BACKGROUND ART Also, the present invention relates to a method and apparatus for an advanced biological wastewater treatment, and more particularly to a method and apparatus for advanced wastewater treatment without sludge discharge using sludge disintegration, in which the sludge dissolved through the sludge disintegration for reducing the sludge and utilizing the same as a carbon source is utilized as a feed of a microorganism.

Generally, wastewater treatments have been rapidly developed together with a development of an activated sludge process using a microorganism and have been conducted in order to remove organic compounds and suspended solids. The treatments have been developed into various modified methods while the treatments have being developed into an advanced wastewater treatment process capable of removing nitrogen and phosphorus. Taking a close look at a principle of the presently developed advanced biological wastewater treatment, nitrogen removal is conducted so

that NH4+ is converted into N02 or N03 by nitrification using microorganism and N2 gas is then discharged through denitrification, and phosphorus removal is conducted so that phosphorus dissolved under anaerobic condition is excessively absorbed under aerobic condition by microorganism, and sludge is then removed. There are many processes for removal of nitrogen and phosphorus using such principle, including A2/0, modified Bardenpho, Virginia Initiative Plant (VIP) and University of Cape Town (UCT), etc.

In order to successively manage such advanced biological treatment processes, biological reactors under anaerobic, anoxic and aerobic conditions should be provided, sufficient carbon sources are necessary for phosphorous release and denitrification under the anaerobic and anoxic condition, and high leveled technical know-how is required for such as discharging sludge absorbing excessive phosphorus in a constant quantity. Further, as shown in FIG. 1, there are required an equipment for thickening, dewatering and storage, etc. , and a final proceeding for incineration and landfill, etc. so as to treat excess sludge discharged from the process.

Looking through problems of wastewater treatment by the presently used installation, most of the installations can remove organic compounds and suspended solids using ac activated sludge process, but hardly remove eutrophication-producing nitrogen and phosphorus, whose substantial part is discharged in a undisposed state to induce eutrophication of lake and river, thus causing serious problems in securing high quality water resources and in conserving natural ecosystem. Thus, it is true that government enhances restriction of nitrogen and phosphorus in discharge water quality standard and concentrically develops and distributes the advanced wastewater treatment process for removal of nitrogen and phosphorus.

However, taking a close look at inflow water quality of a conventional sewer

system for wastewater disposal, practically, most of sewer systems considerably lack a carbon source for biological denitrification and phosphorus release, or have the carbon source with very low concentration hardly to operate the biological treatment.

Accordingly, in order to efficiently manage the advanced wastewater treatment process, organic compound lacking in inflow water should be supplemented by an external carbon source such as methanol. However, such external carbon source such as methanol, etc. is higher in price so that it is hardly used due to economical problem.

Recently, it has been widely studied that organic acid, sludge and foodwaste fermentation broth are utilized instead of the external carbon source.

Also, the advanced biological wastewater treatment process necessarily discharges sludge whose treatment technology is practically dependent on thickening, low efficiency anaerobic digestion treatment, dewatering and landfill. However, in the conventional waste sludge treatment method, sites for landfill is required thus to cause a cost problem. In fact, it has been known that cost for waste sludge treatment by the method corresponds to about 40% of the total cost of wastewater treatment.

Meanwhile, with an enforcement of mandatory control, it is expected to carry the waste sludge in the final landfill, so that new method for waste sludge treatment being required. Thus, if organic sludge discharged from the biological treatment process is re-used as a carbon source for advanced wastewater treatment through pre- treatment, it is most effective to utilize the sludge and it is expected to solve the environmental and economical problems possibly generated upon landfill or incineration of the sludge.

DISCLOSURE OF THE INVENTION Accordingly, the present invention has been made to solve the above-

mentioned problems occurring in the prior art, and an object of the present invention is to provide a method for sludge disintegration in which physical treatment and/or chemical treatment are conducted to sludge necessarily generated from an advanced wastewater treatment process thus to make microorganisms extinct and to decompose their organic structure, firstly reducing the sludge and utilizing the same as a carbon source for denitrification and phosphorus release, thereby increasing removal efficiency of nutrients.

Another object of the present invention is to provide a method and apparatus for advanced wastewater treatment without sludge discharge using sludge disintegration, wherein the sludge treated with physical and/or chemical sludge disintegration is utilized as a carbon source for advanced biological wastewater treatment to hardly generate excess sludge, thus not to generate a problem such as landfill and to possibly to be effectively adapted to inflow water having low concentration.

