KR101264414B1 - Wastewater treatment method for removing nitrogen and phosphate using the phosphorus accumulating organisms - Google Patents

Abstract

PURPOSE: A wastewater disposal method for removing total phosphorus and nitrogen using phosphorus accumulating organisms is provided to activate organisms inside wastewater in order to discharge total phosphorus from an anaerobic tank and an activate absorption mechanism for the total phosphorus in an aerobic tank, thereby lowering the concentration of the total phosphorus from disposed water, and improving removal efficiency for total nitrogen with de-nitrification phosphorus accumulating organism mechanism in a second anoxic tank without an additional organic carbon source. CONSTITUTION: A wastewater disposal method for removing total phosphorus and nitrogen activates phosphorus accumulating organisms by feeding an external carbon source to an anaerobic tank. The feeding amount of the carbon source is automatically controlled by the OUR(Oxygen Uptake Rate) of a wastewater inflow, and the concentration variance of K+, Mg2+ or Ca2+ inside the anaerobic tank, a second anoxic tank, or an aerobic tank. The external carbon source is at least one of acetic acid, propionic acid, or volatile fatty acid. When the temperature of the wastewater is 20 deg. C or higher, or the pH of the wastewater is 6.5 or lower, the activation of glycogen accumulating organisms is restrained by simultaneously adding the acetic acid and the propionic acid as external carbon sources or raising the pH inside the anaerobic tank to 7.5 or higher. The content ratio between the acetic acid and the propionic acid as COD(Chemical Oxygen Demand) is 1:0.1-10. The method uses a wastewater disposal system including a first anoxic tank which is a reaction tank for reducing NO3- and DO(dissolved Oxygen) and is formed at the front end of the anaerobic tank. [Reference numerals] (AA) Start; (BB) Measure the DO of an anaerobic tank; (CC) Stop biological treatment; (DD) Measure the concentration of phosphorus in outflow water; (EE) Measured value > Target water quality; (FF) Calculate OUR and rbCOD of inflow water; (GG) Determine and supply a supply amount of an external carbon source; (HH) Measure K+ in the anaerobic tank and an anoxic tank; (II) Fix the supply amount of the external carbon source

Description

Wastewater treatment method for removing nitrogen and phosphate using the Phosphorus accumulating organisms}

The present invention relates to a method for effectively removing nutrients such as total phosphorus and total nitrogen contained in sewage water by supplying an external carbon source.

Sewage or wastewater containing nitrogen and phosphorus acts as an inhibitor of water quality by accelerating eutrophication of lakes and reservoirs or by promoting algae growth such as green algae or red tide in rivers or oceans. Therefore, in order to prevent eutrophication, nutrient components in sewage or wastewater should be removed before they enter the body of the river or the like.

Conventional nitrogen and phosphorus removal methods include physicochemical treatments and biological treatments. The physicochemical treatments include degassing and denitrifying nitrogen by injecting air while increasing the pH of wastewater. The selective adsorption method using an ion exchange material is disclosed a method of treating nitrogen and precipitation treatment of phosphorus using a flocculant such as slaked lime. However, in the case of such physicochemical methods, maintenance costs are high, and most biological treatment methods having excellent economical efficiency are applied.

The biological nitrogen removal method uses ammonia-nitrogen (NH ₄ ⁺ -N) in the sewage under aerobic conditions rich in dissolved oxygen (DO) to nitrite-nitrogen (NO ₂ ^-- N) and nitric acid using nitrifying bacteria. After nitrification, which is oxidized to -nitrogen (NO ₃ ^-- N), the nitrate-nitrogen (NO ₃ ^-- N) is reduced to nitrogen gas (N ₂ ) using denitrification bacteria under oxygen-free conditions. By denitrification. As described above, biological nitrogen removal requires an aerobic step and an anoxic step, and nitrification in the aerobic step requires dissolved oxygen, and an organic carbon source is required in the denitrification step in the anoxic step.

The organic carbon source induces efficient denitrification by using a carbon source, which is an organic component in the influent sewage, or by injecting an external carbon source such as methanol.

