Wastewater analysis system, methods for increasing the sensitivity of the wastewater analysis system, and methods for sampling from wastewater

Abstract

The invention relates to a method for increasing the sensitivity of a wastewater analysis system (1) for a primary analyte (A1) in a composite sample (31) of wastewater (A) containing a primary analyte (A1) and a secondary analyte (A2), wherein the method comprises at least the following steps: - providing the wastewater analysis system (1) comprising: ◯ a detection device (10) suitable for determining a primary analyte concentration of the primary analyte (A1), wherein the primary analyte concentration correlates fully or partially with a fecal concentration and / or an ammonium concentration; ◯ a sensor (20) suitable for determining a secondary analyte concentration of the secondary analyte (A2); ◯ a sampler (30) suitable for taking a plurality of subsamples (32) from the wastewater (A) and storing the subsamples (32); ◯ a computing unit (40).- sequential extraction of the multitude of subsamples (32) from the wastewater (A) by the sampler (30) at predetermined times over a predetermined period.

Description

The invention relates to a method for sampling wastewater, to a method for increasing the sensitivity of a wastewater analysis system and to a wastewater analysis system.In analytical measurement technology, in particular in the field of water management, environmental analysis, in the industrial field, e.g. in food technology, biotechnology and pharmacy, and for a wide variety of laboratory applications, measured variables such as the pH, the conductivity, or also the concentration of analytes such as ions or dissolved gases in a gaseous or liquid measurement medium are of great importance. These measured variables can be detected and / or monitored, for example, by means of electrochemical sensors, such as, for example, optical, potentiometric, amperometric, voltammetric or coulometric sensors, or also conductivity sensors. In order to monitor a process medium regularly and fully automatically, so-called analyzers are used.The term "analyzer" is intended to mean, in the sense of this invention, a measurement apparatus of process automation technology which measures substance contents determined by a wet chemical method, for example the ion concentration in a medium to be analyzed. A sample is taken from the medium to be analyzed. Usually, the sample is taken fully automatically by the analyzer itself, for example by pumps, hoses, valves, etc. To determine the substance content of a particular species to be determined, reagents developed specifically for the respective substance content and stored in stock in the analyzer housing are mixed with the sample to be measured. A color reaction of this mixture caused thereby is then measured by means of a suitable measuring device, for example by means of a photometer. On the basis of the light absorption and a stored calibration model, the measured value is thus determined at the receiver end.A measuring system, consisting of an analyzer and sampler, is usually operated in such a way that the sampler takes samples from the waste water system at a high frequency and meters mixed samples over a defined period of time (e.g. 1 h or over 24 h) into a bottle basket and thus mixes and stores them in a stable manner by means of cooling. For molecular biological wastewater analysis, the wastewater sample is concentrated and impurities are subsequently eliminated or further concentrated by purification.Subsequently, the extract obtained by concentration and purification is preferably analyzed in the laboratory by means of PCR technology for the presence of nucleic acids of the target organism. Alternatively, the sample may be subjected to other analytical methods.However, the problem here is that the analysis in the laboratory is very time-consuming and costly and also costly / material-consuming (owing to expensive reagents, consumables, disposable tools) and therefore cannot be carried out at the same frequency as the sampling by the analyzer. For this reason, as mentioned above, the samples drawn from the medium are mixed, whereby a sample period of 24 h, for example, is mapped by 24 mixed samples. In the case of low analyte concentrations in the medium, however, it may occur that the present analyte concentration is below the possible detection limit of the microbiological analysis (PCR) or of the analysis system.It is therefore an object of the invention to propose a method which enables reliable, time-saving and cost-effective detection of the analyte even at low analyte concentrations in a simple and efficient manner.This object is achieved according to the invention by a method for increasing the sensitivity of a wastewater analysis system for a primary analyte in a total sample of wastewater comprising a primary analyte and a secondary analyte according to claim 1.The method according to the invention comprises at least the following steps:providing