CA3231914A1 - Monitoring sludge dewatering - Google Patents
Monitoring sludge dewatering Download PDFInfo
- Publication number
- CA3231914A1 CA3231914A1 CA3231914A CA3231914A CA3231914A1 CA 3231914 A1 CA3231914 A1 CA 3231914A1 CA 3231914 A CA3231914 A CA 3231914A CA 3231914 A CA3231914 A CA 3231914A CA 3231914 A1 CA3231914 A1 CA 3231914A1
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- Prior art keywords
- media
- filter
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- coordinate
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- 239000010802 sludge Substances 0.000 title claims description 7
- 238000012544 monitoring process Methods 0.000 title description 3
- 238000000034 method Methods 0.000 claims abstract description 36
- 238000012876 topography Methods 0.000 claims abstract description 25
- 239000000701 coagulant Substances 0.000 claims abstract description 18
- 230000003287 optical effect Effects 0.000 claims description 15
- 239000002002 slurry Substances 0.000 claims description 8
- 230000005484 gravity Effects 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 claims description 4
- 239000004744 fabric Substances 0.000 claims description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 3
- 239000011707 mineral Substances 0.000 claims description 3
- 230000001112 coagulating effect Effects 0.000 claims description 2
- 230000003311 flocculating effect Effects 0.000 claims description 2
- 238000012986 modification Methods 0.000 claims description 2
- 230000004048 modification Effects 0.000 claims description 2
- 239000006228 supernatant Substances 0.000 abstract description 11
- 239000000126 substance Substances 0.000 description 13
- 239000000178 monomer Substances 0.000 description 9
- 239000012465 retentate Substances 0.000 description 8
- 239000007787 solid Substances 0.000 description 7
- 150000003839 salts Chemical class 0.000 description 6
- 238000005286 illumination Methods 0.000 description 5
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 3
- 125000000129 anionic group Chemical group 0.000 description 3
- FQPSGWSUVKBHSU-UHFFFAOYSA-N methacrylamide Chemical compound CC(=C)C(N)=O FQPSGWSUVKBHSU-UHFFFAOYSA-N 0.000 description 3
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 2
- JKNCOURZONDCGV-UHFFFAOYSA-N 2-(dimethylamino)ethyl 2-methylprop-2-enoate Chemical compound CN(C)CCOC(=O)C(C)=C JKNCOURZONDCGV-UHFFFAOYSA-N 0.000 description 2
- DPBJAVGHACCNRL-UHFFFAOYSA-N 2-(dimethylamino)ethyl prop-2-enoate Chemical compound CN(C)CCOC(=O)C=C DPBJAVGHACCNRL-UHFFFAOYSA-N 0.000 description 2
- ROSDSFDQCJNGOL-UHFFFAOYSA-N Dimethylamine Chemical compound CNC ROSDSFDQCJNGOL-UHFFFAOYSA-N 0.000 description 2
- NJSSICCENMLTKO-HRCBOCMUSA-N [(1r,2s,4r,5r)-3-hydroxy-4-(4-methylphenyl)sulfonyloxy-6,8-dioxabicyclo[3.2.1]octan-2-yl] 4-methylbenzenesulfonate Chemical compound C1=CC(C)=CC=C1S(=O)(=O)O[C@H]1C(O)[C@@H](OS(=O)(=O)C=2C=CC(C)=CC=2)[C@@H]2OC[C@H]1O2 NJSSICCENMLTKO-HRCBOCMUSA-N 0.000 description 2
- 150000003926 acrylamides Chemical class 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- QDHFHIQKOVNCNC-UHFFFAOYSA-N butane-1-sulfonic acid Chemical compound CCCCS(O)(=O)=O QDHFHIQKOVNCNC-UHFFFAOYSA-N 0.000 description 2
- 125000002091 cationic group Chemical group 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 239000008394 flocculating agent Substances 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- -1 poly(aluminium chloride) Polymers 0.000 description 2
- UZNHKBFIBYXPDV-UHFFFAOYSA-N trimethyl-[3-(2-methylprop-2-enoylamino)propyl]azanium;chloride Chemical compound [Cl-].CC(=C)C(=O)NCCC[N+](C)(C)C UZNHKBFIBYXPDV-UHFFFAOYSA-N 0.000 description 2
- 238000011179 visual inspection Methods 0.000 description 2
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- 229920001661 Chitosan Polymers 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 244000007835 Cyamopsis tetragonoloba Species 0.000 description 1
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229920000615 alginic acid Polymers 0.000 description 1
- 235000010443 alginic acid Nutrition 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 159000000011 group IA salts Chemical class 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 125000005395 methacrylic acid group Chemical group 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 230000002085 persistent effect Effects 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N phosphonic acid group Chemical group P(O)(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- OEIXGLMQZVLOQX-UHFFFAOYSA-N trimethyl-[3-(prop-2-enoylamino)propyl]azanium;chloride Chemical compound [Cl-].C[N+](C)(C)CCCNC(=O)C=C OEIXGLMQZVLOQX-UHFFFAOYSA-N 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
