MXPA98005784A - Method for monitoring biological activity in flui - Google Patents

Abstract

The present invention relates to a method for monitoring a microbiological process in a fluid source that involves isolating a fluid sample from a fluid source, measuring the pH of the fluid sample at selected time intervals, then analyzing changes in pH, if any, to determine the rate of pH variation of the sample. The oxygen dissolved in the sample is also measured at selected time intervals, in considerable synchronization with the pH measurements, and the changes in dissolved oxygen, if any, are analyzed to determine a regime of biological oxygen consumption for the sample

Description

METHOD FOR MONITORING THE BIOLOGICAL ACTIVITY IN FLUIDS FIELD OF THE INVENTION The present invention relates to a method for monitoring metabolically significant transition points during the microbial metabolism of organic and inorganic substrates and controlling the microbiological process.

BACKGROUND OF THE INVENTION The microbial use of organic and inorganic substrates in metabolic processes can cause detectable changes in measurable parameters such as the oxygen and pH utilization rate. If nitrification is a predominant reaction within a microbial culture, it would be expected that the production of hydrogen ions (H +) from the nitrification process would decrease considerably after the depletion of ammonium (NH4 +) usable at less than a metabolically critical level. As a result, a change in the activity of hydrogen ions in solution, ie the pH, would also be expected. Similarly, the use of oxygen from a microbial culture would be higher in a condition where the substrates would have decreased to less than a metabolically significant level. In both examples the measurable regime of change in pH, hereinafter sometimes referred to as "pH production regime" or "RPpH", and the use of oxygen "or" RCBO ", would be directly affected by the regime substrate metabolism after a time Therefore, assuming that changes in pH and oxygen consumption in a medium would be the result only of microbial metabolic activity, in theory the RPpH and the RCBO could be used to indicate metabolically significant transition points in a microbiological process such as d (pH) / dt or -? (pH) / dt or -? (pH) /? t and RCBO would be defined as d (OD) / dt or -? (OD) / A negative slope of Ph and / or OD would result in a positive measurement of RPpH and / or of RCBO.

BRIEF DESCRIPTION OF THE INVENTION The method of the invention involves the isolation of a sample of fluid from a source of fluids, such as waste water from a purification process. He RPpH is calculated from the pH measurements obtained from the fluid sample and analyzed to quickly determine when metabolically significant transition points occur. The analysis dictates what the necessary control steps are and when they should be carried out in order to maximize the efficiency of the process being monitored.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graphical representation that describes the Michaelis-Menten theory on the kinetics of reactions. Figure 2 is a graph showing the theoretical responses of the oxygen utilization rate (RCBO) and the change in pH regime (RPpH) of a mixed liquor sample as the concentrations of ammonium (NH4 +) and organic material carbonaceous, collectively known as BOD (biochemical oxygen demand), change over time in a microbiological process. Figure 3 is a graph showing the theoretical responses of the oxygen utilization rate (RCBO) and the rate of change in the (RPpH) of a mixed liquor sample as the concentrations of ammonium (NH4 +) and carbonaceous organic material , collectively known as BOD (biochemical oxygen demand), change over time in a microbiological process. Figure 4 shows a schematic front elevational view of the embodiment of the apparatus that could be used to separate and monitor a fluid sample from a fluid source in a bioreactor tank according to the invention. Figure 5 illustrates graphically the relationship between the rate of oxygen change between the suspension and the start of aeration and the RCBO expressed as the% change in oxygen saturation per minute. Figure 6 illustrates graphically the relationship between the change in pH between the suspension and the start of aeration and the RPpH expressed as the change in Ph per minute as the ammonia concentration changes. Figure 7 graphically shows the relationship between the RPpH expressed as the change in pH per minute and the concentration of ammonia, where COD is not a metabolically limiting factor. Figure 8 graphically shows the relationship between the RCBO expressed as the% change in oxygen saturation per minute and the ammonia concentration, where the COD is not a metabolically limiting factor. Figure 9 shows the response of the RPpH expressed as the change in pH per minute under various conditions of ammonia availability and COD. Figure 10 shows the relationships between the RPpH expressed as the change in pH per minute, RCBO expressed as the% change in oxygen saturation per minute, the ammonia concentration and the COD under various ammonia and COD availability conditions.

Figure 11 is a graph of the change in pH and OD versus time under continuous aeration. Figure 12 is a graph of the concentration of pH, NH3-N and d (pH) / dt versus time. Figure 13 is a graph of OD and d (OD) / dt versus time.

