# Patent

## Title
System for measuring the concentration of magnetic ballast in a slurry

## Abstract

A system and method for measuring the concentration of magnetic ballast in a slurry to be analyzed is provided. A detection conduit is provided and configured to receive a slurry to be analyzed. The detection conduit may be surrounded by a set of detection coaxial coils. A reference set of two coaxial coils is also provided. A power source is provided for establishing an electrical current. A measurement subsystem for measuring the differential induced voltage between detection and reference coils is provided to determine the concentration of the magnetic ballast in the slurry.

## Background
FIELD OF THE INVENTION
This invention relates to a system and method for measuring the concentration of magnetic ballast in a slurry, for example a static or non-moving slurry.
SUMMARY OF THE DISCLOSURE
A system for measuring a concentration of magnetic ballast in a slurry is provided. The system comprises a detection conduit surrounded by a first detection coil, the detection conduit configured to receive the slurry, and the first detection coil comprising a first section and a second section both positioned coaxially along the detection conduit. The system further comprises a reference conduit surrounded by a first reference coil, and a second detection coil surrounding the detection conduit and positioned between the first and second sections of the first detection coil along a common axis of the detection conduit. The system further comprises a second reference coil surrounding the reference conduit and positioned in proximity to the first reference coil, and an AC power source configured to generate a magnetic field in the first detection coil and the first reference coil. The system further comprises a measurement device configured to measure a differential induced voltage between the second detection coil and the second reference coil to determine the concentration of the magnetic ballast in the slurry based on the measured differential induced voltage.
The slurry may be a static slurry or a moving slurry. The first detection coil and the first reference coil may be symmetrical. The first and second detection coils and the first and second reference coils may be positioned on a common plane of symmetry perpendicular to each other. The first and second detection coils and the first reference coil may be located on a common plane of symmetry parallel to each other. The first and second detection coils are identical to the first and second reference coils. The system may be configured to measure a concentration of magnetic ballast in a range of about 0.1 mg/l to about 500,000 mg/l. The differential induced voltage between the second detection coil and the second reference coil voltage may be proportional to the concentration of the magnetic ballast in the slurry. The measured voltage of the second detection coil may be proportional to the concentration of the magnetic ballast in the slurry.
A method for measuring a concentration of magnetic ballast in a slurry may be provided. The method comprises providing a system comprising a detection conduit surrounded by a first detection coil, comprising a first section and a second section both positioned coaxially along the detection conduit; a reference conduit surrounded by a first reference coil; a second detection coil surrounding the detection conduit and positioned between the first and second sections of the first detection coil along a common axis of the detection conduit; and a second reference coil surrounding the reference conduit and positioned in proximity to the first reference coil. The method comprises introducing the slurry into the detection conduit and generating a magnetic field in the first detection coil and the first reference coil. The method further comprises measuring an induced differential voltage between the second detection coils and the second reference coil to determine the concentration of the magnetic ballast in the slurry based on the measured differential induced voltage.
Introducing the slurry into the detection conduit may comprise at least partially immersing the system in a component of a wastewater treatment system. The component may include a component selected from the group consisting of a reaction tank, a mixing tank, and aeration tank, a settling tank, a clarifier, a conduit, line or pipe, an impregnation subsystem, a return activated sludge subsystem, a weighting agent recovery subsystem, a wasting system, and combinations thereof. The concentration of the magnetic ballast in the slurry is in a range of about 0.1 mg/l to about 500,000 mg/l.



DESCRIPTION OF THE DRAWINGS
The accompanying drawings are not intended to be drawn to scale. For purposes of clarity, not every component may be labeled in the drawings, nor is every component of each embodiment of the disclosure shown where illustration is not necessary to allow those of ordinary skill in the art to understand the disclosure.
In the drawings:
FIG. 1 presents a schematic of an example of a system for measuring the concentration of magnetic ballast;
FIG. 2 presents a schematic of an example of a system of measuring the concentration of magnetic ballast;
FIG. 3 presents a schematic of an example of a system of measuring the concentration of magnetic ballast;
FIG. 4 presents a schematic of an example of a system of measuring the concentration of magnetic ballast;
FIG. 5 presents a graph displaying a typical curve for magnetite magnetization;
FIG. 6 presents a three-dimensional view showing components of a wastewater treatment system which may utilize the system for measuring the concentration of magnetic ballast; and
FIG. 7 presents a schematic block diagram showing components of another wastewater treatment system which can utilize the system for measuring the concentration of magnetic ballast.



