Device for biodegradation of sanitary napkins

Abstract

DEVICE FOR BIODEGRADATION OF SANITARY NAPKINS Abstract Disclosed is a device (100) for biodegradation of sanitary napkins. The device (100) is cost effective and provides a complete package for biodegradation of plastic as well as the cellulosic part of the sanitary napkins. The device (100) utilizes a synthetically engineered bacteria that has the capability of releasing extracellular degradation enzymes to deteriorate polyethylene (PE) based sanitary pads. The device (100) facilitates ecofriendly way of dealing with colossal amounts of menstrual waste produced each year. Figure 1

Description

DESC:DEVICE FOR BIODEGRADATION OF SANITARY NAPKINSField of the inventionThe present invention relates generally to a sanitary napkin biodegradation and more particularly, to a device for biodegradation of soiled sanitary napkins. Background of the inventionMenstruation has always been considered a taboo in India as well as many different cultures around the world and its waste management is till date an extremely distressing issue. About 336 million girls and women experience menstruation in India, which means that approximately 121 million of them use disposable sanitary napkins, which generates almost 9000 tons of menstrual waste annually. The average woman uses over 11,000 napkins over her lifetime, leaving behind residue far beyond her lifespan. Amongst various menstrual products such as pads, tampons, menstrual cups and cloth, disposable pads continue to remain a popular choice with women, with around 48 percent rural women using sanitary napkin while in urban areas the percentage is around 77 percent as reported by National Family Health Survey (NFHS) 2015-16 report. Discarding of this menstrual waste is a pronounced health and hygiene problem in India as well as around the globe. Most of the countries have developed techniques to manage their fecal and urinary waste but there is still lack of menstrual management practice in the world. In urban areas, where disposable menstrual products are scrapped away by flushing in toilets, throwing in dustbins or through solid waste management, in rural areas, there are many options for getting rid of menstrual waste such as by burying, burning, and throwing in garbage or in pit latrines. What makes conventional sanitary napkins so problematic is their plastic component. A typical pad consists of a) a top sheet made out of polypropylene (PP) or polyethylene (PE) for quick fluid transfer, b) a superabsorbent polymer made out of cellulose or cotton fibers, or acrylic based polymer (sodium / potassium acrylate) that forms gel after absorbing liquid, c) barrier sheet which seals the fluids from leaking or staining clothes, made again from polyethylene and d) Others: adhesives, stickers, odor repellants, lotions, perfumes, and the like. The plastic used in these napkins can take up to 500-800 years to decompose.Currently in India, there is no standardized system for menstrual waste disposal. Disposable pads fall under the Solid Waste Management Rules as Domestic Hazardous Waste – meaning they can be thrown out with household garbage. So they usually end up in landfills and become a breeding ground for potential blood borne pathogens, posing a risk to workers coming in contact with them. Another way of tackling these products is incineration. The incineration involves burning at a specific high temperature in a contained space with monitored emissions. However, due to reckless and unregulated control, burning plastics at less temperature or in an open environment causes improper combustion of these products resulting in release of toxic carcinogenic pollutants like dioxins. Most of the prior art deals with incinerators which either uses bulk incineration or individual pad incinerations. In this method, the waste material is heated at high temperature, mostly above 600 °C. During the heating, the fumes are produced which mainly contain toxic gases like dioxins and furans. These gases cause heavy air pollution. To overcome this problem, some efforts are seen in the prior art to develop an eco-friendly process for the degradation of sanitary pads.Reference may be made to Indian patent application no. 201821021430 that deals with an ecofriendly incinerator to dispose of the used sanitary napkins and bio medical waste. The incinerator comprises an outer shell with provision for charging the material to be incinerated provided with an insulted lid and another opening for the entry of the chimney from the combustion chamber and the bottom portion of the outer shell is provided with a perforated bottom cover for the entry of the air required for combustion, while the combustion chamber houses the heaters in the openings provided at its lower portion and having a grill at its bottom to support the material during combustion and allow the combustion products to fall in to the tray for disposal. The combustion chamber has perforations at upper portion for entry of secondary combustion air. An open bottom sheet metal envelop, having insulation is positioned in between the outer shell and combustion chamber. However, in this invention the material is being incinerated and for the process of combustion high amount of energy is required. Another Indian patent application no. 201921007051 relates to sanitary napkin and similar products disposal device. The object of the invention is to provide an automatic sanitary napkin burning device for safe disposal of used sanitary napkins and similar. This device is compact and having unique shape, height to diameter ratio (1.5) for better stability. More particularly, the napkin incinerator runs by electronic controlling device and provides the users to keep the used napkins inside the combustion chamber of incinerator and