KR20010086936A - High disposal process for purifying the waste water having highly concentrated nutrition salt and its processing apparatus - Google Patents

Abstract

PURPOSE: An advanced biological treatment process for treatment of wastewater containing high concentration nutrient salt is provided, which can treat livestock farming wastewater or leachate which change in the amount and load greatly, minimize the requirement of foreign substrate for denitrification by utilizing raw water as denitrification substrate during anoxic period, minimize man power requirement by automating the operation of reactor and eliminates the requirement of recycle facility and settling tank of continuous process. CONSTITUTION: The process comprises as follows: (i) intermittent aeration step that consists of alternate continuous operations of anoxic and aerobic aeration; (ii) utilize organic matter contained in raw water as denitrification substrate by selectively feeding raw water during only anoxic period; (iii) supply sufficient alkalinity required for complete nitrification during aerobic period; (iv) real time control at controller by detecting nitrate state in continuous batch reactor; (v) induce complete denitrification of residue nitrate using foreign substrate that has high denitrification rate in stead of raw water during final anoxic period; (vi) oxidize organic matter completely.

Description

High disposal process for purifying the waste water having highly concentrated nutrition salt and its processing apparatus}

An object of the present invention is to provide a novel method and apparatus for high concentration wastewater treatment such as livestock wastewater using an intermittent aeration technique, selective oxygen injection during aerobic period, and a control system using a redox potential (ORP) in a continuous batch reactor.

Conventional livestock wastewater treatment methods use biological treatment as the main treatment process, and anaerobic, anaerobic, and aerobic treatment methods are used for this biological treatment process.

In domestic livestock wastewater treatment facilities, aerobic biological treatment is widely used, but the aeration power for oxygen supply is large and a large amount of surplus sludge is generated, which causes problems in treatment and disposal. There was a disadvantage in that water reservation was required.

On the other hand, anaerobic biotreatment using anaerobic microorganisms has been noted for a long time because of the energy saving effect of unnecessary aeration power and the use of methane gas as a by-product. Unlike aerobic digestion by aerobic microorganisms used as electron acceptors, it is carried out by anaerobic microorganisms using carbon in organic molecules as electron acceptors.The anaerobic microorganisms have a very slow growth rate and a very narrow range of optimum growth conditions. Maintenance is the most important factor in ensuring processing efficiency and stability. In addition, most of these anaerobic treatment methods use technology developed in foreign countries with different climatic conditions or raw water phases, which causes many problems in the field application.

In particular, when the anaerobic digestion treatment method is introduced as the primary treatment facility, the concentration of ammonia nitrogen in the anaerobic digestion effluent is very high, which may cause toxicity in the subsequent biological advanced treatment process or cause substrate deficiency during denitrification. It shows the result of increasing the cost.

On the other hand, if animal manure containing a large amount of nitrogen is treated with a combination of anaerobic digestion and nitrogen and throat advanced processing (aerobic treatment), organic carbon compounds are removed and anaerobic reduction does not occur in anaerobic digestion. As a result, C, N, and P are not balanced, which leads to a problem that makes subsequent advanced processing difficult.

In the case of the prevention of eutrophication, the regulation of total nitrogen and total phosphorus regulated in Korea is expected to be strengthened, but the biological nutrients removal (BNR) currently used is the change in flow rate and inflow concentration. Considering the characteristics of livestock wastewater and the profitability of the livestock industry, there is a problem that it is difficult to guarantee stable runoff without introducing a situation.

On the contrary, in the case of the continuous batch reactor in which the intermittent aeration method is adopted in the present invention, it is one of the aerobic biological nutrient removal processes, but unlike the general continuous process, all the processes are performed in a single reactor, and thus, the facilities such as internal return. Since it is not necessary, the cost of facility and required area can be reduced, and only a part of the reactor can be used when there is a flow rate change.

In addition, raw water can be selectively injected only during the anaerobic period to fully utilize it as a denitrification substrate, and the economic cost can be secured by reducing the cost of drugs such as alkali niti for complete nitrification during the expiration period.

In addition, in the present invention, a continuous measurement data profile obtained by developing an advanced processing automation system through continuous measurement of the redox potential (ORP) for the purpose of nitrogen removal is to remove noise components through high frequency analysis and to denitrification. The reaction time can be controlled in real time by detecting the concentration of nitrate in the reaction tank by detecting the relevant response characteristics, and thus the time of complete nitrification during the aerobic period, and the time of complete denitrification of residual nitrate through the external substrate during the final anaerobic period. It is possible to discharge the effluent after the organic matter and nitrogen is sufficiently removed to ensure a stable effluent quality.

