Anaerobic bioreactor for the wastewater-treatment plant

The present invention relates to an apparatus for treating wastewater comprising aerobic microbes and an upflow anaerobic reactor in which the wastewater including various substances such as non-degradable and toxic materials and organic substances could be decomposed biologically. Anaerobic bio-reaction effect could be maximized by maintaining uniformity of inflowing wastewater and recycle sludge or by deferring the heights of inlets.

TECHNICAL FIELD

The present invention relates to an apparatus for treating wastewater including an upflow anaerobic reactor. More particularly, in the anaerobic reactor including aerobic microbes and an upflow anaerobic reactor, outflow tubes of wastewater and returning sludge is introduced by rotating and depending upon occasions, the introduction heights of the wastewater and the returning sludge is differentiated to obtain maximum effects of the anaerobic reaction.

BACKGROUND ART

In Korean Laid-open Patent No. 2000-31978, the inventors of the present invention have disclosed the apparatus for treating wastewater comprising aerobic microbes and an upflow anaerobic reactor and the method therefor. The apparatus can treat organic wastewater containing indecomposable and toxic substances, nutritive materials (N, P) and heavy metals, and maintain high concentration of sludge stably and economically. As a reference, the conventional technique is described inFIG. 1aandFIG. 1b.

As illustrated inFIG. 1a, the conventional apparatus comprises an anaerobic tank, an aerobic tank and a precipitate tank. Concretely, the fixed porous inflow device is installed on the lower portion of the anaerobic tank. Wastewater and returning sludge flow into the inflow device through an inject portion.FIG. 1bdepicts a planar view of the inflow device schematically.

In the conventional method, the returning sludge returned by a return pump is injected to the anaerobic reactor through the inject portion and the inflow device and then stirred continuously by a mixing device so that a biased stream of sludge flowing upward and a blocking circuit phenomenon of an inflow mixture are prevented. However, there are some problems in the conventional technique. Precisely, since the inflow device is fixed and the wastewater or the returning sludge is always thrown onto a fixed region, the concentrations of the wastewater and the sludge are not maintained uniformly and the biased current is not prevented sufficiently even though the mixing device is operated.

DISCLOSURE OF INVENTION

In order to settle the disadvantages of the conventional method described above, the object of the present invention is to provide an apparatus for treating wastewater comprising an anaerobic reactor in which a wastewater outflow tube6aand a returning sludge outflow tube6brotate on the axis so that the wastewater and the returning sludge are discharged uniformly from the constant surface of the anaerobic reactor when the wastewater and the returning sludge are injected to the anaerobic reactor.

In the first type of the present invention, the upflow anaerobic reactor1for treating wastewater comprises a principal axis2which is formed vertically in the center of the anaerobic reactor1and rotates in accordance with a driving force transferred from a driving means; a wastewater inflow tube3and a returning sludge inflow tube4which are installed in an outer and upper portion of the anaerobic reactor1and through which wastewater and returning sludge are injected respectively; a retentive portion5which is installed and fixed on the upper circumference of the principal axis2, rotates with the principal axis2and through which the wastewater and the returning sludge injected from the ends of the wastewater inflow tube3and the returning sludge inflow tube5pass; a single or multiple outflow tubes6which are installed and fixed onto the principal axis2so as to rotate with the principal axis2and have one end connected with the retentive portion5, the other end installed in the inner and lower portion of the anaerobic reactor1and equipped with a porous tube which discharges a mixture of the wastewater and the returning sludge; an outflow device7which is installed onto an upper portion of the anaerobic reactor1and has a weir structure in order to discharge reaction water containing some sludge through the aerobic reactor20; and a sludge condensing device8which is installed onto a lower portion of the anaerobic reactor1and treats the sludge precipitated in the central lower portion of the anaerobic reactor1by using a gravitational force.

The present invention will now be described with references to the accompanying drawings.

The upflow anaerobic reactor1of the present invention, a type of the upper portion inflow type, will be illustrated more clearly, referring toFIG. 2aandFIG. 2b.

