Patent Description:
There are numerous industrial processes which take in raw or first intermediate materials at one end, perform some kind of operation on the material (for example mixing, treating with heat or pressure or chemically altering the material) to produce a second intermediate or end material or product.

The present invention is particularly well suited to the processing of liquid materials, and in particular paints, but may be used for any of the processes above.

In the technical field of paint processing, several raw materials are provided at a first end of the process. These include fillers, dispersants, pigments, latex and acrylic, which must be mixed and treated in several stages before an end product is produced, which is placed in tins to be shipped to customers. During this process, the various materials (in liquid form) are passed through long sections of pipework, and in and out of tanks. In any given process there may be several kilometres of pipework between the introduction of the raw materials and the final paint product.

It is highly undesirable for microbial activity to take place within the process. Production of paint with a high microbial load is unacceptable, and can cause significant problems for the end user (such as an unpleasant odour).

Therefore it is important to check the microbial load in the paint produced by this process on a regular basis.

Until recently, it has been possible to treat the liquid in the process with high amounts of biocide. This effectively kills any microbes which may have an adverse effect on the product. That said, it is generally undesirable to use a high quantity of biocide. Further, recent legislation (in the form of the EU Biocide Regulation) has placed significant limits on the types and amounts of biocide that can be used. Similar regulations exist in the United States of America and most other important economic centres.

Currently, detection of microbial activity is assessed by taking a sample of paint at the end of the process. The sample is sent to a lab to be analysed. Information concerning the microbial load may be delivered some days or weeks later. Detection of an excess of microbial activity would result in the plant being shut down and cleaned, and the affected paint recalled form the market and disposed of. Evidently the reduction in the use of biocides increases the risk that a sample is contaminated.

Systems such as the applicant's CFII (Cell Facts II) device help to increase the speed at which microbial activity can be detected and corrective action initiated before microbial levels can reach critical levels. The CFII device is a combined impedance and fluorescence particle detection system. The liquid to be analysed is diluted, exposed to a suitable fluorescent dye and passed through an orifice. Changes in impedance are measured to detect particle size, and a laser is used to excite the dye and determine particle fluorescence. In this way, the size and type of particles can be detected, which information can be used to estimate microbial activity. The cycle takes less than three minutes. Such a system is discussed in <CIT>.

Although the CFII system has radically improved analysis times (a matter of minutes rather than days), it is only used in a "batch" context. In other words, the system is used to analyse the end-product, and determine if microbial load is unacceptable. If it is, then the batch needs to be either treated or disposed of, and the system cleaned.

<CIT> discloses a device for counting and detecting suspended particles in oil. The device comprises a particle separation system and a particle counting and detecting system. Suspended particles are separated under excitation of standing waves in a separation channel and enter multiple parallel channels. Particles of corresponding sizes enter multiple types of microfluidic channels, changes of magnetic flux are caused, inductance voltage is changed, and changed voltage values are recorded. The particle size, volume, concentration and distribution of particles is determined.

<CIT> discloses a combined impedance and fluorescence particle detection system.

What is required is a method and system which overcomes, or at least mitigates, the above problems.

According to a first aspect of the invention there is provided an apparatus according to claim <NUM>.

According to a second aspect of the invention there is provided a method according to claim <NUM>. The dependent claims defines preferred implementations of the invention.

Advantageously, utilising a combination of satellite units distributed throughout the process line which perform impendence-based analysis yields several beneficial results. For example:.

The combination of a number of satellite units with a main analysis unit (with combined impedance and fluorescence) yields a much higher-performing system than the prior art approach.

An example process and apparatus in accordance with the invention will now be described with reference to the accompanying Figures in which:.

Referring to <FIG>, a schematic and simplified plan view of a paint processing production line <NUM> is shown. The line <NUM> comprises three storage tanks <NUM>, <NUM>, <NUM> each containing a different raw material. Each tank has a respective outflow channel in the form of storage tank outflow pipes <NUM>, <NUM>, <NUM>. The pipes <NUM>, <NUM> connect the storage tanks <NUM>, <NUM> to a first mixing tank <NUM> which mixes the raw materials from the storage tanks <NUM>, <NUM>. The first mixing tank has an outflow channel in the form of a first mixing tank outflow pipe <NUM>.

The first mixing tank outflow pipe <NUM> flows into a second mixing tank <NUM>. The third storage tank outflow pipe <NUM> also flows into the second mixing tank <NUM>, where the materials are mixed. The second mixing tank <NUM> has a second mixing tank outflow pipe <NUM> which flows into a final storage tank <NUM>.

The final storage tank <NUM> is configured to sequentially fill a plurality of individual containers in the form of paint pots <NUM> which are sealed and shipped to the customer.

Each of the above components is typically constructed from steel, specifically a stainless steel.

An apparatus according to the invention is distributed throughout the line <NUM> in <FIG>, and is generally referred to as apparatus <NUM>. The apparatus <NUM> comprises:.