At this point, the various characteristics proposed by the present invention are sufficient as an alternative to low cost, high efficiency and high concentration wastewater treatment.

Therefore, the present invention introduces an intermittent aeration method in which raw water is injected only in an oxygen-free period in a continuous batch reactor, so that organic materials can be used as a denitrification substrate during an anoxic period, and the remaining amount can be oxidized during an aerobic period, and nitrogen is nitrified during an aerobic period. It can be removed by denitrification during and anaerobic period. At this time, by measuring the redox potential (ORP) in the continuous batch reactor (R) continuously, the concentration of nitrate is sensed to determine the completion of nitrification during the aerobic period and the denitrification completion during the final anaerobic period. It is possible to solve the problem of high concentration wastewater treatment, which causes serious problems such as eutrophication, with advantages such as reduction of reaction time, operation cost reduction through chemical cost reduction such as external substrate, and reduction of required site due to simplicity of facility. To provide a processing apparatus and method.

1 is a schematic view showing an entire system consisting of a continuous batch reactor showing an embodiment of the present invention and a control system using a redox potential

2 is a reactor operating cycle table using the intermittent aeration method provided by the present invention

■ Explanation of symbols used in main part of drawing ■

1: inflow water inflow pipe 2: outflow water discharge pipe

T1: Raw water storage tank R: Continuous batch reactor

B: Blower P: Pump

M: Mixer

D: Rail buoy decanter

S1: pH probe

S2: redox potential probe

OI: Optically isolated transmitter

RE: Relay AD: AD Converter

CO: controller (PLC or PC or DCS)

51: Raw water injection + anaerobic period

52-1: First anaerobic period after stopping injection of raw water

52-2: Anaerobic period without raw water injection

53-1: Expiration Period

53-2: Final Expiration Period

54-1: External Substrate Injection + Final Anaerobic Period

54-2: Final anaerobic period without external substrate injection

55: settling and drawing period

1 and 2 are the entire system consisting of a continuous batch reactor (R) and a control system using a redox potential difference showing an embodiment of the present invention, respectively, and continuous batch reactor (R) operation using the intermittent aeration method according to the present invention The cycle is shown.

Raw water is supplied by dividing the total amount of raw water injection into 1/4 from the raw water storage tank T1 to the continuous batch reactor R during the raw water injection period 51 during the four anaerobic periods of FIG. 2. At this time, nitrate is converted to nitrogen gas during the anoxic period (52-1, 52-2) without raw water injection using the supplied raw water as the denitrification substrate, and at the same time, the organic matter is removed.

The organic matter remaining in the denitrification process is removed during the expiration period 53-1. In addition, a nitrification reaction occurs in which ammonia nitrogen is converted to nitrate during the expiration period 53-1.

During the final anaerobic period (54-1) of supplying external substrates, the remaining nitrates were supplied to the external anoxic period (54-) that had not been sufficiently converted to nitrogen gas by the raw water alone during the previous anaerobic period (52-2). Denitrate during 2).

Thereafter, during the final expiration period 53-2, the remaining amount of the external substrate introduced during the final anaerobic period 54-1 is used as the denitrification substrate during the final anaerobic period 54-2.

During the settling and drawing period 55, sludge in the continuous batch reactor R is precipitated and the final treated supernatant is discharged through a rail buoy decanter D.

On the other hand, in the continuous batch reactor (R), a blower (B) for blowing air during the expiration period is installed, and a mixer (M) for achieving a complete mixing state during the anaerobic period is installed.

In addition, ORP probe (S1) and pH probe (S2) are installed to read the redox potential and pH in the reactor, and it is an optically isolated transmitter (OI) and relay for transmitting data read from these sensors to the controller (CO). (R), AD converter (AD) and the like are provided.

The present invention is characterized by providing a high concentration wastewater treatment method using the continuous batch reactor (R) and the reactor operation control system.

Hereinafter, the present invention will be described in more detail through one embodiment.

(Example)

First, to determine the fill ratio for the operation of the continuous batch reactor (R), fill ratio is 1/4, 1/8, 1/12, when the concentration of NH ₄ ⁺ -N in the influent is about 3,400 mg / L. Experiments for deriving the optimal fill ratio with different 1/16 resulted in a maximum nitrification rate of 0.35kgNH ₄ ⁺ -N / m ³ · day at fill ratio 1/12. Fluidity was determined using the relationship between ₄ ⁺ -N concentration and fill ratio.

Based on the above results, the continuous batch reactor (R) was operated in the intermittent aeration operation cycle shown in FIG. 2 to obtain the following results.