Above all, the anaerobic reactor1of the present invention comprises a principal axis2, a wastewater inflow tube3, a returning sludge inflow tube4, a retentive portion5, an outflow tube6, an outflow device7and a sludge condensing device8as described above.

The principal axis2is connected to and fixed to the retentive portion5and the outflow tube6and is formed perpendicular to the center of the anaerobic reactor1so as to rotate together by using a driving force of the principal axis motor M.

The wastewater inflow tube3and the returning sludge inflow tube4are installed onto the outer and upper portion in order to inject the inflow water and the returning sludge flowing back from the final precipitate tank to the anaerobic reactor1by using a driving force of the sludge return pump respectively. The wastewater inflow tube3and the returning sludge inflow tube4can be injected to the inside of the anaerobic reactor1independently as depicted inFIG. 2aandFIG. 2b, but they also can be combined to form one tube in the outside of the anaerobic reactor1and injected to the retentive portion5in a mixed state of the returning sludge to remove inflow water, organic chemicals within the inflow water, nutritive salts and the like (not depicted).

Next, the wastewater and the returning sludge introduced from the ends of the wastewater inflow tube3and the returning sludge inflow tube4are transferred through the retentive portion5. The retentive portion5is also installed and fixed on the upper circumference of the principal axis2and rotates according to the rotation of the principal axis2. The wastewater and the returning sludge are mixed in the retentive portion5. The retentive portion5can be shorten to place only the upper portion of the principal axis2(SeeFIG. 2a) as well as can be extended from the upper portion of the anaerobic reactor1to the lower portion of the principal axis2(SeeFIG. 2b).

The outflow device7is installed on the upper portion of the anaerobic reactor1and has a weir structure in which the reaction water containing some sludge matured sufficiently in the process of the anaerobic reactor1is discharged through the aerobic reactor20. Preferably, the outflow device7which prevents the block phenomenon caused by the sludge and makes the outflow water discharged uniformly has a weir structure which is installed in a radiation mode from the center as disclosed in Korean Laid-open Patent No. 2000-31978.

The outflow device7is installed on the upper portion of the anaerobic reactor1and has a ware structure in which the reaction water containing some sludge matured sufficiently in the process of the anaerobic reactor1is discharged through the aerobic reactor20. Preferably, the outflow device7which prevents the block phenomenon caused by the sludge and makes the outflow water discharged uniformly has a ware structure which is installed in a radiation mode from the center as disclosed in Korean Laid-open Patent No. 2000-31978.

As another the upper portion inflow type of the anaerobic reactor1, the present invention provides an anaerobic reactor1which adopts a mode that the inflow water and the returning sludge are not blended and are discharged to the lower portion in the reactor independently. The present invention will be described more clearly, referring toFIG. 3aandFIG. 3b.

In this type, the wastewater inflow tube3and the returning sludge inflow tube4which can inlet the wastewater and the returning sludge respectively are installed in the outer and upper portion of the anaerobic reactor1independently. In addition, the wastewater retentive portion5apassing through the wastewater and the sludge retentive portion5bpassing through the returning sludge are installed and separated spatially and the wastewater outflow tube6a,6discharging the wastewater are connected directly to the wastewater retentive portion5aand the sludge outflow tube6b,6discharging the returning sludge are connected directly to the sludge retentive portion respectively. The wastewater retentive portion5aand the sludge retentive portion5b(thus, the wastewater outflow tube6a,6and the sludge outflow tube6b,6also) are installed and fixed on the upper circumference of the principal axis2and rotate together according to the rotation of the principal axis2.