DETAILED DESCRIPTION OF THE INVENTION The mechanistic regime from which the chemical reactions proceed can be described in part by the Michaelis-Mind theory, as illustrated in Figure 1. This theory states that the chemical reaction regime is very low at very low substrate concentrations. , but the regime increases as the concentration of the substrate increases, until reaching a point from which there are extremely small increases in the reaction regime, regardless of the amount of increase in the concentration of the substrate. In other words, from that point on, the reaction rate will approach, but never reach the peak, regardless of the amount of increase in substrate concentration. This peak is the maximum reaction rate or V ^. It is a linear extrapolation corresponding to a concentration of substrate equivalent to 2KS. Kg is the substrate concentration at which the metabolic reaction rate is half the maximum reaction rate (Vmax). Hence, from a metabolic perspective, 2KS, is a significant concentration of substrate. The microbial metabolism of a substrate proceeds to more than 2KS, at a maximum and almost constant rate. The metabolic reaction regime can become variable and be limited by the availability of substrate to less than 2 .. As a result, changes could be expected in certain parameters, directly affected by and / or related to the microbial metabolism regime of certain substrates. inorganic and organic, as the concentration of the particular substrate changes. Specifically, with a substrate concentration equivalent to or greater than 2KS, the dependent measurable parameter and / or the rate of change measured in this parameter after a time was relatively constant. As the concentration of the substrate decreases to less than 2KS, the measurable dependent parameter and / or the rate of change measured in this parameter after a time would differ significantly from the average values when the substrate concentration was equal to or greater than 2KS. In many biological reactions it is desired to determine the point at which certain substrates have decreased to less than this metabolically significant 2KS concentration. It is possible to detect changes in the metabolic behavior pattern of a microbial culture by monitoring changes in certain measurable dependent parameters, such as the concentrations of the change of certain organic and inorganic substrates. For example, in many wastewater purification processes it is a goal to reduce the concentrations of certain organic and inorganic substrates to extremely low levels. These substrates generally include those organic substrates known collectively and measured as BOD (biochemical oxygen demand) and / or COD (chemical oxygen demand) and inorganic ammonium (NH4 +). Assuming that the nitrification reaction and the BOD / COD reduction reaction are the two most predominant reactions, one would expect to see characteristic changes in both oxygen utilization (RCBO) as in the pH change regime (RPpH) as the BOD and ammonia decrease to less than the corresponding 2KS values. A disadvantage of the use of RCBO and RPpH as control parameters is that in a continuous process of purification of wastewater, the changes in pH and OD in the fluid medium depend on many factors, such as the concentration of nutrients (phosphoric compounds, nitrogens and carbonaceous biodegradable, and other similar), the concentration of biomass, alkalinity and other similar. These factors change constantly as wastewater passes through the treatment facilities. Consequence, it is difficult to obtain the relationship between the measured parameters and the performance of the waste water purification due to the interference of too many unknown factors that change continuously. Measurements of RPpH and RCBO will not provide more valuable information on the performance of wastewater treatment unless it is possible to detect or maintain constant these interfering factors during the measurement of pH and DO. The use of a device for the detection of biological activity, such as that set forth in U.S. Patent 5,466,604, incorporated herein by reference, makes it possible to isolate in situ residual water samples from the main water entity residual under treatment. Of course other apparatuses according to this invention can be used. In addition, the term "in situ" is used herein to describe any process of isolating fluid samples in real time, regardless of whether the sample remains in the main entity of the fluid, for example, in the wastewater. In other words, apparatuses that physically extract the sample (s) from the main fluid entity can be used, as long as the measurements can be carried out practically in "real time" and / or "in line". The theoretical responses of RCBO and RPpH to changes in the concentration of BOD and ammonia (NH4 +) are shown in Figures 2 and 3 and are explained below. The figures graphically represent the responses of a single sample of mixed liquor (ie, wastewater) and microbes for the removal of biological nutrients (ENB) isolated from the main wastewater entity. The isolated sample goes through alternate periods of aeration and without aeration. Aeration begins and continues until a marginal level of dissolved oxygen is reached higher than the OD level in the main wastewater entity. Once this level is reached, aeration stops and starts again when the dissolved oxygen level in the sample reaches a level marginally lower than the DO level in the main wastewater entity. During the periods in which the aeration is not carried out, both the RCBO and the RPpH are evaluated and calculated as follows: where? OD is equivalent to the change in the level of dissolved oxygen saturation, expressed as the percentage of dissolved oxygen. saturation, measured over a period of time? t; and where? pH is equivalent to the observed change in pH over a period of time? t. As shown in period A of Figures 2 and 3, when both concentrations of NH4 + and BOD are above their corresponding 2 \ values, RCBO remains constant and at its highest relative level, since the use of BOD proceeds the maximum regime and wins the competition against oxygen-consuming nitrification reactions. Hence, RPpH is constant at a moderate level. This pattern of RCBO / RPpH, like those described below, is the expected one, as long as 1) the reactions of nitrification and use of BOD are the predominant reactions in process in the biological sample, 2) the production and activity of the of hydrogen are related to the regime of the nitrification reaction and 3) the reactions are not limited by the availability of oxygen. Subsequently, the continuation of metabolism decreases available NH4 + to less than 2K value. and the nitrification regime, the production of hydrogen atoms drops from a maximum regime to a lower regime in which the concentration of ammonia is a metabolically limiting factor, as shown in period B of Figure 2, RPpH decreases considerably at a relatively low level and RCBO decreases to a relatively moderate level to reflect the decrease in oxygen demand and use caused by the considerably lower nitrification reaction regime. The transition from an ammonia concentration higher than the 2KS value to a lower value than the 2KS value is plotted in the transition between periods A and B in Figure 2. Period C of Figures 2 and 3 shows that the concentration of NH4 + is lower than its 2Ksy value and by decreasing the BOD less than its 2KS value, the RPpH increases very slightly to reflect the change in the net metabolic behavior of the mixed biological population and the RCBO drops to its lowest regime to reflect the extremely high use low oxygen through the reactions of BOD consumption and nitrification. This transition is represented in periods B and C of Figure 2. Period D of Figure 3 shows that where the BOD concentration is lower than the 2KS value, but the NH4 concentration is higher than its value: 2K RPpH increases to its maximum level, reflecting a high nitrification regime and RCBO decreases to a moderate level, reflecting a net decrease in total oxygen use caused by the decreased level of BOD consumption reactions. The highest RPpH is observed under this condition since the buffering effects of the BOD consumption reactions are absent. Normally the production of C02 in the BOD consumption reactions offers a certain amount of pH buffering to the sample through the carbonic acid system. Therefore, in the absence of reactions of BOD consumption and the resulting production of CO2, the RPpH is much higher than the other conditions. It is possible to determine pertinent information on the biological sample based on the example provided above, by monitoring and comparing trends and / or levels of RCBO and RPpH, since they represent key dependent and measurable parameters of the microbial metabolic activity. This example illustrates specifically how one can determine whether 1) both nitrification and elimination of BOD occur simultaneously at the maximum rate, 2) there is nitrification when the BOD has been reduced to levels below its value 21 ^, 3) the reactions of BOD removal continues while ammonia has been reduced to below its 2KS level and 4) both ammonia and BOD have been reduced to less than their respective 2KS values. The direct and continuous comparison of the RCBO and RPpH measured parameters leads to several conclusions about the condition of the wastewater. Without a mixed liquor sample, a large increase in the RPpH is continually monitored and a decrease of the RCBO occurs, this indicates that the BOD has decreased to less than its corresponding 2KS value, while there is still enough ammonia. If a sample of mixed liquor is continuously monitored, it is continuously monitored and a large increase in the RPpH simultaneously in the decrease of the RCBO, this indicates that the BOD has decreased to less than its corresponding 2KS value, while there is still enough ammonia. If a sample of mixed liquor is continuously monitored and the RCBO decreases to a moderate level while the RPpH decreases to almost zero, this indicates that the ammonia has decreased to less than the corresponding 2KS value, while there is still enough BOD. If a mixture of mixed liquor is continuously monitored and the RCBO decreases to a low level while the RPpH increases to a low level, this indicates that both the ammonia and the BOD have decreased to less than their corresponding 2KS values. This condition is also indicated by a decrease in RCBO at a low level and a small increase in RPpH from a level of almost zero to a slightly higher but low level. Table I is a summary of such standards and illustrates how the comparison of the relative values and standards of the measured parameters of RCBO and RPpH provide the pertinent information described above together with Figures 2 and 3.

