KR20090030397A - Apparatus for high rate removal of nitrogen and phosphorus from swtp/wwtp - Google Patents

Abstract

An advanced treatment apparatus for removing nitrogen and phosphorous is provided to automate an aerobic denitrification process to remove nitrogen and use a coagulant to remove phosphorus at a high rate. An advanced treatment apparatus for removing nitrogen and phosphorous comprises a flow control bath(2), a mixing bath(5), an phosphorus discharging bath(7), an aerobic denitrification tank(9), an aeration tank(20), an inclined-plate sedimentation basin(24), a mixing basin(26), a coagulation basin(27), a superhigh filter(31), and a disinfecting device(33). The flow control bath includes a total nitrogen densitometer(3).

Description

{Apparatus for high rate removal of nitrogen and phosphorus from SWTP / WWTP.}

The present invention relates to a high-level treatment for removing nitrogen and phosphorus from influent water in sewage / wastewater treatment plants. Particularly, the present invention relates to a highly automated removal of aerobic denitrification process to biologically remove nitrogen at a high rate, and to remove phosphorus at a high rate using a flocculant. Technology.

The present invention relates to an advanced treatment for removing nitrogen and phosphorus in sewage / waste water at high rates.

And / effluent (the "sewer" referred to collectively) are and the like in the Examples of A _2/0 process, anaerobic aerobic SBR process technology for the biological removal of nitrogen and a typical but because whichever is the nitrogen removal rate of 80% or less in the discharged water The high residual nitrogen concentration and the biological nitrogen process have long residence time (SRT) of sludge, which is a negative factor for biological removal of phosphorus.

Recently, as the regulation of total discharge of environmental pollutants is strengthened for protection of discharged waters and water systems, the concentration of nitrogen and phosphorus in discharged water has to be very low.

Although not widely known, there is a nitrification simultaneous denitrification process (also referred to as an aerobic denitrification process, referred to as "aerobic denitrification" in the present invention), which can increase the nitrogen removal rate without internal sludge circulation and theoretically increase the nitrogen concentration of the effluent. Can be lowered to 1 mg / L.

However, this process has only some known ORP values as a standard of operation, and conditions for effective and stable altitude treatment have not been developed.

In addition, this process also requires a long sludge residence time, so there is a limit to the removal of phosphorus biologically, it was not possible to obtain a low phosphorus effluent.

An object of the present invention is to automatically operate the process in an optimal state using various measuring instruments and automatic control devices in the operation of the aerobic denitrification process, to maximize the nitrogen removal rate while maintaining a stable, and purified by a gradient plate type settler A coagulant is administered to the supernatant to coagulate and filter to keep the phosphorus concentration in the effluent very low.

In the present invention, a total nitrogen concentration meter is installed in the flow adjusting tank, and a total nitrogen concentration meter, ammonia nitrogen concentration meter, nitrate nitrogen concentration meter, DO concentration meter, oxidation complete potential meter, MLSS concentration meter is installed in the aerobic denitrification tank, and a coagulation filter is installed. TMS is installed in the outlet to automatically control the process according to the total nitrogen concentration difference, ammonia nitrogen concentration value, nitrate nitrogen concentration value, redox potential value and phosphorus concentration. To be removed.

The present invention is a fully automatic operation using various measuring instruments and automatic control devices to improve the treatment efficiency of the aerobic denitrification process, which is a high-treatment process, and to remove nitrogen and phosphorus in sewage at a high rate by using coagulation filtration. It maintains very low concentrations of nitrogen and phosphorus, conserves water quality and ecosystems in the effluent, and has a simple process configuration that is economical and easy to maintain.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The sewage flows into the pretreatment facility 1 to remove contaminants and then flows into the flow regulating tank 2, and is transferred to the mixing tank 5 by the inflow pump 4, and the mixing tank 50 of the mixing stirrer 6 is removed. It stirs and mixes evenly with a conveying sludge.

