EP2190802A1

EP2190802A1 - Methods and systems for feedstock production from sewage

Info

Publication number: EP2190802A1
Application number: EP08795282A
Authority: EP
Inventors: Refael Aharon; Israel Biran
Original assignee: Applied Cleantech Inc
Current assignee: Applied Cleantech Inc
Priority date: 2007-08-13
Filing date: 2008-08-13
Publication date: 2010-06-02
Also published as: WO2009023216A1; CN101784505A

Abstract

A cellulosic feedstock composition including a sand content of less than 5% of the composition, an oil content of 1-15% of the composition, a lignin content of less than 10% of the composition, a cellulose content of 40-99% of the composition, and a hemicellulose content of 1-20% of the composition.

Description

METHODS AND SYSTEMS FOR FEEDSTOCK PRODUCTION FROM SEWAGE

REFERENCE TO CO-PENDING APPLICATIONS

Applicant hereby claims priority of U. S. Provisional Patent Application

Serial No. 60/935,429, filed on August 13, 2007, entitled "Device and Methods for Fiber

Extraction" and U. S. Provisional Patent Application Serial No. 61/071,842, filed on May

21, 2008, entitled "Device and Methods for Feedstock Production from Sewage" both incorporated herein by reference, in their entireties.

FIELD OF THE INVENTION

The present invention relates generally to methods and systems for producing feedstock from sewage and more specifically relates to methods and systems for producing cellulosic feedstock from sewage.

BACKGROUND OF THE INVENTION

Cellulose is an organic compound defined as a polysaccharide structured of a linear chain of several hundred to over ten thousand glucose units.

Fibers comprising cellulose can be found in sewage systems, such as municipal sewage waste systems.

The source of cellulose fibers in the municipal sewage waste system is typically from fruits and vegetables, paper, cloths and laundry refuse. For example, a cellulose fiber portion of raw sewage, i.e. untreated sewage, comprises generally 30 - 50% textile fibers, 10 - 35% vegetative fibers and 20 - 40% paper fibers. SUMMARY OF INVENTION

There is thus provided in accordance with an embodiment of the present invention a cellulosic feedstock composition including a sand content of less than 5% of the composition, an oil content of 1-15% of the composition, a lignin content of less than 10% of the composition, a cellulose content of 40-99% of the composition, and a hemicellulose content of 1-20% of the composition. Preferably, the cellulose content includes 60-90% of the composition. Additionally, the cellulosic feedstock composition further includes a nonorganic matter content of less than 30% of the composition. Moreover, the cellulosic feedstock composition further includes an organic matter content of 1-15% of the composition.

In accordance with an embodiment of the present invention the composition is produced from a solid portion of a sewage suspension. Preferably, the composition is produced from the solid portion of the sewage suspension by (i) trapping the solid portion from the sewage suspension, and (ii) removing sand from the solid portion, thereby producing the composition. Additionally, the composition is produced by any one of the following (i) grinding the solid portion (ii) sterilizing the solid portion, and (iii) at least partially drying the solid portion. hi accordance with another embodiment of the present invention trapping the solid portion is performed by a device selected from the group consisting of a netting, a plurality of nettings, a device employing Dissolved Air Floation technology, a conveyor belt formed of conveyor belt mesh, a centrifuge, a flow centrifuge, a hydrocyclonic centrifuge, a screw press, a disk filter, a filter press, a media filter, a filter containing fibers, a biological filter, a filter containing cellulose, a chemical filter, a filter containing silica and a filter employing backflushing technology. Preferably, removing sand is performed by centrifugation, hydrocyclonic centrifugation, vibration sedimentation, ultrasonic sedimentation or Dissolved Air Floation technology. Additionally, removing sand is performed prior to trapping the solid portion or following trapping the solid portion.