this can help in partially waste disposal management. However, for burning of the napkins high temperature has to be maintained. This increases the operating cost of the device. Also, after burning it generates the polluting gases which are responsible for polluting the environment.Another Indian patent application no. 201621027334 discloses an automatic sanitary napkin discarding device. The device includes a tank, a controlling panel and a smoke outlet. The reflecting heat is used to burn the sanitary napkins. The controlling panel is controlling the electric power thus device will start and stop automatically. It is provided with a removable ash tray which collects the ash resulting from burning of the sanitary napkins. Device also has smoke filter, which filter the smoke, trap carbon particles and other element and will throw cleaner smoke in environment. This invention is applicable to all kind of sanitary waste component and products. However, this invention needs electricity for generating the high temperatures for burning. Also after burning, the smoke is produced and to treat that smoke efficient filters need to be used otherwise the generated smoke is hazardous to the environment this increases complexity in design thereby increasing the cost.One of the major components of the sanitary napkins is cellulose. Most sanitary napkins employ cellulose based absorbent core to enhance the retention of fluid as they are environment friendly, biodegradable and excellent biocompatible (Hubbe MA, Ayoub A, Daystar JS, Venditti JS, Pawlak JJ, et al. (2013). However, the methodologies used in the prior art are using the incineration of the sanitary pads and no methods reported so far employ microbes for the degradation of sanitary napkins / pads. Accordingly, there exists a need to provide a device for biodegradation of sanitary napkins that overcomes the above mentioned drawbacks of the prior art.Objects of the inventionAn object of the present invention is to design and develop a new device to facilitate the biodegradation of polyethylene (PE) based sanitary napkins / pads.Another object of the present invention is to construct a synthetically engineered bacterium that has the capability of releasing extracellular degradation enzymes to deteriorate polyethylene (PE) based sanitary napkins.Summary of the inventionAccordingly, the present invention provides a device for biodegradation of sanitary napkins. The device comprises a cutter, a first chamber, a second chamber, a plurality of ultra-violet lamps, a shaft, a conveyor, a plurality of spray nozzles, a plurality of air nozzles and an outlet.The cutter receives sanitary napkins to be disposed of through an inlet. The first chamber is used for shredding plastic of the sanitary napkin into small pieces and for storing shredded plastic therein. The second chamber is a cylindrical shape vessel having a funnel shape bottom. The second chamber is connected to the first chamber and designed for degrading the shredded plastic received therefrom. The transfer of the shredded plastic from the first chamber to the second chamber is controlled by a valve. The plurality of ultra-violet lamps is positioned on a top portion inside the second chamber for sterilization of the shredded plastics before and after the degradation process. The shaft is suspended centrally in the second chamber. The conveyor is configured on the shaft for moving the shredded plastic in an upward direction and a downward direction in the second chamber. Specifically, the conveyor is a helical screw conveyor. The outlet is configured on the bottom portion of the second chamber for removing the degraded plastic and byproducts therefrom. The outlet includes a valve configured therein for controlling the removal of the degraded plastic and byproducts.The plurality of spray nozzles is configured on the top portion inside the second chamber and below the plurality of ultra-violet lamps. The plurality of spray nozzles is used for spraying the synthetically engineered bacteria in the second chamber. The plurality of spray nozzles receives the synthetically engineered bacteria through an inlet. The plurality of air nozzles is configured on a bottom surface of the second chamber. The plurality of air nozzles receives the air through an air inlet. The air leaves the second chamber through an air outlet. The air inlet includes an air filter configured therein and the air outlet includes an air filter configured therein.The device utilizes the synthetically engineered bacteria that release extracellular degradation enzymes that degrade the polymer present in the sanitary napkins. In an embodiment, the device utilizes synthetically engineered E.coli with cellulase gene. In another embodiment, the device utilizes synthetically engineered Pseudomonas aeruginosa having polyethylene degrading enzymes expressed in the presence of T7 promoter and cutinase gene. The polyethylene degrading enzymes are selected from any one of alkane hydroxylase, manganese peroxidise and lignin peroxidases.In another embodiment, the device utilizes synthetically engineered Trichoderma reesei having polyethylene degrading enzymes expressed in the presence of cellobiohydrolase 1. The polyethylene degrading enzymes are selected from any one of alkane hydroxylase, manganese peroxidise, lignin peroxidases and laccase. In yet another embodiment, the device utilizes synthetically engineered Pseudomonas aeruginosa and the Pseudomonas sp with laccase gene expressed in presence of T7 promoter.Brief description of the drawingsFigure 1 shows a device for biodegradation of sanitary napkins, in accordance with the present invention; Figure 2 shows a schematic of a genetic circuit of a synthetically engineered bacterium employed in the device for biodegradation of soiled sanitary