The sewage having passed through the mixing tank 6 is transferred to a phosphorus discharge tank 7 which is maintained anaerobicly, releasing phosphorus accumulated in the cell while being slowly stirred by the stirrer 8 in the anaerobic state, and an aerobic denitrification tank 9. Is transferred to.

The aerobic denitrification tank 9 is provided with a redox potentiometer 14, total nitrogen concentration meter 15, MLSS concentration meter 16, ammonia nitrogen concentration meter 17, nitrogen nitrate concentration meter 18, and DO concentration meter 19. And, the diffuser 1 (10) was installed at the bottom, the diffuser 1 was connected to the air flow control valve 1 (11) through the pipe and the air flow control valve 1 was connected to the air flow variable blower (13).

The various measuring instruments were connected to the control panel 36 by a signal line, and the control panel 36 generated necessary calculation and control signals, and the control signals were connected to the corresponding various mechanical devices.

In the aerobic denitrification tank (9), if the redox potential is maintained at +300 mV (based on hydrogen electrode, + 125 mV for platinum electrode), nitrosomonas, which is a nitrite bacterium, acts as a nitrous oxide (ammonia nitrogen to nitrite (NO ₂ At the same time, nitrite is converted to nitrogen gas (N ₂ ) and released into the air to remove nitrogen from the sewage.

At this time, the DO concentration of the aerobic denitrification tank (9) is maintained in the range 0.2 ~ 0.7mg / L, depending on the influent properties.

In the aerobic denitrification tank 9, if the redox potential is higher than the optimum value (more aerobic state), the nitrate nitrogen is increased in the treated water, and if the redox potential is lower than the optimum value, the ammonia nitrogen is increased.

In both cases, since the nitrogen removal rate becomes worse, if the ammonia nitrogen in the outflow water quality of the aerobic denitrification tank (9) increases above an appropriate value, the redox potential should be increased, and to increase the redox potential, the aerobic denitrification tank (9) is required. The amount of air supplied must be increased.

When the nitrate nitrogen increases above the optimum value, the redox potential should be lowered. To lower the redox potential, the amount of air supplied to the aerobic denitrification tank 9 should be reduced.

Since such a function cannot be manually controlled by a person, the nitrate nitrogen concentration meter 18, the ammonia nitrogen concentration meter 17, the redox potentiometer 14, and the DO concentration meter 19 installed in the aerobic denitrification tank 9 By using the signal to generate the calculation and control signals of [Fig. 4] and [Fig. 5] in the operation control device built in the control panel 36, the operating conditions of the air flow control valve 1 (11) and the air flow variable blower (13) To change automatically.

If the inflow sewage is increased or the concentration is increased, the total nitrogen removal rate decreases due to the lack of MLSS, and the amount of MLSS in the aerobic denitrification tank (9) should be increased to maintain the total nitrogen removal rate ideally. .

To this end, the difference between the total nitrogen concentration values of the total nitrogen concentration meter 3 installed in the flow rate adjustment tank 2 and the total nitrogen concentration meter 15 installed in the outlet of the aerobic denitrification tank 9 exceeds an appropriate value or the aerobic denitrification tank. If the total nitrogen concentration in (9) exceeds a predetermined value, generate the calculation and control signals shown in [Fig. 3] to reduce the operating time of the excess sludge pump 38 or to reduce the rotational speed of the pump. By automatically controlling, increasing the MLSS concentration in the exhalation denitrification tank 9 maintains the total nitrogen removal rate at an appropriate state, and the control panel 36 simultaneously performs calculation and control of [Fig. 3] to [Fig. 5]. Total nitrogen is effectively removed from the denitrification tank (9).

The sewage passing through the aerobic denitrification tank (9) gives up so that the DO concentration is 1 to 2 mg / L in the aerobic tank (20) to oxidize a small amount of ammonia nitrogen which may be untreated in the aerobic denitrification tank to nitrate nitrogen, Increase the activity of aerobic microorganisms.