On the other hand, the wastewater inflow tube3and the returning sludge inflow tube4are fixed on the reactor not to be moved or rotated, but the wastewater retentive portion5aand the sludge retentive portion5brotate with the principal axis2. Therefore, in their composition, the wastewater should be injected from the wastewater inflow tube3to the wastewater retentive portion5aand the returning sludge should be injected from the returning sludge inflow tube4to the sludge retentive portion5b. For this purpose, one portion selected in between the wastewater retentive portion5aand the sludge retentive portion5bis included to the other portion preferably as illustrated inFIG. 4. The wastewater retentive portion5aand the sludge retentive portion5bcan be shorten in the length so that only the upper portion of the principal axis2is placed (SeeFIG. 3a) and can be extended from the upper portion of the anaerobic reactor1to the lower portion of the principal axis2(SeeFIG. 3b).

Like the outflow tube6in the first type of the present invention described above, the wastewater outflow tube6a,6and the sludge outflow tube6b,6are connected directly with the wastewater retentive portion5aand the sludge retentive portion5bin one ends respectively and the other ends are placed on the inner and lower portion of the anaerobic reactor1. At the other ends, the porous tubes are formed so as to discharge the wastewater and the returning sludge.

The second type of the present invention comprises a principal axis2, an outflow device7, a sludge condensing device8and the like, which are common in the structure and the functions with the first type.

In addition, the upflow anaerobic reactor1for treating wastewater for applying the second type of the present invention comprises a principal axis2which is formed vertically in the center of the anaerobic reactor1and rotates according to a driving force transferred by a driving means; a wastewater inflow tube3and a returning sludge inflow tube4which are installed onto the outer and upper portion of the anaerobic reactor1and through which the wastewater and the returning sludge are injected respectively; a retentive portion5which is installed and fixed on the lower circumference of the principal axis2, rotates with the principal axis2, is connected directly with the wastewater inflow tube3and the returning sludge inflow tube4and through which the wastewater and the returning sludge pass; a single or multiple outflow tubes6which are installed and fixed onto the principal axis2, rotate with the principal axis2, have one end connected with the retentive portion5directly, the other end installed on the inner and lower portion of the anaerobic reactor1and equipped with a porous tube which discharges a mixture of the wastewater and the returning sludge; an outflow device7which is installed onto the upper portion of the anaerobic reactor1and has a weir structure in order to discharge reaction water containing some sludge through the aerobic reactor20; and a sludge condensing device8which is installed onto the lower portion of the anaerobic reactor1and treats the sludge precipitated in the central lower portion of the anaerobic reactor1by using a gravitational force.

As a lower portion inflow type, the present invention provides the anaerobic reactor1in which the inflow water and the returning sludge are injected from the lower portion of the anaerobic reactor1. This type will be described more clearly, referring toFIG. 5aandFIG. 5b.

Above all, the upflow anaerobic reactor1like the upper portion inflow type comprises a principal axis2, a wastewater inflow tube3, a returning sludge inflow tube4, a retentive portion5, an outflow tube6, an outflow device7and a sludge condensing device8. The wastewater inflow tube3, the returning sludge inflow tube4, the retentive portion5and the outflow tube6are distributed in the direction from the lower portion to the upper portion of the anaerobic reactor1, which is different from the upper portion inject type described above.

The wastewater inflow tube3and the returning sludge inflow tube4are installed onto the outer and lower portion of the anaerobic reactor1in order to introduce the wastewater and the returning sludge to the anaerobic reactor1respectively. The wastewater inflow tube3and the returning sludge inflow tube4can be injected to the inside of the anaerobic reactor1independently as depicted inFIG. 5a, but they also can be combined to form one tube in the outside of the anaerobic reactor1and be injected to the retentive portion5in a mixed state (not depicted).

Next, the retentive portion5, through which the wastewater and the returning sludge pass, is connected directly to the wastewater inflow tube3and the returning sludge inflow tube4. The retentive portion5is installed onto the contact region of the anaerobic reactor1case and the lower portion of the principal axis2. The retentive portion5has an associated structure (SeeFIG. 5b). The lower part of the retentive portion5is fixed onto the case of the anaerobic reactor1and the upper part of the retentive portion is fixed onto the principal axis2. The inside of the retentive portion5should be separated from the outside of the retentive portion5(preventing liquid from passing). Preferably, the contact region formed in between the lower part of the retentive portion5and the upper part of the retentive part5has a mechanically-sealed bearing structure for the rotation, since the upper part of the retentive portion5—the principal axis2should rotate freely against the lower portion of the retentive part5—the anaerobic reactor1case which are fixed.