Table 1 An example of a preferred apparatus used to isolate a sample of wastewater is shown in Figure 4. Apparatus 11, immersed in batch 2 of wastewater (of which only a portion is shown), includes a detection chamber 8 containing a movable cover 32. Movable cover 32 is pushed in the direction indicated by arrow A, by an internal shaft 56 driven by an Acmé axis 57 connected to the motor 53. In the open position, the rotation of the propeller 48 forces an exchange of waste water between the inside and the outside of the detection chamber 8, and the chamber Detection 8 is filled with a fresh sample of residual water. After some time from p. For example 30 seconds, the motor 53 is programmed to reverse the direction of rotation, the movable cover 32 is pulled towards the direction of the arrow "B" until it closes and completely seals the camera 8. The movable cover 32 and the propeller 48 are driven by the same reversible low RPM motor 53 which coaxially connects to the inner shaft 56 and the outer shaft 55. The coaxial assembly is coated with a stainless steel 54 pipe. The OD concentration is detected by the OD 10 probe. after filling the detection chamber 8 with a fresh sample of waste water and if OD is marginally lower than the concentration of oxygen in the main waste water entity, air and / or oxygen is pumped into the detection chamber 8 through the aeration tube 13 until obtaining said DO concentration. A concentration of OD at a level higher or lower than the concentration of oxygen in the main wastewater entity, in a given range, will ensure that the aerobic metabolic reactions within the detection chamber 8 are the same or similar to those of the process of elimination of nutrients in the main wastewater entity. Similarly, the pH probe detects changes in pH. In addition, the propeller 48 can rotate periodically or constantly to keep the sample well mixed and suspended. The aeration in the apparatus 11 is interrupted for the measurement interval, after reaching the maximum DO concentration. During this period, the residual OD concentration and pH, both without having been affected by the aeration of the wastewater pool in general, are monitored by means of probes. The residual pH and OD signals of probes 12 and 10, respectively, are sent to controllers that convert changes in OD for a time to RCBO and changes in pH during a time of RPpH by numerical differentiation according to the equations ( 6) and (7) described above. In most wastewater plants the BOD and ammonium concentrations in the final effluent are lower than the 2KS values of BOD and N ^ +. When the concentration of BOD and NH4 + in the detection chamber decreases to less than the 2KS values, the aerobic metabolic reactions for the elimination of nutrients are considered completed with significant changes in the values of RCBO and RPpH. The completion of aerobic metabolic reactions for nutrient removal can be detected by RCBO and RPpH analysis according to the criteria indicated in TABLE 1. For other biological processes the substrate concentrations in the medium are generally considerably higher than values of 2KS, to maintain the maximum biological growth rate and production of the target substance. Therefore, the detection of the end of the metabolic reactions will be the signal of the need to add nutrients and substrate, or of the moment of stopping the biological process, or of the moment of obtaining the objective substance produced during the process. Information on aerobic metabolic reactions for nutrient removal, such as nitrification time (TN), denitrification time (TDN), etc., can be used to adjust and control the wastewater purification process. and other aerobic metabolic processes. For example, the measured TN can be compared with the average hydraulic retention time (TRH) of wastewater in the aeration tanks of a wastewater treatment plant. If the TN is considerably shorter than the TRH, the elimination of aerobic nutrients in a section in the center of the aeration pond has been completed. The other aeration ponds after this section in which the nutrient removal has been completed are in fact in a condition of inactivity and do not contribute to the process of purification of the wastewater. In this case, the plant can take the necessary actions to: (1) eliminate the operation of certain sections of aeration ponds to save operating costs and / or (2) accept a larger volume of wastewater and increase in an effective manner the treatment capacity of the plant and / or (3) reduce the regimen of aerobic metabolic reactions so that the TN is similar to TRH in the aeration scenarios and reduce the energy consumption of the air blowers.