the wastewater analysis system comprising: a detection device suitable for detecting a primary analyte concentration of the primary analyte, wherein the primary analyte concentration correlates completely or partially with a fecal concentration and / or an ammonium concentration◯ a sensor suitable for detecting a secondary analyte concentration of the secondary analyte, a sample taker which is suitable for taking a plurality of subsamples from the waste water and storing the subsamples,◯ a computing unit,sequentially taking the plurality of partial samples from the waste water by the sampler at predetermined times over a predetermined period of time,storing the subsamples,determining a secondary analyte concentration for the respective partial sample by the sensor,storing the determined secondary analyte concentration of the respective sub-sample by the computing unit,evaluating the determined secondary analyte concentrations by the computer unit, wherein secondary analyte concentrations are determined which lie in a predetermined range,selecting the stored subsamples having a secondary analyte concentration in the predetermined range to form the total sample,determining the primary analyte concentration of the total sample by the detection device.The method according to the invention makes it possible that reliable detection of the analyte is possible even at low analyte concentrations present in the medium. Since only one sample has to be analyzed, effort and costs are thus saved. The method also minimizes the sampling effort and logistics and thus saves costs. The method thus improves the limit of the detection of the overall system of the workflow.According to one embodiment of the invention, the primary analyte is a SARS-CoV-2 virus, a norovirus, an influenza virus, an antibiotic resistant bacterium, a drug metabolite, a hormone or a fecal and / or urine excreted biological particle and / or organism or fragments thereof.According to a further embodiment of the invention, the predetermined period of time is one day.According to one embodiment of the invention, the secondary analyte concentration is integrated in the evaluation step, wherein the selection step takes place a selection of a largest partial integral, and the partial sample corresponding to the largest partial integral is selected as the total sample.According to an embodiment of the invention, the predetermined range comprises secondary analyte concentrations which deviate by less than 10%, preferably less than 5%, from a maximum secondary analyte concentration and are sequentially adjacent to the maximum secondary analyte concentration or are sequentially adjacent to a selected secondary analyte concentration.According to one specific embodiment of the present invention, the predetermined area is selected by an artificial intelligence and / or algorithms stored in the memory of the computing unit.According to one embodiment of the invention, the predetermined range comprises such secondary analyte concentrations that are greater than a predetermined threshold.The above object is also achieved by a waste water analysis system according to claim 8.The wastewater analysis system according to the invention comprises:a detection device which is suitable for determining a primary analyte concentration of a primary analyte,a sensor suitable for determining a secondary analyte concentration of a secondary analyte,a sampler which is suitable for taking a plurality of partial samples from the waste water, storing the partial samples and mixing certain partial samples to form a total sample, anda computer for storing and evaluating measurement data of the detection device and of the sensor.According to one embodiment of the invention, the computing unit has a digital communication unit which is suitable for being connected to a web-based database system.The above object is also achieved by a method for sampling waste water with a primary analyte and a secondary analyte according to claim 10.The method according to the invention comprises at least the following steps:sequentially taking partial samples from the wastewater,determining a secondary analyte concentration for the respective partial sample,evaluating the determined secondary analyte concentrations, wherein secondary analyte concentrations are determined which lie in a predetermined range,selecting the subsamples having a secondary analyte concentration in the predetermined range to form a total sample,determining the primary analyte concentration of the total sample.The invention is explained in more detail with reference to the following description of the figures. The following are shown:FIG. 1 is a schematic illustration of a wastewater analysis system according to the invention,FIG. 2 : shows a diagram of an ammonium content measured in the medium compared with a SARS-CoV-2 concentration.The wastewater analysis system 1 according to the invention illustrated by way of example in FIG. 1 comprises a detection apparatus 10, a sensor 