In order to effectively perform denitrification in the aerobic denitrification tank, the MLSS concentration was 8 hours and the experimental result of operating at 3000 mg / L. In the present invention, the aerobic denitrification occurred at 5 to 6 hours, which is the residence time of the existing activated sludge process. The MLSS concentration was maintained at 4,500 mg / L.

As the MLSS concentration is so high, the sedimentation properties deteriorate, so that it is difficult to stably occur in the existing gravity sedimentation basin. In the present invention, the sedimentation basin is designed as a gradient plate sedimentation basin 24 having a high sedimentation rate.

Phosphorus removal is carried out by the phosphorus-removing microorganism which released phosphorus in the phosphorus discharge tank 7 in the aerobic state of the aerobic denitrification tank 9, which absorbs 3 to 5 times more than that of normal cells. The microorganisms accumulate in the cells of the microorganisms, and the microorganisms are removed together with the excess sludge in the slant plate settling basin 24 through the aerobic tank 20.

At this time, the phosphorus removal rate is higher than that of the activated sludge process, but the sludge residence time (SRT) of the aerobic denitrification tank 9 microorganism is long, so that the phosphorus removal rate is slightly lowered and the actual removal rate is about 60%.

Therefore, in order to lower the level corresponding to the total amount of environmental pollutant emissions, 0.2 to 0.5 mg / L, phosphorus should be additionally removed by using an aluminum salt (alum) or ferric chloride such as ferric chloride.

Phosphorus inflow in sewage treatment plant is usually about 5mg / L, so if 60% is removed biologically, the remaining concentration is 2,0mg / L, and about 3 ~ 5mole of coagulant for 1 mole of phosphorus to lower it below 0.5mg / L Should be supplied.

Coagulant injection amount is determined using the phosphorus concentration of the total phosphorus concentration meter 25 and TMS by performing the program of [Fig. 6] in the control panel 36 and the coagulant injection controller 30, but the injection amount is the concentration value of the total phosphorus concentration meter 25 The difference between the phosphate concentration and the effluent standard is multiplied by the flow rate and the molar ratio of the coagulant injection, and the injection amount is automatically adjusted.

For phosphorus removal, the supernatant of the swash plate sedimentation basin is in contact with the flocculant supplied from the flocculant injector 28 for a short time of about 1 to 5 seconds in the blended paper 26, thereby forming a floc of precipitated phosphorus compound.

This floc is agglomerated in the flocculation paper 27 for about 5 to 10 minutes to grow into a large floc, and then filtered in a fibrous filter 31, and the filtered solids are transferred to the sludge storage tank 39 by the washing water transfer pump 32.

Since the fibrous filter 31 removes about 85% of the flocs introduced, the phosphorus concentration in the discharged water is 0.3 mg / L or less, and the fibrous filter can maintain its natural state because the loss head is 300 mm or less.

The supernatant that has passed through the fibrous filter 31 is discharged as clean water in which bacteria are removed from the disinfecting apparatus 33.

TMS is installed in the final outlet, and measures the flow rate and various water quality items and transmits them to the control panel 36 and to the outside (Environmental Management Corporation).

Another embodiment of the present invention is to cope with the case where the change in the concentration of the influent sewage is very large, as shown in [Fig. 2].

The process shown in [Fig. 2] is a sludge replenishment tank 41 and a sludge replenishment pump 34-1 added to the process of [Fig. 1]. When the concentration of the influent sewage is rapidly increased, only the excess sludge discharge is adjusted. Since it is difficult to stably maintain the concentration of the effluent below the reference value, at this time, the activated sludge stored in the sludge replenishment tank 41 is pumped to the sludge replenishment pump 34-1, and the exhalation through the mixing tank 5 is performed. It is supplied to bioreactors such as denitrification tanks to decompose rapidly increased sewage contaminants by increasing the concentration of the mixed liquor in the bioreactors.