EXAMPLE A sample of mixed liquor obtained from the aerobic pond of an advanced biological wastewater treatment plant located in Oaks, Pennsylvania was isolated in a container equipped with devices for measuring the pH and dissolved oxygen saturation levels of a sample, as well as devices to aerate and preserve the sample in a well-mixed condition. The data obtained from the devices that measured the levels of dissolved oxygen saturation and pH of the sample were recorded and analyzed by computer to calculate the RCBO and RPpH. The sample was exposed to alternating fixed periods of aerated and non-aerated conditions. Aeration began and continued until a level of dissolved oxygen compatible with that of the main wastewater entity plus a margin was reached when the sample was isolated. Once this level was obtained, aeration was stopped and started again when the oxygen level in the sample decreased to a level lower than the OD range of the main wastewater entity when the sample was isolated. The concentrations of NH4 + and soluble organic carbonaceous substrates were measured and indicated as COD. There was a linear correlation between COD and BOD. Therefore, the COD analysis was used to represent the BOD concentration. During the periods without aeration, whose examples are marked with arrows in Figures 5 and 6, both the RCBO and the RPpH were evaluated and calculated by numerical differentiation, as described above. Figure 5 shows the dissolved oxygen saturation and RCBO during a period of the test in which the COD concentration was consistently higher than 150 mg COD / 1, which was much higher than the 2KS value for COD, but where the concentration of Ammonia varied from a concentration higher than the 2KS value to a concentration lower than the 2KS value. Figure 5 reveals the relationship between the raw dissolved oxygen data, which is the portion of oxygen change between the end and the start of aeration, as indicated, and RCBO Figure 5 also illustrates the transition at the RCBO level from a high level to a moderate level during the significantly metabolic transition when the ammonia concentration decreased to less than its 2KS value. RCBO s expressed as the% change in oxygen saturation per minute. Figure 6 shows the pH of the sample and the RPpH during the same period as shown in Figure 5. During this period the measured COD concentration was consistently higher than 150 mg COD / 1, which was significantly higher than the value 2KS, for COD, but the ammonia concentration varied from a value greater than its 2KS value, to a value less than 2Kg. Figure 6 illustrates the relationship between the raw pH data, that is, the pH change between the end and start of the aeration as indicated and the RPpH.