In order to accomplish these objects, there is provided a method of sludge disintegration for reducing the sludge and utilizing the same as a carbon source for an advanced biological treatment process, the method comprising the step of : conducting physical treatment and/or chemical treatment independently or concurrently to the sludge generated from a biological wastewater treatment process and an advanced wastewater treatment process so as to decompose the sludge, wherein the physical treatment is selected from at least any one method of mechanical decomposition, heating, freezing and defrosting, and ultrasonic irradiation, and the chemical treatment is selected from at least any one method of ozone, acid alkali, hydrogen peroxide and enzyme treatment.

The method for sludge disintegration further comprising the step of separating

and removing inorganic solids having high specific gravity from the sludge generated from the biological wastewater treatment process and the advanced wastewater treatment process by way of a separator for inorganic solids using a centrifugal force, before the step of physical treatment and/or chemical treatment for the sludge.

In the method for sludge disintegration, when the chemical treatment adapts ozone or hydrogen peroxide treatment, acid or alkali is injected to regulate pH so as to increase the decomposition efficiency of sludge.

The method for sludge disintegration is adapted to a conventional advanced treatment process, an advanced treatment using a sequencing batch reactor (SBR), an advanced treatment using an intermittent discharge continuous inflow type SBR or a poor-load treatment plant that water quality of inflow water is lower than value of design standard.

According to the present invention, there is provided a method for advanced wastewater treatment using sludge disintegration, which is an advanced biological wastewater treatment without generating excess sludge, the method comprising the steps of (a) conducting physical treatment and/or chemical treatment independently or concurrently to the sludge generated from a biological wastewater treatment process and an advanced wastewater treatment process so as to decompose the sludge; and (b) injecting the sludge decomposed from the step (a) into an anaerobic/anoxic reactor of the advanced biological wastewater treatment process to utilize the same as a carbon source for denitrification and phosphorus release, wherein the physical treatment is selected from at least any one method of mechanical decomposition, heating, freezing and defrosting, and ultrasonic irradiation, and the chemical treatment is selected from at least any one method of ozone, acid- alkali, hydrogen peroxide and enzyme treatment.

The method for advanced wastewater treatment using sludge disintegration further comprising the step of separating and removing inorganic solids having high specific gravity from the sludge generated from the biological wastewater treatment process and the advanced wastewater treatment process by way of a separator for inorganic solids using a centrifugal force, before the step of physical treatment and/or chemical treatment for the sludge.

In the method for advanced wastewater treatment using sludge disintegration, when the chemical treatment adapts ozone or hydrogen peroxide treatment, acid or alkali is injected to regulate pH so as to increase the decomposition efficiency of sludge.

The method for advanced wastewater treatment using sludge disintegration is adapted to a conventional advanced treatment process, an advanced treatment using a sequencing batch reactor (SBR), an advanced treatment using an intermittent discharge continuous inflow type SBR or a poor-load treatment plant that water quality of inflow water is lower than value of design standard.

According to the present invention, there is provided a system for an advanced wastewater treatment without sludge discharge using sludge disintegration, the system comprising a sludge decomposing device for conducting physical treatment and/or chemical treatment to the sludge; an anaerobic/anoxic reactor; an aerobic reactor; and a carrying device for carrying the sludge decomposed from the sludge decomposing device to the reactor.

The system for an advanced wastewater treatment without sludge discharge using sludge disintegration further comprising a centrifugal separator for separating and removing inorganic solids from the sludge using a centrifugal force.

BRIEF DESCRIPTION OF THE INVENTION

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 is a process view of the representative wastewater treatment plant using a conventional advanced biological wastewater treatment method; FIG. 2 is a schematic view of an embodiment of an advanced wastewater treatment system without sludge discharge using a sludge disintegration method according to the present invention; FIG. 3 is graphs showing a result of adapting a present method of sludge disintegration for reducing sludge and utilizing the same as a carbon source to an advanced wastewater treatment ; FIG. 4 is process views showing another embodiment of the present invention, wherein a present method of sludge disintegration for reducing sludge and utilizing the same as a carbon source is adapted to an advanced wastewater treatment employing a sequencing batch reactor (SBR).