There is thus provided in accordance with another embodiment of the present invention a method for producing a cellulosic feedstock composition from a solid portion of a sewage suspension including (i) trapping the solid portion from the sewage suspension, and (ii) removing sand from the solid portion, thereby producing the cellulosic feedstock composition. Preferably, removing sand is performed prior to trapping the solid portion. Additionally, removing sand is performed following trapping the solid portion. Moreover, removing sand is operative to decrease a sand contact of the composition to less than 5% of the composition. In accordance with another embodiment of the present invention the method includes at least one of the following (i) grinding the solid portion, (ii) sterilizing the solid portion, and (iii) at least partially drying the solid portion. Additionally, the composition includes a sand content of less than 5% of the composition, an oil content of 1-15% of the composition, a lignin content of less than 10% of the composition, a cellulose content of 40- 99% of the composition and a hemicellulose content of 1-20% of the composition. Preferably, the method further includes a non-organic matter content of less than 30% of the composition. Additionally, the method further includes an organic matter content of 1-15% of the composition.

In accordance with yet another embodiment of the present invention the composition is produced from a solid portion of a sewage suspension. Preferably, trapping the solid portion is performed by a device selected from the group consisting of a netting, a plurality of nettings, a device employing Dissolved Air Floation technology, a conveyor belt formed of conveyor belt mesh, a centrifuge, a flow centrifuge, a hydrocyclonic centrifuge, a screw press, a disk filter, a filter press, a media filter, a filter containing fibers, a biological filter, a filter containing cellulose, a chemical filter, a filter containing silica and a filter employing backfiushing technology. Additionally, removing sand is performed by centrifugation, hydrocyclonic centrifugation, vibration sedimentation, ultrasonic sedimentation or Dissolved Air Floation technology.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a simplified block diagram of a system for producing cellulosic feedstock from sewage, constructed and operative in accordance with an embodiment of the present invention; and Fig. 2 is a graph of a solid composition obtained from raw sewage prior to processing in the system of Fig. 1 Vs. a resulting cellulosic feedstock composition following processing in the system of Fig.l . DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to Fig. 1, which is a simplified block diagram of a system for producing cellulosic feedstock from sewage, constructed and operative in accordance with an embodiment of the present invention. As seen in Fig. 1, sewage 10 may be introduced into an initial sand removal device 12.

Sewage 10 may be raw sewage, i.e. sewage flowing within a sewerage waste system prior to standard wastewater treatment thereof. Raw sewage may flow from a municipal sewage waste system or any other sewerage system, such as, for example, industrial or agricultural waste systems.

Raw sewage of the municipal sewage waste system is a suspension comprising approximately 25 - 99.9% liquids and approximately 0.1 - 75% solids.

Typically, the liquid portion comprises water and oils. The solid portion includes sand, non- organic matter, plastic particles, organic matter, organic fibers comprising cellulose fibers and other sewage refuse. Typically, the solid portion of raw sewage is an aggregate of particles containing generally up to 15% sand, 20 - 90% cellulose fibers, 10 - 20% hemicellulose and 3 - 10% lignin. Generally, the solid portion also includes oil and water adsorbed to the particles. Typically, the solid portion of raw sewage includes 1-15% of oil therein.

Alternatively, sewage 10 may also be treated sewage, typically treated by standard wastewater treatment thereof and may be effused into sand removal device 12 from a municipal sewage waste system, a Wastewater Treatment Plant (WWTP) or any location within the WWTP prior to digestion of the sewage therein. Sewage 10 may flow into sand removal device 12 via a pipe or by any other suitable means.

Initial sand removal device 12 is operative to remove sand from sewage 10 by any suitable means. For example, sand may be removed from sewage 10 by sedimentation of the sand and thereafter the sand sediment is discarded from the sand removal device 12. Sedimentation of the sand may be performed by centrifugation, such as hydrocyclonic centrifugation, vibration or ultrasonic sedimentation, for example. Sand sediment may be discarded by any suitable means, such as via a pipe affixed to the sand removal device 12. Additionally, sand may be removed by employing Dissolved Air Floation (DAF) technology.

DAF technology is a process for removal of suspended matter, such as solids or oil, from a suspension. The removal is achieved by dissolving air in the suspension under pressure and then releasing the air at atmospheric pressure in a flotation tank or basin. The released air forms small bubbles which adhere to the suspended matter causing the suspended matter to float to the surface of the suspension. The floating suspended matter is thereafter removed from the surface.