Also illustrated in Figure 6 is the transition in RPpH from a moderate level to a level of almost zero during the metabolically significant transition when the ammonia concentration drops below its 2KS value. RPpH is expressed as the change in pH per minute. Figure 7 shows the changes in measured ammonia levels and the RPpH calculated for the same period, as depicted in Figure 6. Figure 7 also illustrates the transition from RPpH from a moderate level to almost zero during the transition of ammonia concentration of approximately 2KS to less than 2Kg. RPpH is expressed as the change in pH per minute. Figure 8 shows the changes in the ammonia levels measured and the RCBO calculated during the same period illustrated in Figure 5. Figure 8 illustrates the transition of the RCBO from a high level to a moderate level during the transition of concentration of ammonia of more than 2. less than 2? . RCBO is expressed as the% change in oxygen saturation per minute. The uniformity of the response of RPpH to ammonia concentrations is illustrated graphically in Figure 9. This was achieved by adding an ammonia solution to the mixed liquor sample at points where ammonia content in the sample was depleted; that is, T = 120 and T = 170 minutes. In the period between T = 0 and T = 195, the COD concentration was much higher than its 2K value. After T = 195 minutes, the COD concentration dropped to less than its 2KS value. Around T = 90 minutes, a significant transition in the RPpH can be observed as the concentration of ammonia is depleted to less than its 2KS value. Subsequently, additional ammonia was added to T = 120 and T = 170 minutes, when the RPpH was close to the zero level. In Figure 9 it is shown that the RPpH jumped from the level of almost zero immediately before each subsequent addition to a relatively moderate level as that observer between T = 0 and T = 90 minutes. After the subsequent additions of ammonia, the RPpH returned to a level close to zero or low when the ammonia was depleted to less than its 2KS value. There was enough COD and the depletion of ammonia caused a decrease in the RPpH to a level of almost zero in the case of the first addition of ammonia to T = 120 minutes. The depletion of ammonia occurred when the COD concentration had also been depleted to less than its 2KS value, in the second case of ammonia addition at T = 170 minutes. Consequently, the RPpH decreases at a low level, but not zero, as shown in period C of figures 2 and 3. Figure 10 provides a more complete illustration of the data shown in Figure 9, and includes the RPpH calculated, the calculated RCBO and concentrations of ammonia and DCO. Figure 10 provides the best illustration of the transitions of RPpH and RCBO between the different relative levels as important metabolic events occur. It is possible to quickly and accurately determine the time when the concentration of organic and / or inorganic substrates falls below their corresponding 2KS values, as demonstrated in this example, by monitoring the relative levels of RCBO and RPpH in accordance with the invention. Detecting the reduction of a particular substrate at less than its corresponding and metabolically significant 2KS concentration value often indicates a significant change in the condition of a microbial population or its environment, or a change in the metabolic pattern and / or in the behavior of a sample that contains active microbes.

