KR100305777B1 - Toxicity measuring device based on activated sludge respiration rate and its operation method - Google Patents

Abstract

The present invention relates to an apparatus and a method for operating the sewage wastewater treatment plant by stably measuring the respiration rate of activated sludge in an activated sludge process to measure and block toxic substances in the influent in advance.

The present invention is a contact tank (3) for mixing activated sludge and waste water, MLSS (Mixed Liquor Suspended Solid) meter (4) for measuring the activated sludge concentration of the aeration tank (1), continuous breathing rate measuring device for measuring the respiratory rate of activated sludge ( 5), by analyzing the MLSS measurement and respiratory rate measurement to determine the presence of toxic substances 6, the solenoid valve (8a) of the aeration tank inlet pipe and the contact tank discharge pipe solenoid valve (8b) is configured to control, The contact tank waste water supply pump 7a for continuously supplying the waste water and the sludge to the contact tank 3 through the waste water and the sludge supply pipes 11a and 11b, and the contact tank sludge supply pump 7b and the contact tank 3, respectively. Blower 14 for supplying air, MLSS meter 4 above, respiratory rate meter 5, cables for transmitting signals between two solenoid valves 8a, 8b and toxic controller 6 9a, 9b, 10a , 10b), sludge transporting sludge from the contact tank 3 to the respiratory rate meter 5 The gist supply pipe 12, the contact tank 3 and the contact tank sludge discharge pipe 13b for conveying the sludge discharged from the respiratory rate meter 5 to the aeration tank 1, and the respiratory rate meter sludge discharge pipe 13a has a summary. .

Description

Toxicity measuring device based on activated sludge respiration rate and its operation method

The present invention is an essential part of the operation control and automation technology of the sewage water treatment plant. If the toxic material is included in the raw wastewater introduced into the biological process, the active sludge, which is a living microorganism, can be removed from the toxic material by measuring and blocking the presence of the toxic material in advance. The present invention relates to a device and a method of operating the same, which are intended to protect and enable stable operation of a wastewater treatment plant and provide updated efficiency of wastewater treatment.

In general, most wastewater treatment plants use organic sludge, which is a biological treatment method, to remove organic matter in the wastewater.

The biggest problem in operating and managing the activated sludge process is that microorganisms of the process are affected by various external factors, and the performance of the treatment process is degraded and the effluent quality is deteriorated.

Such external factors include qualitative and quantitative changes in the influent sewage, inflow of toxic substances, and temperature changes, and the burden of discharge charges due to the deterioration of effluent quality that occurs immediately when the performance of the process decreases due to these, and other environments. there is a problem.

In addition, it takes a lot of effort and time to return the activated sludge process to degraded performance once, and in the case of severe disturbance, it may take several months to recover, causing considerable economic problems.

The activated sludge process is recognized as a loathing facility due to the occurrence of odors and noise, and is neglected by the workers and coldly avoided by the residents of the surrounding area.

In addition, the operation and management costs are increasing due to the increase of electricity, chemicals, labor costs, etc. In addition, the whole system becomes more complicated and the operation is more difficult to produce effluent that meets the stricter effluent quality standards. It's getting very high.

Toxic substances that can enter the sewage treatment plant include strong acids, strong bases, various heavy metals, organic and inorganic specific pollutants, and they vary greatly depending on the production process of the plant.

In general, activated sludge from wastewater treatment plants is pure in the inflowing raw wastewater over a long period of time, so the adaptability is increased to a certain concentration of toxic substances.

Therefore, it can be said that activated sludge is not suddenly affected by toxic substances that occur constantly during the treatment of wastewater discharged under normal operating conditions.

However, in the event of abnormal operation and cleaning of the production process and restarting after stopping, the concentration of certain toxic substances in the influent may be rapidly increased, which may adversely affect activated sludge.

Therefore, protecting activated sludge by measuring the presence of the toxic substance in advance and taking countermeasures before entering the activated sludge process is an essential technology for continuous and stable operation of the activated sludge process.

The respiration rate is transferred to the ATP (adenosine triphosphate) through the electron transport system composed of dehydrogenases as the substrate is oxidized by the microorganisms, in which oxygen is used as the final electron acceptor.

Oxygen is also consumed in nitrification, where ammonia is converted to nitrates by autotrophic microorganisms.

Therefore, the oxygen uptake rate (breathing rate) is a useful parameter for assessing whether bacteria are healthy and active as steady state.

The respiratory rate of bacteria is a direct measure of the primary function of the activated sludge process and responds rapidly to the presence of inhibitors.

Therefore, measuring the respiratory rate of activated sludge has the advantage of being a very quick and simple biological early warning system (King and Dutka, 1986; Temmink et al., 1993).