Initial sand removal in sand removal device 12 may be performed on sewage 10 as the sewage 10 is flowing. Alternatively sand may be initially removed from sewage 10 as the sewage flow is slowed or halted and sewage 10 is introduced into a tank wherein the initial sand removal is performed.

It is appreciated that the quantity of sand within sewage 10 may vary in accordance with the climate wherein the sewage 10 is located. Sewage 10 is introduced into a solid particle entrapping device 16.

Entrapping device 16 may be comprised of a single net or a multiplicity of nettings for entrapping the solid portion of sewage 10. The multiplicity of nettings may be a series of nettings wherein each subsequent netting is formed with apertures of a smaller size than the previous netting so as to provide additional trapping of solid particles from the sewage 10. A netting mesh may be substantially in the range of 80 - 400 microns, for example.

The nettings may be formed in any suitable configuration and may be formed of any suitable material such as a corrosive resistive material and/or a high pressure resistive material, typically aluminum, for example. It is appreciated that retrieval and entrapping of solid particles from sewage

10 may be achieved in any suitable manner, such as by DAF technology; separation by conveyor belts formed of conveyor belt mesh; centrifugation, such as flow centrifugation or hydrocyclonic centrifugation, for example; separation by screw presses; filtering by disk filters, filter presses, media filters, such as filters containing fibers, for example, biological filters, such as filters containing cellulose, for example, chemical filters, such as filters containing silica, for example, a filter employing backflushing technology, or any other suitable manner for entrapping solids from sewage 10. A backflushing filter may be commercially available from the Salsnes Filter AS company of 279 Postboks, Namsos 7801, Norway, under the catalogue number of SF 6000.

A backflushing filter comprises a screen or a filtration media operative to filter solids such that solids accumulate on a first surface of the screen or filtration media. Liquid, generally water, is introduced to flow from an opposite surface of the screen or filtration media to the first surface thereof. This reverse flow of liquid through the screen or filtration media is used for removing solids accumulated on the screen or filtration media during the filtration process.

A pressure device, such as a pump or a water jet, may be engaged with entrapping device 16. The pressure device is operative to ensure sewage 10 flows unhindered through entrapping device 16, such as by declogging oils and plastic particles accumulated on the net of entrapping device 16. Furthermore, a resulting entrapped solid particle portion 20, trapped by entrapping device 16, may be cleaved by application of pressure by the pressure device thereon. The pressure applied by the pressure device is typically in the range of 10 - 200 Arm, for example.

A vibration element, such as springs, may be provided to enhance flow of sewage 10 within entrapping device 16.

The entrapped solid particle portion 20 of entrapping device 16 is comprised of solid particles and liquids adsorbed to the solid particles, such as oils and water. Generally the solid particles of entrapped solid particle portion 20 exceed a length of approximately 80 microns. Typically, entrapped solid particle portion 20 comprises 10% -

90% of the solids from sewage 10 and includes 20% - 95% organic fibers.

Entrapped solid particle portion 20 may be removed from entrapping device 16 in any suitable manner, such as via conveyer belts, conduits or spiral cams, for example. In a non-limiting example, a yield of 1 ton of cellulose of the solid particle portion 20 is obtained from processing 3300 m of sewage 10 within entrapping device 16 and an amount of 15,000 m³ of cellulose of the solid particle portion 20 is obtained per day.

Entrapped solid particle portion 20 may be introduced into a reservoir 30 via a pipe or by any other suitable means. Preferably, the entrapped solid portion 20 may be introduced into a secondary sand removal device 32 for further removal of sand within entrapped solid portion 20 by any suitable means. Secondary sand removal device 32 may be formed of any one of the abovementioned apparati forming initial sand removal device 12.

In a non-limiting example, initial sand removal device 12 and secondary sand removal device 32 are operative to remove the sand such that approximately less than 5% of the total sand content within solid portion of sewage 10 remains in entrapped solid portion 20.

The entrapped solid portion 20 may be ground in a grinding device 40 by any suitable means, such as by employment of a screw press, a filter or a blender, a stone or knife grinder, for example. The entrapped solid portion 20 may be ground to any suitable particle size, such as to particles with a length of approximately 0.01 - 100 microns, for example.