In response, several control steps can be taken, depending on the particular process. For example, the reduction of a particular substrate in a microbial population could mean a change in the metabolism, in which the production of a desired secondary metabolite could occur, indicating that the process should proceed with a phase of separation, obtaining and / or purification. Likewise, in biological processes in which the object is to maintain a particular protocol of graduated substrate feeding to a microbial population, the ability to detect the reduction of this substrate increases the substrate concentration to more than 2KS can be used to indicate that it is desirable to increase or decrease the substrate feed. The purification of aerobic biological wastewater was treated in Example 1, in which the objective is often to reduce, by biological mechanisms, certain organic and inorganic substrates, such as, for example, the reduction of soluble ammonia and organic carbonaceous substances. Therefore, several control steps can be followed in response to the reduction of one or more of these substrates to levels lower than their 2KS concentration, since the 2K concentration. it is often lower than the low level in desired concentration for many substrates. For example, if both organic and inorganic substrates (ammonia) are smaller than their corresponding 2KS concentration values, the flow rate in the wastewater treatment process can be increased, thus increasing the capacity of the treatment facility. If both organic and ammonia substrates are higher than their concentration values 2Kg, the flow regime in the wastewater treatment process can be lowered. When the ammonia substrate is lower than 2KS, but the organic substrate is greater than 2KS, the aeration of the batch may be decreased due to the lower need for nitrification. Finally, if the organic substrate is less than 2%, but the ammonia substrate is greater than 2K, aeration can be increased to create a more favorable condition for nitrification.

EXAMPLE 2 In Example 2 a sample of mixed liquor was isolated in the same manner as described in Example 1. Continuous aeration of the mixed liquor sample was maintained during the period in which the sample remained isolated. An aeration regime was chosen so that the dissolved oxygen concentration level in the sample was higher than the critical value required for the removal of carbonaceous biological nutrients and ammonia. Changes in oxygen concentration and pH were monitored by a dissolved oxygen probe and a pH probe, as shown in Figure 11. A small amount of mixed liquor was then periodically extracted from the isolated sample and the concentration was analyzed. of ammonia. Figure 12 shows the changes in the concentration of pH and ammonia throughout the period of aeration in which the sample was isolated. The end of nitrification (the ammonia concentration was lower than the detection level, ie 0.1 ppm) was accompanied by a slow increase in the pH value. A derivative of pH was plotted in relation to time, d (pH) / dt, as shown in Figure 12. When the ammonia concentration approached zero, the value of d (pH) / dt passed the second point of zero. The characterization of d (pH) / dt at the second point of zero is also known as the point at which d (pH) / dt changes from a negative value to zero. The time corresponding to said point is defined as the end time of the nitrification of the mixed liquor or TN. In Example 2, and as shown in Figure 12, TN is measured at approximately 75 minutes. The measurement of d (p) / dt in Example 2 is different from that of Example 1. In Example 1 d (ppH) / dt was measured during the period without aeration, while in Example 2, d (pH) / dt was measured with continuous aeration. Due to the continuous removal of CO2 from the mixed liquor, it is possible to see a pH decrease in the pH measurement. Therefore, the RPpH is sometimes negative. Figure 13 shows the dissolved oxygen profile and its derivative, d (OD) dt for the same sample. As the ammonia was consumed, the value of the first derivative of OD d (OD) / dt, began to increase considerably, the value of the nitrification time (TN) measured from OD was also about 75 minutes. A practical application of TN measurement in the control of the biological nitrification process is described below. In a bioreactor or in a series of bioreactors in which the biological nitrification process is being carried out, a sampling device is installed at the beginning of the bioreactor or at the front of the first bioreactor of a series. The measured NT indicates that with the current biomass concentration and the ammonia load, the nitrification will take NT to complete. The hydraulic retention time (TRH) of the mixed liquor in the bioreactor or in the series of bioreactors is calculated considering the flow regime and the flow pattern of the mixed liquor and the arrangement of the bioreactor or the series of bioreactors. The TN is then compared with the hydraulic retention time of the mixed liquor. An appropriate nitrification process will have similar values of TN and TRH in daily operations. When TN is considerably lower than TRH, nitrification is completed in the bioreactor or series of bioreactors before the given HRT, which means the process has additional nitrification capacity. In the case where other contaminants are removed before ammonia nitrification is complete, detection of TN indicates the end of the wastewater treatment process. This indicates that the process can treat more wastewater with the volume in tanks given under the same operating conditions or the process can reduce the volume in tanks in operation and achieve a saving in operating costs.

On the other hand, if the TN lasts longer than the TRH, the concentration of ammonia will be greater than zero, but not necessarily greater than the discharge allowed to ensure the quality of the discharge of the plant, the rate of aeration to the bioreactors is increased and / or mixed liquor concentrations. When the condition in which TN lasts longer than TRH for a prolonged period, this tends to indicate that the process is overloaded in terms of ammonia removal and the treatment facility will probably have to be extended to treat the given volume of wastewater. In general, when comparing TN with HRT, certain information; such as the nitrification capacity of the process, the aeration regime required for the bioreactor or series of bioreactors and the quality of the effluent leaving the bioreactor; or the series of bioreactors and the quality of the effluent leaving the bioreactor; It can be sent to the plant operator to adjust the nitrification process. The invention can be applied to any type of microbial process, including, but not limited to the purification of wastewater (municipal, industrial and bull-like types), pharmaceutical and biotechnological production, brace, fermentation or any other process involving pure populations or mixed microorganisms.