According to Clarke (1977), dissolved oxygen (DO) and respiration rate are rapid and sensitive reactions and are key parameters for relatively simple assays, which are factors that continuously monitor biological systems and clarify their activity.

In their study, dissolved oxygen / respiration rate was very good when compared with factors such as MLVSS, COD, TOC, ATP, BOD, cell count, and cell composition.

The principle of toxicology based on the respiratory rate measurement of activated sludge is largely divided into discontinuous measurement and continuous measurement.

The principle of discontinuity measurement is to assess the toxic effects on microorganisms by measuring the respiratory rate with a series of toxic concentrations under specific conditions.

Usually, four kinds of toxic concentration compounds, sludge, and biodegradable substrates are put in a beaker or test container, and typical test methods include BOD interference test, ISO method A, ISO method B, and OECD method. (King and Dutka, 1986) These methods measure dissolved oxygen concentrations for 0.5-3 hours in short cases (ISO method A and B, OECD method) and 5 days in long cases (BOD disturbance test).

Spanjers et al. (1987) conducted a discontinuous batch test using RA-1000 continuous breathing rate measuring device.

In this study, the toxicities of KCN, 2-nitropropane, triethylphosphate, acetate, etc. were tested using the endogeneous respiration rate to confirm the reduction of endogenous respiration rate in proportion to the amount of toxic compounds.

In the case of discontinuous assays, a common problem is that the analyser determines the toxic effects of certain compounds by artificially mixing the appropriate amount of sample and sludge and measuring the dissolved oxygen concentration under certain conditions. It is not applicable to the field because it cannot be measured.

On the other hand, the continuous respiration rate toxicity test can determine the presence of toxic pollutants in the wastewater in real time.

Continuous measurements include BASF TOXIMETER, RA-1000 respirometer and Rapid Oxygen Demand and TOXicity tester (RODTOX).

Another toxicology measuring device, BASF TOXIMETER, using respiratory rate of activated sludge was developed by Pagga and Gunthner (Pagga and Gunthner, 1981).

That is, dissolved oxygen concentration, sludge concentration, pH, temperature, etc. are measured while continuously supplying activated sludge, wastewater, and return sludge to a 170L small aeration tank.

When the dissolved oxygen concentration reaches 2.0 mg / l, the aeration is stopped and the aeration is repeated again when 0.5 mg / l is reached, and the respiratory rate during the oxygen consumption period is calculated and compared with the value in the normal state. To determine the impact of.

Temmink et al. (1993) tested the toxic effects of wastewater containing herbicide and vinyl chloride on activated sludge using RA-1000 respirometer, and Kim et al. (1994) reported strong acid, strong base, and Co ²⁺ in petrochemical wastewater treatment plants. , Toxic effects of reduced catalyst wastewater were tested.

In both experiments, contact tanks were installed to ensure sufficient contact between the toxic compounds and activated sludge, and as a result, the possibility of continuous toxicity measurement using RA-1000 respirometer was suggested.

RODTOX, developed by Kong et al. (1993), is a batch-type respiratory rate meter that consists of a biological unit, a microprocessor, and an electronic component that links the two parts.

The biological device is a 10L activated sludge reaction vessel, which is continuously aerated, stirred and temperature controlled, and the upper cover is equipped with a DO meter and a pH meter.

Every 30 minutes, a certain amount of wastewater is injected into the sludge to compare the changes in the respiratory rate parameters (peak slope, peak area, peak height) caused by the toxic substances with a percentage inhibition compared to the reference value verified every 2-3 hours. Toxicity was determined by calculating IC ₅₀ ) (Vanrolleghem et al., 1994).

Kong et al. Demonstrated the acute toxic effects of 3,5-dichlorophenol, Cu ²⁺ and CN ^- as a cumulative exposure procedure.

In addition, to test the effects of chronic toxicity, experiments were conducted on 3,5-DCP and copper to establish a toxicology measurement method using a statistical analysis called moving window regression (Kong, 1995).

[references]

Clarke A.N., Eckenfelder W.W.Jr. and Roth J.A., "The development of an influent monitor for biological treatment systems", Prog. Wat. Tech., Vol. 9, No. 5/6, pp. 103-107, 1977.

Kim C.-W., B.-G. Kim, T.-H. Lee and T.-J. Park, "Continuous and early detection of toxicity in industrial wastewater using an on-line respiration meter", Wat. Sci. Tech., Vol. 30, no. 3, pp. 11-19, 1994.