- C02F11/123—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using belt or band filters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
- G01N15/0606—Investigating concentration of particle suspensions by collecting particles on a support
- G01N15/0618—Investigating concentration of particle suspensions by collecting particles on a support of the filter type
- G01N15/0625—Optical scan of the deposits
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/005—Processes using a programmable logic controller [PLC]
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N2015/0042—Investigating dispersion of solids
- G01N2015/0053—Investigating dispersion of solids in liquids, e.g. trouble
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/46—Indirect determination of position data
- G01S17/48—Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/88—Lidar systems specially adapted for specific applications
- G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Dispersion Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
The invention relates to a method for the removal of supernatant from media on a filter, where flocculant and/or coagulants are added to a media to enhance the drainage rate of supernatant, leaving the media at least partially dewatered, during which the surface topography of the media is measured and the amount of flocculant and/or coagulant to be added is a function of the topography of the media above the filter within a region of interest, or regions of interest.
Description
MONITORING SLUDGE DEWATERING
Technical field of the invention The invention relates to a method for the removal of supernatant from media on a filter, where flocculant and/or coagulants are added to a media to enhance the drainage rate of supernatant, leaving the media at least partially dewatered, during which the surface topography of the media is measured and the amount of flocculant and/or coagulant to be added is a function of the topography of the media above the filter within a region of interest, or regions of interest.
The method is performed with a device for dewatering media containing a flocculant and/or coagulant feed device upstream of a filter, where a device, particularly an optical time of flight sensor and/or optical triangulation sensor, is provided downstream of an inflow area in order to digitise the surface topography of the media optically and is connected via a system of control to the flocculant and/or coagulant feed device, in order to control the flocculant and/or coagulant dosage added.
Prior art Methods for separating media from supernatant are known from the state of the art, where the media such as slurry such as sewage biosolids, fibrous media or mineral slurries are dewatered with the addition of flocculant and/or coagulant. Flocculant and/or coagulant is applied to the media first, in order to cause the solid media portion of the media to destabilise, coagulate and flocculate, after which the suspended flocculated media 'flocs' and supernatant suspension is applied to a filter, a gravity drainage deck for example, so that the supernatant portion of the media drains away free of solids, while the concentrated solid portion remains on the filter surface.
Addition of flocculant and/or coagulant as described in the prior art has been controlled either by manual intervention or automation (reference is made to US4105558, US5380440, US5961827, US2007/0090060, US2009/0230033, US20170044034).
Technical problem to be solved The flocculant and/or coagulant dosage is a critical parameter for the efficacy of the dewatering or screening process. An optimal, minimal dosage achieves the lowest possible moisture content. Overdosing will entrain more moisture within the solids, whilst increasing the concentration of flocculant chemicals in the retentate. This over flocculated state provides a stable plateau on which unsupervised operation can occur in a continuous manner in spite of fluctuating media solids concentrations. Underdosing leads to a rapid increase in the retentate moisture content resulting in filter table flooding. This is not conducive to reliable long-term operation.
Traditionally the dosage rate is adjusted manually by the filter operator based on visual inspection. The visual inspection is subject to the empirical judgement of each individual operator potentially leading to different interpretations and thus dosages.
Time constraints aside, it is difficult for an operator to make accurate judgements frequently enough to optimise the filter continuously. Consequently, the objective of the operator is to achieve stable filtration over many hours of operation, in between observations. To reduce the likelihood of underdosing events, operators typically favour high flocculant consumption as the dewatering is more stable.