The outflow tube6is connected directly to the upper part of the retentive portion5and placed on the lower part within the anaerobic reactor1, which can make the inflow water and the returning sludge passing through the retentive portion5injected to the lower part within the anaerobic reactor1. The inflow water and the returning sludge are discharged through a porous tube (having a pore pierced on the tube) or a nozzle which is installed in a surface of the outflow tube6.

In the functions and compositions, the principal axis2, the outflow device7and the sludge condensing device8are same with those of the upper portion inflow type and the retentive portion5and the outflow tube6are also same with those of the upper portion inflow type so that the principal axis2is installed and fixed to rotate together.

As another type of an anaerobic reactor1in the lower portion inflow type, the present invention provides an anaerobic reactor1which adopts a mode that the inflow water and the returning sludge are not blended and are discharged to the lower part within the reactor independently. The present invention will be described more clearly, referring toFIG. 6aandFIG. 6b.

In this type, the wastewater inflow tube3and the returning sludge inflow tube4which can inject the wastewater and the returning sludge respectively are installed onto the outer and upper part of the anaerobic reactor1independently. In addition, the wastewater retentive portion5apassing the wastewater and the sludge retentive portion5bpassing the returning sludge are installed and separated spatially and the wastewater outflow tube6a,6discharging the wastewater is connected directly to the wastewater retentive portion5a. The sludge outflow tube6b,6discharging the returning sludge are connected to the sludge retentive portion5brespectively.

On the other hand, the wastewater inflow tube3and the returning sludge inflow tube4are fixed on the reactor not to be moved or rotated, but the wastewater retentive portion5aand the sludge retentive portion5bshould rotate with the principal axis2. For this purpose, as depicted inFIG. 6beach retentive portion5become a structure associated with the lower retentive portion5fixed on the anaerobic reactor1case and the upper retentive portion5fixed on the principal axis2. Between the wastewater retentive portion5aand the sludge retentive portion5b, one should be included to the other portion preferably. Due to the same reasons with the first type of the lower portion inflow type, preferably, the contact region of the lower retentive portion5—the upper retentive portion5has a mechanically-sealed bearing structure for the rotation.

In the functions and compositions, the principal axis2, the outflow device7and the sludge condensing device8are same as the upper portion inflow type and the retentive portion5and the outflow tube6are also same as the upper portion inflow type so that the principal axis2is installed and fixed to rotate together.

In the anaerobic reactor1having the said functions and structures, the porous tube formed on the outflow tube6has a diameter preventing the block phenomenon by sludge preferably. In addition, when the outflow tube6rotates together according to the rotation of the principal axis2. As the distance of the porous type become nearer to the rotational axis, the time period that each porous tube stays at the specific position on the horizontal surface on which the outflow tube6rotates become longer. Therefore, in order to make the discharging distribution of the wastewater and the returning sludge uniform, the nearer to the rotation axis, the wider the distance between the porous tubes distributed or the smaller the diameter of the porous tube formed preferably. Depending upon the size of the reactor, the kinds of inflow water for the treatment and the like, preferably the distance between porous tubes is in the range of 20 cm˜2 m and the diameter of the porous tube is in the range of 21 mm˜150 mm.

The porous tube can be installed on any position such as a bottom surface, an upper surface and a lateral portion of the outflow tube6. Preferably, in case that the porous tube is installed on the bottom surface, various shapes of nozzle are installed right under the porous tube in order to distribute the wastewater or the returning sludge easily (SeeFIG. 7).

