WO2018152049A1

WO2018152049A1 - Bioremediation and mass-transfer using polyolefin packing

Info

Publication number: WO2018152049A1
Application number: PCT/US2018/017760
Authority: WO
Inventors: Stephen Y. LANG
Original assignee: Lantec Products, Inc
Priority date: 2017-02-14
Filing date: 2018-02-12
Publication date: 2018-08-23

Abstract

An improved mass-transfer packing is created by rolling a commercially available Corrugated Polypropylene (CP) sheet into a cylindrical structure which is then inserted into a cylindrical mass-transfer tower. The open channels within the CP sheet function as flow-channels for the flow of the liquid and gas therein to provide intimate contact between the liquid and gas for mass-transfer. An alternate economical embodiment of the improved mass-transfer packing utilizes stand-off projections such as ribs to increase the flow-capacity of the mass-transfer tower. Another alternate economical embodiment of the improved mass-transfer packing utilizes a CP sheet with two layers of open channels to increase the flow-capacity of the mass-transfer tower. Further, in any of these embodiments of the improved mass-transfer packing, the mass-transfer surface area of the packing can be increased by surface treating the surface of the CP sheet to provide pits and cavities on the CP sheet.

Description

Non-Provisional Patent Application

For

BIOREMEDIATION AND MASS-TRANSFER USING POLYOLEFIN

PACKING

Cross-Reference to Related Applications:

This application claims priority from US Provisional Applications No. 62458713 filed on February 14, 2017.

Field of the Invention

The present invention relates to bioremediation systems such as bio-trickling scrubbers and biological wastewater treatment systems which utilize a polyolefin packing for creating a biofilm wherein bioremediation of fluids containing pollutants is effected. The present invention relates also to non-bioremediation mass transfer systems such as strippers and scrubbers, cooling towers, and oil/water separators.

Background of the Invention:

Packed towers are used for mass transfer operations such as absorption, desorption, extraction, scrubbing, etc. The function of the packing is to facilitate mass transfer between two fluid streams, usually moving countercurrent to each other. Efficiency and rate of mass transfer are enhanced by providing a large surface area in the packing to facilitate contact of the fluids and by breaking the liquid into very fine droplets to enhance mass transfer to a gas phase. One of the most common usages of mass transfer packed towers is for the removal of Hydrogen-Sulfide (H₂S) from gaseous effluents from industrial and municipal plants using biological means. A typical bio-scrubber process for removing H₂S is shown in Fig. 1.

In the biological processing of water or other liquids, bacterial or other microbial cultures are used to convert substrates such as pollutants or organic matter which may be suspended or dissolved in the liquid. Typical applications include the removal of carbonaceous, nitrogenous, and phosphatic compounds from waste water and biosynthetic processes. The cultures are commonly in the form of a thin film (a biofilm) supported on a biofilm support. The biofilm support may comprise a plurality (sometimes thousands or millions) of small packing elements which are normally identical and randomly packed within the remediation apparatus. Further information on biological remediation is available on-line at www.lantecp.com.

The packing elements are normally shaped to give a large surface area to volume ratio, to give good liquid flow, and may comprise either random or structured packing. An example of a random packing which is commonly used in such applications is Lanpac® which is sold by Lantec Products Inc., Agoura Hills, California, U.S.A. and is described in www.lantecp.com. Alternately, a structured packing could be used. An example of a structured packing which is commonly used in such applications is HD-QPAC ® also described in www.lantecp.com. Yet another common packing that is used is foam packing.

All of these packing have their respective advantages and drawbacks. For example, randomly packed elements are relatively less expensive to manufacture and to install. However, they can pack together inside the tower such that the flow spaces (voidage) between them are too small for good liquid flow, substrate distribution, and bacterial growth, i.e. they can occlude one another. They can clog up with biofilm in biological processes if the biofilm becomes too thick. It is difficult to design a random packing element which is easy to manufacture but which gives good local contact between the biofilm and the liquid.

