DEVICE FOR DEWATERING AND METHOD OF MAKING SAME

The present disclosure generally relates to a device for dewatering a material. The device comprises a biodegradable, permeable enclosure configured for receiving the material through an inlet. The permeable enclosure comprises layered biodegradable textiles, an inner portion and an outer portion, derived from renewable resources. The inner portion has an apparent opening size between about 0.5 mm and 3 mm. The outer portion has a ratio of the minimum tensile strength in the warp direction to the minimum tensile strength in the weft direction of about 2.5.

TECHNICAL FIELD

The present disclosure is generally related to a device for dewatering materials, specifically to a permeable enclosure comprising layered biodegradable textiles for dewatering sludge.

BACKGROUND

Slurry is a mixture of liquid and solid components, which typically consists of fine solid particles (the solid fraction) suspended in a liquid fraction (e.g., water). Sludge is a type of slurry produced at industrial facilities, which becomes an input in waste treatment systems. The treatment of waste sludge involves the removal of the liquid fraction from the sludge, also referred to as dewatering. The liquid fraction recovered may be further treated and recycled or subjected to various extraction steps to recover value-added by-products, such as hydrocarbon oil and grease. The dewatering of the sludge to specific criteria (e.g., a targeted remaining water content, etc.) is required for transportation, re-use, or disposal of the sludge. A variety of methods and/or devices can be used for dewatering, such as drying beds, filter presses, geomembranes, centrifuges, vacuum filters, and belt presses.

Commercially available geotextile containers (e.g., tubes and bags) used for dewatering are generally made of a non-woven fabric, specifically a water-permeable plastic material such as polypropylene, polyester and/or polyethylene, with at least one opening for filing. Because such containers are typically used in the construction of hydraulic barrier structures for shore and coastal protection, the use of a water-permeable plastic material ensures that the container exhibits an extended life cycle via the required strength and longevity of the material.

The life cycle assessment of waste sludge produced at industrial facilities includes treatment to recover value-added by-products and consolidation of solids to specified criteria for transport for fill disposal at a landfill. The manufacture of commercially available geotextile tubes is not suitable for long-term disposal or hydrocarbon reclamation options. The non-woven, plastic, permeable material is conservatively designed to retain very fine solids particles with minimal degradation in most environmental conditions. Variability of industrial waste inputs can result in extended dewatering duration due to clogging of the non-woven pores of plastic geotextile materials, which impacts the efficiency of treating sludge at a consistent rate. The resistance of the plastic material to degradation, specifically in landfill conditions, prevents integration of the dewatered sludge solids as fill in the environment. Biofuel facilities also do not want synthetic material for hydrocarbon reclamation during incineration. Also, the associated environmental impact of plastics sourced from non-renewable sources should be considered in the life cycle assessment.

Accordingly, for these and other reasons, there is a need for devices for sludge dewatering, specifically geotextile-based devices, that do not exhibit the shortcomings above.

SUMMARY

According to various aspects, this disclosure relates to a device for removing liquid from a material (i.e., dewatering) and comprising a biodegradable, permeable enclosure configured for receiving the sludge material through an inlet. The permeable enclosure comprises layered biodegradable textiles, as further described below, which are derived from renewable resources.

For example, in accordance with one aspect, this disclosure relates to a device for dewatering. The device comprises a permeable enclosure comprising at least two inner layers of a first woven material and at least one outer layer of a second woven material. The device also comprises an inlet port. The first woven material has an apparent opening size (AOS) when measured according to ASTM D4751 of between about 0.5 mm and about 3 mm. The second woven material has a ratio of a minimum tensile strength in a warp direction of the second woven material to a minimum tensile strength in a weft direction of the second woven material when measured according to ASTM 4595 (minimum tensile strength ratio) of at least about 2.5.

In accordance with another aspect, this disclosure also relates to a device for dewatering. The device comprises a permeable enclosure comprising an inner portion of a first biodegradable woven material and an outer portion of a second biodegradable woven material. The device also comprises an inlet port. The first biodegradable woven material has an apparent opening size (AOS) when measured according to ASTM D4751 of between about 0.5 mm and about 3 mm. The second biodegradable woven material has a ratio of a minimum tensile strength in a warp direction of the second woven material to a minimum tensile strength in a weft direction of the second woven material when measured according to ASTM 4595 (minimum tensile strength ratio) of at least about 2.5.