The single or multiple outflow tube6can be installed, depending upon the scale and the structure of the anaerobic reactor1. Preferably, in case that the diameter of the reactor is in the range of 6˜10 m, four outflow tubes6(in case that the inflow water and the sludge are discharged in a mixed state) or four wastewater outflow tubes6aand the sludge outflow tube6b(in case that the inflow water and the sludge are discharged in a separated state) respectively are installed at 90° C. of angle from the horizontal surface. In the latter case, the installation heights of the wastewater outflow tube6aand the sludge outflow tube6bare preferable to become different. If the outflow tubes6are installed with less than four, they generate the biased flow and if with more than four, the apparatus become complicated and increases the cost to be installed.

If the diameter of the anaerobic reactor1becomes more than 8 m, the inflow water and the sludge cannot be discharged uniformly in between the portion adjacent to the rotational axis and its outer portion, although the porous tube formed onto the outflow tube6is adjusted for the distance and/or the diameter. In this case, the outflow tube6for the portion adjacent to the rotational axis and the outflow tube6for the outer portion are separated and installed so that the biased flow of the inflow water and the sludge can be reduced efficiently (not depicted).

In the anaerobic reactor1of the present invention, the mixing device40which shakes reaction water continuously can be installed, which purifies organic wastewater containing indecomposable and toxic substances and nutritive substances (N, P) within the anaerobic reactor1, since it prevents the biased flow of sludge and proceeds the fermentation reaction actively by microorganisms. In this case, the mixing device40, with 3˜6 devices per a reactor, is installed in an interval of about 50 cm˜1 m from the principal axis2of the anaerobic reactor1. The sludge precipitated from the reaction with the mixing device40is collected in the lower center of the anaerobic reactor1through the sludge condensing device8and discharged to the outside of the reactor by a driving force of the sludge discharging pump.

Hereinafter, among the upflow anaerobic reactor1of the present invention, the second upper portion inflow type anaerobic reactor1is applied to the apparatus for treating wastewater and will be explained clearly about the operation and effects. The structure of the apparatus for treating wastewater is depicted inFIG. 8.

As an example, the apparatus for treating wastewater includes the aerobic reactor20and the final precipitate tank30in addition to the upflow anaerobic reactor1. At this moment, the aerobic reactor20includes an acid radical tube31as an oxygen generator in the bottom part of the aerobic reactor20in order to provide oxygen sufficiently so that it makes air-permeable fermenting bacteria become active. For the aerobic reactor20, any conventional material and structure known to those skilled in the art can be adopted. Besides, the final precipitate tank30is utilized to remove sludge which is degraded efficiently by using the aerated microorganisms within the reaction water of the aerobic reactor20. Preferably, the precipitate tank30in a gravity mode is utilized to remove the sludge slowly by exploiting the gravitational force so that the wastewater is cleaned and purified. Besides, the precipitated sludge is collected in the sludge condensing device8, returned to the sludge retentive portion5bpassing through the returning sludge inflow tube4installed onto the outer and upper portion of the anaerobic reactor1by using the sludge returning pump32and then discharged into the anaerobic reactor1through the sludge outflow tube6b,6. The wastewater is transferred to the wastewater retentive portion5apassing through the wastewater inflow tube3installed onto the outer and upper portion of the anaerobic reactor1and then discharged to the bottom portion of the anaerobic reactor1through the wastewater outflow tube6a,6. At this moment, the wastewater and the returning sludge are discharged from the bottom portion horizontal surface uniformly since the wastewater outflow tube6a,6and the sludge outflow tube6b,6rotate in a determined speed. The sludge decomposed efficiently within the anaerobic reactor1is precipitated in the bottom surface of the anaerobic reactor1by the gravity and then the sludge is separated and discharged through the sludge outflow pump33. In the process of the reaction, the reaction water in which organic substances and toxic substances are decomposed and removed is injected to the aerobic reactor20through the outflow device7. Meanwhile, the anaerobic reactor1provides a driving force which shakes the mixing device40connected with the principal axis2within the aerobic reactor1since the driving apparatus is installed in the upper portion end of the principal axis2.

