KR100331898B1 - Advanced Treatment Process of Domestic Wastewater by Biological and Chemical - Google Patents

Abstract

Sedimentation and sedimentation tank step of sedimentation of sand and contaminants in sewage; In a two-stage aeration tank consisting of a simple aeration tank and a contact aeration tank, nitrogen was nitrified and returned from the ammonia form (NH ₃ ) to the nitric oxide form (NO ₃ ). An anoxic tank step of converting the nitrogen gas into a nitrogen gas by means of a denitifier; A bio-pond step of activating a bio-comp made by solidifying soil microorganisms in a bio-maker and supplying it to an aeration tank; A simple aeration tank step of primary decomposition and nitrification of soil microorganisms from the bio-ponds, aerobic microorganisms in them, and organic matters to be processed by the continuously supplied oxygen; A contact aeration tank step of secondary decomposition and nitrification of the introduced primary decomposition organic material and non-nitrified nitrogen by the microorganisms attached to the media; A settling tank step of removing sludge, to-be-treated and phosphorus from the settling tank by adding a flocculant; And a concentration tank step of increasing the concentration by dehydrating the precipitated sludge, and a sewage treatment method for effectively treating nitrogen and phosphorus, which are organic substances and nutrients in sewage, is disclosed.

Description

Advanced Treatment Process of Domestic Wastewater by Biological and Chemical}

One of the longest and still unresolved problems in sewage treatment methods is poor sedimentation in sedimentation tanks and the simultaneous removal of nitrogen and phosphorus by biological methods. In other words, the existing biological treatment method has a poor ability to cope with load fluctuations of influent water, and the sludge swelling of aeration tanks causing instability of treated water quality due to sedimentation defects caused by overgrowth of filamentous microorganisms in the aeration tanks. Rising sludge occurs frequently in sedimentation tanks, and biologically perfect treatment is very difficult due to the imbalance between organic substances and nutrients in the influent sewage.

Sewage treatment methods in foreign countries are applied with a wide variety of processes, and the nutrient treatment process that is suitable for the sewage characteristics of the country is the main. However, it is hardly known whether biological nutrient removal processes are applicable to domestic low concentration sewage, which has a great change in flow rate and concentration due to regional and seasonal factors, and the concentration of sewage flowing into sewage treatment plants is very low (Wallis-Lage). , CL, et al (1992) .Biological Nutrient Removal Using a Low Strength Waste, WEF 65th Annual Conference & Exposition Proceedings, New Orlearns, Sep. 20-24, 123-134.).

As the nutrient removal process is applied according to the characteristics of sewage, the development of treatment process for effective treatment of domestic sewage with relatively low concentration of organic substances and nutrients is urgently needed.

Accordingly, it is an object of the present invention to provide a biochemical chemical sewage treatment method for preventing sludge from floating in a sedimentation tank and effectively removing nutrients such as nitrogen and phosphorus regardless of the high and low nutrient concentrations contained in sewage.

1 is a block diagram of a biological and chemical advanced sewage treatment system according to the present invention.

2 is a detailed view of a bio-pond according to the present invention.

Figure 3 is a block diagram of Namyangju-si sewage treatment system as a prior art.

<Explanation of symbols for main parts of the drawings>

1: Sedimentation and Precipitation Tank

2: anaerobic tank

3: simple aeration tank

4: contact aeration tank

5: settling tank

6: Bio-pond

7: drug reservoir

8: thickener

9: air generator (compressor)

10: Mixing Mixer

11: Media

30: Bio-maker

40: Bio-comp

MEANS TO SOLVE THE PROBLEM The present inventors aim at the sedimentation and sedimentation tank stage which precipitates and removes sand and contaminants in sewage; In a two-stage aeration tank consisting of a simple aeration tank and a contact aeration tank, nitrogen was nitrified and returned from the ammonia form (NH ₃ ) to the nitric oxide form (NO ₃ ). An anoxic tank step of converting the nitrogen gas into a nitrogen gas by means of a denitifier; A bio-pond step of activating a biocomb made by solidifying soil microorganisms in a bio-maker and supplying it to the aeration tank; A simple aeration tank step of primary decomposition and nitrification of soil microorganisms from the bio-ponds, aerobic microorganisms in them, and organic matters to be processed by the continuously supplied oxygen; A contact aeration tank step of secondary decomposition and nitrification of the introduced primary decomposition organic material and non-nitrified nitrogen by the microorganisms attached to the media; A settling tank step of removing sludge, to-be-treated and phosphorus from the settling tank by adding a flocculant; And it was found that it is achieved through the advanced sewage treatment method according to the invention comprising a concentration tank step to increase the concentration by dehydrating the precipitated sludge.