In accordance with another aspect, this disclosure also relates to a device for dewatering sludge. The device comprises a permeable enclosure. The permeable enclosure comprises a top side and an opposite bottom side, the top side and the bottom side being joined to each other. The top side has a longitudinal extent and a transverse extent. The permeable enclosure also comprises an inlet port on the top side to receive sludge for filling the permeable enclosure. The inlet port is located generally centrally on the top side.

In accordance with another aspect, this disclosure also relates to a device for dewatering sludge. The device comprises a permeable enclosure. The permeable enclosure comprises a top side and an opposite bottom side, the top side and the bottom side being joined to each other. The top side has a longitudinal extent and a transverse extent. The permeable enclosure also comprises an inlet port on the top side to receive sludge for filling the permeable enclosure. The inlet port is located generally at midpoint of the longitudinal extent.

In accordance with another aspect, this disclosure also relates to a device for dewatering sludge. The device comprises a permeable enclosure. The permeable enclosure comprises a top side and an opposite bottom side, the top side and the bottom side being joined to each other. The top side has a longitudinal extent and a transverse extent. The permeable enclosure also comprises an inlet port on the top side to receive sludge for filling the permeable enclosure. The inlet port is located generally at midpoint of the transverse extent.

In accordance with another aspect, this disclosure also relates to a device for dewatering. The device comprises a permeable enclosure. The permeable enclosure comprises at least two inner layers of a first woven material and at least one outer layer of a second woven material. The permeable enclosure also comprises an inlet port. The second woven material has an apparent opening size (AOS) when measured according to ASTM D4751 that is greater than an AOS of the first woven material. The second woven material has a minimum tensile strength in a warp direction of the second woven material when measured according to ASTM 4595 that is greater than a minimum tensile strength in a warp direction of the first woven material. The second woven material has a minimum tensile strength in a weft direction of the second woven material when measured according to ASTM 4595 that is greater than a minimum tensile strength in a weft direction of the first woven material. The first woven material and the second woven material are biodegradable and derived from renewable sources.

In accordance with another aspect, this disclosure also relates to a device for dewatering. The device comprises a permeable enclosure. The permeable enclosure comprises at least two inner layers of a first woven material and at least one outer layer of a second woven material. The permeable enclosure also comprises an inlet port. The first woven material and the second woven material are biodegradable and derived from renewable sources. The device optionally has a surface area of 71 cm2and exhibits a solids concentration factor of at least 5 when dewatering a solution comprising solids for at least 24 hours.

In accordance with another aspect, this disclosure also relates to a device for dewatering. The device comprises a permeable enclosure. The permeable enclosure comprises at least two inner layers of a first woven material and at least one outer layer of a second woven material. The permeable enclosure also comprises an inlet port. The first woven material and the second woven material are biodegradable and derived from renewable sources. The device optionally has a surface area of 71 cm2and exhibits an initial dewatering rate of at least about 0.16 min′ for a solids content of about 11 wt %.

In accordance with another aspect, this disclosure also relates to a device for dewatering. The device comprises a permeable enclosure. The permeable enclosure comprises at least two inner layers of a first woven material and at least one outer layer of a second woven material. The permeable enclosure also comprises an inlet port. The first woven material and the second woven material are biodegradable and derived from renewable sources. The device optionally has a surface area of 8.7 m2and exhibits a solids concentration factor of at least 2 when dewatering a solution comprising solids for at least 52 days over 10 transfers.

It is to be expressly understood that the description and drawings are only for the purpose of illustrating certain embodiments and are an aid for understanding. They are not intended to be limitative.

DETAILED DESCRIPTION

The present disclosure generally relates to a device for removing liquid from a material (i.e., for dewatering the material) and comprising a biodegradable, permeable enclosure configured for receiving the material through an inlet. The permeable enclosure comprises layered biodegradable textiles, as further described below, which are derived from renewable resources. The permeable enclosure produces improved separation efficiency for variable waste sludge inputs and exhibits mechanical properties generally compatible with sludge dewatering applications.

