Definitions

• the present invention is directed to the discovery that the majority of the water contained in municipal waste-water sludge treated by the municipal treatment plants is contained within and between molecular cells.
• the water molecules contained within the cell shall be referred to as "intra-cellular” water molecules, while the water molecules between the cells and bound thereat via both mechanical and electrical bonding shall be referred to as "intercellular” water molecules. It has been the discovery that this intra-cellular and intercellular water makes up the majority of the water in municipal waste-water sludge treated at a municipal treatment plant, which intra- cellular and intercellular water is not typically released by conventional, municipal dewatering methods which process the municipal sludge.
• the present invention also, relates to a system, apparatus and method directed to the safe and effective treatment of previously-dewatered, biologically-active, municipal waste-water sludges, and more, particularly, to a pulsed, electric-field apparatus and related method for the disinfecting and dewatering of previously-dewatered, municipal waste-water sludges in an efficient and effective manner at the level of the individual, molecular cells of the waste material, so as to substantially reduce the resulting volume and weight of the waste material which has to be disposed of by the municipality.
• a "belt filter” type press which is a system of multiple rollers and mesh belts through which the bio-solids waste material is caused to travel between, and which cooperate to squeeze some of the water from the bio-solids waste material
• a dedicated, in-line, centrifuge apparatus of some sort which uses centrifugal force to squeeze some of the water from the bio-solids waste material
• a plate and frame filter press with hydraulic or mechanical drive which uses mechanical pressure to dewater discrete batches of the bio- solids waste material.
• the bio-solids waste sludge that is treated by the municipality will result in a material mixture containing greater than 90% water-content, and less than 10% solids-content prior to the dewatering process by the municipality.
• the dewatering operation there is nevertheless a relatively high water content remaining in the resulting, residual, bio-solids waste material, which residual will be concentrated to a mixture containing about 65% to 80% water-content and about 20% to 35% solids- content at the output-end of the municipality's waste-water treatment apparatus .
• the EPA 503 regulations address and promote the safe and effective disposal of bio-solids waste material by municipalities in accordance with the underlying rational and supporting facts of defining two different classes of residual bio-solids waste material, Class "A” and Class “B", and of the need to have an underlying, regulatory process which adopts a different, regulatory approach for each of the two classes of residual bio-solids waste material, and, thereafter, closely regulating the acceptable avenues of disposal for each of the two classes of bio-solids waste material.
• Class “A” bio-solids waste material is a biologically-inert , non-active waste material, and there are no limitations on the disposition of Class “A” bio-solids waste material by the municipality.
• Class “B” bio-solids waste material is a biologically-active waste material, which may be pathogenic, and, as a result, the disposition of Class "B” bio-solids waste material by the municipality is accomplished in a regulatory manner that is consistent with a highly controlled and regulated commodity at appropriate dump sites .
• Such a novel disinfecting and dewatering process would operate at the cellular level of the bio-solids waste material to rupture the cell wall in a manner non-repairable by the cell structure, thereby facilitating the internal water and related materials within the cell to be squeezed out of the cell structure, so that such is no longer actively contained within the cell structure by the cell.
• the resulting material is a safe, biologically- inert , solid material.
• a general object of the present invention is to provide for the further dewatering of previously- dewatered, bio-solids, municipal waste-water sludge.
• Another object of the present invention is to provide a low cost conversion of Class "B" bio-solids to Class "A” bio- solids .
• a still further object of the present invention is to provide a densified and pelletized end- product suitable for convenient storage and land application without need of specialized equipment.
• a pulsed electric- field system for the disinfecting and dewatering of biologically- active, previously-dewatered, waste-water sludge material, comprising in combination: means for pressurizing the waste material to a predetermined range of pressurization; means for heating the waste material to a predetermined temperature range, the heating means operatively coupled to the pressurization means; means for converting the biologically- active waste material into inert material, the conversion means operatively coupled to the heating means; means for filtering the inert waste material in a predetermined manner, the filtering means operatively coupled to the converting means; and means for discharging the inert waste material in a predetermined manner, the discharge means operatively coupled to the filtering means, whereby the biologically- active waste material is transformed into inert waste material and the resulting volume of inert waste material requiring disposition is substantially reduced.
• a method for the disinfecting and dewatering of biologically-active previously dewatered waste-water sludge material, comprising the steps of: pressurizing the waste material to a predetermined range of pressurization; if necessary, heating the waste material to a predetermined temperature range, the heating step operatively coupled to the pressurization step; converting the biologically-active waste material into inert material, the conversion step operatively coupled to the heating step; filtering the inert waste material in a predetermined manner, the filtering step operatively coupled to the converting step; and discharging the inert waste material in a predetermined manner, the discharge step operatively coupled to the filtering step, whereby the biologically-active waste material is transformed into inert waste material and the resulting volume of inert waste material requiring disposition is substantially reduced.
• This method is called electroporation .