The entrapped solid portion 20 may be introduced into a sterilizer 42 for sterilizing entrapped solid portion 20. Sterilizer 42 may employ any suitable method for sterilizing the solid portion 20, such as steam sterilization, UV sterilization and use of a chemical reagent for sterilization, for example. The entrapped solid portion 20 may be introduced into a drying device 46 for partially drying solid portion 20. Drying device 46 may employ any suitable method for partially drying the solid portion 20, such as drying by evaporation employing heat treatment, cryogenic treatment, vacuum, a press, such as a screw press or a combination thereof. It is appreciated that the order of using the devices described hereinabove may be alternated so as to produce cellulosic feedstock 50 from sewage 10.

A person skilled in the art will appreciate that in the process of producing cellulosic feedstock 50 some of the devices described hereinabove may be obviated without compromising the quality of the produced cellulosic feedstock 50. Cellulosic feedstock 50 may be used to manufacture a plurality of materials, such as, without limiting, textile, combustion products, such as wood pellets, wood chips, fiberboards, plant medium, pulp, paper and biofuels, such as butanol, propane butane and ethanol, for example. The cellulosic feedstock 50 is a composition substantially comprising a sand content of less than 5% thereof, less than 4% thereof, less than 3% thereof, less than 2% thereof, less than 1% thereof or less than 0.5% thereof; an oil content of 1-15% thereof, an oil content of 1% thereof, an oil content of 2% thereof, an oil content of 3% thereof, an oil content of 4% thereof, an oil content of 5% thereof, an oil content of 6% thereof, an oil content of 7% thereof, an oil content of 8% thereof, an oil content of 9% thereof, an oil content of 10% thereof, an oil content of 11% thereof, an oil content of 12% thereof, an oil content of 13% thereof, an oil content of 14% thereof or an oil content of 15% thereof; a lignin content of less than 10% thereof, a lignin content of less than 9% thereof, a lignin content of less than 8% thereof, a lignin content of less than 7% thereof, a lignin content of less than 6% thereof , a lignin content of less than 5% thereof, a lignin content of less than 4% thereof, a lignin content of less than 3% thereof, a lignin content of less than 2% thereof or a lignin content of less than 1% thereof; a cellulose content of 40-99% thereof, a cellulose content of 40-45% thereof, a cellulose content of 45-50% thereof, a cellulose content of 50- 55% thereof, a cellulose content of 55-60% thereof, a cellulose content of 60-65% thereof, a cellulose content of 65-70% thereof, a cellulose content of 70-75% thereof, a cellulose content of 75-80% thereof, a cellulose content of 80-85% thereof, a cellulose content of 85- 90% thereof, a cellulose content of 90-95% thereof or a cellulose content of 95-99% thereof; a hemicellulose content of 1-20% thereof, a hemicellulose content of 1% thereof, a hemicellulose content of 2% thereof, a hemicellulose content of 3% thereof, a hemicellulose content of 4% thereof, a hemicellulose content of 5% thereof; a hemicellulose content of 6% thereof, a hemicellulose content of 7% thereof, a hemicellulose content of 8% thereof, a hemicellulose content of 9% thereof, a hemicellulose content of 10% thereof, a hemicellulose content of 11% thereof, a hemicellulose content of 12% thereof, a hemicellulose content of 13% thereof, a hemicellulose content of 14% thereof, a hemicellulose content of 15% thereof, a hemicellulose content of 16% thereof, a hemicellulose content of 17% thereof, a hemicellulose content of 18% thereof, a hemicellulose content of 19% thereof or a hemicellulose content of 20% thereof, a nonorganic matter content of less than 30% thereof, a non-organic matter content of less than 25% thereof, a non-organic matter content of less than 20% thereof, a non-organic matter content of less than 15% thereof, a non-organic matter content of less than 12% thereof, a non-organic matter content of less than 10% thereof, a non-organic matter content of less than 5% thereof, a non-organic matter content of less than 4% thereof, a non-organic matter content of less than 3% thereof, a non-organic matter content of less than 2% thereof or a non-organic matter content of less than 1% thereof; an organic matter content of 1-15% thereof, an organic matter content of 1% thereof, an organic matter content of 2% thereof, an organic matter content of 3% thereof, an organic matter content of 4% thereof, an organic matter content of 5% thereof, an organic matter content of 6% thereof, an organic matter content of 7% thereof, an organic matter content of 8% thereof, an organic matter content of 9% thereof, an organic matter content of 10% thereof, an organic matter content of 11% thereof, an organic matter content of 12% thereof, an organic matter content of 13% thereof, an organic matter content of 14% thereof or an organic matter content of 15% thereof, Preferably, the cellulose content of the composition comprises 60-90% thereof.