With further reference toFIG. 1, a non-limiting embodiment of a device10for removing liquid from a material (i.e., for dewatering the material) is shown. The device10comprises a permeable enclosure12configured to define a closed compartment14for receiving the material to be dewatered. The compartment14is defined via two transverse seams161and162(not shown), a longitudinal seam18and a fold250in the permeable enclosure12, as further described below.

In this embodiment, the permeable enclosure12comprises an inner portion20and an outer portion22, the inner portion20directly facing the cavity14. The inner portion20may comprise at least two inner layers231and232, however any other suitable number of inner layers23imay be possible in other non-limiting examples (i.e., it may be any suitable number). Each one of the at least two inner layer231,232is made of a first woven material (e.g., a woven textile or fabric) and as such may be made of a certain amount of threads. The threads of each one of the at least two inner layers231and232comprise threads woven in two directions, with a first direction of the threads being perpendicular, or substantially perpendicular, to a second direction of the threads. The first and second directions of the threads may be referred to as weft and warp directions—the warp direction referring to the lengthwise (or longitudinal) direction of the threads that are held stationary in tension on a frame (as the woven material is being made), the weft direction referring to the transverse direction (i.e., perpendicular or substantially perpendicular to the warp direction) along which the threads are drawn through and inserted over and under the threads in the warp direction to form the woven material of either one of the at least two inner layers231and232.

Any suitable weave pattern and/or density of the first woven material may be used. The density of the first woven material may be defined as the number of threads per cm in the warp and weft directions. The higher the value, the more threads there are per cm, and thus the greater the density. The weave pattern may be defined as the pattern of interlacing of the threads in the warp and weft directions—plain weave for example is characterized by a repeating pattern where each warp thread is woven over on a weft thread and then under the next weft thread.

Still in this embodiment, each one of the at least two inner layers231and232of the inner portion20may be made of a single thread (i.e., the first woven material is a woven monofilament material), however either one of the at least two inner layers231and232may be made of a plurality of distinct threads in other embodiments. While each one of the at least two inner layer231,232is made of the same first woven material in this embodiment, this needs not be the case in other non-limiting embodiments.

While the at least two inner layers231,232exhibit some degree of freedom relative to each other (i.e., the inner layer231may move relative to the inner layer232in the x, y and z directions along substantially an entire surface of each one of the inner layers231and232, the at least two inner layers231,232are also secured relative to each other via the two transverse seams161and162and the lateral seam18, which notably defines the sealed compartment14.

In other non-limiting embodiments, while the at least two inner layers231,232exhibit some degree of freedom relative to each other (i.e., the inner layer231may move relative to the inner layer232in the x, y and z directions along substantially an entire surface of each one of the inner layers231and232), the at least two inner layers231,232are also secured relative to each other via the outer portion20at the two transverse seams161and162and the lateral seam18, which notably defines the sealed compartment14.

The inner portion20may be characterized in any suitable way. For example, in this embodiment, the inner portion20may be characterized by an apparent opening size (“AOS”) of the first woven material of which the at least two inner layers231and232are made, the AOS generally corresponding to the largest dimension of the opening formed by the weaving of two subsequent threads of the first woven material in both the warp and the weft directions. Within the context of the present disclosure, the AOS is therefore representative of the approximate largest opening dimension of the first woven material that is available for solid particles to pass through the inner portion20(i.e., to be retained by the inner portion20, the solid particles should exhibit a largest dimension greater than the AOS of the inner portion20). In some non-limiting examples, the AOS of the inner portion20when measured in accordance with ASTM D4751 may be between about 0.5 mm and 3 mm, in some cases between about 0.6 mm and 2.75 mm, in some cases between about 0.7 mm and 2.5 mm, in some cases between about 0.8 mm and 2.25 mm and in some cases between about 1 mm and 2 mm, however any other suitable AOS may be possible in other non-limiting examples. The inner portion20may be characterized in any other suitable manner, for example using the filtration opening size (FOS) method CAN CGSB148.1 No. 10, ASTM D6767 (Pore Size Characteristics of Geotextiles by Capillary Flow Test) and the likes.

