JPH11160305A - Method and device for testing waste water treatment using aerobic microorganism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for evaluating the aptitude of waste water treatment by grasping data which enables the direct evaluation of the conditions of the activity of microorganisms such as changes in the composing speed of pollutants, the breathing speed of oxygen by respiration, etc., of microorganisms in an aeration layer. SOLUTION: In a step 1, a sample waste liquid is inserted into a mixed liquid of an aeration layer, and changes in the concentration of dissolved oxygen are measured in the process of aeration. In a step 2, aeration is halted to interrupt the dissolution of oxygen from the outside and measure the decreasing speed of the concentration of dissolved oxygen. In a step 3, a specified amount of solution containing a substance which can be composed by aerobic microorganisms is added to the mixed liquid, and changes in the concentration of dissolved oxygen are measured in the process of aeration. With an inspection process including these steps as a set, this set is repeated, and characteristic values such as the composing speed, etc., of the component of the concentration of dissolved oxygen by microorganisms in each set to evaluate the aptitude of treatment on the above-mentioned sample waste liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method and an apparatus for testing the suitability of treating wastewater in wastewater treatment using aerobic microorganisms.

[0002]

2. Description of the Related Art Wastewater treatment using aerobic microorganisms represented by activated sludge treatment is the most general wastewater treatment. The basic process of wastewater treatment using aerobic microorganisms consists of putting wastewater into a mixture containing aerobic microorganisms at a high concentration, aerating the air, and using the dissolved oxygen dissolved in the mixture to remove microorganisms from the wastewater. Decomposes pollutants. Generally, various pollutants are present in wastewater, and various microorganisms are involved in decomposing the pollutants. The greatest feature of aerobic microbial treatment is that it can efficiently cope with various wastewaters by highly concentrating the natural biological activities of acclimating various microorganisms corresponding to various pollutants. On the other hand, due to complex biological activities, it is extremely difficult to grasp the cause-effect relationship quantitatively.
The state of treatment varies depending on the characteristics such as substrate fluctuation, and it can be said that there is no same wastewater treatment as one. For this reason, when newly designing an aerobic microorganism treatment device or when treating existing wastewater with an existing device, long-time treatment using wastewater and aerobic microorganisms assumed in a miniature wastewater treatment test machine is required. You need to experiment.

FIG. 1 is a flow chart showing a typical example of a tester conventionally used for performing this experiment. As shown in FIG. 1, the conventional testing machine is a scaled down one-hundredth to one-thousandth of the main part of an actual activated sludge treatment apparatus. The basic method of the test is to add a sample waste solution to the aeration tank with a pump at a constant flow rate, perform aeration treatment in the aeration tank, sample the supernatant water overflowing from the sedimentation tank, and analyze it.
This is a method of checking changes in the quality of treated water such as COD, BOD, and transparency.

In this method, the state of treatment can be evaluated only by the quality of treated water as a result of treatment. Moreover, as an evaluation of water quality, COD is always an indicator of BO in biological treatment.
D is not representative, BOD takes a long time to measure and it takes time to analyze, so the frequency of analysis is limited, and there is a time delay before the phenomenon in the aeration tank is reflected in the supernatant water. There is only a rough change in some things. Furthermore, there is no means in the aeration tank to know the activity of microorganisms, such as the decomposition rate of pollutants or the change in oxygen absorption rate due to the respiration of microorganisms, and the central part of the treatment is almost in a black box state. This is not a problem if the substrate and the concentration of the sample waste liquid do not change, but only extremely insufficient data can be obtained for evaluating a waste liquid whose substrate and concentration change like actual waste liquid.

[0005]

As described above, a conventional tester for testing the treatment performance in wastewater treatment utilizing aerobic microorganisms can obtain only extremely inadequate data as described above. The present invention is different from the conventional method in which data on which the activity of microorganisms, such as the rate of decomposition of pollutants by microorganisms in the aeration tank and the rate of oxygen absorption due to respiration, can be directly evaluated, and the suitability for treatment can be evaluated. And a test method and apparatus.