Automation efforts in prior art used indirect correlations between observable reflected light from a filter or retentate media surface and based on correlations between the reflected light from a region and calibrated moisture or rheological characteristics, control the dosage of chemical additive. Examples of interferents include fugitive and secondary light sources, failure to clean the belt filter and observing an unclean section of belt filter. All skew the sensor specificity and selectivity in the prior art methods, hampering the ability for the observation to appropriately automate the process in their respective regions of interest. The volume of media under observation and the moisture content may not, under a variety of conditions, provide an accurate correlation to the surface area of exposed filter when viewed from above, especially in a system where the inflow solids concentration changes and, the rheological behaviour of these solids varies.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art as detailed below.
Fugitive/Secondary light sources Issue Prior work requires the filter/wire/screen to be clean and always displays the same colour to the camera. The colour received by the camera is the product of two components:
1. The controlled spectrum and intensity of artificial illumination of the target area; and
Technical field of the invention The invention relates to a method for the removal of supernatant from media on a filter, where flocculant and/or coagulants are added to a media to enhance the drainage rate of supernatant, leaving the media at least partially dewatered, during which the surface topography of the media is measured and the amount of flocculant and/or coagulant to be added is a function of the topography of the media above the filter within a region of interest, or regions of interest.
The method is performed with a device for dewatering media containing a flocculant and/or coagulant feed device upstream of a filter, where a device, particularly an optical time of flight sensor and/or optical triangulation sensor, is provided downstream of an inflow area in order to digitise the surface topography of the media optically and is connected via a system of control to the flocculant and/or coagulant feed device, in order to control the flocculant and/or coagulant dosage added.
Prior art Methods for separating media from supernatant are known from the state of the art, where the media such as slurry such as sewage biosolids, fibrous media or mineral slurries are dewatered with the addition of flocculant and/or coagulant. Flocculant and/or coagulant is applied to the media first, in order to cause the solid media portion of the media to destabilise, coagulate and flocculate, after which the suspended flocculated media 'flocs' and supernatant suspension is applied to a filter, a gravity drainage deck for example, so that the supernatant portion of the media drains away free of solids, while the concentrated solid portion remains on the filter surface.
Addition of flocculant and/or coagulant as described in the prior art has been controlled either by manual intervention or automation (reference is made to US4105558, US5380440, US5961827, US2007/0090060, US2009/0230033, US20170044034).
Technical problem to be solved The flocculant and/or coagulant dosage is a critical parameter for the efficacy of the dewatering or screening process. An optimal, minimal dosage achieves the lowest possible moisture content. Overdosing will entrain more moisture within the solids, whilst increasing the concentration of flocculant chemicals in the retentate. This over flocculated state provides a stable plateau on which unsupervised operation can occur in a continuous manner in spite of fluctuating media solids concentrations. Underdosing leads to a rapid increase in the retentate moisture content resulting in filter table flooding. This is not conducive to reliable long-term operation.
Traditionally the dosage rate is adjusted manually by the filter operator based on visual inspection. The visual inspection is subject to the empirical judgement of each individual operator potentially leading to different interpretations and thus dosages.
Time constraints aside, it is difficult for an operator to make accurate judgements frequently enough to optimise the filter continuously. Consequently, the objective of the operator is to achieve stable filtration over many hours of operation, in between observations. To reduce the likelihood of underdosing events, operators typically favour high flocculant consumption as the dewatering is more stable.
Automation efforts in prior art used indirect correlations between observable reflected light from a filter or retentate media surface and based on correlations between the reflected light from a region and calibrated moisture or rheological characteristics, control the dosage of chemical additive. Examples of interferents include fugitive and secondary light sources, failure to clean the belt filter and observing an unclean section of belt filter. All skew the sensor specificity and selectivity in the prior art methods, hampering the ability for the observation to appropriately automate the process in their respective regions of interest. The volume of media under observation and the moisture content may not, under a variety of conditions, provide an accurate correlation to the surface area of exposed filter when viewed from above, especially in a system where the inflow solids concentration changes and, the rheological behaviour of these solids varies.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art as detailed below.
Fugitive/Secondary light sources Issue Prior work requires the filter/wire/screen to be clean and always displays the same colour to the camera. The colour received by the camera is the product of two components:
1. The controlled spectrum and intensity of artificial illumination of the target area; and
2. The intensity of the reflection of the illuminating light at non-absorbed frequencies back to the camera.
The illumination must therefore always be controlled across a broad spectrum of frequencies to ensure that the controlled reflection to the digital camera will be consistently observed and
The illumination must therefore always be controlled across a broad spectrum of frequencies to ensure that the controlled reflection to the digital camera will be consistently observed and
3 processed by the system, without distortion or inaccuracies that prevent appropriate chemical dosage.