DETAILED DESCRIPTION
Some wastewater treatment systems use magnetically separable particles as a settling aid. These particles may include magnetic ballast. The magnetic ballast may be magnetite, which may become enmeshed into a chemical and/or biological floc in a wastewater treatment process. The operation of ballasted wastewater treatment systems requires monitoring, automatically or manually, the level of the magnetic ballast in the slurry in the various components of the system. For example, the level or concentration of magnetic ballast may be monitored in the aeration tank or reaction tank or in a conduit between unit operations, such as between an aeration tank and a clarifier. The level or concentration of magnetic ballast may be monitored in a weighting agent (such as magnetite) impregnation subsystem, various areas of a clarifier, including the surface, sludge blanket and recycle slurry, various areas of magnetite recovery apparatus (magnetic drums, centrifugal separators, and other apparatus), various lines, pipes, conduits or holding tanks within the system, and the like. The range of magnetic ballast concentration that may require measurement may be a range of about 0.1 mg/l to about 500,000 mg/l.
In certain embodiments, systems and methods for measuring the concentration of magnetic ballast in various slurries of a ballasted wastewater system is provided. This may provide for more effective and efficient measurement of the concentration of magnetic ballast in the wastewater system, and may provide for accurate measurement of the concentration of a slurry, including static slurries and moving slurries.
Conventional systems and methods for determining the concentration of magnetic ballast in a slurry of a ballasted wastewater treatment system may include the extraction from the slurry, drying, and weighing of the pure magnetic ballast. The disadvantages of these conventional systems and methods are that they are time consuming and cumbersome. Some portion of fine magnetic ballast particles may be inevitably lost through the sludge, and may not be measured. Others systems and methods are based on the inductive method.
There are several issues that may arise from conventional systems that may use an inductive method. These may include unrestricted, non-uniform magnetic field applied to the slurry, unrestricted, non-uniform magnetic ballast distribution within a slurry sample, unrestricted mutual inductance between detection and reference coils, non-compensated, ambient, parasitic noise signal, unrestricted magnetic field applied to the magnetic slurry, which may result in nonlinear dependence of magnetic ballast properties vs. magnetic field intensity, and unrestricted AC power source voltage fluctuations.
The disadvantages of these systems and methods may provide inaccurate measurements, and indirect proportionality of measured induced voltage versus magnetic ballast concentration.
A system and method may be provided to offer a simplified measurement procedure, with higher accuracy, and direct proportionality of the measured signal versus magnetic ballast concentration in a range of about 0.1 mg/l to about 500,000 mg/l for a slurry, including static and moving slurries.
A system for measuring a concentration of magnetic ballast in a slurry is provided. The system may comprise a detection conduit surrounded by a first detection coil, the detection conduit configured to receive the slurry, and the first detection coil comprising a first section and a second section both positioned coaxially along the detection conduit. The system may further comprise a reference conduit surrounded by a first reference coil, and a second detection coil surrounding the detection conduit and positioned between the first and second sections of the first detection coil along a common axis of the detection conduit. The system may further comprise a second reference coil surrounding the reference conduit and positioned in proximity to the first reference coil, and an AC power source configured to generate a magnetic field in the first detection coil and the first reference coil. The system may further comprise a measurement device configured to measure a differential induced voltage between the second detection coil and the second reference coil to determine the concentration of the magnetic ballast in the slurry based on the measured differential induced voltage.
The system may include a permanent magnet surrounding one of the detection coils and the detection conduit for establishing a magnetic field. This may stop and collects magnetic ballast in the detection conduit so that the measurement device or subsystem may measure very low concentrations of magnetic ballast in the slurry.
A pumping subsystem may direct the moving slurry from a component of a wastewater treatment system to the detection conduit and, in some embodiments, back to the component of the wastewater treatment system.
The slurry of magnetic ballast may be a static slurry or a moving slurry. The system may automatically, continuously, and easily measure the concentration of magnetic ballast in the slurry.
In one embodiment, referring to FIG. 1, first detection coil 1 is a pair of two identical sections that are placed symmetrically; one on each side of the second detection coil 2 along a common axis of symmetry coaxially on a detection conduit 5, for example, a right cylinder. They are connected in series electrically and carry an equal electrical current (I) in the same direction. Such a design of the first detection coil provides the production of near uniform magnetic field in a region of the slurry that is positioned in the detection conduit 5, and that is detected by second detection coil 2. When a current is applied to first detection coil 1, a voltage is induced in detection coil 2. This voltage V2 will change in response to the presence of a magnetic ballast located in detection conduit 5 (of the right cylinder). If a magnetic ballast slurry is present in detection conduit 5 (right cylinder), the voltage V2 will change proportionally. First reference coil 3 and second reference coil 4 are also provided to generate a reference voltage V4. The current (I) is connected to the first reference coil 3 which will induce a voltage V4 in second reference coil 4. The two induced voltages V2 and V4 are compared to each other with a voltage measuring device or subsystem. The difference is used to determine the concentration of magnetic ballast present in the slurry. The measured voltage of the second detection coil may be proportional to the concentration of the magnetic ballast in the slurry.