20, a sampler 30, a computing unit 40 and a database 50.The wastewater analysis system 1 is fed with wastewater A in fluidic terms. The waste water A comprises a primary analyte A1 and a secondary analyte A2. For example, the wastewater analysis system 1 is connected via a hose to a wastewater tank or wastewater duct of a sewage treatment plant or a manure pit. The waste water A comprises human and / or animal faeces and / or urine. In FIG. 1, the wastewater analysis system 1 is shown as a central unit. However, it is also possible for different components of the wastewater analysis system 1 to be arranged in a decentralized manner.The detection device 10 is suitable for determining a primary analyte concentration AK1of the primary analyte A1. The primary analyte A1 is preferably SARS-CoV-2. In an alternative embodiment, the primary analyte A1 is another virus or organism. For example, the primary analyte A1 is influenza virus, norovirus, antibiotic resistant bacterium, drug, drug metabolite, or radioactively infested agricultural fertilizers. The primary analyte A1 is, for example, a nucleic acid of a pathogen (e.g. virus, bacterium) or of another biological particle or organism whose concentration in the waste water is of interest. The biological particle or organism to be detected can be present in the waste water in its entirety or only in fragments or else only as genetic material. The primary analyte A1 comprises, for example, hormones or drugs.The detection device 10 preferably comprises a filtration unit for concentrating the primary analyte A 1. The detection device 10 is suitable for conducting waste water through the filtration unit by means of compressed air and / or mechanical pressure. The filtration unit is suitable for separating a liquid phase via static interactions or size exclusion. For example, the filtration unit comprises a cellulose mixed ester membrane. The filtration unit further comprises a purification unit, for example magnetic silicate beads. The purification unit is suitable for carrying out a concentration of the primary analyte, for example nucleic acids, and a removal of impurities. PCR technology is preferably used for detecting the primary analyte A1. Instead of PCR technology, another technology sensitive to the corresponding analyte can also be used. The detection device 10 is, for example, spatially separated from the sensor 20, from the sampler 30 and the computing unit 40 (not shown). The detection device 10 is, for example, in a laboratory. It is of course also possible for the detection device 10 to be coupled directly to one another together with the sensor 20, the sampler 30 and the arithmetic unit 40.The sensor 20 is suitable for determining a secondary analyte concentration AK2of the secondary analyte A2. The secondary analyte A2is, for example, ammonium or another fecal marker, for example chemical oxygen demand (COD). The sensor 20 is, for example, an optical sensor, preferably a photometric sensor, for example a UV absorption sensor.The sampler 30 is suitable for taking a plurality of subsamples 32 from the waste water A. Furthermore, the sampler 30 is suitable for storing the subsamples 32 drawn from the waste water A, for example in a cooled container, so that the subsample 32 remains chemically / biologically / physically stable. The sampler 30 is also suitable for selecting subsamples 32 and mixing these particular subsamples 32 into a total sample 31. The sampler 30 is also suitable for automatically discarding collected samples / subsamples after predefined limit values or time intervals and thus initializing itself fully automatically for a renewed sampling cycle. Alternatively, the mixing of the partial samples or the warping of the samples can of course also be carried out manually.The computing unit 40 preferably has a memory and is suitable for storing and evaluating measurement data of the detection device 10 and of the sensor 20. The arithmetic unit 40 is likewise preferably suitable for controlling the detection device 10, the sensor 20 and the sampler 30. The computing unit 40 is, for example, a microcontroller or another computing unit. The computing unit 40 preferably has a digital communication unit which is suitable for being connected to the web-based database system 50 in order to continuously transmit, store and graphically provide users the measurement results and status information obtained from the wastewater analysis system 1, that is to say in real time. The computing unit 40 and / or the web-based database system 50 are suitable, for example, for generating alarm messages in real time and sending them to the users in order to inform and warn the user about limit value crossings or about the occurrence of the analyte A 1.The method according to the invention for increasing the sensitivity of the wastewater analysis system 1 for a primary analyte A 1 in the total sample 31 from wastewater A is described below.The method comprises at least the following steps:In a first