Solution and improvement With the optical time of flight sensor and/or optical triangulation sensor approach, the illumination is not continuous and is controlled by designating only the coordinate to be observed, with multiple short duration bursts of light, during an observation period. This saturates that target with an intensity that prevents reflections of fugitive light sources from skewing the measurement technique. The colour of the designated target is not measured, only the angle/time of flight of reflected light is measured to determine the illuminated target height.
Filter cleaning and observation of unclean regions of interest Issue The digital optical camera pixel counting method can calculate the filter surface area covered by media as an inverse of the area of filter identified as not being covered by media on an area-balance colour contrast/discrimination basis. The method cannot determine the depth of the media above the filter within a region of interest, or the volume of media in a region of interest.
The use of gravity drainage deck ploughs to improve dewatering increases the risk of filter belt tears. As such plough design and height is carefully managed and sludge/media can at times move around or under ploughs, presenting in the furrow with sufficient depth to shield the filter from illumination and therefore prevent the camera from detecting the filter belt, resulting in the control philosophy identifying that the surface is subject to underdosing and increasing chemical dosage.
A desired moisture content can only be achieved with the correct dosage because both too much or too little flocculent have a detrimental impact on the efficiency of the dewatering or concentrating process. Where the filter is not sufficiently clean, the pixel counting method dosage will disproportionally favour overdosing as the rheological properties of the sludge cannot be observed due to the presence of unclean, obstructed filter.
Solution and improvement In contrast the optical time of flight sensor and/or optical triangulation sensor approach allows the volume of media to be measured. Automated systematic adjustments to the chemical dose solicit a volume response from the media, allowing the minimum dosage required to achieve the minimum volume to be known and continuously assessed and therefore media moisture content minimised.
The chemical dosing can be controlled to maximise the removal of supernatant volume reaching the end of the gravity drainage zone of a belt press, whilst simultaneously controlling dosage on a dosage volume per media volume basis. In this way, fluctuations in the media volume resulting from process or media changes are always subjected to the optimisation routine for automated chemical volume optimisation and it is understood that for an increased volume of media at its minimum moisture content, a larger volume of chemical must be added to achieve that minimum moisture content.
As such it is recognised that direct measurement and control of supernatant volumes removed from media, particularly when the objective of the coagulant and/or flocculant dosing is for this express purpose, is an improvement over the measurement of rheological behaviour.
Description of the invention More precisely the invention concerns a method for dewatering, a media, said method comprising:
a- Flocculating and/or coagulating the media, b- Deposing said flocculated and/or coagulated media on a filter, c- Performing a surface topography of the media using a laser time of flight sensor and/or an optical triangulation sensor to measure the surface height of the filter along with the media, d- Adjusting the amount of flocculant and/or coagulant to be added in the media according to the topography of the media.
For step a, media is flocculated and /or coagulated using natural or synthetic flocculants and/or coagulants.
Flocculants can be selected in the list: guar gums, chitosan, alginates, water soluble polymers obtained with non-ionic and/or anionic and/or cationic water-soluble monomers.
Non-ionic monomers are preferably selected from the group comprising acrylamide;
methacrylamide; N-mono derivatives of acrylamide; N-mono derivatives of methacrylamide;
N,N derivatives of acrylamide; N,N derivatives of methacrylamide; acrylic esters; and methacrylic esters. The most preferred non-ionic monomer is acrylamide.
Anionic monomers are preferably selected from the group comprising monomers having a carboxylic function and salts thereof; monomers having a sulfonic acid function and salts thereof; monomers having a phosphonic acid function and salts thereof. They include for instance acrylic acid, acrylamide tertio butyl sulfonic acid, methacrylic acid, maleic acid, itaconic acid; and hemi esters thereof. The most preferred anionic monomers are acrylic acid,
Solution and improvement With the optical time of flight sensor and/or optical triangulation sensor approach, the illumination is not continuous and is controlled by designating only the coordinate to be observed, with multiple short duration bursts of light, during an observation period. This saturates that target with an intensity that prevents reflections of fugitive light sources from skewing the measurement technique. The colour of the designated target is not measured, only the angle/time of flight of reflected light is measured to determine the illuminated target height.
Filter cleaning and observation of unclean regions of interest Issue The digital optical camera pixel counting method can calculate the filter surface area covered by media as an inverse of the area of filter identified as not being covered by media on an area-balance colour contrast/discrimination basis. The method cannot determine the depth of the media above the filter within a region of interest, or the volume of media in a region of interest.