Claims (35)

1. - A method for monitoring a microbiological process in a fluid source having a microbiological population, comprising: a) isolating a fluid sample from said source of fluids; b) measuring the pH of said fluid sample at selected time intervals; c) analyze the changes in the pH, if there are any, to determine the variation regime for said sample; d) measuring the quantities of dissolved oxygen in the liquid sample at selected time intervals considerably in synchronization with said pH measurement; and e) analyze the dissolved oxygen changes, if any, to determine a regime of biological oxygen consumption for said sample.

2. The method defined in claim 1, wherein the analysis of changes in pH to determine said pH variation regime is carried out according to the following formula: RPpH = (dpH) / (dt) where RPpH it is said regime of variation of pH, dpH is a change in pH and dt is a change in time and both, dpH and dt approach zero.

3. The method defined in claim 1 wherein said measurement of pH and dissolved oxygen is substantially continuous.

4. The method defined in claim 1, wherein the analysis of the changes in OD to determine said regime of biological oxygen consumption is carried out according to the following formula: RCBO = (dOD) / (dt) where RCBO is said regime of biological consumption, dOD is a change in dissolved oxygen and dt is a change in time and both, dOD and dt are close to zero.

5. The method defined in claim 1 further comprising repeating steps b) to e) in the selected time intervals and comparing the regimen or the regimes of variation of pH and of biological consumption of oxygen just determined with the regime or regimes of variation of pH and of biological consumption of oxygen previously determined.

6. The method defined in claim 5 wherein when comparing said regimes of variation of pH and biological consumption of oxygen just determined with the regimes of variation of pH and biological consumption of oxygen previously determined is determined whether the levels of organic compounds or Inorganic sources of said fluid source are greater or less than their corresponding 2KS concentrations.

7. The method defined in claim 1, further including the execution of the control step in response to changes in said regimes of pH variation and / or biological oxygen control, if any.

8. The method according to claim 7, wherein said source of fluids is aerated and has a process run of the source of fluids and wherein said control step is at least one treatment selected from the group consisting of the increase of the aeration of said source of fluids, the reduction of the aeration of said source of fluids, the increase of said process run of the source of fluids and the decrease of said process run of the source of fluids.

9. The method according to claim 7, wherein a substrate addition feeding protocol is maintained for said microbial population and wherein said control step comprises several additions of said substrate.

10. - The method according to claim 7, wherein said microbiological process produces a desired metabolite and wherein said control step is at least one step selected from the group consisting of the separation of said metabolite from said source of fluids, the obtaining said metabolite and the purification of said metabolite.

11. The method defined in claim 1 wherein said isolation step of said fluid sample is carried out in situ.

12. The method according to claim 1, wherein before said pH measurement steps and the amounts of dissolved oxygen, the fluid sample contains a desired amount of dissolved oxygen.

13. The method according to claim 1, wherein said fluid sample is isolated in a fluid sample chamber, and said fluid sample chamber includes an aerator capable of providing air and / or oxygen to said fluid sample and a sample agitator.

14. The method according to claim 13, further comprising aerating said fluid sample with said aerator during the entire time in which said sample is isolated in said sample container, and the dissolved oxygen and the pH in said sample. sample are measured continuously while said sample is continuously shaken.

15. The method of claim 13 further comprising the aeration steps of said fluid sample with said aerator until said fluid sample contains a desired level of dissolved oxygen saturation before the pH measurement steps and the dissolved oxygen amounts of said fluid sample, and periodically or continuously stirring said sample with said agitator during the steps of measuring the pH and the amounts of dissolved oxygen of said fluid sample.

16. - The method defined in claim 1 applied to a microbiological process selected from a group consisting of the purification of waste water, pharmaceutical production and brace.

17. A method for monitoring a microbiological process in a fluid source having a microbiological population, comprising: a) isolating a fluid sample from said source of fluids; b) measuring the pH of said fluid sample at selected time intervals; c) analyze the changes in pH, if any, to determine the pH production rate for said sample; d) determining when said rate of production of pH 1) changes from a negative value to zero and / or 2) changes to zero a second time; and e) show the results of said determination.

