KR100945458B1 - Apparatus for high rate removal of nitrogen and phosphorus from SWTP/WWTP. - Google Patents

Abstract

The present invention relates to a high-treatment for removing nitrogen and phosphorus at a high rate in a sewage treatment plant or a wastewater treatment plant, and more specifically, to remove nitrogen at a high rate by aerobic denitrification in a fully automatic operation, and high rate of phosphorus using a flocculant. Removal is directed to an advanced treatment apparatus.

To this end, the present invention is a mixing tank for mixing the influent sewage and conveying sludge transferred from the flow control tank, an anaerobic tank for phosphorus release, an aerobic denitrification tank for simultaneous nitrification and denitrification, an aerobic tank to increase the dissolved oxygen concentration, gradient plate type sedimentation basin, flocculation Filters are installed continuously, total nitrogen concentration meter is installed in the flow rate adjustment tank, dissolved oxygen concentration meter, redox potential meter (ORP), total nitrogen concentration meter, ammonia nitrogen concentration meter, nitrate nitrogen concentration meter, and mixed liquid concentration meter are installed in the aerobic denitrification tank. The excess sludge amount and the return sludge amount are automatically adjusted so that the total nitrogen concentration difference between the flow regulating tank and the aerobic denitrification tank is kept constant.The blower and the redox potentiometer for the aerobic denitrification tank are automatically interlocked, and the redox potential is previously determined. Ammonia nitrogen concentration value in aerobic denitrification tank can be maintained at a fixed value. When increasing or decreasing, the air supply is automatically adjusted accordingly, maintaining ideal aerobic denitrification to remove nitrogen to low concentrations, and the supernatant passing through the swash plate settles with coagulant and grows into large flocs in the coagulant, This method is characterized by treating the phosphorus in water at a low concentration by removing the floc.

Aerobic denitrification, total nitrogen, ammonia nitrogen, nitrate nitrogen, advanced treatment. TMS

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 a flow control tank, and a total nitrogen concentration meter, an ammonia nitrogen concentration meter, a nitrate nitrogen concentration meter, a DO concentration meter, a redox potential meter, and an MLSS concentration meter are installed in an aerobic denitrification tank, and a gradient plate settler and a coagulation filter are installed. In the final outlet, TMS is installed so that predetermined process control is automatically performed according to the total nitrogen concentration difference, ammonia nitrogen concentration value, nitrate nitrogen concentration value, redox potential value and phosphorus concentration. Phosphorus was removed at a high rate.

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 adjusting tank 2, and is transferred to the mixing tank 5 by the inflow pump 4, and the mixing stirrer 6 in the mixing tank 5. By the stirring action of, it is mixed with the conveying sludge evenly.

The sewage having passed through the mixing tank 5 is transferred to the 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 the 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 to provide nitrous oxide (ammonia nitrogen to nitrite (NO _2). At the same time, nitrous acid is converted into 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 re-absorbs phosphorus in the aerobic state of the aerobic denitrification tank (9), which releases phosphorus from the phosphorus discharge tank (7), 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 concentration in sewage treatment plant is usually about 5mg / L, so if 60% is removed biologically, the remaining concentration is 2.0mg / L. To lower it below 0.5mg / L, about 3 ~ 5mole of flocculant is added per mole of phosphorus. Must 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 phosphorus concentration and the discharged water standard is calculated by multiplying the flow rate and the molar ratio of the coagulant injection, and automatically adjust the injection amount.

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 into the sludge replenishment pump 34-1, and the exhalation through the mixing tank 5 is performed. It is rapidly supplied to bioreactors such as denitrification tanks, and the concentration of mixed liquor in the bioreactors is raised to an appropriate level to decompose rapidly increased sewage contaminants.

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)