While structured packings are not as susceptible to occlusion as random packing, they are relatively more expensive to manufacture and to install. They may also be subject to channeling wherein the flow distribution of the fluid is not uniform over the entire body of the packing. Thus, the bioremediation efficiency of the packing is vitiated. Foam has high surface area for mass-transfer and is suitable for use with gaseous effluents that contain less than 100 ppm of Hydrogen-Sulfide. However when the Hydrogen-Sulfide concentration is high, the foam packing tends to get plugged which reduces the efficiency of the tower. Further, the foam has a high resistance to the flow of the gas through it. The physical structure of the foam also leads to wicking and collection of water into channels due to surface tension of water, causing uneven distribution and further reducing the efficiency of the tower. Also, foam has very little structural strength. Thus it tends to collapse within itself when it is soaked with a heavy liquid such as water.

As an improvement to foam packing, the HD-QPAC® has been designed for use in towers which can handle Hydrogen-Sulfide concentrations greater than 100 ppm. The HD-QPAC® has a lower physical surface area compared to foam but is less susceptible to wicking. Therefore, in practice, the effective surface area is greater than that of foam. Thus, the Hydrogen-Sulfide removal efficiency of HD-QPAC® is only moderately lower than that of foam despite its lower physical surface area. Research conducted by the applicant's company and others indicates that retention time for HD-QPAC® is about 6 seconds versus 8 seconds for foam to achieve comparable

Hydrogen-Sulfide removal efficiency.

The HD-QPAC® has a lower resistance to the flow of gas through it. Thus in situations where plugging is a concern, users prefer to use the HD-QPAC® as a tower packing instead of foam. The advantage of the HD-QPAC® is that maintenance costs to unplug the tower are reduced as frequent plugging of the tower is avoided. Towers using HD-QPAC® also experience lower downtime resulting in greater capital utilization. Also they are off-line less frequently resulting in reduced odor nuisance complaints from the surrounding community. The disadvantage is that HD- QPAC® is relatively more expensive than foam. Further a larger tower is required to provide the higher retention time required by the HD-QPAC® to achieve comparable Hydrogen-Sulfide removal efficiency. Thus the upfront capital costs of using HD-QPAC® are higher but are somewhat offset by the lower operating costs due to reduced gas-blower horsepower requirements and avoided maintenance to unplug the tower. Further details and advantages of the HD-QPAC® are listed in the applicant's website (www.lantecp.com). The above-mentioned problems with foam towers are further exacerbated by the way the foam is packed in the tower. In conventional foam towers, (shown in Fig.2), foam is rolled into cylindrical sections which are then inserted longitudinally into the cylindrical shell of the tower. This arrangement increases the resistance to flow within the foam resulting in high pressure drop and may cause wicking which might cause the water to flow in rivulets within the foam. Thus there are regions wherein the velocity of the liquid flowing within the packing may be too low to properly wet the entire surface of the foam, or to entrain any solids that may form or that may be precipitated from the liquid onto the surface of the foam. Over time, these deposits may grow larger and larger eventually choking the flow of the fluids within the tower.

There is therefore a need for a simple alternate packing which combines the superior performance of the HD-QPAC® with the low cost and simplicity of the foam packing. The packing should provide a highly effective surface area and high mass transfer efficiency without the concomitant problems of wicking and plugging described above. Summary:

In one embodiment of the improved mass-transfer packing described herein, a

commercially available Corrugated Polypropylene (CP) sheet is rolled into a cylindrical structure. The cylinder is then inserted into a cylindrical mass-transfer tower. The open channels within the CP sheet function as flow-channels for the flow of the liquid and gas therein. Intimate contact of the liquid and gas is thus effected resulting in an improved mass-transfer between the liquid and gas.

In another embodiment of the improved mass-transfer packing described herein, stand-off projections are provided on one planar surface of the CP sheet. When the CP sheet is rolled into a cylinder, the stand-off projections on the first planar surface create a helical cross-sectioned gap between the first and second planar surfaces of the CP sheet. Thus the flow-capacity of the mass- transfer tower is economically increased.

In another embodiment of the improved mass-transfer packing described herein, the standoff projections are configured as ribs. When the CP sheet is rolled into a cylinder, the ribs on the first planar surface cooperate with the second planar surface of the CP sheet to create additional flow-channels. Thus the flow-capacity of the mass-transfer tower is economically increased.

In another embodiment of the improved mass-transfer packing described herein, a CP sheet with two layers of channels is used to economically increase the flow-capacity of the mass-transfer tower.