Hereinafter, the present invention will be described in detail with reference to the configuration of the sewage treatment system shown in the accompanying drawings.

1 is a block diagram of a biochemical high sewage treatment method according to the present invention.

One aspect of the method of the present invention comprises: a sedimentation and sedimentation tank 1 for sedimenting and removing sand and contaminants in sewage; In the two-stage aeration tank, the sludge 13, which was nitrified and returned from the ammonia form (NH ₃ ) to the nitric oxide form (NO ₃ ), was taken as nitrogen as a carbon source using sewage flowing into an anoxic state as a carbon source. An oxygen-free tank (2) for converting and evacuating to the atmosphere; A bio-fond 6 for activating the biocomb 40 made by solidifying soil microorganisms in the bio-maker 30 and supplying it to the aeration tank; Nitrification of nitrogen in the form of ammonia in the object by the activated soil microorganisms supplied from the bio pond 6 and the aerobic microorganisms inhabiting the aeration tank 3 itself, and the oxygen continuously supplied through the air generator 9. Simple aeration tank (3); A contact aeration tank (4) for secondary decomposition and nitrification of organic matter decomposed primarily in the simple aeration tank (3) and nitrogen in the form of ammonia, which has not been completely nitrified due to a short residence time, by a microorganism attached to the media (11); A settling tank (5) for introducing sludge, to-be-treated and phosphorus by injecting a flocculant into the to-be-processed object via the contact aeration tank (4); A biochemical chemical sewage treatment system comprising a concentration tank (8) for dewatering a portion of precipitated sludge to increase its concentration.

Another aspect of the process of the present invention comprises a path 13 for conveying a treated product nitrified in a contact aeration tank 4 to an oxygen-free tank 2; A path 14 for transferring the sludge coagulated and precipitated by the flocculant in the settling tank 5 to the simple aeration tank 3 in order to maintain a continuous sludge supply and proper microbial concentration (MLSS); A path 15 for returning the flocculated sludge to the bio pond 6 in order to promote the continuous supply of microorganisms and the activation of the biocomb 40; A path 17 for transferring excess settling sludge from the settling tank 5 to the thickening tank 8 for dewatering with a high concentration of concentrated sludge; A path 18 for returning the dehydration liquid to the simple aeration tank 3; And the route of movement of wastewater and sludge, such as the route 16 for introducing the microorganisms activated in the bio pond 6 into the simple aeration tank 3.

The role and operation of each reactor of the biochemical chemical sewage treatment method of the present invention will be described in detail as follows. Treated living sewage enters through long collection pipelines and contains large amounts of sand and contaminants. If the sand and contaminants are not removed in advance, it will act as a factor to reduce the failure of the machine and the processing efficiency of subsequent processes, and to prevent this in advance, and to settle the role of equalization to minimize the hourly flow rate and concentration change of sewage. Precipitation tank 1 was installed. Sedimentation and sedimentation tank (1) is a place where the odor is severe, and if necessary, the odor can be completely covered and the odor substance can be collected and processed. The treated matter which has passed through the sedimentation and sedimentation tank (1) flows into the anoxic tank (2). The object is subjected to a simple aeration tank (3) and a contact aeration tank (4), the nitrogen in the form of ammonia is completely nitrified from NO ₂ → NO ₃ form. Nitrified material is returned from the contact aeration tank (4) to the anoxic tank (2) via the path (13), and the nitrogen in the form of nitric oxide is decomposed by the denitrification bacteria using the organic material in the incoming water as a carbon source. ₃ → NO ₂ → NO → N ₂ O → N ₂ is reduced and exhausted to the atmosphere, and in the anoxic tank (2), the mixing mixer for smooth contact and mixing with denitrification bacteria and carbon source and NOx-N (10) Is equipped. As an electron donor used for denitrification, external carbon sources such as acetic acid, citric acid, and methanol are useful, but due to economic problems, organic materials of the target carbon source are used.