King E.F. and B.J. Dutka, "Respirometric techniques, In: Toxicity testing using microorganisms", Vol. 1, Eds. Bitton G. and Dutka B.J., CRC Press, Florida, USA, pp. 75-112, 1986.

Kong Z., "Toxicity monitoring of wastewaters in activated sludge processes by a respirographic biosensor", Thesis, Gent Univ., 1995.

Kong A., P.A. Vanrolleghem and W. Verstraete, "An activated sludge-based biosensor for rapid IC50 estimation and on-line toxicity monitoring", Biosens. Bioelectron., Vol. 8, pp. 49-58, 1993.

Pagga U. and W. Gunthner, "The BASF TOXIMETER-a helpful instrument to control and monitor biological waste water treatment plants", Wat. Sci. Tech., Vol. 13, pp. 233-238, 1981.

Spanjers H. and A. Klapwijk, "Measurement of the toxicity of KCN and some organic compounds for activated sludge using the WAZU-respiration meter", Proc. Intern. Congress on Recent Advances in the Management of Hazardous and Toxic Wastes in the Process Industries, 1987.

Temmink H, P. Vanrolleghem, A. Klapwijk and W. Verstraete, "Biological early warning systems for toxicity based on activated sludge respirometry", Wat. Sci. Tech., Vol. 28, No. 11/12, pp. 415-425, 1993.

Vanrolleghem P.A., Z. Kong, G. Rombouts and W. Verstraete, "An on-line respirographic biosensor for the characterization of load and toxicity of wastewaters", J. Chem. Tech. Biotechnol., Vol. 59, pp. 321-333, 1994.

The present invention is to measure and block the toxic substances contained in the influent in advance by continuously measuring the respiratory rate of the activated sludge in the wastewater treatment plant activated sludge process, and to protect the activated sludge, which is a living microorganism, from the toxic substances in the wastewater treatment plant. It is to renew the efficiency of stable operation and wastewater treatment.

1 is an overall configuration diagram showing an embodiment of the present invention

2 is a correlation between the activated sludge and the substrate load which is the principle of the present invention

☞ Explanation of symbols used in the main part of the drawing ☜

1; Aeration tank 2; Settler

3; Aeration tank 4; Floating solids concentration meter (MLSS meter)

5; Respiration analyzer

6; Toxicity controller

7a; contact bath wastewater supply pump 7b; contact bath sludge supply pump

8a; aeration tank inlet pipe solenoid valve 8b; contact tank outlet pipe solenoid valve

9a; MLSS signal transmission cable 9b; Respiration rate signal transmission cable

10a; aeration valve solenoid valve adjustment signal transmission cable

10b; Contact signal solenoid valve control signal transmission cable

11a; contact tank wastewater supply pipe 11b; contact tank sludge supply pipe

12; respiratory rate meter sludge inlet pipe

13a; breath rate sludge discharge line 13b; contact tank sludge discharge line

14; blower

1 is a view showing the configuration of a device for measuring the toxicity of wastewater by activated sludge respiration rate according to the present invention,

The present invention consists of a measuring device section consisting of a contact tank 3 of 20 liters, a continuous respiration rate measuring instrument 5, a mixed liquor suspended solid (MLSS) meter and a toxicity controller 6 corresponding to the control part.

The two sludge pumps 7a and 7b and the respective supply pipes 11a and 11b continuously supply the activated sludge of the wastewater and the aeration tank 1 to the contact tank 3.

The contact tank 3 is aerated by the blower 14, and the wastewater and the activated sludge are mixed, and the mixed sludge is supplied to the continuous breath rate measuring instrument 5.

Continuous respiration rate measuring instrument 5 is a device capable of continuously measuring the respiration rate of the aeration tank activated sludge developed by Manotherm (Netherlands).

The continuous respiration rate measuring instrument 5 is a 0.75L sealed respiration chamber and a pump for introducing sludge, four solenoid valves for adjusting the flow direction of the sludge, and a dissolved oxygen (DO) concentration in the respiratory chamber. It consists of a DO electrode and a control board that controls these measurement systems and collects and outputs data. Such a configuration of the continuous respiration rate measuring device 5 is common.

Respiratory rate data of activated sludge measured every minute is transferred to a computer in ASCII (ASCII) format.

Sludge which is drawn at a constant flow rate and whose respiratory rate is measured in the respiratory chamber is discharged continuously to the outside.

There is a monad type correlation between the respiration rate of activated sludge and the substrate load. That is, at low substrate loads, the respiration rate is proportional to the substrate load, and if the substrate load is above a certain level, the respiration rate is constant regardless of the load, and there is a transition region between the two regions (see FIG. 2).

At this time, the constant respiration rate regardless of the substrate load is called the maximum respiration rate (R _max ).