In another embodiment of the improved mass-transfer packing described herein, any of the CP sheets described above can be horizontally packed to form cubes or oblong structures with the open channels all oriented in the same direction to function as flow channels for the passage of the gas and liquid there-through. The cubic or oblong configured packing can be utilized in a non- circular cross-sectioned mass-transfer tower.

Further, in any of the embodiments of the improved mass-transfer packing described herein, the mass-transfer surface area of the packing can be increased by surface treating. In this procedure, the surface of the CP sheet is roughened using water-soluble salts which are incorporated into the polyolefin resin mixture prior to the extrusion of the CP sheet. After extrusion, the salts are dissolved in water to create indentations or pits or cavities on the surface of the CP sheet. The area of the pitted surface is larger than the area of the non-pitted surface resulting in an increased surface area for mass-transfer between the liquid and gas. By increasing the proportion of water- soluble salts in the polyolefin resin mixture, cavities can be created within the body of the CP sheet to provide a reticulated foam structure to the body of the CP sheet. This enhancement also provides alternate flow pathways for the liquid and gas between the flow-channels should a flow-channel be clogged due to deposition of precipitated solids therein.

Description of the Drawings:

Figure 1 is a process-diagram representation of a typical bio-remediation tower.

Figure 2 is a vertical cross-sectional representation of a mass-transfer tower of the prior art which uses a foam packing as the mass-transfer media. The foam packing is configured as spirally wound (coiled) foam sheets arranged longitudinally within the tower shell.

Figure 3 is an isometric representation of a commercially available Corrugated Polypropylene (CP) sheet 10 which is used to create an improved packing. Figure 4 is a cross-sectional representation of flow channel 10c within the Corrugated Polypropylene (CP) sheet 10 shown in Fig. 3.

Figure 5 is an isometric representation of the Corrugated Polypropylene (CP) sheet shown in Fig. 3 which is rolled into a spirally coiled tube-like configuration to form Corrugated

Polypropylene Packing (CPP) 12 for use as an improved packing.

Figure 6 is a representation of a bioremediation tower 110 wherein the CPP 12 of Figure 5 are installed to provide an economical yet highly improved bioremediation process. The CPP 12 are supported on support structures which also provide disengaging spaces between the packing.

Figure 7 is another representation of a bioremediation tower 110 wherein the CPP 12 of Figure 5 are installed to provide an economical yet highly improved bioremediation process. All of the CPP 12 are supported on a single support structure without disengaging spaces between the packing.

Figure 8 is another representation of a bioremediation tower 110 wherein the CPP 12 of Figure 5 are installed to provide an economical yet highly improved bioremediation process. All of the CPP 12 are supported on a single support structure. One or more layers of FID-QPAC® are provided between adjacent CPP 12 to create disengaging spaces between the sheets.

Figure 9a is an isometric representation of a Corrugated Polypropylene sheet 14 which is surface treated to create an improved packing with even greater bioremediation efficiency or greater mass-transfer efficiency compared to the commercially available non-surface treated Corrugated Polypropylene sheet described in the above figures.

Figure 9b is an isometric detail representation of the Corrugated Polypropylene sheet 14 of Figure 9a showing the reticulated foam structure of the packing body.

Figure 10a is an isometric representation of an economical double stacked Corrugated Polypropylene sheet 16 which has multiple layers of flow channels which may be used to create an improved packing.

Figure 10b is a cross-sectional representation of flow channels 16c within the double stacked Corrugated Polypropylene sheet 16 shown in Fig. 10a. Figure 1 la is an isometric representation of another economical Corrugated Polypropylene (CP) sheet 18 which has external ribs 18r which function as flow channels when the CP sheet is coiled to create an improved packing.

Figure 1 lb is a cross-sectional representation of flow channels 18c within the ribbed Corrugated Polypropylene (CP) sheet 18 shown in Fig. 11a.

Figure 12 is an isometric representation of the Corrugated Polypropylene Packing (CPP) sheet 10 shown in Fig. 3 which is stacked into an oblong or cubic configuration 19 for use as an improved packing. Detailed Description:

As used herein, the term "mass-transfer tower" refers to any equipment that is used to facilitate the transfer of a chemical species from one fluid stream to another by a mass-transfer process such as diffusion, etc. with or without the use of a "packing" (defined below). Further, within the context of this description, the mass-transfer tower may incorporate colonies of live micro-organisms to metabolize certain chemical compounds which are deemed to be pollutants into harmless products of metabolization.