On the other hand, in the biological removal method, phosphorus is removed by phosphorus accumulating bacteria under anaerobic conditions. Phosphorus accumulating bacteria store ingested organic matter in the form of PolyHydroxy Butyrate (PHB) in cells, and the energy required for storage is ATP (Adenosine) in the cells. TriPhosphate uses energy obtained in the process of hydrolysis into Adenosine DiPhosphate (ADP), which releases phosphorus in the form of orthophosphate (PO ₄ ^3- -P). Thereafter, the phosphorus in the influent sewage is removed by absorbing an amount of phosphorus several times more than the amount of phosphorus released in the anaerobic stage for the growth and resynthesis of phosphorus accumulating bacteria in the aerobic stage.

In general, a method of biologically removing phosphorus and nitrogen at the same time is performed in a process in which both anaerobic conditions, anoxic conditions, and aerobic conditions are formed, and various methods have been developed and put into practice in domestic wastewater treatment facilities. Currently, the practices applied to sewage treatment plants include this tuoh (A ² / O) method in biological phosphorus and total nitrogen removal process. The ATO method is composed of anaerobic conditions, anoxic conditions and aerobic conditions sequentially. As described in the biological phosphorus removal method, phosphorus released from an aerobic reactor is removed by appropriately removing microbial sludge that absorbs a larger amount of phosphorus than in an aerobic reactor.

Phosphorus accumulating organisms (PAOs) require a certain amount of readily biodegradable COD (rbCOD) to be activated, but they are scarce in most sewage waters. This can be solved, but there is no method for activating PAOs or controlling the supply amount of the external carbon source according to the type of external carbon source. In addition, there is no known method of inhibiting the activation of glycogen accumulating organisms (GAAs), which are competitors of phosphorus accumulating microorganisms when the water temperature is elevated.

The total phosphorus abatement technology currently used in sewage treatment plants does not have an optimized process to remove sediment using a chemical flocculant after biological treatment, and the removal of phosphorus using a chemical flocculant requires excessive chemical use and chemical sludge. Due to the high cost of treatment, the increase in processing cost is disadvantageous in terms of economic feasibility and environment.

Republic of Korea Patent Publication No. 2005-0098051 Republic of Korea Patent Publication No. 2005-0006347 Republic of Korea Patent Publication No. 2003-0038931

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of supplying an external carbon source and automatically controlling the amount of supply to activate Phosphorus accumulating organisms (PAOs) by simultaneously removing total phosphorus and total nitrogen in the wastewater by a biological method. will be.

Another object of the present invention is to provide a method for efficiently removing total phosphorus and total nitrogen in wastewater by inhibiting glycogen accumulating organisms (GAOs) that are activated while maintaining PAOs activity when the summer water temperature is elevated.

The present invention utilizes a biological wastewater treatment system, preferably, a wastewater treatment system including a first anaerobic tank (T01), an anaerobic tank (T02), a second anoxic tank (T03), an aerobic tank (T04), and a settling tank (T05). And, it relates to a method for removing total phosphorus and total nitrogen in the wastewater, characterized in that to activate the phosphorus accumulation microorganisms (PAOs) by supplying an external carbon source to the anaerobic tank (T02). The external carbon source can be used in any way, but at least one selected from acetic acid, propionic acid or volatile fatty acid, more preferably using acetic acid. It is one of the important features of the present invention that the external carbon source is automatically controlled according to the oxygen consumption rate (OUR) of the influent sewage and the concentration change of K ⁺ , Mg ²⁺ or Ca ²⁺ .

According to the present invention, an example of a method for removing total phosphorus and total nitrogen in wastewater, characterized by activating phosphorus accumulating microorganisms (PAOs) by supplying an external carbon source,

(1) Calculate the required amount of external carbon source (A) from the difference in the target phosphorus concentration (b) from the target phosphorus concentration (a) in the effluent discharged from the wastewater treatment plant, and the oxygen uptake rate of the influent wastewater (Oxygen Uptake Rate). Measuring OUR) hourly to automatically calculate the amount of organic matter that can be biologically decomposed (rbCOD) to calculate the amount of external carbon source (B) that is additionally needed according to the hourly change;

(2) the inflow water is moved to the anaerobic tank (T02) and injecting the supply amount (A + B) of the external carbon source determined in step (1), by measuring the dissolved oxygen (DO) value in the anaerobic tank (T02) dissolved Supplying an external carbon source when the amount of oxygen (DO) is 0.5 mg / l or less;