napkin, in accordance with an embodiment of the present invention;Figure 3 shows a schematic of a genetic circuit of a synthetically engineered bacterium employed in the device for biodegradation of soiled sanitary napkin, in accordance with another embodiment of the present invention; and Figure 4 shows a schematic of a genetic circuit of a synthetically engineered bacterium employed in the device for biodegradation of soiled sanitary napkin, in accordance with yet another embodiment of the present invention.Detailed description of the inventionThe foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.The present invention provides a device for biodegradation of soiled sanitary napkins. The device provides a complete package for biodegradation of plastic as well as the cellulosic part of the sanitary napkins. The device utilizes specific microbes produced by a synthetic biology for biodegradation of different parts of the sanitary napkins. This present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.Now referring to figure 1, a device (100) for biodegradation of soiled sanitary napkins in accordance with the present invention is shown. In an embodiment, the device (100) is made up of stainless steel. However, it is understood here that the device (100) can be made of any other suitable material in other alternative embodiments. As shown in figure 1, the device (100) comprises a cutter (4), a first chamber (8), a second chamber (12), a plurality of ultra-violet lamps (16) (hereinafter, “UV lamps (16)”), a conveyor (20), a shaft (24), a plurality of spray nozzles (28), a plurality of air nozzles (32) and an outlet (60).The cutter (4) receives the sanitary napkins / raw plastic to be disposed of through an inlet (2). The cutter (4) is positioned on the first chamber (8). The first chamber (8) is designed to shred plastic of the sanitary napkin into small pieces. The shredded plastic is stored in the first chamber (8). The shredded plastic from the first chamber (8) is transferred to the second chamber (12) through a transferring means (not shown). The transferring means includes a pneumatic transfer, a conveyor and other suitable means known in the art. The transfer of the shredded plastic from the first chamber (8) to the second chamber (12) is controlled by a valve (36). The valve (36) is closed after transfer of the shredded plastic as per requirement to the second chamber (12) to avoid contamination. In an embodiment, the valve (36) is a pneumatic valve. However, it is understood here that any other type of valve (36) may be used in other alternative embodiments of the present invention.The second chamber (12) is connected to the first chamber (8). The second chamber (12) is a cylindrical shape vessel that includes a funnel shape bottom. The second chamber (12) is designed to degrade the shredded plastic. The UV lamps (16) are positioned on a top portion inside the second chamber (12). The shaft (24) is suspended centrally in the second chamber (12). The conveyor (20) is configured on the shaft (24). In an embodiment, the conveyor (20) is a helical screw conveyor. However, it is understood here that any other type of conveyor (20) may be used in other alternative embodiments of the device (100). The conveyor (20) is used to move the shredded plastic in an upward direction and a downward direction in the second chamber (12).The plurality of spray nozzles (28) are configured on the top portion inside the second chamber (12) and below the UV lamps (16). The plurality of spray nozzles (28) is used for spraying the synthetically engineered bacteria. The plurality of spray nozzles (28) receives the synthetically engineered bacteria i.e. cell biomass / microbes through an inlet (40). The UV lamps (16) are used for sterilization of the shredded plastics before and after the degradation process. In accordance with the present invention, the UV radiation eliminates the risk factors in the device (100). Further, the device (100) is completely sterilized by passing the hot air through an air inlet (44). The plurality of air nozzles (32) are configured on a bottom surface of the second chamber (12). The plurality of air nozzles (12) receives the air through the air inlet (44). The air inlet (44) includes an air filter (48) configured therein. In the second chamber (12), the aeration is also provided. The air leaves the second chamber (12) through an air outlet (52). The air outlet (52) includes an air filter (56) configured therein to avoid contamination. In an embodiment, the air filters (48, 56) have capacity of 0.2 micron. However, it is understood here that the air filters (48, 56) having different filtering capacity may be used in other alternative embodiments of the device (100). The degraded plastic and byproducts are removed from the second chamber (12) through the outlet (60). The outlet (60) is configured on the bottom portion of the second chamber (12). The outlet (60) includes a valve (64) configured therein for controlling removal of the degraded plastic and byproducts from the second chamber (12). In an embodiment, the valve (64) is a mechanical valve. However, it is understood here that any other type of valve (64) may be used in other alternative embodiments of the present invention. Specifically, the degraded plastics and by-products are removed from the bottom side of the second chamber (12) with the help of a helical screw conveyor and a pneumatic transportation.In accordance with the present invention, the device (100) utilizes specific microbes / engineered bacteria produced by a synthetic biology for biodegradation of different parts of the sanitary napkins. The synthetically engineered bacteria release extracellular degradation enzymes that degrade the polymer present in the sanitary napkins. Figure 2 shows a schematic