As used herein, the term "packing" refers to any structure that is used in a mass-transfer tower to create generally intimate contact between two fluid streams to facilitate the transfer of a chemical species between the fluid streams by a mass-transfer process such as diffusion, etc.

As used herein, the term "mass transfer position" refers to the positioning of the packing within the mass-transfer tower such that the first and second fluid streams can come into generally intimate contact with each other over the surface of the packing to facilitate the transfer of a chemical species from one fluid stream to another by a mass-transfer process such as diffusion, etc.

As used herein, the term "separation means" refers to physical structure that is used to separate a first layer of packing from an adjacent layer of packing to create a "gas-disengaging space" (defined below) between adjacent layers of packing in a mass-transfer tower.

As used herein, the term "standard tower support" refers to well-known physical structure that is commercially available to support packing within mass-transfer towers as described in Chemical Engineering handbooks, textbooks, and literature. As used herein, the term "gas-disengaging space" refers to the void space between the bottom of the physical structure that is used to support a layer of packing within the mass-transfer tower and the top of another layer of packing located below the support.

As used herein, the term "olefin" refers to a chemical compound made up of hydrogen and carbon that contains one or more pairs of carbon atoms linked by a double bond and having the general formula "CnH_2n". Olefins are also called alkenes. Examples of olefins are ethylene, propylene, butylene, etc.

As used herein, the term "polyolefin" refers to any chemical polymer that is created using olefin monomers such as ethylene, propylene, butylene, etc as building blocks.

As used herein, the term "polypropylene" refers to a chemical polymer that is created using propylene monomers as building blocks.

As used herein, the term "bioremediation tower" refers to a mass-transfer tower wherein live micro-organisms are used to metabolize harmful organic pollutants contained in one of the fluid streams to less harmful chemicals such as carbon-dioxide and water.

Applicant's improved packing provides highly effective surface area and high mass transfer efficiency without the concomitant problems of wicking and plugging described above. Applicant' improved packing is fabricated by coiling Corrugated Polypropylene (CP) sheets 10 into rolls 12 or stacking CP sheets into blocks 19 as described below. CP sheets 10 are similar to commonly used corrugated cardboard packing sheets but are made of polypropylene rather than cardboard. CP sheets 10 are commonly used for packing industrial and commercial items to protect them from damage during handling and transportation. CP sheets 10 are available from commercial sellers such as www.interstateplastics.com and retailers such as Home Depot and others.

Figure 3 shows a CP sheet 10 as commonly available from the above mentioned sources. CP 10 is generally available as rectangular sheets having a length "L" of 96 inches, a width "W" of 48 inches, and a thickness "T" which may vary between 0.125 to 0.25 inches. The process for manufacturing the CP sheet 10 creates tube-like channels 10c which are open at both ends and which run longitudinally in the width "W" direction. The thickness "T" corresponds to the width of the open channels which are generally square or rectangular in cross-section. However, the open channels 10c could have any suitable cross-sectional shape such as circular, semi-circular, triangular, hexagonal, trapezoidal, etc.

Figure 4 is a cross-sectional representation of one of open channels 10c which run longitudinally in the width "W" direction from end 10a to end 10b. The applicant uses channels 10c as flow channels in his improved packing, wherein the flow of the liquid and gas occurs primarily within channels 10c as described below.

To create the improved packing, applicant rolls CP sheet 10 along its length "L" into a tubelike configuration (as shown in Figure 5) to create a spirally coiled Corrugated Polypropylene Packing (CPP) 12 having a length "W" and a diameter "D" which provides a snug fit of CPP 12 inside the tower.

Figure 6 is a representation of an improved bioremediation tower 100 (similar to that shown in Figure 2) wherein CPP 12 have been inserted for use as mass-transfer packing. Improved bioremediation tower 100 comprises a vertical mass-transfer tower 110 wherein CPP 12 of Figure 4 are installed. Tower 110 is a standard design counter-flow mass-transfer tower with a lower gaseous effluent inlet 114, a lower liquid effluent outlet 118, an upper cleaned gas outlet 116, and an upper clean liquid inlet 112.