step, the wastewater analysis system 1 described above is provided. This means that the wastewater analysis system 1 is supplied with wastewater A and is ready for operation.In a next step, the plurality of subsamples 32 are taken sequentially from the wastewater A by the sampler 30. For example, the removal takes place in an hour cycle or every 10 minutes. The removal takes place over a predetermined period of time T, for example over a day. The sub-sample 32 has a volume of 100 ml to 50 liters, for example. Preferably, a volume-proportional sampling is carried out. In this case, the volume of the partial sample is defined in proportion to this value as a function of the volume of the total flow of the sample source, for example of the clarifier. The individual sampling takes place in a few seconds, for example by suction of the sample or by a compressed air system. The subsamples 32 are filled by the sampler 30 in containers, for example bottles, which are arranged in a bottle basket. The containers are arranged, for example, in a type of carousel with 24 bottles which are filled sequentially. Thus, a bottle basket with, for example, 24 bottles represents one day. It is of course also possible to provide more or fewer containers for receiving the subsamples 32. The sub-sample 32 is preferably numbered or filled in numbered containers.Next, the subsamples 32 are stored. The partial sample 32 is preferably stored in the sampler 30 in a cooled manner. This allows the sub-samples 32 to remain stable.A step of ascertaining a secondary analyte concentration AK2for the respective partial sample 32 is then carried out by the sensor 20. The concentration of ammonium (NH4-N) is determined by photometric analysis by the sensor 20. A reagent is added to the respective partial sample 32, which leads to a color change depending on the NH4-N concentration. This color change is then measured by the sensor, in particular a photometer. By carrying a sample with known NH4-N concentration, the measurement system can be linearized and the NH4-N concentration of the sample can thus be determined. This linearization is performed in detail as follows: First, a raw value absorption is determined for a standard carried along. The standard carried is a known concentration of NH4 N. Then, a raw value of an absorbance of a zero concentration standard (e.g., cleaning solution) is determined. By means of a linear correlation between determined absorption and known NH4-N concentration, the use of a first-order (linear) function can be used.Next, a step of storing the determined secondary analyte concentration AK 2 of the respective sub-sample 32 is carried out by the computing unit 40. Figure 2 shows, by means of the curve which is represented by a full line, an exemplary development of the secondary analyte concentration AK2over 24 hours. In the example shown in FIG. 2, the secondary analyte concentration AK2was not measured discretely, but quasi-continuously, i.e. in very short time intervals between the times Tiof the sampling. However, the curve appears as a continuous curve, since for the sake of illustration the measurement points have been connected to one another.A step of evaluating the determined secondary analyte concentrations is then carried out by the arithmetic unit 40. This step is preferably carried out at the end of each day, i.e. when, for example, 24 hourly partial samples 32 have been drawn from the wastewater A and filled into a container. In the evaluation step, a maximum secondary analyte concentration AKmaxis preferably determined among all secondary analyte concentrations AK 2 of all subsamples 32 (see FIG. 2 ). In addition, for example, all secondary analyte concentrations AK2 are determined, which are arranged in a predetermined range B around the maximum secondary analyte concentration AK2.According to an alternative embodiment, in the evaluation step, the ammonium concentration profile is integrated between the time intervals of the wastewater sampling, followed by a selection of the largest partial integral and thus a selection of the most relevant wastewater partial sample. This evaluation is particularly useful in the case of time-proportional sampling. If a volume-proportional sampling takes place, an additional multiplication of the partial integrals with respective flow volume flows is carried out. This leads to obtaining a cargo value (i.e., integration of the ammonium cargos). Subsequently, a selection of the largest ammonium load partial integral and thus a selection of the corresponding most relevant wastewater sample takes place.The predetermined range B preferably comprises secondary analyte concentrations AK2, which deviate by less than 10%, preferably less than 5%, from the maximum secondary analyte concentration AKmaxand are sequentially adjacent to the maximum secondary analyte concentration AKmaxor are sequentially adjacent to a selected secondary analyte concentration AK2. By "sequentially adjacent" is meant here that a measured value, i.e. a