[0006]

The activity of aerobic microorganisms can be estimated by measuring respiration (oxygen consumption rate). In the test method of the present invention, a change in dissolved oxygen concentration (hereinafter referred to as DO) in the following three steps is measured, and data necessary for aerobic microorganism treatment is obtained by data processing using a computer. In step 1, the sample waste liquid is introduced into the mixed solution in the aeration tank, and the change in DO during the process of aerating the mixed solution is measured. In step 2, the aeration is stopped, the incorporation of oxygen from the outside is stopped, and the rate of DO decrease is measured. Step 3 measures the change in DO during the process of adding a prescribed amount of a solution containing a substance that can be easily decomposed by the aerobic microorganism to be used (hereinafter referred to as a reference BOD addition solution) and aerating the mixture. The obtained change in DO is processed by a computer to obtain characteristic values characterizing the shape of the change curve of DO in each step. In the test method of the present invention, the inspection process including at least step 1, step 2, and step 3 is performed as a set, and the set is repeatedly performed, whereby characteristic values such as the decomposition rate of the BOD component by the microorganisms obtained in each set are obtained. By continuously measuring, the suitability of aerobic microorganisms for treating a sample waste liquid is evaluated.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the events underlying the present invention will be described. 2, 3, and 4 are diagrams illustrating the measurement principle of the present invention. From the state in which the mixed liquid containing activated sludge in the aeration tank is pre-aerated and kept at a high DO, a liquid containing a BOD substance serving as a bait is charged, and the mixed liquid is aerated. Decomposes the BOD substance in the waste liquid while consuming oxygen, the DO decreases, and continues to decompose the BOD substance at a value that balances the consumption rate of oxygen and the supply rate of oxygen by aeration. Part D
Form an O change curve. Since the consumption rate of oxygen by microorganisms becomes a small value mainly due to basal respiration when the BOD substance in the waste liquid is completely decomposed, DO rises as shown in the transition rising part of FIG. 2, and the DO change curve of the breathing part of FIG. Balance at the indicated high value. The change of DO during this time is expressed by the following equation (1). Where DOsat: saturated oxygen concentration DO: dissolved oxygen concentration of the mixed solution ASact: amount of oxygen consumed by activated sludge in basic respiration per unit time BODact: amount of oxygen consumed by activated sludge in decomposing BOD components per unit time Kabs: oxygen The moving speed coefficient Kabs of is expressed by equation (2). Kabs = G · η / V (2) where G: Aeration air volume V: Aeration tank capacity of test machine η: Oxygen dissolving efficiency (coefficient determined by aeration method, diffuser shape, etc.) ( In the equation (1), Kabs is a constant that becomes a constant value if the test apparatus is determined, DOsat is a function of temperature, and is a constant that becomes constant when the temperature is made constant under the test conditions.

[0008] ASact is the rate of consumption of oxygen by basal respiration of microorganisms. Since it is a basal breath, it is not directly related to the BOD component and is almost constant in a short time such as one set (in the embodiment, a cycle). However, rapid changes in the habitat environment such as influx of poisons and pH, water temperature, and electrical conductivity hinder biological activity and change in a decreasing direction. In the long term, it increases or decreases due to a change in the microflora constituting the activated sludge due to nutritional balance, relative excess or deficiency of the BOD with the amount of sludge, sludge concentration, and the like.

BODact is the rate of consumption of oxygen by which microorganisms are decomposing BOD components. BODact varies greatly depending on whether or not the BOD component is a substance which is easily biodegradable, whether or not microorganisms have adapted to the substance. In other words, BODact is a rate coefficient of decomposition reaction of BOD substance by microorganism, and DO, concentration of BOD substance,
It is a function of the state of the microorganism, but if DO is 0.5 ppm or more, and BOD substance concentration is several ppm or more, BODac
It is empirically known that it has little effect on t.

In order to estimate the magnitude of ASact + BODact, it can be estimated by using the expression (3) where the first term on the right side of the expression (1) is 0, that is, by observing the change in DO with the supply of oxygen cut off. FIG. 3 is a diagram showing this change in DO. As shown in the drawing, if the phenomenon is limited to a phenomenon for several minutes, the DO decreases almost linearly in the range where the DO is approximately 0.5 ppm or more. Considering that the measurement time of the test method of the present invention is about 5 minutes, D
Under the condition that O is approximately 0.5 ppm or more, the value on the right side of the equation (3) is a constant, and the absolute value of the slope of the straight line is equal to the magnitude of (ASact + BODact). This is referred to herein as β. β indicates the oxygen consumption rate of the microorganism. If this value is large, the microorganism is active, and if it is small, the activity is slow.