CPP 12 is installed within tower 110 such that flow channels 10c of CPP 12 are generally parallel to the longitudinal axis of tower 110. During operation of tower 110, the polluted fouled air which may contain Hydrogen Sulfide and other pollutants is introduced through the lower inlet 114 while make-up water with added nutrients is recirculated from bottom outlet 118 to upper inlet 112 by a recirculation pump. The make-up water is sprayed over CPP 12 which are located between upper inlet 112 and lower inlet 114. The flowrate of make-up water is adjusted to provide a smooth, laminar flow downwards over the internal surfaces of flow channels 10c without impeding the flow of the foul air upwards through flow channels 10c. (See www.lantecp.com/products/hd-q- pac/biotricklingarticle/ for further details of operation of a typical bio-remediation tower.)

The gas and liquid flowrates are selected to minimize the wicking and plugging within channels 10c of CPP 12. By maintaining the flowrates at a suitable level, small rivulets of liquid flowing within CPP 12 are prevented from coalescing and forming bigger streams within tower 110. Generally the velocity of the liquid stream over the surfaces of channels 10c of CPP 12 is maintained at approximately 1 foot per second. This assures that almost all the physical surface area of channels 10c of CPP 12 is utilized for mass-transfer. Very little of the physical surface area of CPP 12 is bypassed due to wicking of the liquid within CPP 12. Therefore the effective surface area of CPP 12 is almost equal to its physical surface area. Thus the mass-transfer efficiency of improved bioremediation tower 100 is increased relative to the prior art foam tower shown in Figures 1 and 2. Since the mass-transfer efficiency of improved bioremediation tower 100 is greater than that of the prior art bioremediation towers, less surface area and therefore a smaller quantity of packing is required compared to a prior art bioremediation tower.

Depending on the application, a plurality of CPP 12 can be provided within tower 110 as shown in Figure 6. Each CPP 12 or a smaller plurality of CPP 12 can be supported on support structure 120t within tower 110. Support structure 120t can be a metal or non-metal structure which is capable of bearing the load of liquid laden CPP 12 while still providing enough open volume to function as a gas disengaging space 120v. Within gas disengaging space 120v, the gas and liquid separate before entering the upper and lower CPP 12 respectively. Support structure 120t can be made of a suitable metal such as steel, aluminum, etc. or a suitable non-metal such as plastic, wood, concrete, fiberglass, or other fiber-reinforced plastic. In actual practice it is recommended that support structure 120t also be designed to support the weight of personnel who may stand on it during the initial installation of CPP 12 or during subsequent maintenance operations. Standard tower support structure such as those commercially available from suppliers such as Koch

Industries and Sulzer may be used also for this purpose.

It is imperative that as much of the gas and fluid streams flow within flow-channels 10c of CPP 12 as intimate contact of the gas and fluid streams is highly desirable for efficient mass- transfer. Therefore, it will obvious to persons skilled in the art to provide a central non-flow core to prevent the gas and liquid streams flowing within the tower from being diverted from flow channels 10c of CPP 12 during operation of the tower. The central non-flow core will divert the gas and liquid streams from the generally open central core of CPP 12 into flow-channels 10c in CPP 12. Alternately, some other means of blocking the flow from the center of the tower such as caps or baffles also can be provided for this function. Alternately as shown in Figure 7, all of the CPP 12 within tower 110 may be supported on a single support structure 120t. However, the risk of wicking and plugging may increase with such an arrangement.

An alternative arrangement of tower 100 is shown in Figure 8 wherein a layer of HD- QPAC® 120q is sandwiched between adjacent CPP 12 to provide the advantages of both CPP 12 and FID-QPAC® in a single bioremediation or mass-transfer tower. FID-QPAC® layer 120q will function not only in its normal capacity as a bio-environment or mass-transfer element but also as the disengaging space between adjacent coiled CPP sheets to reduce wicking as described above. This arrangement also has the added advantage of eliminating the relatively expensive intermediate support structure 120t shown in Figure 6.