delete delete A sewage treatment plant having a pretreatment facility, comprising: a flow rate adjusting tank (2) for adjusting a flow rate; A mixing tank 5 for mixing the sewage introduced from the flow rate adjusting tank 2 with the conveying sludge; A phosphorus discharge tank 7 for releasing phosphorus by stirring the sewage from the mixing tank 5 in an anaerobic state; An aerobic denitrification tank 9 for removing nitrogen by applying a redox potential to the sewage passing through the phosphorus discharge tank 7 to release nitrogen into the air; Abandoning the DO concentration to 1 to 2mg / L for the sewage passing through the aerobic denitrification tank (9) to oxidize the untreated small amount of ammonia nitrogen with nitrate nitrogen to increase the activity of aerobic microorganisms An aerobic tank 20; An inclined plate settling basin 24 for removing the microorganisms contained in the sewage passing through the exhalation tank 20 with excess sludge; A mixed paper 26 for stirring the supernatant water passing through the inclined plate settling paper 24 with a flocculant to form flocs of precipitated phosphorus compounds; Agglomeration paper 27 for agglomerating the flocs of the formed phosphorus compound and growing them into large flocs; A fibrous filter (31) for filtering the flocculated floc; Sequentially install a disinfection device 33 for removing bacteria from the supernatant passing through the fibrous filter, The flow rate adjusting tank 2 is provided with a total nitrogen concentration meter 3, and the aerobic denitrification tank 9 has a redox potentiometer 14, a total nitrogen concentration meter 15, an MLSS concentration meter 16, and an ammonia nitrogen concentration meter 17. ), A nitrogen nitrate concentration meter (18) and a DO concentration meter (19) are installed, and a total phosphorus concentration meter (25) is installed at the top water outlet of the inclined plate sedimentation basin (24), In the control panel 36, A first step of determining whether a difference in total nitrogen concentration between the influent water and the aerobic denitrification tank 9 exceeds a set value; A second step of determining whether the total nitrogen concentration of the aerobic denitrification tank (9) exceeds a reference value when it is determined not to exceed in the first step; A third step of controlling to maintain the current operating state of the excess sludge pump and determining to proceed to the sixth step when it is determined that the second step is not exceeded; A fourth step of reducing the operation of the excess sludge pump and determining whether the MLSS concentration of the aerobic denitrification tank 9 increases when it is determined that the first and second steps are exceeded; If it is determined that the MLSS concentration does not increase in the fourth step, a fifth step of controlling to check whether the influent is rapidly increased, the excess sludge pump, the flow meter, and the MLSS system; The control program comprising a sixth step of controlling to measure the influent and the total nitrogen concentration of the aerobic denitrification tank 9 after determining that the MLSS concentration is increased in the fourth step or after performing the third step. By measuring the total nitrogen concentration difference between the total nitrogen concentration meter (3) and the total nitrogen concentration meter (15), and automatically adjusts the amount of excess sludge removal so that the difference is kept within a predetermined range, the MLSS concentration required for degreasing Nitrogen and phosphorus high removal rate device of the sewage / wastewater treatment plant, characterized in that to maintain. The control panel 36, according to claim 3, A seventh step of determining whether the ammonia nitrogen concentration of the aerobic denitrification tank exceeds a predetermined criterion; and if it is determined that the criterion does not exceed the criterion in the seventh step, the current ORP value is maintained and the process proceeds to the fifteenth step. An eighth step of controlling the control unit; and a ninth step of determining whether the air volume of the aerobic denitrification tank increases if the ORP set value is increased proportionally if it is determined that the reference is exceeded in the seventh step, and the ninth step is increased. A tenth step of controlling to check the blower, the control valve and the flow meter if it is determined not to be performed; an eleventh step of determining whether the DO concentration of the exhalation denitrification tank is increased if it is determined to increase in the ninth step, and the eleventh step; If it is determined that the increase does not occur in the step 12 and the control step to check the diffuser, the flow meter and the DO concentration meter, and to increase in the eleventh step In step 13, if it is determined that the ORP value is increased, and if it is determined that it is not increased in step 13, step 14 for controlling to check the ORP system and the DO concentration meter, and in step 13, are determined to increase. Or a fifteenth step of controlling to measure the ammonia nitrogen concentration in the aerobic denitrification tank 9 after performing the eighth step; A sixteenth step of determining whether the ammonia nitrogen concentration of the aerobic denitrification tank exceeds a predetermined criterion; and if it is determined not to exceed the criterion in the sixteenth step, the current ORP value is maintained and the procedure proceeds to the twenty-fourth step A seventeenth step of controlling the control unit; and if it is determined that the reference is exceeded in the sixteenth step, an eighteenth step of proportionally decreasing the ORP set value and determining whether the air volume of the aerobic denitrification tank is reduced; A nineteenth step of controlling to check the blower, the control valve and the flowmeter if it is determined not to be performed; and a twentyth step of determining whether the DO concentration of the aerobic denitrification tank is reduced if it is determined to decrease in the eighteenth step; If it is determined that the reduction does not occur in the step 21, the control is performed to check the DO densitometer and the flow meter, and in step 20, If it is determined that the ORP value is reduced in step 22, and if it is determined that the step is not decreased in step 22, the step 23 of controlling to check the ORP system and the DO concentration meter is determined to decrease in the step 22 or Control program comprising a twenty-fourth step of controlling to measure the ammonia nitrogen concentration of the aerobic denitrification tank (9) after performing the seventeenth step A device for removing nitrogen and phosphorus in the wastewater / wastewater treatment plant, characterized in that it automatically adjusts the amount of air supplied to the aerobic denitrification tank so that the nitrate nitrogen concentration and the ammonia nitrogen concentration in the aerobic denitrification tank are kept within a predetermined standard. . The method according to claim 3, in the control panel 36 and the coagulant injection regulator 30, A twenty-fifth step of controlling to measure the total phosphorus concentration in the supernatant; A twenty-sixth step of calculating the total phosphorus removal amount by [total phosphorus removal = flow rate x (total phosphorus concentration-total phosphorus concentration based on discharged water)]; A twenty-seventh step of calculating the coagulant injection amount by [coagulant injection amount = total phosphorus removal amount × coagulant mole ratio]; A twenty-eighth step of generating a coagulant injector operation speed control signal corresponding to the coagulant infusion amount calculated by the twenty-seventh step and applying it to the coagulant injector; After the 28th step, check whether the total phosphorus concentration of TMS is within the discharge water quality standard value, and if it is within the standard value, proceed to the above 25th step, and if not within the standard value, increase the molar ratio of the coagulant after the above step S27. Control program consisting of the 29th step of controlling to proceed to By performing the adjustment, the coagulant injection amount is automatically adjusted according to the total phosphorus concentration so that the total phosphorus concentration in the effluent is maintained within the standard value, nitrogen and phosphorus removal rate of the wastewater treatment plant. The apparatus for removing nitrogen and phosphorus in the sewage / wastewater treatment plant according to claim 3, 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 apparatus for removing nitrogen and phosphorus in the sewage / wastewater treatment plant according to claim 3, wherein a sludge sludge supplementary tank 41 and a sludge supplementary pump 34-1 are installed to additionally supply the return sludge to the aerobic denitrification tank. .

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