of a genetic circuit of the synthetically engineered bacteria employed in the device (100). Specifically, the vector / synthetically engineered bacterium comprise a cellulose inducible promoter, which makes it specific to cellulose based waste only. In an embodiment, the synthetically engineered bacteria are E.coli with cellulase gene. In accordance with the present invention, cellulase gene (Biobrick: BBa_K805011) is constitutively overexpressed in the synthetically engineered E.coli. The cellulase cleaves cellobiose residues and ß -glycosidic bonds in the cellulose chain thereby hydrolysing cellulose to soluble oligosaccharides such as sophorose (2-0-,3-glucopyranosyl-Dglucose). Specifically, cbh1 promoter (GenBank: D86235.1; 70044 to 71544) from T. reesei is employed to directly activate gene expression in response to cellulose degradation. Cellulose degradation acts as an inducer for de novo production and secretion of downstream genes, starting a cycle where glucose and sophorose are produced until the complete cellulose degradation thereby providing the immobilized cellulose as an inducer for the expression of plastic degrading enzymes, biofilm formation and also acts as carbon source for growth of the synthetically engineered bacteria. As shown in figure 2, the genetic circuit consists of a cbh1 regulated laccase (Biobrick: BBa_K729002) or PETase (Biobrick: BBa_K808025) and biofilm formation gene (Biobrick: BBa_K805015). The wild type microorganisms deteriorate polyethylene with the help of degradative enzymes and the degradation is enhanced when the biofilm is involved. Figure 3 shows a schematic of a genetic circuit of the synthetically engineered bacteria employed in the device (100) in accordance with another embodiment of the present invention. In this one embodiment, the synthetically engineered bacteria are Pseudomonas aeruginosa having polyethylene degrading enzymes expressed in the presence of T7 promoter and cutinase gene. Specifically, the polyethylene degrading enzymes are selected from anyone of alkane hydroxylase (AlkB: EC 1.14.15.3), manganese peroxidise (EC 1.11.1.13) and lignin peroxidases (EC 1.11.1.14). The polyethylene degrading enzymes and cutinase (EC 3.1.1.74) genes are expressed constitutively in the presence of T7 promoter in a Pseudomonas aeruginosa system.The sanitary napkins are pretreated with UV irradiation and pro-oxidants before incubating with genetically modified organism. The UV irradiation helps in reducing the polymer chain size and enhances the surface roughness and hydrophilicity, which helps colonization (biofilm formation) of Pseudomonas on the surface of a polymer. Similarly, the treatment with pro- oxidants results in the formation of oxidized groups such as carboxyl, carbonyl and hydroxyl on the surface of polymer. These are further potentially metabolized enzymatically after incubating with synthetically engineered Pseudomonas aeruginosa with AlkB and cutinase gene, wherein alkane hydroxylase participate in n-alkane oxidation pathway by hydroxylating the terminal carbon. Similarly, cutinase hydrolyses the polypropylene ultimately mineralizing to CO2 and H2O or byproducts of metabolism which are exploited for the biosynthesis of valuable products like polyhydroxyalkanoates (PHA) and biosurfactants (BS) through the metabolic pathway of Pseudomonas aeruginosa.Figure 4 show a schematic of a genetic circuit of the synthetically engineered bacteria employed in the device (100) in accordance with yet another embodiment of the present invention. In this one embodiment, the synthetically engineered bacteria are Trichoderma reesei having polyethylene degrading enzymes expressed in the presence of cellobiohydrolase 1. To design synthetically engineered organism which is more stable and to increase the production of enzymes with high and natural capacity, the filamentous fungus Trichoderma reesei (T. reesei) is exploited in the degradation of polymer present in the sanitary napkins.The polyethylene degrading enzymes are selected from anyone of alkane hydroxylase (AlkB: EC 1.14.15.3), manganese peroxidise (EC 1.11.1.13), lignin peroxidases (EC 1.11.1.14) and laccase (EC 1.10.3.2). The polyethylene degrading enzymes are expressed in the presence of native cellulolytic gene promoters, especially cellobiohydrolase 1 (cbh1) (Figure 4). These promoters are strongly activated in the presence of mainly cellulose and derivatives thereof which is one of the major components of the sanitary napkins. The native hydrophobin and cutinase genes facilitate the degradation of polypropylene initially. Further, Trichoderma speed up the process of degradation by forming a biofilm naturally on the surface of the polymer. In yet another embodiment, the synthetically engineered Pseudomonas aeruginosa and the Pseudomonas sp with laccase gene expressed in presence of T7 promoter are co-cultivated. This compatible combination of species with different polymer degrading genes helps to degrade the different types of polymer within a shorter period of time. Advantages of the invention:1. The device (100) is cost effective and utilizes a synthetically engineered bacterium that has the capability of releasing extracellular degradation enzymes to deteriorate polyethylene (PE) based sanitary pads. 2. The device (100) provides a complete package for biodegradation of plastic as well as cellulosic part of the sanitary napkins.3. The device (100) facilitates ecofriendly way of dealing with colossal amounts of menstrual waste produced each year.4. The present invention facilitates regulation of cellulose inducible promoters to control endogenous or heterologous genes expression with an inexpensive inducing agent thereby achieving great commercial benefit.The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the present invention.