The bio-pond 6, which plays a very important role in the biochemical chemical sewage treatment method of the present invention, is composed of a biocomb 40 and a biomaker 30, which are already known technologies, and the detailed configuration thereof is shown in FIG. do. The most important thing in biological treatment is the rapid removal of organic substances by microorganisms and the stable treatment water quality through separation of processed materials and microorganisms. Accordingly, in the present invention, a biocomb 40 solidified with soil microorganisms having excellent ability to remove organic matter and excellent sedimentation efficiency, called 'bio-clod' in the art, was used. The biocomb 40 used in the present invention secures soil microorganisms that are highly adaptable to wastewater treatment, so that actinomycets, bacillus sp., Micrococcus luteus, and pseudomonas sp. .) After extracting and culturing, it can be prepared by performing an immobilization operation using about 1% of the microorganisms, and a nutrient-rich ingredient and additive to prevent the immobilized microorganisms from being eluted in a short time. The bio maker 30 filled with the biocomb 40 activates the solidified soil microorganisms using oxygen continuously supplied, and the microorganisms in the sludge which are continuously conveyed through the conveying line 15 from the sedimentation tank 5 are supplied. By promoting the activation is to play a role in activating the microorganisms without the continuous supply of the bio-comp (40). In general, the period of activation of soil microorganisms in the bio maker 30 was found to take 2-3 days.

The to-be-processed product via the oxygen-free tank 2 flows into the simple aeration tank 3. The inflowed processed material nitrates organic substances through metabolism using oxygen supplied from the air generator 9 to the microorganisms activated in the bio pond 6 and the aerobic microorganisms living in the aeration tank 9. In this process, the microorganisms activated in the bio pond 6 serve to promote more efficient nitrification reactions, which occur in the following reactions.

Nitrosomonas

^{_{NH 4 + + 3/2 O 2 NO}} 2 - + H 2 O + 2H +

Nitrobacter

^{_{NO 2 - + 1/2 O 2 NO}} 3 -

Above, ammonia is NO ₂ in the same ^{reaction-microorganisms} involved in the process in which a nitride is consumed in eggplant (Nitrosomonas (N. europaea, N. monocella )) nitro, with nitro and microorganisms Socorro suspension (Nitrosocossus) group, and the second reaction the NO ₃ ^- nitrification takes place by a microorganism to the genus bakteo (Nitrobacter (N. agilis, N. winogradskyi )) nitro, and nitro SOCIETE seutiseu (Nitrosocystis) of the.

The workpiece to be processed via the simple aeration tank 3 flows into the contact aeration tank 4. Contact aeration tank (4) is filled with a plate-like media (11) that can be attached to a large amount of microorganisms inhabited, and the microorganisms attached to the filled media (11) are removed from a simple aeration tank by ensuring a long sludge residence time Secondary nitrification of non-organic materials was added to secure stable MLSS in the aeration tank, allowing it to adapt to changes in the concentration of influent water and to minimize sludge production and save sludge treatment costs.

The workpiece through the contact aeration tank 4 flows into the settling tank 5. The outflow water of the contact aeration tank 4 introduced therein is mixed with microorganisms and treated water, and a coagulant from the chemical storage tank 7 is introduced into the proper amount through the line 12 to promote the precipitation in the settling tank 5. Solids and sludge are effectively separated. As a result, the treatment water quality is stable, the treatment efficiency is excellent, and the phosphorus contained in the object to be treated is effectively precipitated and removed through a chemical reaction with the flocculant.

In the sedimentation tank (5), the treated material from which nutrients and microorganisms have been completely removed is finally discharged, and the precipitated sludge is returned to the simple aeration tank (3) through the line (14) and 30% to 50% of the influent water is titrated in the aeration tank. The MLSS is maintained and returned to the bio pond 6 via line 15 to facilitate activation of the solidified soil microorganisms. Excess sludge other than the settling sludge conveyed via lines 14 and 15 enters the thickener tank 8. The precipitated sludge is reduced by sludge volume through condensation, and then disposed of by dewatering and landfill. The concentrated supernatant and desorption filtrate are returned to the simple aeration tank via line 18 for reprocessing.

In the above sewage treatment system, the flow of waste water is designed to be caused by gravity due to the elevation difference of each reactor, and the sludge conveyance and the amount of flocculant are controlled by adjusting the operating time of the pump having the same flow rate or by using a pump having a different flow rate. do.

Hereinafter, the Example of this invention is described. The following examples are presented for purposes of illustration only to aid in understanding the present invention, and the present invention is not limited by these examples.

<Example>

The artificial sewage was prepared on a laboratory scale, and the composition and characteristics of the biochemical sewage treatment system are shown in Table 1 below.

Each reactor was made of acrylic and the treatment flow rate was 10 L / day.

Configuration of sewage treatment system of the present invention Size (stay time) Characteristic Anaerobic tank simple aeration tank contact aeration tank sedimentation tank biofond 1.87 L (3 hours) 2.5-3.3 L (6 to 8 hours) 1.25 L (2 hours) 1.25 L (2 hours) 0.4 L (2 days ^* ) Cylindrical, with mixer mixer MLSS concentration: 2500 to 4000 mg / L with plate media (60% filling) Cylindrical biocom filling * The residence time of the bio pond is long because the flow rate is smaller than that of other reactors.