Now, assuming that (ASact + BODact) in the second term of equation (1) is a constant value and this value is β, equation (1) gives DO> 0.5 ppm
DO = α + (α−DO ₀ ) exp (−Kabs · t) (4) where α = DOsat−β / Kabs. Here, DO ₀ is the DO value at the start.

For the sake of simplicity, it is assumed that the BOD substance is of one type and that its components are well adapted to microorganisms and can be easily and completely decomposed.
Assuming that act is constant within the measurement time, DO
The change curve decreases with the addition of the BOD solution according to equation (3) (D
The DO value decreases to a value close to DO = α = DOsat−β / Kabs where t = ∞, and the BOD component is decomposed. This is referred to herein as the lower DO value. Eventually B
When the OD material is completely decomposed, BODact = 0 and the oxygen consumption rate is only ASact, so that the DO value rapidly increases to the DO value represented by DO = DOsat-ASact / Kabs. This is referred to herein as the higher DO value. In addition, the curve of the transition rising portion and the breathing portion that rises from a low DO to a high DO is DO = α1 + (α1-DOb) exp (−Kabs · (tt _vp )) (5) where α1 = DOsat−ASact / Kabs DOb: can be approximated by a lower DO. Here, t _vp : the start time to shift to the transition rising portion. The curve of the BOD decomposition portion in FIG. 4 shows this change. h1 = DOh-DOb = BODact / KabsDOh: High DO represents the degree of decomposition rate of the sample waste liquid by the microorganism. Also, the dotted line in FIG. 4 is the equation (1) where BODact = 0.
DO = α ₀ + (α ₀ −DO ₀ ) exp (−Kabs · t) Equation (6) where α ₀ = DOsat−ASact / Kabs is expressed by this dotted line and Equation (4). The area S1 surrounded by the solid line can be approximately approximated by S1 = t × BODact / Kabs (7) Therefore, if the reaction is completed as in the precondition, S1 / Kabs becomes the BOD value itself. The present invention evaluates the suitability of a waste liquid for treatment of activated sludge by performing analysis based on the above events.

Next, a specific test method will be described. FIG. 5 is a diagram showing the measuring method of the present invention. In the test method of the present invention, the change in DO in the following three steps is measured, and the information required for aerobic microorganism treatment is obtained by data processing using a computer. In step 1, the sample waste liquid is introduced into the mixed solution in the aeration tank, and the change in DO during the process of aerating the mixed solution is measured. In step 2, the aeration is stopped and the incorporation of oxygen from the outside is stopped, and the rate of DO reduction is measured. In step 3, the change in DO during the process of adding the prescribed amount of the reference BOD addition solution and aerating the mixed solution is measured. The test method of the present invention comprises at least step 1,
By repeatedly performing this set with the inspection process including Step 2 and Step 3 as one set, by continuously measuring the characteristic values such as the decomposition rate of the BOD component by the microorganisms obtained in the set, the sample waste liquid of the microorganism is obtained. This is to evaluate the suitability for processing. Here, the processing time in each step varies depending on the concentration and biodegradability of the waste liquid and the standard BOD added liquid, and generally, step 1 is set to 15 to 35 minutes, step 2 is set to about 5 minutes, and step 3 is set to about 15 to 30 minutes. Is done.

The meaning of each step (process) will be described below with reference to FIG. Step 1 is a step of checking the degradability of the sample waste liquid by aerobic microorganisms. In step 1, simultaneously with the start, aeration of the mixed solution in the aeration tank is started, and sample waste liquid is injected into the aeration tank at a set flow rate for a set time by a sampling pump. When starting from a high DO, if the sample waste liquid can be decomposed by sludge, the sludge decomposes and consumes dissolved oxygen, so the DO drops to a value at which the oxygen consumption rate and the oxygen supply rate by aeration are balanced. Decomposes pollutants inside. After decomposition, the consumption rate of oxygen becomes a small rate due to the respiration of sludge, so that DO rises and becomes high final DO. FIG. 5-1 is a typical example showing this change. In FIG. 5, -3 shows a high DO which is balanced with the supply rate by aeration when the activated sludge has the oxygen consumption rate only by respiration. h1-1 is a value indicating the difference between the high DO and the lowest value of the DO curve. -2 is a calculated value of a DO change curve corresponding to the equation (4) when the oxygen consumption rate is only breathing. S1 indicates the area surrounded by the curve -1 and -2 in the time of step 1. h1-2 is high DO
H1-3 represents the difference between the saturated oxygen concentration and the higher DO.