The slurry has a tendency to settle by gravity and to distribute unevenly across and along the cylindrical sample volume. The higher the irregularity of magnetic field and/or magnetic ballast concentration, the more irregular the induced voltage is and therefore the measured value of the magnetic ballast concentration. The uniformity of the magnetic field is directly related to minimizing the measurement error.
In another embodiment, when measuring the concentration of magnetic ballast in a static slurry, the sample to be analyzed and first and second detection set of coils 1 and 2 are positioned horizontally to maximize magnetic ballast distribution uniformity along the sample volume. The even distribution of static slurry and magnetic ballast along and across the sample volume does not change during the time of measurement, provided the sample is well mixed prior to measurement.
In another embodiment, when measuring the concentration of magnetic ballast in a moving slurry, the analyzed sample and set of detection coils are positioned vertically to maximize magnetic ballast distribution uniformity across the sample volume. The even distribution of moving slurry and magnetic ballast along the sampling volume is provided by continual flow of the slurry.
In another embodiment, the AC power source is conditioned, for example, has the stabilized amplitude, for example about 10 to about 40 volts, or about 24 volts, a frequency in a range of about 0.1 to about 10,000 Hz, preferably about 400 Hz, and a sinusoidal shaped output current. This may minimize the measurement error.
In another embodiment, where a broad range of magnetic ballast concentration can be measured, the detection and reference coil assembly may be a symmetrical block, with a common plane of symmetry perpendicular to the detection set axis of symmetry, and which includes a reference set axis of symmetry. As shown in FIG. 2, such a configuration provides an absence of mutual inductance between the first and second detection coils 1, 2 and first and second reference coils 3, 4, and therefore provides the direct proportionality of measured voltage, or voltage differential, versus magnetite concentration, simplifying the procedure of calibration and measurement. The first and second detection coils and the first and second reference coils are positioned on a plane of symmetry perpendicular to each other.
In another embodiment, when in the vicinity of powerful electrical and/or electronic sources of parasitic electromagnetic field, the first and second detection coils 1,2 and first and second reference coils 3,4 assembly is a bloc of two identical sets, with a parallel axis of symmetry and with the same direction of the current (I) and excited magnetic field (Be) in the first detection coil and first reference coils. As shown in FIG. 3, such a configuration provides the mutual compensation for induced external magnetic field parasitic noise signals in the second detection coil 2 and second reference coil 4, and therefore provides higher measurement accuracy. Referring to FIG. 3, the values and direction for magnetic field (Be) in both detection coils 1,2 and reference coils 3,4 are the same. The values for magnetic fields (B1) and (B3) will be the same in the absence of a magnetic ballast slurry and different in the presence of a magnetic ballast slurry. The direction is the same. The first and second detection coils and the first and second reference coils may be positioned on a plane of symmetry parallel to each other.
In another embodiment, the detection coil and reference coil assembly is a block of two identical sets 1,2 and 3,4 with a parallel axis of symmetry and with an opposite direction of the current and the excited magnetic field in the first detection coil 1 and first reference coil 3. As shown in FIG. 4, such a configuration may provide compensation for the eddy currents in the ambient electro-conducting objects induced by detection and reference magnetic fields, and therefore may provide the compensation of the parasitic voltage induced by the magnetic field of these eddy currents in the secondary detection coil 2 and second reference coil 4, and therefore provides higher measurement accuracy. The directions of magnetic fields (B1 and B3) are different.
In another embodiment, the magnetic field strength in the sample slurry is less than 500 A/m. A typical curve for magnetite magnetization is represented by line 9 FIG. 5.
This restriction provides the linear dependence of measured voltage versus magnetite concentration and its independence from the slurry flocculation quality, and therefore simplifies the calibration and measurement procedure and raises measurement accuracy.
In another embodiment, the position of the secondary reference coil 4 or its section(s) can be moved relative to the first reference coil 3 location and can be fixed at a position that provides equal or higher voltage induced in the second detection coil 2 than the voltage induced in second reference coil 4. This provides the monotonous change of measured voltage versus monotonous change of magnetic ballast concentration into the whole range, and therefore simplifies the calibration and measurement procedure and raises measurement accuracy.