It will be readily appreciated that when the at least two inner layers231and232are made of the same first woven material, the inner portion20, the inner layer231and the inner layer232will each exhibit the same AOS however, when the at least two inner layers231and232are not made of the same first woven material, the AOS of the inner portion20will be based upon the lowest AOS of either one of the at least two inner layers231,232, which in this case will constitute the approximate largest opening dimension available for material to pass through the inner portion20.

It will also be readily appreciated that the AOS of the inner portion20may be chosen such that at least some solid particles present in the material to be dewatered that is loaded in the sealed compartment14, as further described below, are retained within the sealed compartment14by the inner portion20(i.e., a largest dimension of the at least some of the solid particles of the material to be dewatered is greater than the AOS of the inner material20). As such, a water fraction of the material to be dewatered may permeate through the inner portion20while at least some of the solid particles of the material are retained within the sealed compartment14. As such, the AOS may generally be representative of the dewatering potential of the device10. The AOS of the inner portion20may also be chosen such that clogging and/or blinding of the device10is minimized during operation of the device10—for example, if it is known that the material to be dewatered comprises solid particles with a largest dimension of about 5 mm, selecting an inner portion20with an AOS of about 1 mm (i.e., 5 times smaller than the known largest dimension of the solid particles of the material to be dewatered) may result in clogging and/or blinding of the device10as a single particle may obstruct at once several openings.

The inner portion20(i.e., the first woven material) may also exhibit a minimum tensile strength in the warp direction when measured according to ASTM 4595 of at least about 7 kN/m, in some cases at least about 8 kN/m, in some cases at least about 9 kN/m and in some cases even more and a minimum tensile strength in the weft direction when measured according to ASTM 4595 of at least about 5 kN/m, in some cases at least about 6 kN/m, in some cases at least about 7 kN/m and in some cases even more. Still in this embodiment, a ratio of the minimum tensile strength in the warp direction to the minimum tensile strength in the weft direction of the inner portion20may be about 1.2, in some cases about 1.3, in some cases about 1.4 and in some cases even more.

Still in this embodiment, the first woven material may be biodegradable, i.e. it may be subject to biodegradation. Biodegradation may be defined in any suitable manner—for example the first woven material may be biodegradable as it experiences some physical and/or chemical change as a result of exposure to some environmental factor, such as but not limited to light, heat, moisture, wind, chemical conditions, or biological activity. For example, the first woven material may be degraded into carbon dioxide, water and biomass as a result of the action of microorganisms (e.g., bacteria, fungi and the likes) or enzymes. In some non-limiting examples, the first woven material may be entirely or substantially degraded in moist and warm conditions in less than 3 years, in some cases in less than 2 years, in some cases in less than 1 year and in some cases even less.

The first woven material may also be derived from renewable sources. Within the context of the present disclosure, the term renewable sources refers to sources that naturally replenish themselves to replace a portion that is depleted, used or consumed. This includes for example wood, plants and the likes. In this embodiment, the first woven material of the at least two inner layers231,232, which is biodegradable and derived from renewable sources may be any suitable material, such as but not limited to woven jute, woven hemp, woven flax and the likes.

Still in this embodiment, the device10also comprises an outer portion22comprising at least one outer layer241made of a second woven material. In this embodiment, the second woven material is different from the first woven material. Much like the first woven material, any suitable weave pattern and/or density of the second woven material may be used such that the weave pattern and/or density of the second woven material may be identical to, substantially identical to or different from the weave pattern and/or density of the first woven material. The second woven material is a woven monofilament material in this embodiment, however it may also be made of a plurality of distinct threads in other embodiments. While the outer portion22may also exhibit some degree of freedom relative to the inner portion20along substantially an entire surface of each one of the inner and outer portions20,22, the outer portion22is also secured to the inner portion20via the two transverse seams161and162(not shown) and the lateral seam18, thereby defining the sealed compartment14, as further described below.