Hereinafter, the process for treating wastewater by exploiting the upflow anaerobic reactor1will be illustrated in accordance with each stage clearly (SeeFIG. 8).

Stage 1: Inflow of Inflow Water to Anaerobic Reactor

The inflow water such as organic wastewater including indecomposable and toxic substances and nutritive substances (N, P) is injected into the anaerobic reactor1through the wastewater inflow tube3installed on the outer and upper part of the anaerobic reactor1, the wastewater retentive portion5aand the wastewater outflow tube6a,6.

Stage 2: Fermentation in Anaerobic Reactor

In order to purify inflow water containing indecomposable and toxic substances and nutritious substances and injected to the anaerobic reactor in the previous stages efficiently, the activated sludge is introduced to the anaerobic reactor1through the returning sludge inflow tube4installed on the outer and upper portion of the anaerobic reactor1, the sludge retentive portion5b, and the sludge outflow tube6b,6. Then, the sufficient fermentation is induced by repeatedly stirring the mixing device40installed on the principal axis within the reactor in the range of 3˜20 rpm (Sometimes, the mixing device40can be omitted in case that reaction water is mixed by the outflow tube6itself).

In the meantime, in order to purify organic wastewater more efficiently which includes indecomposable and toxic substances or nutritive substances such as nitrogen or phosphorus and heavy metals (not depicted), the anaerobic reactor1of the present invention can be installed plurally in a series. In this case, reaction water firstly fermented in the anaerobic reactor1installed in the front side is transferred to the wastewater inflow tube3of the anaerobic reactor1installed in the rear. Thereafter, the returning sludge including partial sludge of the aerobic reactor20which is inner-circulated by the inner rotation pump is injected to the anaerobic reactor1installed in the rear side and is secondly fermented with preventing an upward drift of sludge in a proper condition (the mixing device40is operated, if necessary). This stirring prevents a blocking circuit phenomenon of inflowing mixtures resulted from a high concentration of sludge when the sludge in the anaerobic tank1and an organic wastewater mixture increase by performing the above reaction.

At this moment, preferably the rotational speed of the mixing device40or the outflow tube6is in the range of 3˜10 m/min at a circumference speed based on a circle drawn by an outer block of the mixing device40or the outflow tube6. When the circumference speed is under 3 m/min, the blocking circuit phenomenon disturbs a sufficient reaction. When the circumference speed is above 10 m/min, the merit of a pressing-out type reactor cannot be fully considered since it is mixed completely.

Stage 3: Outflow Into Aerobic Reactor

Some sludge precipitated through the previous procedure is collected to the sludge condensing device8installed on the bottom center of the anaerobic reactor1and discharged by the driving force of the sludge discharging pump33. The reaction water including some upward sludge is discharged from the anaerobic reactor1to the aerobic reactor20through the outflow device7placed in the upper portion of the anaerobic reactor1.

Stage 4: Aeration in Aerobic Reactor

Oxygen is supplied sufficiently to reaction water including some sludge discharged from the anaerobic reactor1in the previous procedure through the acid radical tube31. Consequently, organic substances and the like within wastewater are oxidized, decomposed and purified into inorganic substances such as H2O, CO2or so on to activate aerobic or permeable bacteria in the sludge highly. Ammonia nitrogen and organic nitrogen are changed to nitric nitrogen and the sludge takes phosphorus excessively.

Stage 5: Separation of Pure Water and Return of Sludge

Pure water is separated from the reaction water partially purified in the previous aeration process and moved to the final precipitation tank30. The sludge precipitated by the gravity is collected on the sludge condensing device8placed in the bottom center of the anaerobic reactor1, returned into the anaerobic reactor1through the returning sludge inflow tube4placed on the outer and upper portion of the anaerobic reactor1by using the driving force of the sludge return pump32and exhausted to outside through the sludge reducer of the sludge digestion tank or the dehydrator using the driving force of the sludge outflow pump33in the anaerobic reactor1.