18. The method defined in claim 17, wherein the analysis of the pH changes to determine said pH production regime is carried out according to the following formula: RPpH = (dpH) / dt where RPpH is said regime of pH production, dpH is a change in pH and dt is a change in time, and dpH and dt approach steel.

19. The method defined in claim 17 wherein said pH measurement is substantially continuous.

20. The method defined in claim 17 further comprising: f) measuring the amounts of dissolved oxygen in said fluid sample in the selected time intervals considerably in synchronization with said pH measurement and g) analyzing the changes in dissolved oxygen , if any, to determine a regimen of biological oxygen consumption for said sample.

21. The method defined in claim 19 in which the analysis of the changes in dissolved oxygen to determine said regime of biological oxygen consumption is carried out according to the following formula: RCBO = (dOD) / (dt) where RCBO it is said regime of biological consumption, dOD is a change in dissolved oxygen and dt is a change of time, and doD and dt approach zero.

22. The method defined in claim 17, further comprising repeating steps a) to e) at selected time intervals and comparing the newly determined pH production regimes with the previously determined pH production regimes.

23. The method defined in claim 20 further comprising repeating steps a) to g) at selected time intervals and comparing the newly determined pH production and biological oxygen consumption regimes with the pH and pH production regimes. biological oxygen consumption determined with the previously determined oxygen production and pH production regimes.

24. The method defined in claim 17 further comprising the step of executing a control step in response to the change of said pH production regime (s).

25. The method defined in claim 24, wherein said source of fluids is aerated and has a process run from the source of fluids, and wherein said control step is at least one treatment selected from the group consisting of increase the aeration of said source of fluids, decrease the aeration of said source of fluids; increase said process march of the fluid source and decrease said process flow of fluid source.

26. The method according to claim 24, wherein said control step comprises determining a nitrification time as the time elapsed between the isolation of the sample and the rate of pH production that changes from said negative value to zero and / o which changes back to zero for the second time, measure the hydraulic retention time in said fluid source and compare said nitrification time with said hydraulic retention time.

27. The method according to claim 26, wherein said control step further comprises increasing the rate of fluid entry to the source of fluids or reducing the rate of aeration to the source of fluids when said nitrification time is lower. that said hydraulic retention time, or increase the rate of aeration of the source of fluids when said nitrification time is greater than said hydraulic retention time.

28. The method defined in claim 17, wherein said isolation step of said fluid sample is performed in situ.

29. The method according to claim 17, in which before the indicated steps of measuring the pH and the amounts of dissolved oxygen, the fluid sample contains dissolved oxygen, from zero to 100% saturation.

30. The method according to claim 17, wherein said fluid sample is isolated in a fluid sample chamber, said fluid sample chamber includes an aerator capable of providing air and / or oxygen to said fluid sample. and a sample agitator.

31. The method of claim 30 further comprising the steps for aerating said fluid sample with said aerator until said fluid sample contains dissolved oxygen, at a level higher than the DO level in the sample when it is isolated, by a margin, before the steps of measuring the pH of said fluid sample, and periodically stirring said sample with said agitator during the steps of measuring the pH of said fluid sample.

32. The method defined in claim 17 wherein said microbiological process is selected from the group consisting of purification of waste water, pharmaceutical or biotechnological production, brace and fermentation.

33. The method according to claim 32, further comprising aerating said fluid sample with said aerator for the entire duration in which said sample is isolated in said sample container, and the dissolved oxygen and pH in said sample is they measure continuously while said sample is continuously shaken.

34. The method defined in claim 17, further comprising considerable continuous aeration of said fluid sample. 35.- A method to monitor and control a microbiological process in a fluid source that contains a microbial population that comprises: a) isolating a sample of fluid from said source of fluids; b) measuring the pH of said fluid sample at selected time intervals; c) analyze changes in pH, if any, to determine the pH production rate for said sample; d) determining when said rate of production of pH 1) changes from a negative value to zero and / or 2) changes to zero a second time; and e) performing a control step in response to changes in said regime or pH production regimes, wherein said control step comprises: f) determining a nitrification time as elapsed time between the isolation of the sample and the pH production regime that changes from a negative value to zero and / or that changes to zero a second time; g) measuring the hydraulic retention time in said fluid source and comparing said nitrification time with said hydraulic retention time; and h) increasing the rate of fluid entry to the source of fluids or reducing the rate of aeration of the source of fluids when said nitrification time is less than said hydraulic retention time, or increasing the rate of aeration of the source of fluids when said nitrification time is greater than said hydraulic retention time.