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for an advanced wastewater treatment without sludge discharge using sludge disintegration and an apparatus thereof of the present invention will be described in detail with reference to the accompanying drawings. The following description and drawings are provided for the only purpose of illustration for easy understanding and are not therefore limited thereto.

FIG. 2 is a schematic view of an embodiment of an advanced wastewater treatment system without sludge discharge using a sludge disintegration method, particularly using ozone according to the present invention.

As shown in FIG. 2, according to the advanced biological wastewater treatment without sludge discharge, using a centrifugal separator 22 for inorganic solids, inorganic solids having high specific gravity are separated and removed from a part of the sludge of an aerobic reactor 21, and using a sludge decomposing device 23 using ozone, the sludge is decomposed and dissolved to be carried to an anaerobic/anoxic reactor 20. A part of the decomposed sludge carried to the anaerobic/anoxic reactor 20 is utilized'as a carbon source for denitrification and phosphorus release under an anaerobic/anoxic condition, and the other sludge is utilized as a feed of microorganisms at the reactor 21.

To be more specific, the centrifugal separator 22 for inorganic solids separates and removes inorganic solids with relatively higher specific gravity from the sludge using a centrifugal force to restrict an accumulation of inorganic solids in the reactor, thereby malcing organic sludge undischarged.

The sludge decomposing device using ozone decomposes microorganisms in the excess sludge using an oxidizing power of ozone, thus making the sludge decomposed biologically faster and easily. Extinction of microorganisms is obtained by a contact of microorganisms in the excess sludge with the powerful oxidizer, ozone, by which cell membrane being damaged and broken. A part of microorganisms broken by such process are utilized as a carbon source for denitrification and phosphorus release in the anaerobic/anoxic reactor 20, and the other microorganisms are carried to the aerobic reactor 21 and are utilized as a feed for aerobic microorganisms.

FIG. 3 is a result of sludge disintegration according to the present invention, wherein dissolution of the carbon source is shown when performing an ozone treatment at a doses of ozone of 0. 1-5. 0 gO3/gSS, an ultrasonic irradiation treatment, a

heat treatment at 30~150°C, an enzyme treatment, and a freezing and defrosting treatment. In the result, a quantity of organic compounds is dissolved from the sludge.

The physical treatment adapted to the sludge decomposing device 23, such as ultrasonic treatment, heat treatment, freezing and defrosting treatment and mechanical decomposition among the treatments, does not cause a problem in the biological treatment process, and the ozone treatment as a chemical treatment has no residual property even though it effectively decomposes sludge due to powerful oxidizing power, so that it may be proper to be adapted to the biological treatment process and it may not be poisonous because the remaining ozone in the water after reaction is converted into oxygen.

The method of sludge disintegration for reducing sludge and utilizing the same as a carbon source can be adapted to a poor-load treatment plant. In the conventional biological wastewater treatment process, in order to obtain the stable treatment efficiency, microorganisms and feeds should be controlled in proportion to each other. However, there may be provided a case in which water quality of inflow water at the sewer system for wastewater disposal is very lower than value of design standard, so that the biological treatment process is hardly performed, which is called a case of the poor-load treatment plant. In this case, if the method of the present invention for sludge disintegration for reducing sludge and utilizing the same as a carbon source is adapted thereto in order for the stable biological treatment, feeds for microorganisms lacking in a raw water can be supplemented thus to resolve the problem of poor-load.

INDUSTRIAL APPLICABILITY As described before, according to the method for sludge disintegration for

reducing sludge and utilizing the same as a carbon source, the sludge necessarily generated from the advanced biological wastewater treatment is decomposed by physical treatment and/or chemical treatment, which makes microorganisms extinct and decomposed in their structure, thus reducing the sludge, and the decomposed sludge is injected under the anaerobic/anoxic condition of the advanced biological treatment process so as to utilize the same as a carbon source for denitrification and phosphorus release, thus securing organic compounds in the treatment and effectively increasing the removal efficiency of nutrients.

Also, according to the method for the advanced wastewater treatment without sludge discharge using sludge disintegration, nitrogen and phosphorus are effectively removed by injecting the secured carbon source into the reactor, so that excess sludge is hardly generated, thus not to cause the problem of landfill and to be effectively adapted to inflow water with low concentration.

Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.