As described above, some microbes such asNitrosomonas, Nitrobacter, Denitrifier, Sulfate reducing bacteria,Pseudomonas, Achromobacter, Aerhobacter, Micrococcus, Bacillus, Proteus, Flavobacterium, Acinetobacter, CorynebacteriumorMycobacteriumcan be applied to the anaerobic reactor1or the aerobic reactor20in the method for treating wastewater in accordance with the present invention. In addition, some permeable microbes also can be used in accordance with the sorts of organic substances included in wastewater.

As illustrated above, the apparatus for treating wastewater of the present invention including the anaerobic reactor1, which treats organic wastewater including indecomposable and toxic substances and nutritive substances by using permeable microbes and the upflow anaerobic reactor, can treat wastewater more efficiently than the conventional apparatus for treating wastewater.

EXPLANATION OF SYMBOLS IN THE FIGURES

2: principal axis

4: returning sludge inflow tube

31: acid radical tube

40: mixing device

Practical and presently preferred embodiments of the present invention are illustrative as based on the hydraulic experiments and examples. The hydraulic experiments have estimated hydraulic characteristics of the upflow anaerobic reactor in the present invention. Preferred Embodiments relates to a management of waster water by using the apparatus for treating wastewater including the upflow anaerobic reactor1in the present invention (SeeFIG. 8). Hydraulic experiments and examples will explain only the effect of the present invention, and it will be appreciated that those skilled in the art, on consideration of this disclosure, may make modifications and improvements within the scope of the present invention.

Examination of Hydraulic Characteristics in Anaerobic Reactor

In order to elucidate hydraulic characteristics of the upflow anaerobic reactor1, experiments were performed. The mixing device40which had a size of 8 cm in width and 2 cm in length was equipped with 3 layers in the anaerobic reactor1which had a size of 9 cm in diameter and 30 cm in height.

In order to measure the degree of dispersion according to the operation of the reactor1, the water solution with 500 ppm of chloride ion concentration was put into the reactor1through2thin hoses installed in 5 cm of height from the bottom of the reactor1without an injection of returning sludge. Tips of the hoses (corresponding to the nozzle of the reactor1practically) were apart from the principal axis by 4 cm and 1.5 cm respectively. Chloride ion solution was injected to make the retentive period of the hoses reach 1 and 3 hours respectively.

The rotations of the mixing device40were varied to 0, 3, 5, 10 rpm respectively. The rotational values such as 0, 3, 5, 10 rpm were equal to circumference speeds such as 0.00, 0.75, 1.25, 2.51 m/min respectively.

In the graphs, as time passed the changes of concentrations in the outflow water were illustrated based on the retentive time. The chloride ion concentration of the inflow water is regarded as C0, the chloride ion concentration of the outflow water is regarded C and the time in which the chloride ion concentrations of the inflow water is identical to that of and of the outflow water is regarded as T0.FIG. 9aandFIG. 9brepresented the results in 1 and 3 hours of the retentive time respectively.

As illustrated in figures, in case that the retentive time was 1 hour without blending, chlorine ion was started to be detected gradually in the outflow water after 1 hour and the concentration of chloride ion reached C0after 1 hour and 20 minutes. Then, in case that the mixing intensity was 3 rpm, chlorine ion was started to be detected in the outflow water after 55 minutes and the concentration of chlorine ion reached C0after 1 hour and 15 minutes. Meanwhile, in case that the mixing intensity was 5 rpm, chloride ion was started to be detected after 30 minutes and the concentration of chlorine ion reached C0after 1 and half hours. In case that the mixing intensity was 10 rpm, chloride ion was started to be detected after 5 minutes from the injection and the concentration of chloride ion reached to C0after 1 and half hours.

In case that the retentive period was 3 hours and the mixing intensity was 3 rpm, chloride ion was started to be detected after 3 hours and the concentration of C0was detected in the outflow water within 10 minutes. However, in case that the mixing intensity was 3 rpm, chloride ion was started to be detected after 25 minutes and its concentration became identical to the concentration of the inflow water after 4 hours. Furthermore, in case that the mixing intensity was 5 rpm, chloride ion was started to be detected after 30 minutes and in case that the mixing intensity was 10 rpm after 15 minutes became similar to a perfect mixing form.