• Figure 1 is a flow schematic of the process of the invention
• Figure 2A is a proximate-to-scale, general arrangement of the system of the invention.
• Figure 2B is an elevational view of the pelletizing- heads section of the apparatus of Fig. 2A;
• Figure 2C is a front, elevational view of the discharging conduits from the pelletizing-heads section of Fig. 2B to a collector;
• Figure 3 is an elevational cross-sectional view showing the general arrangement of the disruptor cell;
• Figure 4 is an elevational cross-sectional view showing the general arrangement of the filtration module.
• FIGs. 1 and 2A there is shown in Figs. 1 and 2A the apparatus 10 of the invention for dewatering previously-dewatered municipal waste-water sludge, or for treating animal and/or plant waste.
• the apparatus 10 of the invention is added on to the outlet of a conventional municipal waste-water treatment plant for dewatering bio-solids sludge.
• the apparatus 10 is a secondary, or tertiary, system for the further dewatering of previously-dewatered sludge that has been dewatered by a primary system. It is, of course, possible to use the apparatus 10 alone, so that it serves as the only dewatering system; however, owing to financial restraints, it is envisioned that the apparatus 10 will serve to further dewater previously-dewatered sludge.
• a conventional municipal waste-water treatment plant typically comprises belt filter presses, centrifuges, plate and frame, or other, conventional dewatering technologies that discharge the sludge-material via conveyor to a storage bin, hopper, container or truck body for intermediate retention prior to transit for off-site disposal.
• a conveyer is indicated by reference numeral 11 in Fig. 1, and it constitutes the outlet, or end-point, at which the conventional dewatering technique terminates, and the apparatus 10 of the present invention begins to function.
• the output of the conveyer 11 is fed to a truck, or the like, for off-site disposal, it is instead directed to the inlet of the apparatus 10 of the invention by means of a variety of standard, material-handling equipment and methods that discharge the output from the conveyer 11 into the input of the apparatus 10 of the present invention.
• the input of the apparatus of the invention is a conically-shaped hopper 12 with spiral feed 14.
• This conically-shaped hopper with spiral feed 12 will uniformly charge, or load, the previously-dewatered, bio-solids waste- water sludge exiting the conventional dewatering apparatus via conveyer 11 into a double-screw auger feed-section 16 having a hydraulically driven, self-priming positive displacement pump 18, such as Abel Pumps Corporation's Model "SH" with cone valves, whereby the thick-consistency sludge is pressurized.
• a hydraulically driven, self-priming positive displacement pump 18, such as Abel Pumps Corporation's Model "SH" with cone valves whereby the thick-consistency sludge is pressurized.
• the double-screw auger feed-section 16 can also be utilized to introduce various alkaline or acidic chemicals to enhance the electroporation effect of the disruptor cell, discussed hereinbelow, or to modify the PH of the bio-solids to conform to the intended land use application, or to enhance the dewatering effect of the filtration module.
• the previously- dewatered, bio-solids, waste-water sludge is alternately drawn through one of two suction valves, and then into one of two pump cavities 20, 22, and pumped through one or two discharge valves into a common discharge port 23.
• the pump pistons 24, 26 are driven by hydraulic cylinders 24', 26' via piston rods 24", 26".
• the hydraulic cylinders are powered by a conventional hydraulic power-package 28.
• the common discharge port 23 is connected via piping 30 to the inlet of a helical heat exchanger 32, such as that manufactured by Graham Manufacturing Company, Model "Helixflow" .
• the heating source 34 to the exchanger is preferable low pressure steam.
• the exiting bio-solids sludge temperature is controlled via a standard thermostatic steam valve-control to a range of between 40 degrees C. and 60 degrees C. Temperatures below 40 degrees C. tend to depress the electroporation effect of the disruptor cell, while temperatures above 60 degrees C. tend to "scale" certain types of bio-solids to the interior of the walls of the heat exchanger. The electroporation effect is not noticeably enhanced at temperatures above 40 degrees C. In those cases where the bio-solids sludge is of such a consistency that it readily and easily flows without having to raise its temperaure, then the step of heating the bio-solids sludge, and the equipment described above for heating it, may be dispensed with.
• the heat exchanger also, incorporates a vent to collect various off-gasses resulting from the heating process, in a conventional manner.
• the off-gasses are preferably collected via a vacuum pump for subsequent, ambient discharge or treatment as dictated by the content of the off-gasses.
• the main purpose of venting is that the electroporation performance can be enhanced by eliminating as much air as possible from the sludge material, and so that, as the material is heated in the heat exchanger, there will not be included vapors created.
• the disruptor cell 42 consists of an electrically- grounded, cylindrically-shaped, outer metallic shell or annular pipe 44, with an internal, electrically-insulated, high voltage electrode 46.
• the electrode design is such as to provide laminar flow characteristics over its leading surface into an approximate 3/8" (1 cm) annulus between it and the annular pipe 44, to thereby create a uniform disruption zone.