In general, waste liquids contain various components, and often contain components that are hardly biodegradable by aerobic microorganisms. For this reason, the change curve of DO is slightly different from that of a single component, and once the DO has decreased, it gradually increases as the process proceeds, and the final value is the set time for the hardly decomposable substance in the waste liquid. In many cases, the decomposition is not completed, and therefore, it often ends with a value slightly lower than DO obtained from the oxygen absorption rate due to the respiration of sludge. If the decomposition reaction is completed in time, S1 / Kabs
Is approximately the BOD itself, but if there is a difference as in h1-2 in the figure, an error occurs. However, in general, this difference is sufficiently smaller than h1-1, and the analysis according to the present invention does not pose a practical problem because the change in the magnitude of the BOD is more important than the absolute value of the BOD. h1-1 is a value indicating the decomposition rate of the waste liquid of the activated sludge. For example, if the sludge acclimates to the waste liquid, it gradually increases as the cycle is repeated, and conversely, if there is an inhibitory substance in the waste liquid component, the cycle is increased. There is a change such as a gradual decrease during repetition, and it is an important index. S1 also shows the same tendency as h1-1, and is an index that becomes larger than h1-1 when the decomposition reaction is stopped halfway. h1-2 is an index indicating the degree of decomposition of the hardly decomposable component. If this value is small, it can be estimated that the hardly decomposable component is small and the microorganism can be easily processed to a low BOD. There is a high possibility that it will flow out without processing. As h1-2 increases or decreases during the repetition of the cycle, it becomes a criterion for determining whether or not the microorganism can be adapted to the waste liquid. In step 1, the above items become important characteristic values.

In step 2, the oxygen consumption rate ASact by the basic respiration of the microorganism and the BOD at the end of step 1
This is a step of observing the consumption rate BODact of oxygen due to decomposition, and is a step of measuring β. In step 2, the aeration is stopped, the supply of oxygen from the outside is stopped, and the rate at which DO decreases is measured. As described above, the obtained decrease curve is substantially a straight line as shown in FIG.
Can be obtained. β is the value at the end of step 1 (1)
It represents the rate of consumption of oxygen by ASact + BODact in the equation. Continuously measuring β and observing the change means knowing the degree of completion of the decomposition in Step 1. Also, if the activity of activated sludge is inhibited due to the strong toxicity of sample waste liquid, β
Shows a value smaller than ASact. β is a value used as a judgment material for determining whether or not the microorganism is acclimated to the waste liquid or whether it is operating normally. In step 2, β is an important characteristic value.