The cellulosic feedstock 50 may comprise particles with a length of 0.01 microns-100 mm, a length of 0.01 - 1 microns, a length of 1- 5 microns, a length of 5-10 microns, a length of 10-20 microns, a length of 20-30 microns, a length of 30-40 microns, a length of 40-50 microns, a length of 50-60 microns, a length of 60-70 microns, a length of 70-80 microns, a length of 80-90 microns, a length of 90-100 microns, a length of 100-150 microns, a length of 150-200 microns, a length of 200-250 microns, a length of 250-300 microns, a length of 300-350 microns, a length of 350-400 microns, a length of 400-450 microns, a length of 450-500 microns, a length of 500-550 microns, a length of 550-600 microns, a length of 600-650 microns, a length of 650-700 microns, a length of 750-800 microns, a length of 800-850 microns, a length of 850-900 microns, a length of 900-950 microns, a length of 950-1000 microns, a length of 1-5 mm, a length of 5-10 mm, a length of 10-15 mm, a length of 15-20 mm, a length of 20-25 mm, a length of 25-30 mm, a length of 30-35 mm, a length of 35-40 mm, a length of 40-45 mm, a length of 45-50 mm, a length of 50-55 mm, a length of 55-60 mm, a length of 60-65 mm, a length of 65-70 mm, a length of 70-75 mm, a length of 75-80 mm, a length of 80-85 mm, a length of 85-90 mm, a length of 90-95 mm or a length of 95-100 mm.

A residual, substantially liquid portion 60, discharged from entrapping device 16, comprises the liquid portion of sewage 10 and relatively small solid particles, typically particles with a length of less than approximately 80 microns. Liquid portion 60 may be discarded or may flow to a wastewater management system 70, such as back to the municipal sewage waste system, a WWTP or any location prior to digestion within the WWTP, for example, in any suitable manner, such as by conduits. Alternatively, liquid portion 60 may be introduced into an additional feedstock production system 80 for producing additional feedstock from sewage 10.

It is appreciated that producing the cellulosic feedstock 50 according to the method described hereinabove provides for a plurality of superior benefits. For example, the entrapped solid particle portion 20 obtained from sewage has relatively less lignin in comparison with solids retrieved from vegetative sources, such as, wood, wheat and corn. For a non-limiting example, entrapped solid particle portion 20 retrieved from sewage 10 contains 30% - 60% less lignin than solids retrieved from corn. Thus use of entrapped solid particle portion 20 retrieved from sewage 10 allows for producing cellulosic feedstock 50 with a relatively small volume of lignin. This may be advantages in production of a paper product from the cellulosic feedstock since the quality of the paper product increases as the lignin volume decreases therein.

An additional benefit is that fibers of entrapped solid particle portion 20 have a larger total surface area than fibers retrieved from vegetative sources. This is due to disintegration of the fibers within the sewage 10 and due to cleaving of fibers by urging of the pressure device thereon. Thus use of fibers of entrapped solid particle portion 20 enhances the efficiency of feedstock production due to the relatively large fiber surface area, which allows for increased contact with processing materials, such as contact with a hydroproxy wash for manufacturing products from the cellulosic feedstock 50, for example. Another benefit is that fibers of entrapped solid particle portion 20 obtained from sewage have a relatively high cellulose content, as described hereinabove, thus allowing for production of high quality products therefrom. For example, ethanol, which comprises mainly cellulose, may be produced from the cellulosic feedstock 50. Conventionally, following treatment of sewage 10 in a wastewater management system, typically a WWTP, the volume of solids within the sewage 10 is reduced. For example the volume of solids within the sewage 10 is conventionally reduced by 30 - 40% due to anaerobic processing within a digestion tank in the WWTP. Anaerobic processing of sewage 10 produces sludge. Typically, sludge is disposed of by drying and landfilling thereafter.