The outer portion22may be characterized in any suitable way. For example, the outer portion22may exhibit a minimum tensile strength in the warp direction when measured according to ASTM 4595 of at least about 30 kN/m, in some cases at least about 31 kN/m, in some cases at least about 32 kN/m, in some cases at least about 33 kN/m, in some cases at least about 34 kN/m, in some cases at least about 35 kN/m, in some cases at least about 36 kN/m, in some cases at least about 37 kN/m, in some cases at least about 38 kN/m, in some cases at least about 39 kN/m, in some cases at least about 40 kN/m and in some cases even more. The outer portion22may also exhibit a minimum tensile strength in the weft direction when measured according to ASTM 4595 of at least about 10 kN/m, in some cases at least about 11 kN/m, in some cases at least about 12 kN/m, in some cases at least about 13 kN/m, in some cases at least about 14 kN/m and in some cases even more. Still in this embodiment, a ratio of the minimum tensile strength in the warp direction to the minimum tensile strength in the weft direction of the outer portion22may be about 2.5, in some cases about 2.6, in some case about 2.7, in some cases about 2.8, in some cases about 2.9, in some cases about 3, in some cases about 3.1, in some cases about 3.2, in some cases about 3.3, in some cases about 3.4 and in some cases even more.

In this embodiment, the outer portion22generally exhibits a minimum tensile strength in the warp direction when measured according to ASTM 4595, a minimum tensile strength in the weft direction when measured according to ASTM 4595 and a ratio of the minimum tensile strength in the warp direction to the minimum tensile strength in the weft direction that are greater than those of the inner portion20.

It will be readily appreciated that the minimum tensile strength in the warp and weft direction of the outer portion22may be chosen such that the outer portion22is configured to maintain the permeable enclosure12under hydraulic pressure when the device10is loaded with the material to be dewatered, for example when the minimum tensile strength of the outer portion20is at least about 36 kN/m in the warp direction and about 13 kN/m in the weft direction, specifically about 36.6 kN/m in the warp direction and about 13.8 kN/m in the weft direction.

The outer portion22(i.e., the second woven material) may also exhibit an AOS when measured in accordance with ASTM D4751 of between about 1 mm and about 5 mm. In a preferred embodiment, the AOS of the outer portion22may be greater than the AOS of the inner portion20, the inner portion20being generally configured for retention of the solid particles present in the material to be dewatered, the outer portion22being generally configured to maintain the permeable enclosure12under hydraulic pressure.

Still in this embodiment, much like the first woven material, the second woven material may be biodegradable and derived from renewable sources. As such, in some non-limiting examples, the second woven material may be entirely or substantially degraded in moist and warm conditions in less than 3 years, in some cases in less than 2 years, in some cases in less than 1 year and in some cases even less.

The second woven material may be any suitable material such as but not limited to woven coir (i.e., coconut fiber), woven jute, woven hemp and the likes.

With further reference toFIG. 5, the device10also comprises an inlet port26, the inlet port26being configured to engage any other corresponding port (e.g., male or female corresponding port) of a tube to convey and fill the sealed compartment14with the material to be dewatered. For example, the inlet port26allows a pump to be connected to the device10to fill the sealed compartment14with sludge. In this embodiment, the inlet port26may comprise an opening260which is sewn directly with the inner and outer portions20,22of the permeable enclosure12and thereby directly connects with the sealed compartment14. The opening260may be made of any suitable material, such as but not limited to a plastic material (e.g., reinforced polypropylene and the likes) or a metal (e.g., aluminum, steel and the likes) and may be of any suitable shape, such as but not limited to circular, square and the likes. The inlet port26also comprises a gasket264and a flange fitting262that are secured to the opening260sewn with the permeable enclosure12using at least one securing mean2661, such as but not limited to at least one threaded fastener (e.g., bolt or screw) and the likes, which effectively creates a sealed connection between the inlet port26and sealed compartment14. With respect to the length and the width of the device10, as shown inFIG. 1, the inlet port26may be positioned generally in a central location of the device10, that is generally in a middle of the length (from the first transverse seam161to the second transverse seam162) and, even more preferably a middle of the width (from the lateral seam18to the fold250) of the device10. Without wishing to be bound by theory, the generally central location of the inlet port26may facilitate the homogeneous distribution of the material to be dewatered within the device10as it is being filled. Any other suitable configuration of the inlet port26may be possible in other embodiments—for example, the inlet port26may be positioned generally at a midpoint of the longitudinal extent, at a midpoint of the transverse extent and the likes.