In step 3, a prescribed amount of the reference BOD addition solution is added at the start time, and the DO which changes by aeration is measured. The difference from step 1 is that step 1 is to add the sample waste liquid to check the degradability of the sample, while step 3 is to check the change in the activity of the microorganism using the waste liquid whose degradability is known as an index. The microorganism added to the substance added in step 3 has already been sufficiently adapted to the substance, and if the activity of the microorganism is normal, the absorption rate of oxygen increases at the same time as the addition as shown by the curve in FIG. Then, while the components are decomposed, the DO value is stabilized at a low DO value which is balanced by the oxygen consumption rate of (BODact + ASact) and the oxygen supply rate by aeration shown in the equation (4). When the waste liquid is completely decomposed, it rises sharply and rises to a high DO value which is balanced by the oxygen absorption rate of ASact as shown by the equation (5). FIG. 5-1 is a typical example showing this change. In the figure, -3 shows a high DO which is balanced with the supply rate by aeration when the microorganisms consume oxygen only by respiration. h3-1 is a value indicating the difference between the high DO and the lowest value of the DO curve. -2 is a calculated value of a DO change curve corresponding to the equation (4) when the oxygen consumption rate is only breathing. S3 is -1 during the time of step 3.
And the area enclosed by -2. h3-3 is the difference between the saturated oxygen concentration and the higher DO, the same value as h1-3 in Step 1, h3-2 is the difference between the higher DO and the final value of the -1 curve, and By BODact by h1-
It shows almost the same value as 2. h3-1 is the decomposition rate of the standard BOD additive liquid, and the area S3 surrounded by the dotted line and the solid line is the decomposed BO of the standard BOD additive liquid within the measurement time of step 3.
This is an amount corresponding to D. If the sample effluent is toxic and the microorganisms are damaged, the rate of decomposition of the standard BOD-added solution will decrease, or decomposition will normally stop at an intermediate stage even though it can degrade to carbon dioxide and water. H if a failure occurs
3-1 S3 changes. Prior to the test, a standard h3-1 (hereinafter referred to as hs) using a normal microorganism
And S3 (hereinafter referred to as Ss) are measured and compared with this value to further clarify changes in h3-1 and S3. In step 3, h3-1, S3 and h3-2 are characteristic values.

The BOD component of the reference BOD additive liquid used in step 3 can be a substance which can be easily decomposed by the microorganism used, and is usually decomposed by a typical waste liquid treated by an activated sludge treatment apparatus assumed in a test. A substance with good properties is suitable. Generally, methanol is easily decomposable by microorganisms and can be used for general purposes.

The reference value can be easily obtained by the following method with the test apparatus of the present invention. Generally, ASact, hs, and Ss are determined prior to the test.
The activated sludge mixture used for the test is put into the aeration tank of the test apparatus. The BOD of the mixed solution used is already sufficiently treated, and the activated sludge used is sludge having normal biological activity. Step 1 is performed from this state. In the normal step 1, a sample waste liquid is added, but in this step, aeration is performed without adding a sample waste liquid. In this state, the decrease of DO in step 2 is measured, and the slope of the straight line at this time is ASact. In this state, the process proceeds to step 3, where h3-1 and S3 are measured by adding the reference BOD additive solution and measuring h3-1 and S3, respectively. In this specification, this series of steps is referred to as a reference value acquisition cycle.

Next, an example of the transition of the DO change curve obtained by the test method of the present invention for a typical waste liquid will be described. FIG.
Is a typical example of a waste liquid that can be treated without any problem with activated sludge.
The DO change curve obtained in step 1 of FIG. 6 shows sufficiently large h1-1 and S1 as -1 from the first cycle, and from -1 to -2 as the cycle is repeated.
It changes in the direction of -3, and h1-1 and S1 both become constant at a slightly larger value than the initial value. This indicates that the sludge has acclimated to the sample waste liquid. In Step 2, -1 to -2,
With the change in the direction of -3, β becomes constant at a small value almost close to ASact. This indicates that in step 1, the BOD has been almost completely processed. In step 3
With the change from -1 to -2, -3, the curve becomes almost the same as the reference value, showing the values of h3-1 and S3 until the last cycle. This is evidence that the sample effluent has no inhibitory effect on activated sludge.

FIG. 7 is a typical example of a toxic waste liquid. In step 1 of FIG. 7, as the cycle is repeated, DO
The shape of the change curve changes to a small value in both h1-1 and S1 in the direction of the arrow in the figure (from -1 to -2, -3).
This indicates that the decomposition rate of the contaminants in the waste liquid decreases and the decomposition also becomes insufficient. In step 2, β gradually decreases in the direction of the arrow in the drawing (from -1 to -2, -3) and becomes smaller than ASact.
This indicates that the respiration rate of microorganisms is affected. Further, in step 3, h3-1 and S3 both change to small values in the direction of the arrow in the figure (from -1 to -2, -3). This indicates that BOD components, which should be easily decomposed, cannot be decomposed. Since all the indexes from step 1 to step 3 are deteriorated, it is understood that the sample waste liquid is toxic to activated sludge and is not suitable for treatment. It can be said that the more rapid this change, the more toxic the waste liquid.