• the high voltage electrode 46 is preferably generated, or pulsed, in a uni-polar or bi-polar mode, and at an amplitude of 25,000 to 100,000 volts per centimeter, at a frequency of 3 to 5 hertz, althought other frequencies may be employed, and for a duration dependent upon the characteristics of the bio-solids material being treated.
• the laminar-flowing sludge is subject to what may be called an "electro-baric" field, which is an electric field exposed to constant-pressure flowing media.
• a conventional, solid-state pulse generator 48 having a capacitive discharge circuit receives power from a power supply 50. Power switching is accomplished via a spark gap, "Thiotron", or solid state switch.
• the pulse control unit, the power supply and switching sub-system are standard commercially available items regularly used in the electric power, laser, and biotechnology industries .
• the controlling principle at work within the disruptor cell is electroporation.
• sufficient voltage potential develops along the molecular cell wall to result in an imbalance of forces, which causes the rupture of the molecular cell wall.
• the cell undergoes "lysis", which is the loss of intra cellular fluids and materials.
• lysis the loss of intra cellular fluids and materials.
• the cell dies, and its liquid content is released, which liquid content is mostly water molecules.
• high voltage discharges releases or breaks inter cellular water mechanical/electrical bonds.
• the bio-solids material becomes sufficiently biologically inert to meet Class "A" EPA 503 standards, and, is suitable for extended dewatering.
• the disruptor cell 42 is directly connected to, and longitudinally axially in-line with, a filtration module 52 consisting of two electrically charged metal filtration membranes 52', 52", and which is best seen in Figs. 2A and 4.
• the outer, filtering membrane 52' is a concentric cylinder, or porous metal pipe
• the inner, filtering membrane 52" is an expanding, frustoconical-shaped metal member, such that the annular region between the inner and outer filtering elements gradually and continually narrows or tapers along the length of flow in the filtration module. This geometry between the two filtering elements creates a continual decreasing cross-sectional area along the length of the filtration module.
• the concentric filtration surfaces conserve overall space while optimizing a characteristic of bio-solids under pressure, which characteristic is the migration and adherence of liquids to a contact surface, whereby the liquid water is separated from the solid content of the waste.
• the metal filter membranes that may be used are those manufactured by the Porous Metal Components division of Newmet Krebsoge, Deerfield, Illinois.
• the use of low voltages for aiding in filtration is a well-known method of separating out particles from water, and is also utilized on the filtration surfaces of the filters 52', 52", and produced via low-voltage supply 61.
• the filtration cell is operated at a pressure of between 1000 to 1500 psi, depending upon the desired level of additional dewatering, and the clarity of the liquid filtrate.
• the liquid filtrate is collected from the tapering inner metal membrane filter 52" and the parallel outer metal membrane filter 52' via a liquid-collection assembly 60, which consists of an external drain pan 62 and an internal drain 64 combining to a common drain to a liquid metering unit 66.
• the liquid metering unit is conventional instrumentation, and is used to monitor system performance.
• the liquid meter discharges to the return piping 68 of the apparatus.
• the tapering or narrowing annular region between the two membranes causes a constant pressure on the sludge as it flows.
• the operating pressures within the annular region between the two metal membranes will be between 1000 - 1500 psi, which causes any remaining water in the sludge to be "squeezed out” .
• the disinfected and twice-dewatered bio-solids material exits the filtration module through a pelletizing head 70 with a rotating cutter assembly 72, as best seen in Figs. 2A and 4, and then conveyed in a collector-conveyer 73 for subsequent disposal.
• the bio-solid material is biologically inert, since, whereas a normal healthy bacteria or virus has DNA which is reproducible, once the DNA mechanism for the bacteria or virus is broken, as occurs in the present invention, the resulting biological material is inert thereafter.
• the pelletizing head consists of a plurality of circular plates each having a circular array of holes coincident with the annular, exit-flow channel of the filtration module.
• the rotating cutter assembly shears the extruded bio-solids into pellets which drop onto the solids- collection conveyor which transfer the disinfected, twice- dewatered, volume/mass reduced bio-solids to the existing storage bin, hopper, container, or truck body for intermediate retention prior to transit for off-site disposal .
• each of the metal filter membranes 56', 56" will typically be a 10 -micron mesh.
• the metal membranes 56', 56" will have to be cleaned periodically. To do this, scrapers would be provided. Alternatively, back-pulsing the metal membranes with steam may be used.
• the discovery of the present invention which is, that the majority of the water contained in municipal waste sludge is intra-cellular - may be carried out using other techniques for irreparably rupturing the cell membranes. For example, ultrasonic waves may be employed.

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• 1997
  • 1997-11-12 JP JP2000520389A patent/JP2001522721A/ja active Pending
  • 1997-11-12 CA CA002307724A patent/CA2307724C/en not_active Expired - Fee Related
  • 1997-11-12 EP EP97946649A patent/EP1028918A1/en not_active Withdrawn
  • 1997-11-12 AU AU51776/98A patent/AU5177698A/en not_active Abandoned

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