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RU-2861622-C2 - MONITORING SLUDGE DEWATERING

RU2861622C2RU 2861622 C2RU2861622 C2RU 2861622C2RU-2861622-C2

Abstract

FIELD: filters. SUBSTANCE: invention relates to a method for removing supernatant from a medium on a filter. Flocculation and/or coagulation of the medium is performed. Said flocculated and/or coagulated medium is deposited on a filter. The surface topography of the medium is measured using a laser time-of-flight sensor and/or a triangulation optical sensor to measure the height of the filter surface with the medium. The amount of flocculant and/or coagulant added to the medium is adjusted according to the topography of the medium. The filter moves during the dewatering of the medium, and the sensors are fixedly mounted above the filter. EFFECT: increasing the reliability of measurements and control of coagulant/flocculant dosing by using a laser time-of-flight sensor and/or a triangulation optical sensor, optimal dosing and reduction of coagulant/flocculant consumption. 10 cl

Inventors

  • DOWD, ANDREW
  • SCHROETER, Russel

Dates

Publication Date
20260506
Application Date
20220919
Priority Date
20210920

Claims (14)

  1. 1. A method of dehydrating a medium, characterized by the fact that
  2. a) - perform flocculation and/or coagulation of the medium,
  3. b) - precipitate the said flocculated and/or coagulated medium on a filter,
  4. c) - measure the surface topography of the medium using a laser time-of-flight sensor and/or a triangulation optical sensor to measure the height of the filter surface with the medium,
  5. d) - adjust the amount of flocculant and/or coagulant added to the medium in accordance with the topography of the medium.
  6. 2. The method according to claim 1, wherein said method is a method carried out in real time, wherein the filter is moving and the laser time-of-flight sensor and/or triangulation optical sensor is mounted stationary above the filter on which the flocculated and/or coagulated medium is deposited.
  7. 3. The method according to claim 1 or 2, wherein step d) of the method is carried out on one observed area of the environment or on more than one observed area of the environment based on gravimetric analysis.
  8. 4. The method according to any one of claims 1 to 3, wherein said medium is a suspension, emulsion or pulp from a municipal, inorganic or fibrous source of origin.
  9. 5. The method according to any one of paragraphs 1-4, in which the filter is a continuous wire, a belt, a vacuum plate filter, a filter cloth, a belt filter press or a gravity drain mat.
  10. 6. The method according to any one of paragraphs 1-5, in which the surface of the filter and/or the surface topography of the medium is scanned, the topography of the medium is measured and recorded in the database as a set of two-dimensional coordinate data as an x, y coordinate system at the scanning frequency or data transfer rate.
  11. 7. The method according to any one of paragraphs 1-5, in which the surface of the filter and/or the surface topography of the medium is scanned, the topography of the medium is measured and recorded in the database as a set of three-dimensional coordinate data as a coordinate system x, y, z at a scanning frequency or data transfer rate.
  12. 8. The method of claim 6 or 7, wherein said coordinate database is accessed by a programmed procedure to classify the topography of the environment in coordinates at one observed section of the environment or at more than one observed section of the environment in comparison with the topography of the environment with a given value and/or a matrix of coordinate heights of given values, thereby identifying a height with a coordinate the same as, or with some degree of error, as with respect to the given value or matrix of given values.
  13. 9. The method according to claim 6 or 7, in which, using a programmed procedure, a cloud database of point coordinates is connected, data is selected from the observed sections of the environment for integrating the area(s) of the cross-sectional surface and/or calculating the volume of the environment in the observed section(s), identifying this cross-sectional surface area and/or volume as the same, or with some error, as in relation to a given value.
  14. 10. The method according to claim 8 or 9, in which the specified value is obtained or recorded for transmission, modification, import and/or subsequent use by scanning a filter and recording the topography data of the environment as reference information.

Description

Field of technology to which the invention relates The present invention relates to a method for removing supernatant from a medium on a filter, in which a flocculant and/or coagulant is added to the medium to increase the drainage rate of the supernatant removed from the medium, at least partially dehydrated, and when implementing the method, the surface topography of the medium is measured and the amount of flocculant and/or coagulant to be added is determined, depending on the topography of the medium on the filter within the observed area or areas. The method is carried out using a device for dewatering a medium, containing a means for feeding a flocculant and/or coagulant, located upstream relative to the filter, and downstream relative to the water inflow section, a device is located, in particular, an optical time-of-flight sensor and/or an optical triangulation sensor, intended for optical digitalization of the surface topography of the medium and connected via a control system to the means for feeding the flocculant and/or coagulant, for regulating the added dosed amount of flocculant and/or coagulant. State of the art The prior art includes methods for separating a medium from a supernatant liquid, in which a medium, such as a suspension (e.g., biosolids from wastewater, fibrous material, or mineral sludge), is dewatered by adding a flocculant and/or coagulant. The flocculant and/or coagulant are added to the medium, first to destabilize the solid portion of the medium, coagulating and flocculating it. The resulting suspension of "flocs"—the suspended flocculated medium and supernatant—is then fed to a filter, such as a gravity filter, and a portion of the liquid phase of the medium, free of the solid phase, is removed, while a portion of the medium, containing the concentrated solid phase, remains on the filter surface. In the prior art, the addition of flocculant and/or coagulant is controlled by operator intervention or automatically (in this connection, reference may be made to patent documents US 4105558, US 5380440, US 5961827, US 2007/0090060, US 2009/0230033, US 20170044034). Technical problem solved by the invention The dosed amount of flocculant and/or coagulant is a critical parameter for the efficiency of the dewatering or filtration process. The optimal minimum dose ensures the lowest possible moisture content. Excessive doses will remove more moisture present in the solid phase, increasing the content of flocculant chemicals in the concentrate. This excess flocculation creates a stable level at which the process can continue uncontrolled for a long time, despite fluctuations in the solid phase concentration. Insufficient doses will cause a rapid increase in moisture content in the concentrate, leading to flooding of the vacuum disc filter. This is detrimental to reliable and long-term filter operation. Typically, the dosage is adjusted manually by the filter operator based on visual inspection. Each operator's visual inspection is dependent on their experience with the situation, potentially leading to different decision-making conclusions and, consequently, different dosages. Therefore, even without time constraints, it is difficult for the operator to make accurate situational assessments sufficient for continuous filter optimization. Consequently, the operator's task is to ensure a stable filtration process over many hours of operation, between inspections. To reduce the likelihood of underdosing, operators typically prefer high flocculant consumption, as the dewatering process is more stable under these conditions. Prior art process automation measures included the use of indirect relationships between the measured reflected light from a filter or from the surface of a medium concentrate and were based on correlations between the reflected light from a section and precisely defined moisture parameters or rheological characteristics, as well as the adjustment of the chemical additive dosage. Examples of interfering factors include random and secondary radiation sources, the inability to clean the belt filter, and the inability to monitor the uncleaned section of the belt filter. In prior art methods, all errors are related to the selectivity and non-selectivity of the sensor, which prevent monitoring that would ensure proper process automation in the relevant zones under consideration. The volume and moisture content of the medium being studied cannot, under a variety of conditions, provide an accurate correlation with the filter surface area uncovered by sediment, as viewed from above, particularly in a system in which the concentration of the solid phase in the incoming filter stream varies and the rheological properties of this solid phase change. The object of the present invention is to overcome and eliminate at least one of the disadvantages inherent in the prior art described in detail below. Accidental/secondary radiation sources Problem Previous studies require that the f