Comparative Example

The sewage treatment system of Namyangju City, which does not use a flocculant and a bio pond, included an anaerobic conditioning zone, an anaerobic reactor, an anoxic tank, an oxygen tank, and a precipitation tank. The sewage treatment efficiency of the Example and the comparative example is shown in Table 2 below.

BOD TN (total amount of nitrogen) TP (total amount of phosphorus) Concentration (mg / L) % Removal Concentration (mg / L) % Removal Concentration (mg / L) % Removal Comparative example Influent 190 - 31 - 4.3 - Treated water 18 90.5 9.0 71.0 0.9 79.0 Example (Invention) Influent 249 - 43 - 9.1 - Treated water 6.3 97.5 8.5 80.2 0.6 93.4

As can be seen from Table 2, it was found that the sewage treatment efficiency by the biochemical system of the present invention is superior to the conventional sewage treatment system in terms of biological oxygen demand and nitrogen and phosphorus removal rate.

The biological and chemical sewage treatment method according to the present invention prevents deterioration of treated water quality due to poor sedimentation in the sedimentation tank, regardless of the concentration of organic substances in sewage, and removes nutrients such as nitrogen and phosphorus together to remove lake water and streams. Not only can it block the eutrophication of sewage, but the efficiency of sewage treatment is also excellent and the maintenance of sewage treatment system is economic.

Claims (3)

Sedimentation and sedimentation tank step of sedimentation of sand and contaminants in sewage; An anoxic tank stage in which the sludge nitrified and returned from the two-stage aeration tank consisting of a simple aeration tank and a contact aeration tank is converted into nitrogen gas by denitrification bacteria using the sewage introduced into an anoxic state as a carbon source and exhausted into the atmosphere; A bio-pond step of activating a bio-comp made by solidifying soil microorganisms in a bio-maker and supplying it to an aeration tank; A simple aeration tank step of primary decomposition and nitrification of soil microorganisms from the bio-ponds, aerobic microorganisms in them, and organic matters to be processed by the continuously supplied oxygen; A contact aeration tank step of secondary decomposition and nitrification of the introduced primary decomposition organic material and non-nitrified nitrogen by the microorganisms attached to the media; A settling tank step of removing sludge, to-be-treated and phosphorus from the settling tank by adding a flocculant; And A bio-chemical advanced sewage treatment method comprising a concentration tank step of increasing the concentration by dewatering the precipitated sludge. Sedimentation and sedimentation tanks for sedimentation of sand and contaminants in sewage; In the two-stage aeration tank, the sludge returned by nitrification of nitrogen from the ammonia form (NH ₃ ) to the nitric oxide form (NO ₃ ) is converted to nitrogen gas by denitrification bacteria using the sewage flowing into the anoxic state as a carbon source. An oxygen-free tank for exhausting into the air; Bio Pond to activate the bio comp produced by solidifying the soil microorganisms in the bio maker to supply to the aeration tank; A simple aeration tank for nitrifying nitrogen in the form of ammonia in the object by activated soil microorganisms supplied from the bio-ponds, aerobic microorganisms inhabiting the aeration tanks themselves, and oxygen continuously supplied through an air generator; A contact aeration tank for secondary decomposition and nitrification of organic matter decomposed firstly in a simple aeration tank and nitrogen in ammonia form, which has not been completely nitrified due to a short residence time, by a microorganism attached to the media; A precipitation tank for inputting a flocculant into the workpiece through the contact aeration tank to remove sludge, the workpiece and phosphorus; And A biochemical chemical sewage treatment system comprising a concentration tank for dewatering a portion of precipitated sludge to increase its concentration. The method of claim 1, A path for returning the nitrified material from the contact aeration tank to the anoxic tank; A route for transporting sludge coagulated and precipitated by the flocculant in the settling tank to a simple aeration tank to maintain a continuous sludge supply and proper microbial concentration (MLSS); A route for returning the flocculated sediment sludge to the bio pond in a simple aeration tank to promote the continuous microbial supply and activation of the biocomb; A path for transferring excess settling sludge from the settling tank to the thickening tank for dewatering the concentrated sludge at high concentration; A path for returning the dehydration liquid to a simple aeration tank; And A bio-chemical advanced sewage treatment method comprising a path for introducing activated microorganisms into a simple aeration tank.