However, when toxic substances are injected into activated sludge, the metabolism of microorganisms is affected by the toxic substances, and at the same time, the maximum respiration rate is reduced.

The extent to which the maximum respiration rate is reduced by toxic substances depends on the concentration of the toxic substance and the contact time.

The present invention is based on this activated sludge maximum respiration rate measurement.

Waste water and activated sludge are supplied to the aeration tank 3 at a constant flow rate and aerated to maintain a total mixed state of the sludge while maintaining the dissolved oxygen concentration in the aeration tank 3 to 5.0 mg / l or more.

The mixing ratio of raw wastewater and sludge is kept above the level at which the maximum respiration rate can be obtained.

The mixed sludge staying in the contact tank 3 for a predetermined time is fed to the continuous breathing rate measuring instrument 5, and the respiratory rate is measured every minute.

At this time, the respiration rate is the maximum respiration rate (R _max ).

The sludge discharged from the continuous respiration rate measuring instrument 5 may be returned to the aeration tank 1 or may be discharged to the drain.

The respiratory rate data measured every minute are transmitted to the toxic controller 6 via the signal cable 9b and recorded and processed.

In the normal state where no toxic substances are introduced, the maximum respiration rate is always maintained at a constant value, but if the toxic substance is contained in the raw wastewater, the maximum respiration rate decreases rapidly or gradually depending on the type and concentration of the toxic substances.

The MLSS meter 4 installed in the aeration tank 1 continuously measures the activated sludge concentration and transmits it to the computer via the signal cable 9a.

The collection, processing, and display of data continuously measured on an online instrument is performed by the toxic controller 6.

Toxicity controller 6 stores the entered respiratory rate data every minute and MLSS (Mixed Liquor Suspended Solid) data averages every minute and calculates MLVSS (Mixed Liquor Volatile Suspended Solid) values using the previously entered MLSS / MLVSS ratio. Save as a value.

The respiratory rate measurement is divided by the MLVSS value to calculate the specific maximum respiration rate (r _max ) and stored as a separate variable.

The maximum respiratory rate is averaged for 24 hours and used as the daily average maximum respiratory rate.

Thus, when the measured value decreases below 80% of the reference value by comparing the maximum respiratory rate measured continuously with the reference value, it is judged to be toxic and alerts the driver and decreases below 60% .The solenoid valve of the aeration tank 1 wastewater inlet pipe 8a To close off the inflow of waste water.

In selecting the maximum respiratory rate reference value, once the toxic substance is measured more than once a day, the daily average value is lower than the normal value. Therefore, the daily average value of the day on which the toxicity alarm is issued to ensure the validity of the reference value is excluded from the standard value. The daily average for the previous day is taken as a reference.

Toxic substances are present in the contact tank 3 after the toxicity is measured. After the toxicity alarm is issued, the solenoid valve 8b at the bottom of the contact tank 3 is opened to discharge all the sludge in the contact tank 3 for the continuous inflow toxicity measurement. Then supply fresh waste water and sludge to continue to measure respiration rate.

When the toxicity is detected as described above, the wastewater flowing into the aeration tank 1 is blocked by using the aeration tank 1 inlet solenoid valve 8a and bypassed to a separate tank.If the storage tank capacity is sufficient, toxic substances are stored in the storage tank without a separate tank. The wastewater contained is stored, and the toxic wastewater in which the toxicity is detected is treated or diluted biologically in an aeration tank 1 by the physicalization method.

Example

The experiment was carried out by attaching a toxicity measuring device according to the present invention to a pilot-scale activated sludge process in which the pigment wastewater treatment plant was reduced to about 1 / 1,200.

Activated sludge system consisted of raw water storage tank, mixing tank, aeration tank (3㎥) of 4 stages of 750L, sedimentation tank and discharge water storage tank.Waste water is the wastewater generated from the pigment production plant. The CODcr concentration was 1,200 mg / l and the inlet load of the aeration tank was operated at 2.8 kg CODcr / m 3 · day (see Table 1).

Operating conditions of pilot-scale activated sludge system parameter value Influent Flow 2.12㎥ / day Mixing tank repair time (HRTcc) 13.6 min Aeration tank repair time (HRTat) 8.5 * 4 = 34hrs Influent Concentration 1,200 mgCODcr / l Activated Sludge Concentration (MLSS) 4,000 mg / l Volume load rate (Lv) 2.8㎏CODcr / ㎥day F / M ratio (food to microorganism) 0.85kgCOD / kgMLVSSday Sludge Retention Time (SRT) 20 days

As a result of measuring the maximum respiration rate by adjusting the pH of the raw wastewater to 3, the maximum respiration rate decreased by 20, 40, 60, 80% when the contact tank pH was 6.5, 6.0, 5.5, and 4.9, respectively.