Each of the above components will be described in detail.

Referring to <FIG>, a satellite unit 202a is shown in more detail. The satellite units are very similar, and as such only the unit 202a is shown.

The unit 202a comprises a flow loop <NUM>, a sample flow channel <NUM>, valves 212a, 212b, satellite analyser <NUM> and dilutant tank <NUM> having dilutant flow channel <NUM>.

The flow loop <NUM> comprises an entry point <NUM> and exit point <NUM> both in fluid communication with the storage tank outflow pipe <NUM>. The pipe <NUM> contains a fluid <NUM> under pressure. Because the exit point <NUM> is downstream of the entry point, a flow is established in the flow loop <NUM>.

The sample flow channel <NUM> has an entry opening <NUM> in fluid communication with the flow loop <NUM>, and flows into the satellite analyser <NUM>. The valves 212a, 212b can be selectively opened and closed (by a controller of the satellite analyser) to feed a discrete sample of liquid to the analyser <NUM> of known volume (in this example <NUM>).

The satellite analyser <NUM> comprises several controlled valve-controlled flow channels and is configured to meter dilutant from the tank <NUM> via the channel <NUM> to dilute the sample to e.g. <NUM> in volume. A small amount of diluted sample (approximately <NUM>µl) is then passed through an orifice to both count and size the particles therein using impedance analysis. The satellite analyser comprises a controller <NUM> having a processor, memory and communication means in the form of an antenna <NUM> which is configured to communicate with the system controller <NUM>.

Impendence analysis has been used in the art, and for example is explained in the applicant's prior application <CIT>. In summary, the orifice has a pair of electrodes disposed on opposite sides thereof. The analyser comprises circuitry capable of measuring a signal representative of the impedance variation between the electrodes. The diluent (typically an electrolyte) has a known impendence across the orifice. As particles pass through the orifice, the impendence will increase and then decrease. Each "peak" represents a particle, and the height of the peak and / or area under the peak is representative of particle size. Because the orifice is very small (in the order of <NUM>), only one particle can pass through at any given time.

The satellite controller <NUM> stores results data for each sample, and is configured to communicate the assay results data (representative of the size and number of particles passing through the orifice) to the system controller <NUM> via the antenna <NUM>.

Once the sample has been analysed, the system is flushed, and a further sample is taken. The satellite units sample at a frequency of <NUM> minutes.

It is important to note that the satellite analysers <NUM> only use impedance measurement, and do not (in this embodiment) comprise means for measuring fluorescence. They are therefore simple and inexpensive.

The controller <NUM> comprises a processor, memory and display unit. In this embodiment, it is a PC. As discussed above, each satellite analyser is in communication with the controller <NUM>. This may be via a wired connected, or wireless such as Wi-Fi, Bluetooth (RTM) or similar technology. Results data from the sample impendence assay are communicated to the controller <NUM> which carries out analysis of the data.

The analysis unit <NUM> combines both impedance analysis with fluorescence analysis. The analysis unit <NUM> is similar to the applicant's CFII device discussed above, and as well as impedance measurement undertakes fluorescence analysis using a laser. This can determine whether fluctuations in particle size and number are a symptom of a chemical process or a biological process.

Once the production line <NUM> is started, material flows from the raw material storage tanks <NUM>, <NUM>, <NUM> through the system to the final storage tank <NUM>. Each satellite unit 202a etc. samples the material flowing through each pipe at regular (<NUM> minute in this embodiment) intervals. Each satellite unit 202a etc. communicates assay results data for each sample to the controller <NUM>.

The controller <NUM> contains baseline data representative of an acceptable number and size distribution of particles for each satellite unit. An example baseline for satellite unit 202a is shown as curve B in an S-N graph <NUM> in <FIG>. The X-axis represents the size of the particles (S) and the Y-axis the number (N) of particles of that size. The baseline data may be obtained by calibration- i.e. by analysing a sample with a known / acceptable level of microbial activity, or from stored data. It will be noted that a certain number and size distribution of particles is expected- notwithstanding the presence of microbes, any given sample will contain chemical (non-biological) particles which are not of concern.

A first result from satellite unit 202a is shown as profile P1 in <FIG>, which is within a predetermined, acceptable range of the baseline B. The manner in which an acceptable deviation from B is determined may be selected by the skilled addressee without undue burden, and based on known statistical methods. In this example, for ease of understanding, two parameters will be used- the X axis coordinate of the curve peak (the size of the particles highest in number, or the mode average, of the sample), and the area under the curve (representative of the total number of particles in the sample). If microbiological activity increases, it will be expected that both will increase in subsequent samples.