determined concentration, has been determined directly before or directly after another measured value.According to an alternative embodiment, the predetermined area B is selected by an artificial intelligence stored in the memory of the computing unit 40. This means that the artificial intelligence is fed with the input variables secondary analyte concentration AK2, time Ti of the sampling, flow rate (in the case of volume-proportional sampling) and further data, for example weather data and / or weather forecast data. The artificial intelligence then outputs the optimum region B, which identifies specific secondary analyte concentration AK2or the partial samples 32 connected thereto. The artificial intelligence thus outputs, for example, the numbers of the subsamples 32 which fall within the area B.According to an alternative embodiment, the predetermined range B comprises such secondary analyte concentrations AK2that are greater than a predetermined threshold value S. The threshold value S is, for example, the average value between the highest measured secondary analyte concentration AK2and the lowest measured secondary analyte concentration AK2.Next, a step of selecting the sub-sample 32 associated with the maximum secondary analyte concentration AK2, as well as the sub-samples 32 having a secondary analyte concentration AK2in the predetermined range B, is performed. Since the sub-samples 32 are preferably numbered, the arithmetic unit 40 preferably determines the number of the sub-samples 32.In the case that a plurality of partial samples 32 have been selected, i.e. lie in the predetermined range B, a step of mixing the selected relevant partial samples 32 by the sampler 30 to form a total sample 31 takes place. The total sample 31 is preferably filled in a container which is large enough to receive the partial samples 32, or transferred from the containers of the partial samples 32 into the container of the total sample 31. The mixing step is performed automatically or manually, for example. The mixing step is particularly advantageous in the case of very small volumes, for example 100 ml, of the subsamples 32.Furthermore, a step of determining the primary analyte concentration AK 1 of the total sample 31 takes place by the detection device 10. The detection device 10 preferably performs a PCR analysis on the whole sample 31, wherein nucleic acids are detected and quantified. As mentioned above, it is also possible to use another analysis system for determining the primary analyte concentration AK1, if the primary analyte A1 is, for example, a drug metabolite.FIG. 2 shows, on the basis of the dotted curve, an example of a profile of the primary analyte concentration AK 1, which was determined from a plurality of sequential partial samples 32. However, no selection of the subsamples 32 was made here on the basis of their secondary analyte concentration AK2.As seen in Figure 2, it was demonstrated that there is a correlation between the concentration of ammonium and the concentration of SARS-CoV-2viruses. Since SARS-CoV-2 viruses are present in particular in faeces and the presence of faeces in the waste water A increases the concentration of ammonium, ammonium can be used as an indicator for the optimum sampling period or the optimum selection of waste water samples.Thanks to the invention, the limit of the detection of the overall system (consisting of sampling, sample processing and analysis) is reduced by the ammonium dependent selection of the samples. The wastewater analysis system 1 is thus more sensitive since samples having a high viral load are not mixed with samples having a low sample load before analysis by the detection device 10 as before. Thanks to the selection of the samples in the region B, a dilution or concentration attenuation of the analyte to be examined is thus avoided if it is assumed that the analyte is not present in the same concentration at all times of day.Furthermore, the invention enables sample processing and analysis of partial samples in the specific relevant region B to theoretically not allow sampling over the entire day, but only in a reduced period of time T', if the daily concentration profile is approximately identical, which results in a further saving in costs and effort during sampling.The logistic, manual, material, time and cost-related outlay is reduced by the wastewater analysis system 1 according to the invention for sample transport, processing and analysis.Thanks to the invention, it is possible to improve the detection limit of the wastewater analysis system 1 and to avoid false epidemiological conclusions (such as false-negatives, as the case may be).List of reference characters1 Wastewater analysis system 10 Detection device 20 Sensor 30 Sampler 31 Total sample 32 Partial sample 40 Computing unit 50 Database A Wastewater A1 Primary analyte A2 Secondary analyte AK1 Primary analyte concentration AK2 Secondary analyte concentration T Period Ti Time B Region AKmax Maximum secondary analyte concentration S Threshold value T' Reduced period