It is a particular feature of the present invention that solids of the sewage 10 are removed from sewage 10 prior to entering the digestion tank within the WWTP. Preferably, removal of solids from sewage 10 is performed prior to entering a primary sedimentation tank within the WWTP. This allows for maximal removal of solids from sewage 10 prior to settling of solids within the sedimentation tank.

Removal of solids from the sewage 10 decreases the volume of the solid components to be digested or anaerobically processed within the WWTP. For example, introducing sewage 10 into entrapping device 16 may bring to volume reduction of the solids within sewage 10 by approximately 40%. Thus removing the solids from the sewage according to the method described hereinabove provides an additional benefit by decreasing the solid volume to be processed within the WWTP.

EXAMPLE

Experimental Procedure:

100 m³ of raw sewage, including a solid portion of approximately 0.1 % of the raw sewage, was obtained from a municipal sewage waste system. As seen in Fig. 2, the composition of the raw sewage solid portion generally comprises 12.5% sand; 5% oils; 4.5% lignin; 42.5% non-organic matter; 17.5% organic matter; 2.5% hemicellulose and 15.5% cellulose. The raw sewage was introduced into a hydrocyclone centrifuge at a pressure of 3 Atm for initial sand removal from the raw sewage. Thereafter the raw sewage was introduces into an entrapping device formed of a net of a 250 micron mesh. Approximately 50Kg of solids were entrapped within the net. The residual liquid portion was discarded.

Secondary sand removal was performed by sedimentation in a conical- shaped pool wherein the sand sunk to the bottom of the pool. The sedimented sand was discarded and the remaining portion was introduced into a sterilizer at a temperature of 85°C for 10 minutes. The solid portion was pressed in a screw press for partial removal of liquids therefrom.

Experimental Results:

As seen in Figure 2, a resulting cellulosic feedstock composition was produced in the system described hereinabove wherein the cellulosic feedstock composition generally comprises 0.5% sand; 9% oils; 4% lignin; 14% non-organic matter; 12% organic matter; 4% hemicellulose and 56.5% cellulose.

It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described herein above. Rather the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove as well as variations and modifications which would occur to persons skilled in the art upon reading the specifications and which are not in the prior art.

Claims

We claim:

1. A cellulosic feedstock composition comprising: a sand content of less than 5% of said composition; an oil content of 1-15% of said composition; a lignin content of less than 10% of said composition; a cellulose content of 40-99% of said composition; and a hemicellulose content of 1-20% of said composition.

2. A composition according to claim 1 wherein said cellulose content comprises 60-90% of said composition.

3. A composition according to claim 1 or claim 2 further comprising a nonorganic matter content of less than 30% of said composition.

4. A composition according to any one of claims 1-3 further comprising an organic matter content of 1-15% of said composition.

5. A composition according to any one of claims 1-4 wherein said composition is produced from a solid portion of a sewage suspension.

6. A composition according to claim 5 wherein said composition is produced from said solid portion of said sewage suspension by:

(i) trapping said solid portion from said sewage suspension; and (ii) removing sand from said solid portion, thereby producing said composition.

7. A composition according to claim 6 wherein said composition is produced by any one of the following:

(i) grinding said solid portion;

(ii) sterilizing said solid portion; and

(iii) at least partially drying said solid portion.

8. A composition according to claim 6 or claim 7 wherein said trapping said solid portion is performed by a device selected from the group consisting of: a netting, a plurality of nettings, a device employing Dissolved Air Floation technology; a conveyor belt formed of conveyor belt mesh, a centrifuge, a flow centrifuge, a hydrocyclonic centrifuge, a screw press, a disk filter, a filter press, a media filter, a filter containing fibers, a biological filter, a filter containing cellulose, a chemical filter, a filter containing silica and a filter employing backflushing technology.

9. A composition according to any one of claims 6-8 wherein said removing sand is performed by centrifugation, hydrocyclonic centrifugation, vibration sedimentation, ultrasonic sedimentation or Dissolved Air Floation technology.