(3) The influent flowing through the anaerobic tank (T02) is a step of re-absorbing and accumulating the total phosphorus flowing into the second anaerobic tank (T03), the difference in the total phosphorus concentration difference between the anaerobic tank (T02) and the second anoxic tank (T03). Deriving a change amount over time to determine whether to supply an additional external carbon source, the denitrification reaction and dPAOs (denitrification PAOs) reaction by the phosphorus accumulation microorganisms (PAOs) at the same time;

(4) after denitrification in step (3), the influent flows to an aerobic tank (T04) to remove phosphorus by ingesting excess phosphorus by phosphorus accumulating microorganisms (PAOs); And

(5) precipitate excess phosphorus accumulated microorganisms (PAOs) contained in the wastewater discharged to the sedimentation tank (T05) from the aerobic tank (T04) to produce sludge, the sludge is recycled to the first anoxic tank (T01) And determining whether the target is achieved by measuring the total phosphorus concentration in the effluent;

How to remove the total phosphorus and total nitrogen from the wastewater containing.

The concentration (a) of phosphorus in the effluent is calculated from the rbCOD calculated in the effluent in step (1), and the difference between the target concentration of phosphorus (b) is calculated to determine the required amount of the external carbon source, that is, the concentration of phosphorus to be removed. It is calculated by the following <formula 1>.

<Formula 1>

Required amount of external carbon source (mg / l) = n × [Concentration of phosphorus in effluent (a)-concentration of phosphorus in target effluent (b)]

(In <Formula 1>, the required amount of external carbon is required by n times the number of [ab]. For example, when acetic acid is the external carbon source, it is preferably 8 to 12 multiples of the above [ab]. When using a carbon source, it is preferable to apply the same ratio as the multiple of the acetic acid in terms of COD concentration.)

The automatic control of the supply of external carbon source is supplied when the dissolved oxygen (DO) in the anaerobic tank is 0.5 mg / l, firstly the external carbon source required amount (A) calculated from the effluent in step (1) and the oxygen consumption rate of the influent ( The external carbon source requirement (B), further calculated by OUR), is determined by the oxygen consumption rate measured at 30 minute to 2 hour intervals.

In the anaerobic tank of step (2) is characterized in that the phosphorus accumulation microorganisms (PAOs) in the anaerobic tank (T02) takes in the external carbon source to release the total phosphorus.

Since the phosphate ions present in the water in step (3) take the form of phosphates combined with alkali metal ions, it is preferable to use concentration values of K ⁺ , Mg ²⁺ or Ca ²⁺ as indicators for total phosphorus release. Do. However, Mg ²⁺ may be formed as MgO or Mg (OH) ₂ in neutral so that the solubility may be low, and Ca ²⁺ may be easily combined with CO ₃ ^2- or PO ₄ ^3- to form insoluble salts. As a result, measurement errors may occur.

Alkali metal ions, K ^+, are present in the PAOs microorganisms in a state in which total phosphorus is bound by K _x Mg _y (PO ₃ ) _z , and thus has a proportional relationship with the concentration of PO ₄ ^3- (Korean Journal of Water Treatment Vol. 13, No. 3). 79-84, 2005). Thus, it is highly desirable to use the concentration of K ⁺ as an indicator for total phosphorus release.

In step (3), the K ⁺ concentration change amount (ΔK) between the anaerobic tank and the second anoxic tank is monitored by time, and the difference of the K ⁺ concentration change amount (D = ΔKt ₁ -ΔKt during a predetermined time (t ₀ to t ₁ ) _{When 0} ) is D ≦ ₀ , the external carbon source supply is increased by 0.5 to 2% of the initial supply (COD concentration ratio), and when the ratio of K ⁺ concentration change is D> 0, the calculated in step (2) The external carbon source is fixed and supplied.

<Formula 2>

K ⁺ concentration variation (ΔK) = (K ⁺ concentration in the anaerobic tank) - (the anoxic tank in K ⁺ concentration)

<Formula 3>

Difference of K ⁺ Concentration Variation during t Time (D) = [K ⁺ Concentration Variation at Δ = 1 (KT ₁ )]-[K ⁺ Concentration Variation at Δ = 0 (ΔKt ₀ )]

(Wherein t = 0: the first measurement time of phosphorus concentration in the influent, t = 1: second measurement time of phosphorus concentration after the first measurement.)

The interval between the first measurement time and the second measurement time is controllable in the wastewater treatment system, and is preferably measured at intervals of 1 to 10 minutes.