In addition, the pH of the wastewater and the contact tank showed a difference of 1 when the retention time of the contact tank was 12.7 minutes and the volume of the contact tank was 7.5L.

Therefore, the pH of the raw water was adjusted to 5.5, 5.0, 4.5, and 3.9, respectively, and the actual and maximum respiration rates were simultaneously measured (see Table 2).

Under the given conditions, the maximum respiratory rate was twice as high as the actual respiratory rate when comparing the maximum respiration rate, which is a measurement variable of the toxicity measuring device, and the actual respiration rate, which is the state variable of activated sludge activity. .

Therefore, by using the toxic sensitizer according to the present invention, the toxic effect of the activated sludge of the aeration tank upon acid toxicity can be detected in about ten minutes with a twice higher sensitivity.

Effect of Hydrogen Ion Concentration on Specific Respiration Rate and Maximum Specific Respiration Rate Example One 2 3 4 Influent pH 5.5 5.0 4.5 3.9 r _max, inital 86.1 74.2 80.0 83.3 r _max, final 67.7 32.0 28.6 17.5 Response (r _max, %) 21.4 56.9 64.3 79.0 r _max, inital 27.5 27.5 28.1 25.5 r _max, final 24.6 20.4 20.6 15.7 Response (r _a, %) 10.5 25.8 26.7 38.4

Note) Response =

The toxic effect measurement system of the activated sludge process developed by the present invention can primarily protect the activated sludge from toxic substances by measuring the presence of toxic substances introduced into the activated sludge process in advance, and also automate and operate the wastewater treatment plant. It can function as an essential key element of the technology that controls the control.

In particular, it can be usefully used in a treatment plant that combines sewage and wastewater.

In general, the sewage and sewage flowing into the sewage treatment plant do not contain toxic substances. Therefore, under normal operating conditions, the activated sludge is relatively less likely to be affected by toxic substances. It is very likely that the activated sludge will be toxically affected by the specific pollutants generated by them, which will likely deteriorate the performance of the treatment plant.

Therefore, in the sewage wastewater treatment plant that can be toxicly affected by such toxic industrial wastewater, it is possible to use the present invention to protect the activated sludge process from toxic substances and to enable continuous and stable operation. You can get a back.

Claims (2)

In constructing the toxicity measuring device of sewage water, Activated sludge is withdrawn from the contact tank wastewater supply pump 7a and the aeration tank 1 for supplying the wastewater, and the wastewater and sludge are continuously supplied by the contact tank sludge supply pump 7b, and the introduced sludge and the wastewater are aerated by the air supplied from the blower 14. A continuous respiration rate measuring instrument 5 for measuring the respiratory rate of activated sludge transferred through the mixed contact tank 3 and the sludge conveying tube 12 of the contact tank 3, and the signal output from the continuous breathing rate measuring instrument 5 and the microbial concentration in the aeration tank 1 Toxic controller 6, which collects and processes the data measured by transmission of signals output from MLSS (Mixed Liquor Suspended Solid) meter 4 to determine the presence of toxic substances based on the change in maximum respiratory rate and to alert the driver The solenoid valve 8a of the aeration tank 1 and the contact tank 3 of the aeration tank 1 connected to the toxic controller 6 to control the inflow of wastewater according to the measurement of toxic substances Toxicity measuring apparatus of the wastewater by consisting of a solenoid valve 8b of the contact tank discharge pipe 3 for discharging the sludge in the activated sludge respiration characterized. Using the data measured continuously on the respiratory rate meter 5 and the Mixed Liquor Suspended Solid (MLSS) meter 4, the maximum respiratory rate is continuously calculated and based on these data stored on a daily basis, a 24-hour average is used to calculate the baseline maximum ratio. The respiratory rate is calculated and compared with the maximum respiratory rate calculated continuously and the standard maximum respiratory rate on the previous day. An alarm is issued when the maximum respiratory rate decreases to 80% or less of the standard maximum respiratory rate. If the solenoid valve 8a of the inlet pipe is automatically shut off and the maximum respiratory rate is reduced more than once by 60% or less, the average maximum respiratory rate on the day is not determined by the standard maximum respiratory rate on the following day, but the average maximum respiratory rate on the previous day is determined. If the toxic substance is in the influent flowing into the activated sludge process by setting the standard maximum respiratory rate of the next day, A method of operating a toxicology measurement apparatus according to activated sludge respiration rate, characterized in that to measure the toxic substances on the basis of the decrease in the maximum specific respiration rate.