The above description uses standard commercially available CP sheets in the

bioremediation and mass-transfer processes. The bioremediation and mass-transfer can be greatly enhanced by increasing the surface area of the Corrugated Polypropylene sheets that is available for creating the bio-film and for mass-transfer. The surface area of the Corrugated Polypropylene sheets can be easily increased by adding water-soluble salt crystals, such as Sodium Chloride

(NaCl) or Sodium Carbonate (NaC0₃), or other similar chemical compound to a plastic resin, such as Polypropylene, while the plastic resin is being fed to the raw material bin of the extruding machine used to extrude the Corrugated Polypropylene sheet. After the resin/chemical mixture gets melted and extruded, the finished cooled Corrugated Polypropylene sheet can subsequently be rinsed with water to remove the water-soluble chemical and leave indentations or pits or cavities 14v on the surface of CP sheet 14 as shown in Figure 9b. This modified method of manufacturing surface treated CP sheet 14 creates more surface area in the media for bacteria growth and for mass-transfer. An improved packing created by coiling surface treated CP sheet 14 as described above for CPP 12 will provide greater bioremediation efficiency or greater mass-transfer efficiency compared to the commercially available non surface treated Corrugated Polypropylene sheet.

If the cavities 14v are made deep enough, then some of the cavities will form holes 14h in the solid polypropylene structure of surface treated CP sheet 14 to create a porous foam -like structure (or reticulated structure or a matrix or a "Swiss-cheese" structure). Holes 14h will be randomly distributed in the polypropylene body of CP sheet 14. The hole size easily can be controlled by controlling the size of the water-soluble salt crystals in the extrusion process. The surface area and porosity of surface enhanced CP sheet 14 can be easily controlled by varying the proportions of water-soluble salt crystals and resins in the extrusion process. When CP sheet 14 is coiled to form a CPP (as described above for CPP 12), holes 14h can provide cross-channel flow within the CPP and thereby improve the intimate contact between the gas and liquid and enhance mass-transfer within the CPP. Thus the holes will improve the overall mass-transfer efficiency of the CPP. The holes also provide alternate flow pathways for the liquid and gas between the flow- channels should a flow-channel be clogged due to deposition of precipitated solids therein.

Other means of producing pits and cavities such as physically nicking the surface of the CP sheet or punching holes in the body of the sheet with a sharp tool may also be practiced to increase the surface area for mass-transfer.

It will be obvious that other configurations of the Corrugated Polypropylene sheet may be used to provide similar results. For example, Figures 10a and 10b show a representation of an economical double stacked Corrugated Polypropylene (CP) sheet 16 which has multiple layers of flow channels 16c which may be used to create an improved packing. Less polypropylene is required for this configuration without vitiating its function as an improved packing.

Yet another economical design is obtained by modifying CP 10 shown in Fig. 3 by providing stand-off projections on one of its planar surfaces. When this modified CP sheet is coiled as described above for CPP 12, these projections create a generally helically-cross-sectioned flow space within the coiled sheet wherein intimate contact between the gas and liquid can take place to facilitate mass-transfer. The stand-off projections could take any suitable shape such as interrupted ribs, short columns, etc. As one example, Figures 1 1a and 1 lb show a representation of an economical Corrugated Polypropylene (CP) sheet 18 which has external ribs 18r which will function as flow channels when CP sheet 18 is coiled as described above for CPP 12. Yet other configurations of stand-off projections will be obvious to persons skilled in the art. It will be obvious also that stand-off projections similar to those described above can be provided also for CP 16 of Figs. 10a and 10b.

The improved packing described herein has several advantages over the foam packing and HD-QPAC® packing of the prior art. For example, since channels 10c are linear, the velocity of the liquid over the internal surface of channels 10c can be increased to remove easily excess buildup of biofilm or other chemical precipitates which may be impeding the flow of the liquid and gas through the channels.

Yet another aspect of using the coiled CP sheet packing described herein is that it will be much easier to dislodge built-up sulfur and biofilm by spraying with liquid because the flow channels are straight compared to the tortuous flow channels in foam media or HD QPAC®. This is an important operational feature in bioscrubbers with high hydrogen sulfide loading where generally there is much sulfur-buildup in the bottom layers. With the coiled CP sheet packing described herein, it will be easy to clean those layers if access is designed into the tower.

The spirally coiled CP sheets 10 may be used in other mass-transfer tower applications such as absorbers, desorbers, scrubbers, distillation columns, etc. Such applications will be obvious to persons having ordinary skill in the art.