Claims

Method for increasing the sensitivity of a wastewater analysis system (1) for a primary analyte (A1) in a total sample (31) from wastewater (A) with a primary analyte (A1) and a secondary analyte (A2), wherein the method comprises at least the following steps: - providing the wastewater analysis system (1) comprising: ◯ a detection device (10) which is suitable for determining a primary analyte concentration (AK1) of the primary analyte (A1), wherein the primary analyte concentration (AK1) correlates completely or partially with a fecal concentration and / or an ammonium concentration ◯ a sensor (20) which is suitable for determining a secondary analyte concentration (AK2) of the secondary analyte (A2), ◯ a sampler (30) which is suitable for determining a concentration of secondary analyte (AK2) of the primary analyte (A2), taking a plurality of partial samples (32) from the wastewater (A) and storing the partial samples (32), a computing unit (40), - sequentially taking the plurality of partial samples (32) from the wastewater (A) by the sampler (30) at predetermined times (T1, T2) over a predetermined period of time (T), - storing the partial samples (32), - determining a secondary analyte concentration (AK2) for the respective partial sample (32) by the sensor (20), - storing the determined secondary analyte concentration (AK2) of the respective partial sample (32) by the computing unit (40), - evaluating the determined secondary analyte concentrations (AK2) by the computing unit (40), wherein secondary analyte concentrations (AK2) are determined, which lie in a predetermined region (B), - selecting the stored subsamples (32) which have a secondary analyte concentration (AK2) in the predetermined region (B) in order to form the total sample (31), - determining the primary analyte concentration (AK1) of the total sample (31) by the detection device (10).The method according to claim 1, wherein the primary analyte (A1) is a SARS-CoV-2 virus, a norovirus, an influenza virus, an antibiotic resistant bacterium, a drug metabolite, a hormone or a fecal and / or urine excreted biological particle and / or organism or fragments thereof.The method according to claim 1 or 2, wherein the predetermined period of time (T) is one day.Method according to one of the preceding claims, wherein the secondary analyte concentration (AK2) is integrated in the evaluation step, wherein the selection step takes place as a selection of a largest partial integral, and the partial sample (32) corresponding to the largest partial integral is selected as the total sample (31).Method according to any of the preceding claims, wherein the predetermined range (B) comprises secondary analyte concentrations (AK2) which deviate by less than 10%, preferably less than 5%, from a maximum secondary analyte concentration (AKmax) and are sequentially adjacent to the maximum secondary analyte concentration (AKmax) or are sequentially adjacent to a selected secondary analyte concentration (AK2).Method according to one of the preceding claims, wherein the predetermined region (B) is selected by an artificial intelligence and / or algorithms stored in the memory of the computing unit (40).Method according to one of the preceding claims, wherein the predetermined range (B) comprises such secondary analyte concentrations (AK2) that are greater than a predetermined threshold value (S).Wastewater analysis system (1) comprising: - a detection device (10) which is suitable for ascertaining a primary analyte concentration (AK1) of a primary analyte (A1), - a sensor (20) which is suitable for ascertaining a secondary analyte concentration (AK2) of a secondary analyte (A2), - a sampler (30) which is suitable for taking a multiplicity of subsamples (32) from the wastewater (A), storing the subsamples (32) and mixing specific subsamples (32) to form an overall sample (31), and - a computing unit (40) for storing and evaluating measurement data of the detection device (10) and of the sensor (20).Wastewater analysis system (1) according to Claim 8, wherein the computing unit (40) has a digital communication unit which is suitable for being connected to a web-based database system (50).Method for sampling from waste water (A) with a primary analyte (A1) and a secondary analyte (A2), wherein the method comprises at least the following steps: - sequentially taking partial samples (32) from the waste water (A), - determining a secondary analyte concentration (AK2) for the respective partial sample (32), - evaluating the determined secondary analyte concentrations (AK2), wherein secondary analyte concentrations (AK2) are determined which lie in a predetermined range (B), - selecting the partial samples (32) which have a secondary analyte concentration (AK2) in the predetermined range (B) in order to form a total sample (31), - determining the primary analyte concentration (AK1) of the total sample (31).

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