As considered the above results, in case that the mixing density was 0 and 3 rpm, the ideal plug flow was approached and in case that the mixing density was 5 and 10 rpm, the perfect mixing form was achieved.

Preferred Embodiments

(1) Standard of Pilot Plant System

1) The first type of the present invention, in which wastewater and the returning sludge were introduced to the retentive portion placed on the upper portion of the principal axis and were distributed as a mixed state, was applied as an anaerobic reactor. The concrete structure and standard of the anaerobic reactor were demonstrated in Table 1 as followed.
2) The aerobic reactor: 2.0 m in width, 3.0 m in length, 5.5 m in height, 26 m3in effective capacity.
3) The precipitate tank: 2.4 m in diameter, 3.0 m in length, 11 m3in effective capacity.

TABLE 1standarddiameter 2.4 m, height 5.5 mcapacity23 m32 outflow tubesdiameter 100 mm, diameter of a circleformed by a rotation, 2.3 m3 nozzles for eachdistance from center of each nozzle tooutflow tubethe principal axis 64, 90, 110 cm.diameter of a nozzle 80 mmheight from bottom to a nozzle 1 m3 mixing deviceeswidth 50 cm, length 2.3 mplaced high from the bottom by 2, 3, 4 mrespectively
(2) Operation Condition
1) Flow quantity for treatment: 150 m3/day
2) Rotational speed of principal axis: 0.5 rpm (corresponding to about 3.5 m/min in the circumference speed of the mixing device)
3) Temperature of treatment: treatment in buildings at 20˜28° C.
(3) Result

Biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended substance (TSS), total nitrogen concentration (TN) and total phosphorus concentration (TP) of the concentrations of the inflow water and the outflow water were measured total 7 times with a 7 day interval after the apparatus for treating wastewater became stabilized. Concretely, these results of the measurement were illustrated in Table 2 and each treatment efficiency and average efficiency was shown in Table 3.

As demonstrated above, while the BOD concentration of the inflow water was changed from 157.2 to 278.0 mg/L, the BOD concentration of the outflow water was treated by more than 96% on the average and varied in the range of 7.0˜8.0 mg/L. The nitrogen concentration of the inflow water was changed from the range of 33.1˜37.9 mg/L to the range of 6.2˜10.6 mg/L in the outflow water and treated by more than 70%. The phosphorus concentration of the outflow water was changed from the range of 2.9˜6.7 mg/L to the range of 0.1˜0.9 mg/L in the outflow water and stably treated by more than 90%.

After the apparatus for treating wastewater was stabilized, the concentration of sludge within the anaerobic reactor1and the aerobic reactor20and the concentration of the returning sludge and the discharging sludge were measured and demonstrated in Table 4.

In the apparatus of the present invention for treating wastewater including the anaerobic reactor1, the highly concentrated sludge was discharged from the anaerobic reactor1. Especially, it is confirmed that the concentration of sludge is very high when the aerobic reactor20and the anaerobic reactor1were operated.

INDUSTRIAL APPLICABILITY

As described and confirmed above, the present invention provides the upflow anaerobic reactor1which can be applied to a system for treating wastewater. The anaerobic reactor1of the present invention can be utilized to treat indecomposable and toxic substances or organic wastewater including nutritive substances such as nitrogen or phosphorus and heavy metals biologically in the industrial facilities for treating wastewater. Furthermore, wastewater can be managed economically since the sludge of the reactor is maintained in the high concentration and the volume can be reduced to less than the volumes of other biological reactors. Especially, since the sludge of the upflow anaerobic reactor1is concentrated highly, the concentration tank could be omitted for the sewage treatment plant. The first precipitate tank30also can substitute for the reactor and therefore saves the plant space and reduces both the construction cost and the operational cost additionally.