The use of gravity drainage deck ploughs to improve dewatering increases the risk of filter belt tears. As such plough design and height is carefully managed and sludge/media can at times move around or under ploughs, presenting in the furrow with sufficient depth to shield the filter from illumination and therefore prevent the camera from detecting the filter belt, resulting in the control philosophy identifying that the surface is subject to underdosing and increasing chemical dosage.
A desired moisture content can only be achieved with the correct dosage because both too much or too little flocculent have a detrimental impact on the efficiency of the dewatering or concentrating process. Where the filter is not sufficiently clean, the pixel counting method dosage will disproportionally favour overdosing as the rheological properties of the sludge cannot be observed due to the presence of unclean, obstructed filter.
Solution and improvement In contrast the optical time of flight sensor and/or optical triangulation sensor approach allows the volume of media to be measured. Automated systematic adjustments to the chemical dose solicit a volume response from the media, allowing the minimum dosage required to achieve the minimum volume to be known and continuously assessed and therefore media moisture content minimised.
The chemical dosing can be controlled to maximise the removal of supernatant volume reaching the end of the gravity drainage zone of a belt press, whilst simultaneously controlling dosage on a dosage volume per media volume basis. In this way, fluctuations in the media volume resulting from process or media changes are always subjected to the optimisation routine for automated chemical volume optimisation and it is understood that for an increased volume of media at its minimum moisture content, a larger volume of chemical must be added to achieve that minimum moisture content.
As such it is recognised that direct measurement and control of supernatant volumes removed from media, particularly when the objective of the coagulant and/or flocculant dosing is for this express purpose, is an improvement over the measurement of rheological behaviour.
Description of the invention More precisely the invention concerns a method for dewatering, a media, said method comprising:
a- Flocculating and/or coagulating the media, b- Deposing said flocculated and/or coagulated media on a filter, c- Performing a surface topography of the media using a laser time of flight sensor and/or an optical triangulation sensor to measure the surface height of the filter along with the media, d- Adjusting the amount of flocculant and/or coagulant to be added in the media according to the topography of the media.
For step a, media is flocculated and /or coagulated using natural or synthetic flocculants and/or coagulants.
Flocculants can be selected in the list: guar gums, chitosan, alginates, water soluble polymers obtained with non-ionic and/or anionic and/or cationic water-soluble monomers.
Non-ionic monomers are preferably selected from the group comprising acrylamide;
methacrylamide; N-mono derivatives of acrylamide; N-mono derivatives of methacrylamide;
N,N derivatives of acrylamide; N,N derivatives of methacrylamide; acrylic esters; and methacrylic esters. The most preferred non-ionic monomer is acrylamide.
Anionic monomers are preferably selected from the group comprising monomers having a carboxylic function and salts thereof; monomers having a sulfonic acid function and salts thereof; monomers having a phosphonic acid function and salts thereof. They include for instance acrylic acid, acrylamide tertio butyl sulfonic acid, methacrylic acid, maleic acid, itaconic acid; and hemi esters thereof. The most preferred anionic monomers are acrylic acid,
4 acrylamide tertio butyl sulfonic acid (ATBS), and salts thereof. Generally, salts are alkaline salts, alkaline earth salts or ammonium salts.
Cationic monomers are preferably selected from the group comprising dimethylaminoethyl acrylate (DMAEA) quaternized or salified; dimethylaminoethyl methacrylate (DMAEMA) quaternized or salified; diallyldimethyl ammonium chloride (DADMAC);
acrylamidopropyltrimethylammonium chloride (APTAC);
methacrylamidopropyl-trimethylammonium chloride (MAPTAC).
Coagulants can be selected in the list: poly(diallyldimethylammoniunn chloride), polymers obtained by reaction of dimethylamine and epichlorohydrin, ferric chloride, poly(aluminium chloride).
Preferably, the method is an inline method wherein the filter is moving and the laser time of flight sensor and/or the optical triangulation sensor are fixed above the filter on which the flocculated and/or coagulated media is deposed.
Advantageously, step d) of the method is carried out in a region of interest of the media, or multiple regions of interest of the media on a weighted basis.
The media coagulated and/or flocculated by the method of the invention is preferably a slurry, a sludge, or a pulp of any municipal, mineral, or fibrous origin.
