FORM 2
THE PATENT ACT 1970
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
.1. TITLE OF THE INVENTION
METHOD FOR PULVERISATION OF SOLIDS PRESENT IN BIOMETHANATED SPENT WASH
2. APPLICANT
(a) NAME: PRAJ INDUSTRIES LIMITED
(b) NATIONALITY: Indian Company
(c) ADDRESS: PRAJ House, Bavdhan, Pune-411021, INDIA
3. PREAMBLE TO THE DESCRIPTION
The following specification describes the invention and the manner in which
it is to be performed.

4. DESCRIPTION
FIELD OF THE INVENTION
The invention relates to a method of pulverisation of solids present in biomethanated spent wash [BSW] produced in an alcohol distillery, more particularly to drying of solids present in BSW to form a powdery mass and using said mass as a component of a fertilizer.
BACKGROUND
Sugar industry is one of the largest agro based industry, which contributes substantially to the economic development of several communities worldwide. The sugar factories in India produce about 15 million tons of sugar by crushing about 150 million tons of sugarcane. The annual byproduct production is about 7 million tons of press mud and about 8 million tons of molasses. Molasses is utilized in distilleries for the production of ethanol. The distilleries producing alcohol generate billion litres of spent wash annually. The spent wash and press mud cause disposal and pollution problems. The raw spent wash contains very high values of BOD and COD, beside solids. Therefore, to alleviate the problem of spent wash disposal it is subjected to biomethanation process where significant reduction of BOD and COD occurs along with production of bio-gas as a useful energy source. The effluent discharged of biomethanation process is known as biomethanated spent wash [BSW]. Although BSW has significant

fewer BOD and COD values and solids, it is still a polluting stream if left to open disposal sites as presently done, creating significant air, water and soil pollution. Recently, regulators have also tightened the requirements of BSW disposals and it is now imperative to sugar factories and distilleries to employ new methods of the treatment of BSW that are more effective, economical and eco-friendly.
BSW is made up of solid materials left unused in biomethanation process; these solids are mostly in the form of organic and inorganic complexes creating pollution everywhere if left as such. A compositional analysis of a sample of BSW is provided in Table 1. Presently, BSW is left in open fields to compost and then remains are used as a fertilizer, etc. At some large factories it is evaporated to partially recover water that is disposed off in natural streams or recycled, and the concentrated part is left for composting or drying.
TABLE 1: Typical composition of ordinary BSW stream:

Sr. No. PARAMETER UNIT VALUE
1 PH - 7.0-8.0
2 COD ppm 30000 - 70000
3 BOD mg/L 10000-32000
4 Volatile Acids mg/L 700-1200
5 Alkalinity mg/L 12000-22000
6 Total Solids % by weight 1.5-8.0
7 Suspended Solids % by weight 0.2-1.0
8 Ammoniacal Nitrogen [NH3-N] mg/L 1500-3000

One current method of the BSW treatment is evaporation; herein BSW from biogas reactors is stored in open lagoons to get rid of volatile matters present in it as various gases. Then this BSW from lagoons is fed to a multiple effect evaporation process wherein it is concentrated up to 35% of total solids by weight. The process condensate water generated from this evaporation process is either disposed off or used for gardening or any other non-process applications due to high ammoniacal nitrogen content with other associated impurities of varying nature, rendering it not suitable for process and utility applications. Besides, the evaporation stage of BSW faces severe problem of clogging of heat exchanger surfaces due to fouling and scaling. This leads to significant expenditures on the cleaning of the evaporators and its working efficiencies. However, evaporation of BSW in open fields is increasingly coming under restrictions of regulators, hence new methods for treatment or destruction of BSW are needed that are economical and eco-friendly. The invention presented herein discloses a method of pulverisation of BSW having several advantages over known methods.
BRIEF DESCRIPTION OF THE DRAWINGS
Particular examples of a method in accordance with this invention will now
be described with reference to accompanying drawing, in which:

FIGURE 1 is an exemplary plan of the invention showing several features that control method of pulverisation of solids present BSW feed stream. The solids present in said BSW are concentrated up to 30% by weightln an evaporator and preheated using a heat exchanger. Then said hot stream is subjected to hot surfaces of a double drum dryer leading to formation powdery mass out of solids present in BSW and water removed as steam. This scheme has several elements that significantly contribute to the method of the invention.
DETAILED DESCRIPTION OF THE INVENTION
In one embodiment of present invention, as illustrated in FIGURE 1 BSW with at least 4% total solids by weight [1] is first received in an evaporation unit [A], where it is concentrated up to 30% total solids by weight forming a concentrated stream [2]. Said concentrated stream [2] is heated up to 80 C in a heat exchanger [B] leading to formation of a hot stream. Then said hot stream [3] is further subjected a drum dryer [C]. On the hot surfaces of said drum dryer remaining water is evaporated from said hot stream leading to formation of a powdery mass. Said powdery mass is scraped from the surfaces of said drum dryer and collected using a conveyor [D] in a collection tank [E]. The said powdery mass [powdery production] may be used as a component of fertilizer or fertilizer as such.

In another embodiment, said concentred BSW containing about 20 to 30% total solids was subjected to different conditions on a double drum dryer as shown in TABLE 2. The process conditions and outcomes are list in the table. The dryer consisted of two drums rotating in opposite directions to each other and contacting at outer surfaces. Steam was supplied to inside of said drums making the outer surfaces of drums hot. Said concentrated stream was poured on drum surfaces between portion where of two drums contact each other as shown in FIGURE 1. Due to conduction drying on hot surfaces, moisture was evaporated from said concentrated stream leading to formation of said powdery mass, which was removed and collected in a collection tank. Steam was used as energy source as up to 3 barg pressure in said drums. The steam pressure and RPM of said drums were adjusted so that said powdery mass of uniform characteristics was afforded.
TABLE 2:

No. Feed
Temp.
[°C] Drum
Temp.
PC] Steam
pressure
[barg] Drum RPM Moisture in
powdery mass [% W/W] Nature of mass
1 33 100 3.0 1.5 4.0 Free flowing
2 33 100 3.0 3 5.0 Free flowing
3 33 85 1.5 1.5 4.0 Free flowing
4 33 85 1.5 3 4.5 Free flowing
5 33 75 0.5 4 ND Sticky

In yet another embodiment, the composition of said powdery mass [pulverised solids of BSW] was analysed and is listed in TABLE 3.
TABLE 3:

No. Property Unit Value
1 Moisture Weight % 2.67
2 pH - 10
3 Gross calories Cal/gm 1308
4 N Value Weight % 2.42
5 P Value Weight % 0.31
6 K Value Weight % 18.86
7 Sulphur Weight % 1.71
8 Ash Weight %' 47.26
Embodiments provided above give wider utility of the invention without any limitations as to the variations that may be appreciated by a person skilled in the art. A non-limiting summary of various embodiments is given above, which demonstrate the advantageous and novel aspects of method disclosed herein.

5. CLAIMS
WE CLAIM:
1. A method for pulverisation of solids present in biomethanated spent
wash comprising:
(a) providing a biomethanated spent wash;
(b) evaporating said spent wash in an evaporator to concentrate solids present in it forming a concentrated spent wash;
(c) preheating said concentrated spent wash to about 80 °C;
(d) spraying said concentrated spent wash on hot surface of a drum dryer for desired time period leading to formation of a powdery mass from solids present it;
(e) scraping said powdery mass from surface of said drum dryer; and
(f) collecting said powdery mass using a conveyer.
2. The method of claim 1, wherein said biomethanated spent wash is a
waste product of a distillery unit with about 4% of total solids by
weight.

3. The method of claim 1, wherein said biomethanated spent wash is concentrated by evaporation to contain about 20 to 30% of total solids by weight.
4. The method of claim 1, wherein drying surface of said drum dryer has a temperature about 80 to 110 °C.
5. The method of claim 1, wherein said drum dryer is a double drum type dryer.
6. The method of claim 1, wherein said powdery mass contains no more than 10% moisture.
. 7. The method of claim 1, wherein said powdery mass contains up to 50% of ash by weight.
8. The method of claim 1, wherein said powdery mass is used as a fertilizer component.
9. A method substantially as described hereinbefore.