10. A composition according to any one of claims 6-9 wherein said removing sand is performed prior to said trapping said solid portion or following said trapping said solid portion

11. A method for producing a cellulosic feedstock composition from a solid portion of a sewage suspension comprising:

(i) trapping said solid portion from said sewage suspension; and

(ii) removing sand from said solid portion, thereby producing said cellulosic feedstock composition.

12. A method according to claim 11 wherein said removing sand is performed prior to said trapping said solid portion.

13. A method according to claim 11 or claim 12 wherein said removing sand is performed following said trapping said solid portion.

14. A method according to any one of claims 11-13 wherein said removing sand is operative to decrease a sand contact of said composition to less than 5% of said composition.

15. A method according to any one of claims 11-14 further comprising at least one of the following:

(i) grinding said solid portion;

(ii) sterilizing said solid portion; and

(iii) at least partially drying said solid portion.

16 A method according to any one of claims 11-15 and wherein said composition comprises: a sand content of less than 5% of said composition; an oil content of 1-15% of said composition; a lignin content of less than 10% of said composition; a cellulose content of 40-99% of said composition; and a hemicellulose content of 1-20% of said composition.

17. A method according to claim 16 further comprising a non-organic matter content of less than 30% of said composition.

18. A method according to claim 16 or claim 17 further comprising an organic matter content of 1-15% of said composition.

19. A method according to any one of claims 16-18 wherein said composition is produced from a solid portion of a sewage suspension.

20. A method according to any one of claims 11-19 wherein said trapping said solid portion is performed by a device selected from the group consisting of: a netting, a plurality of nettings, a device employing Dissolved Air Floation technology; a conveyor belt formed of conveyor belt mesh, a centrifuge, a flow centrifuge, a hydrocyclonic centrifuge, a screw press, a disk filter, a filter press, a media filter, a filter containing fibers, a biological filter, a filter containing cellulose, a chemical filter, a filter containing silica and a filter employing backflushing technology.

21. A method according to any one of claims 11-20 wherein said removing sand is performed by centrifugation, hydrocyclonic centrifugation, vibration sedimentation, ultrasonic sedimentation or Dissolved Air Floation technology.

22. A method for producing a cellulosic feedstock composition from a solid portion of a sewage suspension comprising:

(i) trapping said solid portion from said sewage suspension; and (ii) removing sand from said solid portion, thereby producing said cellulosic feedstock composition said cellulosic feedstock composition comprising: a sand content of less than 5% of said composition; an oil content of 1-15% of said composition; a lignin content of less than 10% of said composition; a cellulose content of 40-99% of said composition; and a hemicellulose content of 1-20% of said composition.

23. A method according to claim 22 wherein said removing sand is performed prior to said trapping said solid portion.

24. A method according to claim 22 or claim 23 wherein said removing sand is performed following said trapping said solid portion.

25. A method according to any one of claims 22-24 wherein said removing sand is operative to decrease a sand contact of said composition to less than 5% of said composition.

26. A method according to any one of claims 22-25 further comprising at least one of the following:

(i) grinding said solid portion;

(ii) sterilizing said solid portion; and

(iii) at least partially drying said solid portion.

27. A method according to any one of claims 22-26 wherein said trapping said solid portion is performed by a device selected from the group consisting of: a netting, a plurality of nettings, a device employing Dissolved Air Floation technology; a conveyor belt formed of conveyor belt mesh, a centrifuge, a flow centrifuge, a hydrocyclonic centrifuge, a screw press, a disk filter, a filter press, a media filter, a filter containing fibers, a biological filter, a filter containing cellulose, a chemical filter, a filter containing silica and a filter employing backflushing technology.

28. A method according to any one of claims 22-27 wherein said removing sand is performed by centrifugation, hydrocyclonic centrifugation, vibration sedimentation, ultrasonic sedimentation or Dissolved Air Floation technology.

29. A method according to any one of claims 22-28 further comprising a nonorganic matter content of less than 30% of said composition.

30. A method according to any one of claims 22-29 further comprising an organic matter content of 1-15% of said composition.

31. A method according to any one of claims 22-30 wherein said composition is produced from a solid portion of a sewage suspension.