When activating the phosphorus accumulating microorganisms (PAOs) in the step (2), in the anaerobic tank (T02) to release the total phosphorus, in the second anaerobic tank (T03) and aerobic tank (T04) the mechanism of absorbing more than several times the total amount of the phosphorus is activated The concentration of total phosphorus flowing out of the treated water is reduced. In addition, in the second anoxic tank (T03), the total nitrogen removal efficiency is also improved without supplying additional organic carbon sources by the dPAOs (denitrification PAOs) mechanism, thereby improving biological total phosphorus and total nitrogen removal efficiency.

On the other hand, when the water temperature rises above 20 ° C. or when the pH is 6.5 or less, phosphorus accumulating microorganisms (PAOs), which are hydrophilic microorganisms, are weakened relative to glycogen accumulating microorganisms (GAOs), which are comparable microorganisms, and thus, total phosphorus removal efficiency is increased. Because of this, it is preferable to use both acetic acid and propionic acid as the external carbon source or to raise the pH to 7.5 or more to inhibit the activity of glycogen accumulating microorganisms (GAOs). The ratio of the amount of acetic acid and propionic acid used is preferably propionic acid 1 to 100 relative to acetic acid 10 in terms of COD ratio.

The GAOs microorganisms are activated when the temperature rises and are synthesized and stored as a glycogen carbon source, but the release and accumulation mechanism of total phosphorus does not occur at all, which is an adverse effect on the removal of total phosphorus. The phosphorus accumulating microorganisms (PAOs) synthesize PHB (PolyHydroxy Butyrate) in the body by ingesting an external carbon source in the anaerobic state, and convert ATP to ADP to obtain energy (7.4 kcal / mole), wherein the polyphosphate in the body It decomposes PO ₄ ^{3 -} is characterized in that intake and discharge the total phosphorus in the form, for more than a few times the total phosphorus discharge gaining energy to decompose the PHB accumulation under aerobic conditions excess. Therefore, the total phosphorus discharged the sludge ingested excessively out of the system has the effect of removing the total phosphorus from the waste water.

The rbCOD in the influent sewage can be fermented in anaerobic state and converted to acetic acid to be used for total phosphorus release. The colloid or particle COD can also be hydrolyzed and converted to acetic acid, but very little. The rbCOD in the influent can be measured by the oxygen consumption rate (OUR), and the total phosphorus (TP) of the influent sewage is usually 3 to 8 mg / l, and if the total phosphorus release is appropriate, PO ₄ ^3- in anaerobic tank (T02) The effect is that the total phosphorus in the form rises to 40 mg / l. In anaerobic conditions, aerobic heterotrophs are atrophy and do not consume acetic acid, so phosphorus accumulating microorganisms (PAOs) are activated by ingesting most of acetic acid.

If NO ₃ ⁻ is present in the anaerobic tank (T02), denitrification takes place using rbCOD by denitrification microorganisms. If dissolved oxygen (DO) exists, rbCOD is consumed by heterotrophic microorganisms. Therefore, it is preferable to use a wastewater treatment system in which the first anoxic tank T01, which is a reaction tank for reducing NO ₃ ⁻ and dissolved oxygen (DO), is installed at the front end of the anaerobic tank T02.

In the second anaerobic tank T03, phosphorus accumulating microorganisms (PAOs) are accumulated by ingesting total phosphorus using NO ₃ ⁻ instead of oxygen, and NO ₃ ⁻ is converted into N ₂ to remove total nitrogen. This phenomenon is called dPAOs action. That is, the mechanism of dPAOs is to obtain electrons and energy by oxidizing PHB in the cell in anoxic state and to reduce it to total nitrogen using NO ₃ -N as an electron acceptor.

In general, the role of the second anoxic tank (T03) in the wastewater treatment is denitrification. In this case, the denitrification microorganism requires a carbon source, but the phosphorus accumulating microorganisms (PAOs) of the present invention can denitrify without the need for a carbon source, thereby reducing total nitrogen in the wastewater. Removal is effective.

The present invention relates to a method for effectively removing total phosphorus biologically by utilizing the physiology of phosphorus accumulating microorganisms (PAOs). Therefore, the biological nutrient removal (BNR) processes shear place the first anoxic tank (T01) of oxygen and NO ₃ ^- to reduce the adverse effect on the accumulation of microbes (PAOs) to remove and supply the external carbon source to the anaerobic tank (T02) activated It is preferable to make it.