The device10may be of any suitable dimension and may be configured to receive any suitable volume of the material to be dewatered. For example, in some embodiment, the device10may have a length from the first transverse seam161to the second transverse seam162of about 3.8 m and a width from the lateral seam18to the fold250of about 2.3 m when the device10is not filled with any material. The device10may also be configured to receive a volume of material to be dewatered of about 8 m3. It will be readily appreciated that, in this embodiment, the device10is configured to exhibit a generally cylindrical and/or tubular shape at least along a central portion of the device10when the device10is loaded with the material to be dewatered. Without wishing to be bound by theory, the generally cylindrical and/or tubular configuration of the device10when loaded may minimize the potential points of failure at the seam. Any other suitable size and/volume of the device10may be possible in other embodiments.

With further reference toFIG. 2, a non-limiting embodiment of a process200for making the device10is shown. The at least two inner layers231and232and the at least one outer layer241are first each provided with an identical, or substantially identical, shape30comprising four sides31,32,33and34. While in this non-limiting example the shape30is square, any other suitable shape may be used in other non-limiting examples, i.e. the shape30may be substantially square, rectangular, substantially rectangular etc. The at least two inner layers231and232and the at least one outer layer241are superposed onto each other and then sewn together at step210along the four sides of the shape30(i.e., along sides31,32,33and34in this non-limiting example). Each one of the sides31,32,33and34may then be sewn together at step220with a border of reinforced polypropylene (RPE) plastic37, or any other suitable plastic. The shape30comprising the at least two inner layers231and232and the at least one outer layer241sewn together along sides31,32,33and34may then be folded along an axis36at step230and the device10is then formed at step240by sewing the border of RPE along the following sides:32together (i.e.,32first half+32second half),33together (i.e.,33first half+33second half) and31with34(31+34). It will be readily appreciated that sewing the sides32+32and33+33creates the transverse seams161and162, respectively, while the lateral seam18is created via sewing the sides31+34. In this example, the transverse seams161and162are therefore joined together via the lateral seam18on one side, and via the fold250in the permeable enclosure12. Any other suitable process for making the device10may be possible in other embodiments.

FIG. 3shows a variant of the process described inFIG. 2. In this non-limiting embodiment, a process300for making the device10is shown. The at least two inner layers23′1and23′2and the at least one outer layer24′1are first each provided with an identical, or substantially identical, shape30′ comprising four sides31′,32′,33′ and34′. While in this non-limiting example the shape30′ is square, any other suitable shape may be used in other non-limiting examples, i.e. the shape30′ may be substantially square, rectangular, substantially rectangular etc. The at least two inner layers23′1and23′2are larger, or substantially larger, than the at least one outer layer24′1. The at least two inner layers23′1and23′2and the at least one outer layer24′1are superposed onto each other and, with further reference toFIG. 4, the at least two inner layers23′1and23′2folded over the at least one outer layer24′1at step210′ along the four sides of the shape30′ (i.e., along sides31′,32′,33′ and34′ in this non-limiting example). Each one of the sides31′,32′,33′ and34′ may then be sewn together at step220′ and over the lines38A and38B to create the border37′. The shape30′ comprising the at least two inner layers23′1and23′2and the at least one outer layer24′1sewn together along sides31′,32′ and33′ may then be folded along an axis36′ at step230′ and the device10is then formed at step240′ by sewing the border along the following sides:32′ together (i.e.,32′ first half+32′ second half),33′ together (i.e.,33′ first half+33′ second half) and31′ with34′ (31′+34′). It will be readily appreciated that sewing the sides32′+32′ and33′+33′ creates the transverse seams16′1and16′2, respectively, while the lateral seam18′ is created via sewing the sides31′+34′. In this example, the transverse seams16′1and16′2are therefore joined together via the lateral seam18′ on one side, and via the fold250′ in the permeable enclosure12. Any other suitable process for making the device10may be possible in other embodiments.

EXAMPLES

The following examples are for illustrative purposes only and are not meant to limit the scope of the device described herein.