FIG. 8 is a typical example of a waste liquid which is hardly decomposable but has no toxicity to activated sludge. In step 1 of FIG. 8, only small values h1-1 and S1 are shown from the beginning, and this tendency does not change even if the cycle is repeated (-1, -2, -3). Β in step 2 is a value slightly larger than ASact and indicates a direction slightly smaller than a substantially constant value (-1, -2, -3). In step 3, h3-1 and S3, which are almost the same as the reference hs and Ss,
And there is almost no change (-1, -2,-
3). FIG. 9 shows a typical example of a waste liquid which is hardly decomposable at first, but can be treated if the sludge acclimates. Step 1 of FIG.
Initially, the h1 and S1 are small at first, but gradually change to show the large h1-1 and S1 as the cycle is repeated (changes from -1 to -2 and -3). Step 2
Is slightly larger than ASact, but the direction of change is undefined due to the situation of the process change in step 1 (-1, -2, -3). In step 3, the reference hs, S
At h3-1 and S3, which are almost the same as s, there is almost no change (-1, -2, -3).

FIG. 10 is a typical example of a waste liquid showing temporary toxicity. In step 1 of FIG. 10, h1-1 from the beginning until n cycles (3 cycles in the figure, and so on),
S1 changes in the direction of decreasing, and when the activated sludge acclimates to temporary toxicity, it changes in the direction in which h1-1 and S1 increase (from -1 to -2, -3, -4,-). 5 direction). Β in step 2 changes from the beginning to decrease in the n-th cycle, and increases in the reverse direction after the n-th cycle (from -1 to -2, -3, -4,
-5 direction). In step 3, h3-1 and S3 similarly change in the direction of decreasing until the nth cycle, and change in the direction of returning to the original state after the nth cycle (from -1 to-).
Change in the direction of 2, -3, -4, -5). This type of waste liquid includes, for example, a waste liquid whose salt concentration is significantly different from the mixed liquid of the activated sludge to be used, and a waste liquid containing components having completely different components from the activated sludge to be used and having moderate toxicity.

FIG. 11 is a typical example of the waste liquid of the BOD load over. In step 1 of FIG. 11, h1-1 does not change, but S1 increases, and the shape of the DO change curve changes in a direction in which the final value gradually decreases and h3-1 increases (from -1 to -2, -2). -3 direction). Since h1-1 does not change, the activated sludge decomposes BOD normally, but shows that it cannot be processed within the time of Step 1. In step 2, β increases steadily (changes from -1 to -2, -3). In step 3, since the BOD left unprocessed in step 1 and step 2 is carried over to step 3, h3-1 does not change much, but S3 increases steadily. The final value does not rise sufficiently and h3-3 increases (from -1 to -2, -3
Changes in the direction). As described above, as in the typical examples of FIGS. 6 to 11, this cycle is repeatedly performed with step 1 to step 3 as one cycle, and the change of the characteristic value in each process is continuously obtained and analyzed, thereby obtaining the sample waste liquid. The treatment characteristics of activated sludge can be accurately evaluated.

In the above description, the inspection process is step 1
Although the case where one cycle is constituted in the order of → step 2 → step 3 has been described, in the test method of the present invention, although the respective steps are interconnected, step 1 is a step of inspecting the biodegradability of the sample waste liquid. Step 2 is a step of testing the oxygen absorption rate of the microorganism, and Step 3 is a reference BOD.
The order of each step is not limited to the above, since it has a function independent of the step of testing the activity of the microorganism from the biodegradability of the liquid. When the order is changed, for example, in the description of the typical example of FIGS. 6 to 11, the start position of each step and the shape of the DO curve are different due to the influence of the previous step, but the change of the DO curve at each step is different. The direction is the same in any order, and the evaluation method using the characteristic value of each step is also common. Steps 1, 2, and 3 are the basis of the test method of the present invention. Even if other inspection steps are added to steps 1, 2, and 3, as long as the functions of each step are used, It does not depart from the invention.