The configuration of the wastewater treatment process of the present invention includes a reaction tank in which a first anaerobic tank (T01), an anaerobic tank (T02), a second anoxic tank (T03), an aerobic tank (T04), and a settling tank (T05) are sequentially formed.

The first anoxic tank (T01), which is a total denitrification tank at the front of the A ² / O method, utilizes its own COD in the denitrification process of NO ₃ -N contained in the returned sludge. It can reduce consumption and reduce sludge production. As a result, the rbCOD can be fully utilized in the total phosphorus release process. In addition, the amount of dissolved oxygen is lowered so that the optimum conditions for total phosphorus release by PAOs microorganisms in the anaerobic tank (T02).

Sewage water enters the anaerobic tank (T02) and supplies an external carbon source to activate phosphorus accumulating microorganisms (PAOs).

The relationship between total phosphorus release from anaerobic tank (T02) to aerobic tank (T04) and the growth of phosphorus accumulating microorganisms (PAOs) is, for example, when 10 g acetic acid is supplied to anaerobic tank (T02), 3 g of phosphorus accumulating microorganisms (PAOs) are produced. This is effective to remove about 1g gross phosphorus. As such, the method of removing total phosphorus in sewage water using phosphorus accumulating microorganisms (PAOs) is more than three times more cost effective than using an external carbon source (acetic acid) than using a chemical coagulant.

In the second anoxic tank (T03), traditional denitrification takes place, and dPAOs mechanism by phosphorus accumulating microorganisms (PAOs) occurs. Therefore, when phosphorus accumulating microorganisms (PAOs) are activated, the denitrification efficiency is improved without the need for an external carbon source.

In the steps (3) and (4), the total phosphorus concentration is measured by supplying and increasing the external carbon source step by step when the difference between the K ⁺ values of the anaerobic tank T02 and the second anoxic tank T03 decreases with time. If absent or increased, it is desirable to have a fixed supply of external carbon sources.

In step (3) and (4) it is characterized by controlling the supply of external carbon source by monitoring the K ⁺ concentration in real time.

The wastewater treatment apparatus used in the method for removing total phosphorus and total nitrogen in the wastewater of the present invention includes a first anoxic tank (T01), an anaerobic tank (T02), a second anoxic tank (T03), an aerobic tank (T04), and a settling tank (T05). Doing; In order to measure the rbCOD of the influent OUR measuring module (D01) is mounted on the influent side, the anaerobic tank (T02) is equipped with a metering pump for controlling the external carbon source, the anaerobic tank (T02) and the second anaerobic tank (T03) ) Is equipped with a K ⁺ (Mg ²⁺ or Ca ²⁺ ) probe type sensor (D02) for indirectly measuring the concentration of PO ₄ -P. In addition, it is preferable to use TMS for the total phosphorus concentration of the final effluent, and a PLC or computer (D03) which is connected to the OUR and K ⁺ concentration and the total phosphorus concentration of the effluent is comprehensively controlled. It is characterized by (see FIG. 2).

The present invention relates to a method for inducing activation of PAOs microorganisms in sewage water. By activating the PAOs microorganisms in this manner, the release of total phosphorus in the anaerobic tank (T02) and the absorption mechanism of total phosphorus in the aerobic tank (T04) is activated to decrease the concentration of total phosphorus flowing out of the treated water, and at the same time the second anoxic tank (T03) In this case, total nitrogen removal efficiency can be improved without supplying additional organic carbon source by dPAOs (denitrification PAOs) mechanism, thereby improving the efficiency of total nitrogen or total phosphorus removal.

Therefore, the present invention can improve the removal of total phosphorus and total nitrogen in the wastewater, and is a more economical and stable water quality than the case of using a chemical flocculant, so it is an environmentally friendly method for removing phosphorus or total nitrogen.

1 is a diagram illustrating an algorithm for removing total phosphorus and total nitrogen in wastewater.
Figure 2 is a sewage treatment block diagram according to an embodiment of the sewage treatment method of the present invention.
<Description of Signs of Major Parts of Drawings>
T01: First Anaerobic Tank
T02: anaerobic tank,
T03: second anaerobic tank
T04: aerobic tank,
T05: settling tank,
D01 OUR measurement module,
D02: probe sensor module probes K ⁺ , Mg ²⁺ or Ca ²⁺ ,
D03: Computer or PLC module for data control and storage.
3 is a result of measuring the oxygen consumption rate (OUR) of the influent.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. These examples are only for illustrating the present invention in more detail, it is obvious to those skilled in the art that the scope of the present invention is not limited by these examples.