Advantageously, the filter for step c) of the method is a continuous wire, belt, filter table, filter cloth, belt filter press or gravity drainage deck In a preferred embodiment, the filter surface and or media surface topography are scanned, and the media topography is measured and recorded to a database as a two-dimensional coordinate dataset as a x, y coordinate system at any scan frequency or baud rate.
In another preferred embodiment the filter surface and or media surface topography are scanned, and the media topography is measured and recorded to a database as a three-dimensional coordinate dataset as a x, y, z coordinate system at any scan frequency or baud rate.
Advantageously, coordinate database is accessed by a programmed routine, to classify the topography of the media at coordinates in a region of interest and/or multiple regions of interest against a set point media topography and/or a matrix of coordinate set point heights thereby identifying the height at a coordinate as the same, or in some measure of error with respect to that set point or matrix of set points thereof.
Cationic monomers are preferably selected from the group comprising dimethylaminoethyl acrylate (DMAEA) quaternized or salified; dimethylaminoethyl methacrylate (DMAEMA) quaternized or salified; diallyldimethyl ammonium chloride (DADMAC);
acrylamidopropyltrimethylammonium chloride (APTAC);
methacrylamidopropyl-trimethylammonium chloride (MAPTAC).
Coagulants can be selected in the list: poly(diallyldimethylammoniunn chloride), polymers obtained by reaction of dimethylamine and epichlorohydrin, ferric chloride, poly(aluminium chloride).
Preferably, the method is an inline method wherein the filter is moving and the laser time of flight sensor and/or the optical triangulation sensor are fixed above the filter on which the flocculated and/or coagulated media is deposed.
Advantageously, step d) of the method is carried out in a region of interest of the media, or multiple regions of interest of the media on a weighted basis.
The media coagulated and/or flocculated by the method of the invention is preferably a slurry, a sludge, or a pulp of any municipal, mineral, or fibrous origin.
Advantageously, the filter for step c) of the method is a continuous wire, belt, filter table, filter cloth, belt filter press or gravity drainage deck In a preferred embodiment, the filter surface and or media surface topography are scanned, and the media topography is measured and recorded to a database as a two-dimensional coordinate dataset as a x, y coordinate system at any scan frequency or baud rate.
In another preferred embodiment the filter surface and or media surface topography are scanned, and the media topography is measured and recorded to a database as a three-dimensional coordinate dataset as a x, y, z coordinate system at any scan frequency or baud rate.
Advantageously, coordinate database is accessed by a programmed routine, to classify the topography of the media at coordinates in a region of interest and/or multiple regions of interest against a set point media topography and/or a matrix of coordinate set point heights thereby identifying the height at a coordinate as the same, or in some measure of error with respect to that set point or matrix of set points thereof.
5 Preferably, the coordinate point cloud database is accessed by a programmed routine, selecting data from within regions of interest to integrate the cross-sectional surface area(s) and/or calculate the volume of the media within the region(s) of interest, identifying that cross-sectional surface area and/or volume, as the same, or in some measure of error with respect to a set point.
Advantageously, with the method of the invention, a setpoint is obtained or recorded for export, modification, importation, and/or later use, by scanning a filter and recording the media topography for reference purposes.
Examples Optical time of flight and/ or optical triangulation The optical time of flight sensor and/or optical triangulation sensor illumination is not continuous and is controlled by designating only the coordinate to be observed, with multiple short duration bursts of light, during an observation period. This saturates that target with an intensity that prevents reflections of fugitive light sources from skewing the measurement technique. The colour of the designated target is not measured, only the angle/time of flight of reflected light is measured to determine the illuminated target height. This solves the technical issues related to colour discrimination brought about by fugitive light, media colour changes, filter colour changes, deficient belt cleaning and media ploughing.
Furthermore, the technique of quantifying the cross-sectional surface area and/or volume of media on the filter, allows the measurement and control of supernatant volumes removed from media. The key objective of the coagulant and/or flocculant dosing is for this express purpose.
As such, the method described is an improvement over the measurement of un-utilised filter as a quantification of rheological behaviour, where rheological behaviour is altered by many physio-chemical relationships, rather than just the volume of supernatant in the retentate media.
Cross-sectional media surface area From the digitised information, the cross-sectional surface area of the media above the filter can be measured for comparison to a set point and the chemical dosage optimised.
Media distribution From this digitised information, the distribution of the media above the filter can be measured for comparison to a set point and the chemical dosage optimised to control the wetted surface area of the filter cloth.