Alternately, as shown in Fig. 12, a plurality of CP sheets 10 can be stacked to form blocks 19 which can be installed in towers with a rectangular footprint. Alternately, block 19 can be cut as needed to fit the periphery void spaces between the free edge of a rolled CP sheet and the inner diameter of the tower. Yet alternately, block 19 can be cut to form a cylindrical flow core to fit the central void space of a round tower instead of installing a central non-flow core as described above. Blocks 19 are installed so that the liquid and gas can flow vertically downwards and upwards respectively within channels 10c. Such applications will be obvious to persons having ordinary skill in the art. It will also be obvious to use surface-enhanced sheets (CP 14) or double stacked sheets (CP 16) or ribbed sheets (CP 18) to form blocks 19 to enable more efficient mass-transfer.

Further it will obvious to that the surface treatment to increase effective mass-transfer can be applied to any one of the configurations of the CPP described above.

It is to be realized that only preferred embodiments of the invention have been described and that numerous substitutions, modifications and alterations are permissible without departing from the spirit and scope of the invention as defined in the following claims.

Claims

Claims:

I claim:

1) A packing for use in a mass transfer tower, the packing comprising

a generally flat rectangular or square sheet made of polyolefin,

the sheet having a major linear "L" dimension and a minor linear "W" dimension and internal through-open flow-channels generally oriented along its minor "W" dimension,

the sheet being spirally wound along its major "L" dimension to form a generally cylindrically coiled structure having flow channels generally axially oriented with the length of the cylindrical structure along its minor "W" dimension.

2) The packing of claim 1, wherein the sheet is a standard commercially available

Corrugated Polypropylene (CP) sheet having a single internal layer of flow channels generally oriented along its minor "W" dimension.

3) The packing of claim 2, wherein the CP sheet is further surface treated to create a

rough surface to provide a larger surface area for mass-transfer than the surface area of a standard commercially available corrugated polypropylene packing sheet.

4) The packing of claim 1, wherein the sheet is a corrugated polypropylene (CP) sheet having a single internal layer of through-open flow channels generally oriented along its minor "W" dimension and stand-off projections along one of its planar surfaces.

5) The packing of claim 4, wherein the stand-off projections are ribs which are generally oriented along its minor "W" dimension pf the sheet.

6) The packing of claim 4, wherein the sheet is further surface treated to create cavities which provide a larger surface area for mass-transfer. 7) The packing of claim 6, wherein the cavities are through holes which form cross-flow channels in the body of the sheet. 8) The packing of claim 1, wherein the sheet is a corrugated polypropylene (CP) sheet having at least two internal layers of through-open flow channels generally oriented along its minor "W" dimension.

9) The packing of claim 8, wherein the sheet is further surface treated to create cavities which provide a larger surface area for mass-transfer.

10) The packing of claim 9, wherein the cavities are through holes which form cross-flow channels in the body of the sheet. 11) The packing of claim 1, wherein the sheet is a polypropylene corrugated sheet (CP) having at least two internal layers of through-open flow channels generally oriented along its minor "W" dimension and stand-off projections along one of its planar surfaces. 12) The packing of claim 11, wherein the stand-off projections are ribs which are

generally oriented along its minor "W" dimension.

13) The packing of claim 11, wherein the sheet is further surface treated to create cavities which provide a larger surface area for mass-transfer.

14) The packing of claim 13, wherein the cavities are through holes which form cross- flow channels in the body of the sheet. 15) A mass transfer tower, wherein at least one of the packing of claim 1 is located ii mass transfer position within the tower.

16) A mass transfer tower, wherein more than one of the packing of claim 1 is located in a mass transfer position within the tower.

17) The mass transfer tower of claim 11, further including separation means between adjacent packings to create a gas-disengaging space there between. 18) The mass transfer tower of claim 17, wherein the separation means is HD-QPAC® supplied by Lantec Products Inc.

19) The mass transfer tower of claim 17, wherein the separation means is a standard tower support as practiced in chemical mass-transfer unit operations.

20) The mass transfer tower of claim 15, wherein the packing is colonized by live

micro-organisms which facilitate the destruction of pollutants in the influent fluid stream. 21) A packing for use in a mass transfer tower, the packing comprising

a plurality of generally flat rectangular or square sheets made of polyolefin, the sheet having a "L" dimension and a "W" dimension and internal through-open flow-channels generally oriented parallel to its "W" dimension,

the sheets being stacked together in an upright position to provide a generally oblong or cubic block with the flow channels generally vertically oriented for the flow of a fluid therein.

22) A mass transfer tower wherein at least one of the packing of claim 21 is located in a mass transfer position within the tower.