&Lt; Example 1 >

Sewage treatment system consisting of the first anaerobic tank (T01), anaerobic tank (T02), the second anaerobic tank (T03), the aerobic tank (T04) and the settling tank (T05), the total hydraulic residence time (HRT) is 8 hours (hr), The daily treatment flow rate is 10m ³ / d, the mixed liquor suspendes solid (MLSS) is 2,000 mg / l, and the water temperature is 0.7 mg / l acetic acid in the influent at 15 ± 3 ℃. The concentrations and removal efficiencies of the average total influent and effluent at the time of supply were measured (see Tables 1 and 2).

<Example 2>

Except for supplying 2 mg / L of acetic acid to the influent in terms of COD, the same system and conditions as in Example 1 were carried out to measure the average total phosphorus concentration and the removal efficiency of the influent and the effluent. The measurement results are shown in Tables 1 and 2.

<Example 3>

Except for supplying acetic acid of 4 mg / L acetic acid in terms of COD was carried out under the same system and conditions as in Example 1 to measure the average total phosphorus concentration and removal efficiency of the influent and effluent. The measurement results are shown in Tables 1 and 2.

<Example 4>

Injecting acetic acid and propionic acid under the condition of 25 ± 3 ℃ was carried out in the same system and conditions as in Example 1 except that 8 mg / l was supplied to the influent by calculating the COD ratio 1: 1. The average total phosphorus concentration and removal efficiency were measured. The measurement results are shown in Tables 1 and 2.

&Lt; Comparative Example 1 &

Except for not installing the first anoxic tank (T01) and acetic acid was not supplied to the influent, it was carried out under the same system and conditions as in Example 1 to measure the average total concentration and removal efficiency of the influent and the effluent. The measurement results are shown in Tables 1 and 2.

Comparative Example 2

Under the condition that the water temperature is 25 ± 3 ℃, except that acetic acid was not supplied to the influent, it was carried out under the same system and conditions as in Example 1 to determine the concentration and removal efficiency of the average total influent and effluent. The measurement results are shown in Tables 1 and 2.

Table 1. Average phosphorus concentrations (mg / l) and removal efficiencies (%) of influent and effluent.

^a The injection amount of acetic acid is a value calculated by chemical oxygen demand (COD). In Example 4, acetic acid and propionic acid were injected 1: 1, that is, 4 mg / l.

Table 2. Average total nitrogen concentrations (mg / l) and removal efficiencies of influent and effluent.

^a The injection amount of acetic acid is a value calculated by chemical oxygen demand (COD). In Example 4, acetic acid and propionic acid were injected 1: 1, that is, 4 mg / l.

Claims (6)

Oxygen consumption rate (OUR) of the influent sewage and the supply of external carbon sources to activate the phosphorus-accumulating microorganisms (PAOs) supplied to the anaerobic tank according to the concentration change of K ⁺ , Mg ²⁺ or Ca ²⁺ in the anaerobic tank and the second anoxic tank or in the aerobic tank. How to remove the total phosphorus and total nitrogen in the wastewater, characterized in that the automatic control. The method of claim 1,
Wherein said external carbon source is at least one selected from acetic acid, propionic acid or volatile fatty acids. delete The method of claim 1,
When the sewage water temperature is 20 ° C. or higher or pH is 6.5 or less, acetic acid and propionic acid are simultaneously added to the external carbon source; The method of removing total phosphorus and total nitrogen in the wastewater, characterized in that to increase the pH of the anaerobic tank to 7.5 or more to inhibit the activity of glycogen accumulation microorganisms (GAOs). 5. The method of claim 4,
The content ratio of acetic acid and propionic acid is a chemical oxygen demand (COD) ratio of 1: 0.1 to 10, characterized in that the total phosphorus and total nitrogen in the sewage water. The method of claim 1,
A method for removing total phosphorus and total nitrogen in sewage water, characterized by using a sewage water treatment system having a first anoxic tank, which is a reaction tank for reducing NO ₃ ⁻ and dissolved oxygen (DO), in front of the anaerobic tank.

Images