Next, an apparatus embodying the present invention will be described. FIG. 12 is a flow chart of an example of the apparatus. This device is
An aeration tank (1) for introducing and mixing the activated sludge mixture, a measuring container (2) for measuring the DO of the mixed liquid from the aeration tank, and a dissolved oxygen meter (3) for measuring the DO of the mixed liquid in the measuring container. )
A settling tank (4), an overflow (5), an aeration circulation pump (6) for returning the mixed solution from the settling tank to the aeration tank and sucking air with an aspirator; An aspirator (7) for sucking air by a water flow of an aeration circulation pump;
A stirring pump (8) for stirring the mixed solution to secure a flow rate near the measurement sensor of the dissolved oxygen meter, a BOD addition metering pump (9) for adding a reference BOD solution, and a tank (10) for containing the BOD solution. ) And a waste liquid metering pump that adds sample waste liquid
(11), a tank (12) for holding the sample waste liquid, a heater (13) for keeping the mixed liquid in the aeration tank constant, a converter (14) for the dissolved oxygen meter, and control of the entire device And the data obtained
It has a personal computer (15), which is the brain of this device for analyzing data.

The personal computer (15) has a relay output board for controlling the pump and the like and an A / D conversion board for taking in an analog signal from the converter of the dissolved oxygen meter into the personal computer. I'm in the slot. In addition, the aeration tank (1), the measurement container (2), and the sedimentation tank (4) are connected by piping. To conduct a waste liquid treatment test, the aeration tank (1), the measurement vessel (2), and the sedimentation tank (4) are first filled with a mixed liquid of activated sludge.

In step 1, the aeration circulation pump (6) is started under the control of the personal computer, and the waste liquid metering pump is started.
Start (11) and put the sample waste liquid into the aeration tank. When a preset time elapses, the waste liquid metering pump is stopped by a control signal from a personal computer. The addition time of the waste liquid varies depending on the concentration and the decomposition rate of the waste liquid, but is set to about 1 to 5 minutes when the processing time of Step 1 is about 30 minutes. The aeration circulation pump (6) aspirates the mixed solution while sucking air with the aspirator (7) and sends it to the aeration tank, and the aeration tank → the measuring vessel →
A flow of the mixed solution is formed from the settling tank to the aeration tank. The mixed solution that increases due to the addition of the sample waste liquid is separated into solid and liquid in a sedimentation tank, and the supernatant water flows out of the system through an overflow pipe (5). In the aeration tank, the activated sludge of the sample waste liquid enters the measurement container while consuming dissolved oxygen, and the DO of the mixed liquid is measured.

In step 2, when the processing time in step 1 elapses, the aeration circulation pump (6) is stopped and the stirring pump (8) is started under the control of the personal computer. Since the aeration circulation pump (6) is stopped, the mixed liquid containing dissolved oxygen is not supplied to the measurement container, and no new oxygen is supplied because the measurement container is isolated from the outside air.
The stirring pump merely circulates through the inside of the measuring vessel in order to generate a flow rate in the sensor part of the dissolved oxygen meter and does not supply oxygen. In this state, since the activated sludge consumes oxygen already dissolved, the amount of DO which decreases is measured.

In step 3, when the processing time in step 2 elapses, the stirring pump (8) is stopped by the control signal from the personal computer, the aeration circulation pump (6) is started, and the BOD addition metering pump (9) is started. Add the BOD solution into the aeration tank. When a predetermined time elapses, the BOD addition metering pump is stopped by control from a personal computer. The addition time varies depending on the concentration and biodegradability of the BOD solution, but is set to about 1 to 4 minutes when the treatment time is about 25 minutes. In this state, the DO of the mixed liquid in the measurement container is measured.

After the elapse of the processing time in step 3, the process returns to step 1 again by the control signal from the personal computer, and the waste liquid metering pump (11) is started while the aeration circulation pump (6) is started. The measurement is performed by repeating the cycle in this manner.
The change data of DO obtained in each process is taken into the personal computer from the converter (14) through the A / D conversion board of the personal computer, and the characteristic value of each process is calculated from the shape analysis of the curve and stored. In addition to storing the data in the apparatus, trend display and analysis with the data of the past cycle are performed as necessary, thereby making it possible to judge the suitability for the treatment with the activated sludge as shown in FIGS. In the case of the reference value acquisition cycle, in step 1, only the aeration circulation pump (6) is started by the control signal from the personal computer without starting the waste liquid metering pump (11).