The use of this apparatus enhances the operation and maintenance of water and waste water treatment systems that use magnetic ballast.
The new system and method for measuring the concentration of magnetic ballast in a slurry may be based upon inductive method. Specifically, the structure of the detection coil set is established, where the first detection coil is a pair of two identical sections that are placed symmetrically, one on each side of the second detection coil along a common axis, connected in series and carrying an equal electrical current in the same direction, producing a region of uniform magnetic field in the analyzed slurry.
In one embodiment, the systems and methods for measuring a concentration of magnetic ballast in a slurry, such as those described in FIGS. 1-4 may include measuring a concentration of a slurry in any one of the various components or subsystems of wastewater treatment systems, for example in U.S. Pat. No. 7,695,623, and U.S. Pat. No. 6,099,738 patent, or any other wastewater treatment system known to those skilled in the art that may utilize a magnetic ballast. For example, the magnetic ballast slurry may be provided from any of the various components of wastewater treatment system 100 of FIG. 5, such as aeration tank 102, clarifier 104 (including a sludge blanket in a clarifier), any of lines 106, 108, 110, 112, 114, 116, 118, or 120, tank 122 of weighting agent impregnation subsystem 124, return activated sludge subsystem 132, weighting agent recovery subsystem 134, and/or wasting subsystem 136. Further details regarding the operation of system 100 and the various components discussed above are disclosed in detail in the U.S. Pat. No. 7,695,623, incorporated herein by reference.
The magnetic ballast slurry may be provided from any of the various components of wastewater treatment system including any of the various components from wastewater treatment system 150, of FIG. 6, as disclosed in U.S. Pat. No. 6,099,738, for example, a reaction tank, such as coagulation tank 152, nucleation tank 154 and/or flocculation tank 156. The slurry may also be provided from settling tank 158. Further details concerning the components and operation of wastewater treatment system 150 are disclosed in detail in U.S. Pat. No. 6,099,738, incorporated herein by reference.
The method for measuring the concentration of a magnetic ballast in slurry of this disclosure includes providing a detection conduit surrounded by a set of coaxial detection coils configured to receive the slurry, providing a reference conduit surrounded by a set of coaxial reference coils, and measuring the differential induced voltage between one of the set of coaxial detection coils and one of the set of coaxial reference coils to determine the concentration of the magnetic ballast in the slurry.
A method for measuring a concentration of magnetic ballast in a slurry may comprise providing a system comprising a detection conduit surrounded by a first detection coil, comprising a first section and a second section both positioned coaxially along the detection conduit; a reference conduit surrounded by a first reference coil; a second detection coil surrounding the detection conduit and positioned between the first and second sections of the first detection coil along a common axis of the detection conduit; and a second reference coil surrounding the reference conduit and positioned in proximity to the first reference coil. The method may comprise introducing the slurry into the detection conduit and generating a magnetic field in the first detection coil and the first reference coil. The method may further comprise measuring an induced differential voltage between the second detection coils and the second reference coil to determine the concentration of the magnetic ballast in the slurry based on the measured differential induced voltage.
Introducing the slurry into the detection conduit may comprise at least partially immersing the system in a component of a wastewater treatment system. The component may include a component selected from the group consisting of a reaction tank, a mixing tank, and aeration tank, a settling tank, a clarifier, a conduit, line or pipe, an impregnation subsystem, a return activated sludge subsystem, a weighting agent recovery subsystem, a wasting system, and combinations thereof. The concentration of the magnetic ballast in the slurry may be in a range of about 0.1 mg/l to about 500,000 mg/l.
In some embodiments, the method may include immersing the detection conduit in a slurry and disposing the reference conduit outside the component of the wastewater treatment system. The slurry may be a static slurry or a moving slurry.
It is to be appreciated that embodiments of the systems, apparatuses and methods discussed herein are not limited in application to the details of construction and the arrangement of the apparatus components and system operations as set forth in the above description or illustrated in the accompanying drawings. The apparatuses, systems and methods are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. In particular, systems, apparatuses and features discussed in connection with any one or more embodiments are not intended to be excluded from a similar role in any other embodiment.
Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Any references to embodiments or elements or acts of the apparatus and methods herein referred to in the singular may also embrace embodiments including a plurality of these elements, and any references in plural to any embodiment or element or act herein may also embrace embodiments including only a single element. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Any references to positional or spatial orientation are intended for convenience of description, not to limit the present apparatus and methods or their components.
Having described above several aspects of at least one embodiment, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