Advantageously, with the method of the invention, a setpoint is obtained or recorded for export, modification, importation, and/or later use, by scanning a filter and recording the media topography for reference purposes.
Examples Optical time of flight and/ or optical triangulation The optical time of flight sensor and/or optical triangulation sensor illumination is not continuous and is controlled by designating only the coordinate to be observed, with multiple short duration bursts of light, during an observation period. This saturates that target with an intensity that prevents reflections of fugitive light sources from skewing the measurement technique. The colour of the designated target is not measured, only the angle/time of flight of reflected light is measured to determine the illuminated target height. This solves the technical issues related to colour discrimination brought about by fugitive light, media colour changes, filter colour changes, deficient belt cleaning and media ploughing.
Furthermore, the technique of quantifying the cross-sectional surface area and/or volume of media on the filter, allows the measurement and control of supernatant volumes removed from media. The key objective of the coagulant and/or flocculant dosing is for this express purpose.
As such, the method described is an improvement over the measurement of un-utilised filter as a quantification of rheological behaviour, where rheological behaviour is altered by many physio-chemical relationships, rather than just the volume of supernatant in the retentate media.
Cross-sectional media surface area From the digitised information, the cross-sectional surface area of the media above the filter can be measured for comparison to a set point and the chemical dosage optimised.
Media distribution From this digitised information, the distribution of the media above the filter can be measured for comparison to a set point and the chemical dosage optimised to control the wetted surface area of the filter cloth.
6 Ploughed media furrow geometry On the gravity drainage deck portion of belt filter presses there is typically multiple series of ploughs to turn the sludge over in order to maximise the release of free water. Immediately behind these ploughs a furrow is present.
From this digitised information, the geometry of the furrows is measured, and the chemical dosage optimised to maintain set point furrow width or a ratio of furrow area to total filter belt media area.
Region of interest geometric features From this digitised information, the geometry of a selected region of interest is measured and the chemical dosage optimised, or alarms triggered to alert operators of a specific condition, such as but not limited to, filter hole/tear detection, low/high volume alarms, belt filter tracking issues, no flow/no movement and other persistent abnormal condition monitoring alarms.
1st trial: Belt filter press unit flocculant dosage is not controlled/
governed via any mechanism and is set at a fixed pump speed or fixed flow rate by an experienced operator.
Observation:
= the retentate media has a greater volume due to increased moisture content = the retentate media topography has a lower standard deviation due to increased moisture content = the belt filter press is not prone to instability when slurry is consistent, but at the cost of increased flocculant usage.
= the belt filter press is more prone to instability when slurry is inconsistent, and more than the prescribed dosage is justified.
2nd trial: By using method of the invention coagulant/flocculant dosages less than those prescribed by an experienced operator were observed.
Observations:
= the retentate media has a reduced volume due to lower moisture content at the determined optimal dosage.
= the retentate media topography has a higher standard deviation due to lower moisture content at the determined optimal dosage = the belt filter press is not prone to instability when slurry is consistent, and the cost of flocculant usage is less than that of fixed pump speed and fixed flow rate control by an experienced operator.
From this digitised information, the geometry of the furrows is measured, and the chemical dosage optimised to maintain set point furrow width or a ratio of furrow area to total filter belt media area.
Region of interest geometric features From this digitised information, the geometry of a selected region of interest is measured and the chemical dosage optimised, or alarms triggered to alert operators of a specific condition, such as but not limited to, filter hole/tear detection, low/high volume alarms, belt filter tracking issues, no flow/no movement and other persistent abnormal condition monitoring alarms.
1st trial: Belt filter press unit flocculant dosage is not controlled/
governed via any mechanism and is set at a fixed pump speed or fixed flow rate by an experienced operator.
Observation:
= the retentate media has a greater volume due to increased moisture content = the retentate media topography has a lower standard deviation due to increased moisture content = the belt filter press is not prone to instability when slurry is consistent, but at the cost of increased flocculant usage.
= the belt filter press is more prone to instability when slurry is inconsistent, and more than the prescribed dosage is justified.
2nd trial: By using method of the invention coagulant/flocculant dosages less than those prescribed by an experienced operator were observed.
Observations:
= the retentate media has a reduced volume due to lower moisture content at the determined optimal dosage.
= the retentate media topography has a higher standard deviation due to lower moisture content at the determined optimal dosage = the belt filter press is not prone to instability when slurry is consistent, and the cost of flocculant usage is less than that of fixed pump speed and fixed flow rate control by an experienced operator.