In the apparatus shown in FIG. 12, a measuring vessel (2) and a stirring pump (8) are provided outside the aeration tank (1), and the DO value is measured by the dissolved oxygen meter (3). (2) may be set in the aeration tank, and the inside of the aeration tank may be stirred by the stirring pump (8), and the DO value in the aeration tank may be measured by a dissolved oxygen meter provided in the tank.

[0033]

The conventional tester for testing the treatment performance in wastewater treatment utilizing aerobic microorganisms has an extremely insufficient data.
Data can only be obtained. On the other hand, the use of the test method and apparatus according to the present invention enables the behavior in the aeration tank, which has been almost in a black box state, to be quantitatively evaluated as numerical values representing the BOD decomposition rate and the activity state of the microorganism. This greatly improves the reliability of the basic design values, for example, when a new treatment device is created, and when the existing equipment is used for wastewater treatment, the quality of treated water is stable and trouble is prevented. This is very useful, and if used for controlling driving equipment, a large energy saving effect can be achieved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a conventional test apparatus.

FIG. 2 is a diagram for explaining the phenomena of step 1 and step 3;

FIG. 3 is a diagram illustrating the phenomenon of step 2;

FIG. 4 is a diagram illustrating the phenomena represented by equations (4) to (7).

FIG. 5 is a diagram showing a measurement method of the present invention.

FIG. 6 is a diagram showing a transition of a DO change curve when a waste liquid that can be decomposed without trouble is tested.

FIG. 7 is a diagram showing a transition of a DO change curve when a test is performed on a highly toxic waste liquid.

FIG. 8 is a diagram showing a transition of a DO change curve when a test is performed for a waste liquid that is hardly decomposable but has no toxicity.

FIG. 9 is a diagram showing a transition of a DO change curve when a waste liquid which is hardly decomposable but can be treated if sludge is acclimated is tested.

FIG. 10 is a diagram showing a transition of a DO change curve when a waste liquid having a temporary toxicity is tested.

FIG. 11 is a diagram showing a transition of a DO change curve in a case where a test is performed on a waste liquid of a BOD load over.

FIG. 12 is a flowchart of an example of the apparatus of the present invention.

[Description of Signs] 1 Aeration tank 2 Measuring vessel 3 Dissolved oxygen meter 4 Sedimentation tank 6 Aeration circulation pump 8 Stirring pump 10 BOD liquid tank 12 Sample waste liquid tank 15 PC

Claims (2)

[Claims] 1. A method for testing the suitability of a waste liquid in wastewater treatment using an aerobic microorganism, comprising the steps of: introducing a sample waste liquid into a mixed solution containing aerobic microorganisms; Step 1 of measuring DO change
And step 2 of measuring the rate of reduction of DO in a state in which the aeration is stopped and the incorporation of oxygen from the outside is stopped. The inspection process including the step 3 of measuring the change of DO in the process of aerating the liquid is repeatedly performed as a set, and the measurement result is processed by a computer to calculate the change curve of DO or the change in each step. Obtain characteristic values that characterize the shape of the curve,
A test method for wastewater treatment using aerobic microorganisms, wherein the suitability for treatment of the sample waste liquid is evaluated based on a change in a DO change curve or a change in the characteristic value between the steps. 2. An apparatus for testing the suitability of treating wastewater in wastewater treatment utilizing aerobic microorganisms, comprising: an aeration tank in which a mixed solution containing aerobic microorganisms is charged and aerated; and a change in dissolved oxygen concentration DO of the mixed solution. Measuring means for measuring the liquid mixture, a sedimentation tank for performing solid-liquid separation of the mixed liquid, a means for circulating the mixed liquid between the aeration tank and the sedimentation tank, and a sample waste liquid and a substance which is easily decomposed by aerobic microorganisms. Means for adding a reference BOD additive solution to the aeration tank or the measuring section, respectively; step 1 of adding a fixed amount of sample waste liquid to the mixture, aeration of the mixture, step 2 of stopping the aeration, and step 2 Each step is controlled so that this set can be repeated as a set of the inspection process including step 3 in which the reference BOD additive liquid is added in a fixed amount and the mixed liquid is aerated, and D in each step is controlled. A wastewater treatment test apparatus utilizing an aerobic microorganism, comprising a computer for calculating the change in O and outputting a change curve of DO and / or a characteristic value characterizing the shape of the change curve of DO; .