Claims

,CLAIMS:We claim:

1. A device (100) for biodegradation of sanitary napkins, the device (100) comprising:a cutter (4) for receiving sanitary napkins to be disposed of through an inlet (2), a first chamber (8) for shredding plastic of the sanitary napkin into small pieces and for storing shredded plastic therein;a second chamber (12) being a cylindrical shape vessel having a funnel shape bottom, the second chamber (12) connected to the first chamber (8) and designed for degrading the shredded plastic received therefrom;a plurality of ultra-violet lamps (16) positioned on a top portion inside the second chamber (12) for sterilization of the shredded plastics before and after the degradation process;a shaft (24) suspended centrally in the second chamber (12), the shaft (24) having a conveyor (20) configured thereon for moving the shredded plastic in an upward direction and a downward direction in the second chamber (12);a plurality of spray nozzles (28) configured on the top portion inside the second chamber (12) and below the plurality of ultra-violet lamps (16), the plurality of spray nozzles (28) used for spraying the synthetically engineered bacteria in the second chamber (12), the plurality of spray nozzles (28) receives the synthetically engineered bacteria through an inlet (40); a plurality of air nozzles (32) configured on a bottom surface of the second chamber (12), the plurality of air nozzles (12) receives the air through an air inlet (44), the air leaves the second chamber (12) through an air outlet (52); andan outlet (60) configured on the bottom portion of the second chamber (12) for removing the degraded plastic and byproducts therefrom, the outlet (60) having a valve (64) configured therein for controlling the removal of the degraded plastic and byproducts,wherein, the synthetically engineered bacteria release extracellular degradation enzymes that degrade the polymer present in the sanitary napkins.

2. The device (100) as claimed in claim 1, wherein the transfer of the shredded plastic from the first chamber (8) to the second chamber (12) is controlled by a valve (36).

3. The device (100) as claimed in claim 1, wherein the conveyor (20) is a helical screw conveyor.

4. The device (100) as claimed in claim 1, wherein the air inlet (44) includes an air filter (48) configured therein and the air outlet (52) includes an air filter (56) configured therein.

5. The device (100) as claimed in claim 1, wherein the synthetically engineered bacteria are E.coli with cellulase gene.

6. The device (100) as claimed in claim 1, wherein the synthetically engineered bacteria are Pseudomonas aeruginosa having polyethylene degrading enzymes expressed in the presence of T7 promoter and cutinase gene.

7. The device (100) as claimed in claim 6, wherein the polyethylene degrading enzymes are selected from any one of alkane hydroxylase, manganese peroxidise and lignin peroxidases.

8. The device (100) as claimed in claim 1, wherein the synthetically engineered bacteria are Trichoderma reesei having polyethylene degrading enzymes expressed in the presence of cellobiohydrolase 1.

9. The device (100) as claimed in claim 8, wherein the polyethylene degrading enzymes are selected from any one of alkane hydroxylase, manganeseperoxidase, lignin peroxidases and laccase.

10. The device (100) as claimed in claim 1, wherein the synthetically engineered bacteria are Pseudomonas aeruginosa and the Pseudomonas sp with laccase gene expressed in presence of T7 promoter.