## Claims

1. A system for measuring a concentration of magnetic ballast in a slurry comprising:
a detection conduit surrounded by a first detection coil, the detection conduit configured to receive the slurry, and the first detection coil comprising a first section and a second section both positioned coaxially along the detection conduit;
a reference conduit surrounded by a first reference coil;
a second detection coil surrounding the detection conduit and positioned between the first and second sections of the first detection coil along a common axis of the detection conduit;
a second reference coil surrounding the reference conduit and positioned in proximity to the first reference coil, wherein the first and second detection coils and the first and second reference coils are positioned on a common plane of symmetry perpendicular to each other;
an AC power source configured to generate a magnetic field in the first detection coil and the first reference coil; and
a measurement device configured to measure a differential induced voltage between the second detection coil and the second reference coil to determine the concentration of the magnetic ballast in the slurry based on the measured differential induced voltage.

2. The system of claim 1, wherein the slurry is a static slurry.

3. The system of claim 1, wherein the slurry is a moving slurry.

4. The system of claim 1, wherein the first detection coil and the first reference coil are symmetrical.

5. The system of claim 1, wherein the first and second detection coils are identical to the first and second reference coils.

6. The system of claim 1, configured to measure a concentration of magnetic ballast in a range of about 0.1 mg/l to about 500,000 mg/l.

7. The system of claim 1, wherein the differential induced voltage between the second detection coil and the second reference coil voltage is proportional to the concentration of the magnetic ballast in the slurry.

8. A method for measuring a concentration of magnetic ballast in a slurry comprising:
providing a system comprising:
a detection conduit surrounded by a first detection coil, comprising a first section and a second section both positioned coaxially along the detection conduit;
a reference conduit surrounded by a first reference coil;
a second detection coil surrounding the detection conduit and positioned between the first and second sections of the first detection coil along a common axis of the detection conduit; and
a second reference coil surrounding the reference conduit and positioned in proximity to the first reference coil, wherein the first and second detection coils and the first and second reference coils are positioned on a common plane of symmetry perpendicular to each other;

introducing the slurry into the detection conduit;
generating a magnetic field in the first detection coil and the first reference coil; and
measuring an induced voltage between the second detection coils and the second reference coil to determine the concentration of the magnetic ballast in the slurry based on the measured differential induced voltage.

9. The method of claim 8, wherein introducing the slurry into the detection conduit comprises at least partially immersing the system in a component of a wastewater treatment system.

10. The method of claim 9, wherein the component includes a component selected from the group consisting of a reaction tank, a mixing tank, and aeration tank, a settling tank, a clarifier, a conduit, line or pipe, an impregnation subsystem, a return activated sludge subsystem, a weighting agent recovery subsystem, a wasting system, and combinations thereof.

11. The method of claim 8, wherein the concentration of the magnetic ballast in the slurry is in a range of about 0.1 mg/l to about 500,000 mg/l.