Dewatering tests were conducted to evaluate the sludge dewatering capabilities of various woven materials. Three devices were tested with different materials: device1with woven polypropylene, which is not biodegradable, not renewable and with an AOS of 0.425 mm; device2with a double layer of woven, biodegradable material derived from renewable sources and with an AOS of between about 1 mm and about 2 mm; and device3with2inner layers and one outer layer of woven, biodegradable material derived from renewable sources, the2inner layers with an AOS of between about 1 mm and about 2 mm and the outer layer with an AOS of between about 1 mm and about 5 mm. Devices1,2and3were made using samples of the materials having a surface of about 71 cm2, the devices being configured to receive a volume of sludge of about 50 L at a minimum of about 87 kPa head pressure. The sludge tested had an average solids content of 11.8 wt % and were dosed to a minimum of 40 ppm of coagulant and flocculent. The solids content (in wt %) of the retentate (i.e., dewatered sludge) and filtrate (drained fluid) were determined for quantitative comparison by performing mass measurements before and after drying in an 80° C. oven for a minimum of 24 hours. The solids concentration factor for the retentate (based on the ratio between the solid content in wt % of the retentate vs. the sludge) was also measured. The results are summarized in Table 1 below.

Device3exhibited a retentate solids content higher than that of devices1and2. Similarly, the solids concentration factor obtained with device3was higher than the one obtained with devices1and2. Also, while both devices2and3were able to dewater the tested volume of sludge using a single step of sludge transfer, device1required 3 different sludge transfers to address dewatering resistance. Of note, device3also dewatered a greater volume of sludge when compared to devices1and2.

With further reference toFIG. 6, the cumulative dewatering rates of the filtrate (in min′) during the first hour of dewatering for each one of devices1(items A(1), A(2) and A(3) for the first, second and third sludge transfers, respectively),2(item B) and3(item C) were also measured from volume measurements at various time intervals and plotted as a function of the solids content (in wt %) of the retentate. It can be appreciated that, generally, the higher the solids content of the retentate, the lower the dewatering rate. As can be seen fromFIG. 6, device3exhibited the highest initial dewatering rate with about 0.171 min−1for a solids content of about 11 wt %, decreasing to about 0.03 min−1for a solids content of about 22.2 wt %. By comparison, during the first transfer device1exhibited an initial dewatering rate of about 0.085 min−1for a solids content of about 9.5 wt %, while device2exhibited an initial dewatering rate of about 0.068 min−1for a solids content of about 20.1 wt %.

Dewatering tests were conducted to evaluate the sludge dewatering capabilities of various woven materials. Two devices were tested with different materials: device4with woven polypropylene, which is not biodegradable, not renewable and with an AOS of 0.425 mm and device5with2inner layers and one outer layer of woven, biodegradable material derived from renewable sources, the2inner layers with an AOS of between about 1 mm and about 2 mm and the outer layer with an AOS of between about 1 mm and about 5 mm. Devices4and5were made using samples of the materials having a surface of about 8.7 m2, the devices being configured to receive a volume of sludge of about 66 to 2,973 L over 10 to 17 transfers. The sludge tested had an average solids content of 40.6 wt % and were dosed to a minimum of 25 ppm of coagulant and flocculent. The solids content (in wt %) of the retentate (i.e., dewatered sludge) were determined for quantitative comparison by performing mass measurements before and after drying in an 80° C. oven for a minimum of 24 hours. The solids concentration factor for the retentate (based on the ratio between the solid content in wt % of the retentate vs. the sludge) was also measured. The results are summarized in Table 2 below.

The solids concentration factor obtained with device5was higher than the one obtained with device4. Also, device5was able to dewater a comparable total tested volume of sludge with 10 sludge transfers in comparison to device4that required 17 sludge transfers. Of note, device5also dewatered a comparable volume of sludge in fewer days than device4.

Certain additional elements that may be needed for operation of some embodiments have not been described or illustrated as they are assumed to be within the purview of those of ordinary skill in the art. Moreover, certain embodiments may be free of, may lack and/or may function without any element that is not specifically disclosed herein.

Any feature of any embodiment discussed herein may be combined with any feature of any other embodiment discussed herein in some examples of implementation.

In case of any discrepancy, inconsistency, or other difference between terms used herein and terms used in any document incorporated by reference herein, meanings of the terms used herein are to prevail and be used.

Although various embodiments and examples have been presented, this was for purposes of description, but should not be limiting. Various modifications and enhancements will become apparent to those of ordinary skill in the art.