplied to the aeration tube (12b)
 of the secondary aeration tank (12) via the secondary return tube (19);
 and, as above, it is supplied to the aeration tube (13b) of the tertiary
 aeration tank (13) via the tertiary return tube (20) from the outer tank
 (12a) of the secondary aeration tank (12). It is then cycled through in
 the same manner as it is in the first aeration tank (11), and is
 re-introduced into the outer tank (10a) of the collected bubble mixture
 aeration tank (10) through the first bubble transfer tube (22). The
 purified liquid overflow from the outer tank (13a) of the tertiary
 aeration tank (13) accumulates in the treated liquid reservoir tank (21).
 The purified liquid in the treated liquid reservoir tank is available for
 use as cleaning water. Its high fertilizer response component content,
 however, renders it useful as a highly liquefied fertilizer.
 The above-mentioned aeration treatment will achieve the following results:
 an approximately 100% removal rate of Escherichia coli; a 100% removal
 rate of ammonia gas; a 99% removal rate of biochemical oxygen demand
 (BOD); a 99% removal rate of floating suspended matter (SS); a 99% removal
 rate of turbidity (TU); a 99% removal rate of ammonia nitrogen; a 92%
 removal rate of total ammonia (T-N); a 71% removal rate of chemical oxygen
 demand (COD), and an 82% removal rate of total organic carbon (TOC).
 The high purification performance and purification effects achieved by this
 organic waste fluid aeration tank and aeration apparatus are due to the
 production of high density bubbles by concentrated aeration and the
 continuous expulsion of organic substances adhered to these bubbles.
 Oxygen suitable for the reproduction of microorganisms, which are treated
 biologically in the outer tank, can always be supplied.
 Various reactors can be utilized for the treatment process, allowing a wide
 range of options. Because no secondary sedimentation tank is required,
 costs for construction, operation and maintenance of such a tank are
 spared. The process also removes the need to select a
 microorganism/nutrient ratio loading reference and mean a residence time;
 prevents the growth of fibrous microorganisms; allows easy maintenance of
 dissolved oxygen and regulation of the flux volume and control of
 activated sludge; prevents problems with the occurrence of bulky sludge,
 floating or nocardia bubbles; and allows a short treatment time. In
 particular, the process allows the easy and economical treatment of swine
 excretory liquid.
 INDUSTRIAL APPLICABILITY
 The organic waste fluid aeration tank and aeration treatment system of this
 invention are suitable not only for the treatment of ordinary waste fluid,
 such as from food processing factories, but also for the treatment of
 livestock wastes, which have a high BOD load and a high viscosity.
 Particularly, due to low cost performance, an approximate 100% removal of
 ammonia gas and the resultant absence of Escherichia coli, it has the
 advantage of being usable as washing water and as liquefied fertilizer.