7 = the belt filter press is less prone to instability when slurry flow is inconsistent over multi hour time scales, as the inconsistency is observed, and the optimal dosage determined and applied.
8
Claims (10)
1 . Method for dewatering a media said method comprising:
a- Flocculating and/or coagulating the rnedia, b- Deposing said flocculated and/or coagulated media on a filter, c- Performing a surface topography of the media using a laser time of flight sensor and/or an optical triangulation sensor to measure the surface height of the filter along with the media, d- Adjusting the amount of flocculant and/or coagulant to be added in the media according to the topography of the media.
a- Flocculating and/or coagulating the rnedia, b- Deposing said flocculated and/or coagulated media on a filter, c- Performing a surface topography of the media using a laser time of flight sensor and/or an optical triangulation sensor to measure the surface height of the filter along with the media, d- Adjusting the amount of flocculant and/or coagulant to be added in the media according to the topography of the media.
2. Method according to claim 1, wherein the method is an inline method wherein the filter is moving and the laser time of flight sensor and/or the optical triangulation sensor are fixed above the filter on which the flocculated and/or coagulated media is deposed.
3. Method according to claim 1 or 2, wherein step d) is carried out in a region of interest of the media, or multiple regions of interest of the media on a weighted basis.
4. Method according to any one of claims 1 to 3, wherein the media is a slurry, a sludge, or a pulp of any municipal, mineral, or fibrous origin.
5. Method according to any one of claims 1 to 4, wherein the filter is a continuous wire, belt, filter table, filter cloth, belt filter press or gravity drainage deck.
6. Method according to any one of claims 1 to 5, wherein the filter surface and or media surface topography are scanned, and the media topography is measured and recorded to a database as a two-dimensional coordinate dataset as a x, y coordinate system at any scan frequency or baud rate.
7. Method according to any one of claims 1 to 5, wherein the filter surface and or media surface topography are scanned, and the media topography is measured and recorded to a database as a three-dimensional coordinate dataset as a x, y, z coordinate system at any scan frequency or baud rate.
8. Method according to any one of claims 1 to 6, wherein the coordinate database is accessed by a programmed routine, to classify the topography of the media at coordinates in a region of interest of the media and/or multiple regions of interest of the media, against a set point media topography and/or a matrix of coordinate set point heights thereby identifying the height at a coordinate as the same, or in some measure of error with respect to that set point or matrix of set points thereof.
9. Method according to any one of claims 1 to 7, wherein the coordinate point cloud database is accessed by a programmed routine, selecting data from within regions of interest of the media to integrate the cross-sectional surface area(s) and/or calculate the volume of the media within the region(s) of interest, identifying that cross-sectional surface area and/or volume, as the sarne, or in some measure of error with respect to a set point.
10. Method according to any one of 1 to 9, by which a setpoint is obtained or recorded for export, modification, importation, and/or later use, by scanning a filter and recording the media topography for reference purposes.
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AU2021903023 | 2021-09-20 | ||
AU2021903023A AU2021903023A0 (en) | 2021-09-20 | Method for removal of supernatant from media slurry | |
PCT/EP2022/075967 WO2023041783A1 (en) | 2021-09-20 | 2022-09-19 | Monitoring sludge dewatering |
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US4105558A (en) | 1975-04-08 | 1978-08-08 | Heinrich Hans J | Apparatus for draining of muddy liquids |
US5380440A (en) | 1992-06-09 | 1995-01-10 | Anikem Pty. Limited | Two dewatering of slurries controlled by video system |
US5961827A (en) | 1996-08-28 | 1999-10-05 | Baehr; Albert | Apparatus for dewatering of sludge and similar substances |
US7303685B2 (en) | 2005-10-21 | 2007-12-04 | Clark John W | Polymer control system |
US8293097B2 (en) | 2008-03-17 | 2012-10-23 | Bowers Jr Gregory Scott | System for continuous optimization of wastewater treatment |
WO2015066275A1 (en) * | 2013-10-30 | 2015-05-07 | Flsmidth A/S | Feed conditioning automation |
AT515757B1 (en) | 2014-04-23 | 2018-08-15 | Andritz Ag Maschf | Method and device for dewatering sludge on a sieve |
EP3440019A1 (en) * | 2016-04-08 | 2019-02-13 | Remirez, Jose, Antonio | Automated dosing system and method with light profiling for wastewater filtration system |
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