When the concentration of the influent sewage is lowered, the sludge precipitated in the inclined plate settling basin is first charged to the sludge replenishment tank 41 to the full water level, and the remaining excess sludge is transferred to the sludge storage tank through the excess sludge pump 38 and removed, and then concentrated condenser Dehydrate in (40) and take out the dehydrated cake to the outside for disposal.

The process configuration of the present invention is basically similar to the activated sludge method, and only the operating conditions and some of the facilities in the structure are different. Therefore, if the existing activated sludge process is improved or partially supplemented, it can be seen that it can be applied as it is.

1 is a process chart showing the configuration of the present invention.

2 is a process chart showing another embodiment of the present invention.

Figure 3 is an explanatory diagram of a total nitrogen removal program for maintaining the optimum process of the present invention.

4 is an explanatory diagram of the ammonia nitrogen control program for maintaining the optimum process of the present invention.

5 is an explanatory diagram of a nitrate nitrogen control program for maintaining an optimal process of the present invention.

6 is an explanatory view of a total phosphorus control program for optimal process maintenance of the present invention.

Claims (7)

In the sewage treatment plant with a pretreatment facility, the flow control tank (2), mixing tank (5), phosphorus discharge tank (9), aerobic denitrification tank (9), aerobic tank (20), inclined plate settling basin (24), mixed paper (26) , Nitrogen and phosphorus high removal rate of the sewage / wastewater treatment plant, characterized in that the flocculation paper (27), ultra-fast filter (31), disinfection device (33) is installed continuously. The total nitrogen concentration meter (3) is provided in the flow rate adjusting tank (2), and the aerobic denitrification tank (9) is provided with a redox potentiometer (14), a total nitrogen concentration meter (15), an MLSS concentration meter (16), and ammonia properties. The sewage / wastewater treatment plant characterized in that a small concentration meter (17), a nitrogen nitrate concentration meter (18), and a DO concentration meter (19) were installed, and a total phosphorus concentration meter (25) was installed at the upper water outlet of the inclined plate settling basin (24). Nitrogen and phosphorus high removal rate device. The method according to claim 1 or 2, wherein the control panel 36 performs the control program of [Fig. 3], and measures the total nitrogen concentration difference between the total nitrogen concentration meter 3 and the total nitrogen concentration meter 15, and the difference is beforehand. The apparatus for removing nitrogen and phosphorus in the sewage / wastewater treatment plant, by automatically adjusting the amount of excess sludge removed so as to be maintained within a predetermined range, so as to maintain the MLSS concentration appropriately. 3. The aerobic denitrification according to claim 1, wherein the control panel 36 performs the control programs of FIGS. 4 and 5 to maintain the nitrate nitrogen concentration and the ammonia nitrogen concentration in the aerobic denitrification tank within the predetermined criteria. Nitrogen and phosphorus high rate removal device of the sewage / wastewater treatment plant, characterized in that to automatically adjust the amount of air supplied to the tank. According to claim 1 and 2, the control panel 36 and the coagulant injection controller 30, the control program of [Fig. 6] is carried out, the coagulant injection amount is automatically adjusted according to the total phosphorus concentration to maintain the total phosphorus concentration in the discharged water within the reference value Nitrogen and phosphorus high removal rate device of the sewage / wastewater treatment plant, characterized in that as possible. The apparatus for removing nitrogen and phosphorus in the sewage / wastewater treatment plant according to claim 1 or 2, wherein the air quantity supply device is constituted by the diffuser 1 (10), the air volume control valve 1 (11), and the air volume variable blower (13). . The nitrogen and phosphorus in the sewage / wastewater treatment plant according to claim 1 or 2, wherein a sludge sludge supplementary tank 41 and a sludge supplementary pump 34-1 are provided so as to supply additional sludge to the aerobic denitrification tank. High rate removal device.

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