Under the conditions of average raw water concentration SCODcr 10,000mg / L and average volume load 1kgCOD / m ³ · day, the removal efficiency of organic matter was above 93% and the removal rate was 0.93kgCOD / m ³ · day.

The biological oxygen demand of BOD ₅ was 6,000mg / L of influent and 10mg / L of effluent, and the average removal rate was 99.8%.

The average nitrification rate was more than 99.7% when raw water average NH ₄ ⁺ -N 3,400mg / L, the discharge quality was below 5mg / L, and the average nitrification rate was 0.34kgNH ₄ ⁺ -N / m ³ · day.

The method of injecting the raw water into the reactor at a time during the initial anaerobic period (single feeding), the continuous feeding of the raw water continuously during the reaction period (continuous feeding), and the oxygen-free period adopted in the present invention selectively As a result of comparing the three types of intermittent feeding, the effluent NH ₄ ⁺ -N was found to be less than 1/5 of the intermittent supply compared to the temporary supply or the continuous supply, and the effluent quality was significantly improved. there was.

In addition, in the continuous feeding, as the reaction proceeds, nitrates accumulate due to the denitrification substrate deficiency during anoxic period, but the system for controlling the denitrification reaction time by using ORP in the intermittent feeding adopted in the present invention. When used, the phenomenon of nitrate accumulation in the reactor did not appear at all, and the reaction time could be flexibly adjusted according to the condition of the reactor to ensure the quality of the effluent.

In addition, raw water can be fully utilized as a denitrification substrate, which can reduce the use of external substrates by more than 70% compared to temporary supply.

In addition, NH ₄ ⁺ -N, which contains 13,000 mg / L of alkali nitrile in raw water, is insufficient to completely nitrate NH ₄ ⁺ -N during aerobic period. As a result, there was no need to replenish alkalinity during the expiration period, thus reducing drug costs.

By detecting the completion time of nitrification and the completion of denitrification by using ORP, the reaction time can be fluidly determined by the controller according to the properties of the incoming raw water.The reaction time is shortened when the raw water phase is lower than the set value. The treatment capacity could be increased, and when the raw water phase was high, the effluent quality could be guaranteed regardless of the load fluctuation by giving sufficient reaction time until the reaction completion time was detected.

As described above, the continuous batch reactor operation system for the high concentration wastewater treatment according to the present invention is capable of removing and removing organic substances and nitrogen, while also allowing automation and control of the reactor operation. You can expect.

First, it can be equipped with a system capable of stable and high-cost treatment at high cost for the treatment of high concentration wastewater such as livestock wastewater or leachate with high generation amount or load fluctuation.

Second, by using raw water as denitrification during anoxic period, the external substrate requirement for denitrification can be minimized, and alkalinity for complete nitrification can be fully replenished during the expiration period, thus reducing the operating cost burden.

Third, by automating the operation of the reactor can also reduce the manpower costs required to operate and manage the reactor,

Fourth, it can be usefully applied when the construction of a small treatment plant is required, such as a continuous treatment plant or a sedimentation tank, which requires a separate treatment plant site or installation inside the building.

Claims (2)

Intermittent aeration process consisting of a series of alternating anaerobic and aerobic periods, Selectively inject raw water only during the period of anaerobic use to fully utilize organic matter in the raw water as denitrification substrate, After the process to ensure that the supply of alkali nitritic for complete nitrification during the expiration period, Detecting nitrate status in a continuous batch reactor to perform real time control in the controller, During the final anaerobic period, a process for inducing complete denitrification of residual nitrates using an external substrate having a high denitrification rate instead of raw water Thereafter, a high treatment process for the treatment of high concentration nutrient-containing wastewater, characterized in that it comprises a process for complete oxidation of the remaining organic matter during the final expiration period. In the continuous batch reactor (R), the raw water can be supplied from the raw water storage tank (T1) using the pump (P) through the influent inlet pipe (1), and the effluent water from the effluent discharge device (D) using the pump (P). In constructing an advanced treatment device for the treatment of high concentration nutrient-containing wastewater having an effluent discharge pipe (2) to discharge the; In the continuous batch reactor (R) by installing an ORP probe (S2) for continuously measuring the redox potential (ORP), and pH probe (S1) to detect the complete nitrification time during the expiration period by grasping the behavior of nitrate Optically isolated transmitter (OI), AD converter (AD), and relay (RE) are installed to transmit to the controller (CO) to configure on / off of each pump (P) and blower (B). In the continuous batch reactor (R), a blower (B) for supplying air during the expiration period, and a mixer (M) for achieving a complete mixing state during the anaerobic period is installed for the high concentration nutrient-containing wastewater treatment Device.