The peak of P1 (A) is shown as well as the area (X). This data is represented in the first row of a results table <NUM> of <FIG>, stored by the controller <NUM> for each satellite unit. Referring to <FIG>, a visual display graphic <NUM> provided by the controller <NUM> for satellite unit 202a is shown. The graphic <NUM> has a time axis (x-axis) and a particle count axis (y axis). Three bands of particle count are provided, coloured green (low count), yellow (medium count) and red (high count). Sample data points are plotted and the operator can easily identify a trend towards an unacceptable particle count (red) and take remedial action (as will be discussed below). In reality, multiple curves (one per satellite unit) may be shown on the graphic <NUM>. Further graphics with different parameters may also be shown on the controller display.

A further profile P2 is shown in <FIG> in which the particles have grown in both size and number (the peak has increased from A to B, and the number from X to Y). Moving on to P3, size and number have increased again (from B to C, and Y to Z).

The operator can clearly see from the display <NUM> that the trend at satellite unit 202a indicates an increase in particle size and count. This may be indicative of microbial activity, or a symptom of a chemical process taking place which is out of the ordinary. As soon as the monitored parameter or parameters enter the red zone, an alert is produced.

At this point, the operator takes a sample from the location of the satellite unit 202a and takes it to the analysis unit <NUM> for combined impedance / fluorescence analysis. This combined analysis determines conclusively whether the increased size and number of particles is a result of increased microbiological activity. If it is, the operator adds a biocide upstream of the satellite unit in question.

For example, if the satellite unit 202a detects high microbial activity, the problem likely lies with the raw material in the tank <NUM>. Either the material can be replaced (following cleaning), switched to a different tank or a biocide can be added.

In the event that e.g. biocide is added to the tank <NUM>, the satellite unit is used to verify its effectiveness. The trend in increase in size and number of particles will reverse (i.e. move back into the "yellow" and "green" zones). This occurs as the biocide lyses the microbial cells.

If it does not, the satellite unit will communicate this to the controller. At this point, the operator can attempt to increase the dose, or change the type of biocide used. Alternatively, he or she can carry out a more detailed biocide effectiveness test series as will be discussed below.

It will be noted that the system described herein can pinpoint the source of microbial contamination which means that targeted remedial action can be taken. This represents a significant increase in efficiency.

The combined impendence / fluorescence analyser can be used to study the efficacy of various biocides until an appropriate solution is found.

Referring to <FIG>, such a process <NUM> not according to the invention is shown. At step <NUM>, a sample is taken from a batch of material having high / unacceptable microbial activity. At step <NUM> it is introduced into the combined impedance / fluorescence analyser (such as a CFII). At step <NUM>, the sample is analysed and at step <NUM> the biological activity assessed based on the result.

At step <NUM>, a further sample is taken from the batch. At step <NUM> a biocide is added. At step <NUM> it is introduced into the combined impedance / fluorescence analyser (such as a CFII). At step <NUM>, the sample is analysed and at step <NUM> the biological activity assessed based on the result.

The results from the biocide assay are then compared both to the original sample (without biocide) from step <NUM>, and to a baseline set of results <NUM>. If the biocide has reduced the microbial activity from the original sample <NUM>, and is within a predetermined tolerance of the baseline data <NUM> the biocide dosage regime is deemed "OK" and the same concentration and type can be used to treat the entire batch.

If the microbial activity has not decreased, or decreased to a level which remains unacceptable compared to the baseline, the method returns to step <NUM> to try a different biocide and / or higher concentration.

As such, the analyser can be used iteratively to determine the most effective biocide regime for the batch.

As such the analyser can also be used to support and accelerate the experiments required by standardised challenge tests.

The system <NUM> may be configured as a fully automated closed-loop system. An automatic biocide dispenser may be provided upstream of at least one satellite unit and automatically activated as the controller <NUM> detects a particle parameter moving out of the predetermined range.

The satellite units do not need to connect to a central controller, but may instead produce a local alert signal (such as a visual or audible alert). This may then prompt the operator to conduct a full impendence / fluorescence test. The system is capable of generating results data on individual measurements to establish whether or not predetermined criteria, such as critical levels of microbial load and activity are breached.

Claim 1:
An apparatus (<NUM>) for the detection of microbiological activity in an industrial process (<NUM>), the apparatus (<NUM>) comprising:
a plurality of satellite units (202a, 202b...) configured to sample a liquid from the industrial process at a plurality of respective locations, in which each satellite unit is configured to periodically analyse a sample, each satellite unit being configured to carry out an impedance analysis to count and measure the size of particles passing through an orifice, in which each satellite unit is configured to generate sample results data corresponding to the number and size of particles in each sample;
wherein the apparatus is characterised by:
a processing unit (<NUM>) configured to compare the sample results data to a predetermined criterion and to generate an alert signal if the sample results data is outside of the predetermined criterion or establishes a trend approaching the predetermined criterion; and,
a main analysis unit (<NUM>) in the form of a combined impedance and fluorescence system, configured to perform combined impedance and fluorescence analysis of a sample of liquid from the industrial process following generation of the alert signal.