The present invention relates to a modified anaerobic process for producing organic manure and/or biogas fron substances such as pressnud from sugar sills, agricultural and/or industrial wastes.
Pressmud is a waste product from sugar factory obtained during the cane juice clarification. The quantity generated is approximately 3.5 to 4 % of the cane crushed in the sugar mill. Thus a mill of 5000 T. cane per day crushing oapacity generates about 175 to 200 T pet day of pressmud. Disposal of this large quantity from the factory premises has posed a problem to sugar factories.
Host sugar factories offer their pressmud as it turns out of the factory to farmers who take the waste material and dump it on wayside or in fields. Normally, the farmers store this material and after a period of composting and maturing use it as organic manure. Substances such as pressmud and other wastes has many valuable nutrients but cannot be directly applied into cultivable lands. The high cost of transportation, storage problems and necessity for composting it before soil applications are deterrents to more widespread usage of this valuable product. In some oases where the pressmud or wastes have to be disposed as land-fill the requirement of large areas of land and possible ground water pollution may not be economically and environmentally advisable.

Therefore a need is felt for developing a process for converting substances such as pressmud, agricultural and/or industrial wastes into an organic manure which can be readily applied into the soil.
There are several aerobic processes in use among the sugar factories where the material is stored in open and applying windrow system of aerobic digestion with or without the help of micro organism used as innoculum. The following problems are associated with the existing process.
1. Material has to be stored in open requiring large land area
with no protection during rainy days and likely-hood of ground
water pollution,
of
2. A long composting time of the order several weeks is
^ required.
3. Loss of valuable nutrients in the manure due to exposure to
sun and rain.
The object of the present invention is to provide a process which will overcome the problems faced in the existing process and to provide a rich compost, minimising the composting time, the land/space requirement and providing an organic manure which can be readily applied to the soil while providing biogas.
The process is based on anaerobic digestion and also generates biogas for capital use in the process.

Acconpanyinfi drawing shows a preferred flow chart of the process according to the invention.
The invention provides a modified anerobic process for producing orgauiic manure and/or biogas from substances such as pressnud from sugar mills, agricultural and/or industrial wastes said process comprising preparing a slurry with water and/or treated spent wash effluent from the plant, adjusting the pH of the slurry using standard chemical additives reducing the particle size to desired level, pumping the slurry into bio-reactors for anaerobic digestion retaining the slurry in said bio-reactors for predetermined number of days for digesting to achieve predetermined C;N ratio, centrifuging the slurry after recovering the bio-gas generated during digestion, discharging the wet cake from the bio-reactor by decanting, dewatering, drying and pulverising or pelletizing to obtain the organic manure. The organic manure thus obtained is of high quality for agricultural use.
There have been attempts to process pressmud in combination with cow-dung and that has lead to many problems. The process according to the invention, eliminates use of any other organic additives and entirely utilises the pressmud and the spent wash from distilleries which are readily available from sugar factories and distilleries. The digestion time or the retention

tine in bio-reactor is drastically reduced to 3 to 5 days in contrast to the existing anaerobic process of 30 days and more or aerobic process of 12 weeks. Production of biogas is another important contribution to generation of non-conventional energy.

The present invention relates to an anaerobic process lor producing organic manure and/or biogas from substances such as pressmud from sugar mills, agricultural and/or industrial wastes.
Pressmud is a waste product from sugar factory obtained during the cane juice clarification. The quantity generated is approximately 3.5 to 4Z of the cane crushed in the sugar mill. Thus a mill of 5000 T cane per day crushing capacity generates about 175 to 200 T per day of pressmud. Disposal of this large quantity from the factory premises has posed a problem to sugar factories.
Most sugar factories offer their pressmud from the factory to farmers who take the waste material and dump it on wayside or in fields. Normally, the farmers store this material and after a period of composting and maturing use it as organic manure. Substances such as pressmud and other wastes has many valuable nutrients but cannot be directly applied into cultivable lands. The high cost of transportation, storage problems and necessity for composting it before soil applications are deterrents to more widespread usage of this valuable product. In some cases where the pressmud or wastes have to be disposed as land-fill. The requirement of large areas of land and possible ground water pollution makes it uneconomic and not advisable due to environment pollution.

Therefore it is proposed to convert substances such as pressnud, agricultural and/or industrial wastes into an organic nanure which can be readily applied to soil and a biogas which is a valuable non-renewable source of energy by preparing a slurry with water and effluents such as spent wash sewage water and other industrial liquid wastes.
There are several anaerobic processes in use among the sugar factories where the material is stored in open and applying windrow system of anaerobic digestion with or without the help of micro organism used as innoculam. The following problems are associated with the existing process.
1. Material has to be stored in open requiring large area
with no protection during rainy days and likely-hood of ground
water pollution.
2. A long composting time of the order several weeks is required.
3. Loss of valuable nutrients in the manure due to exposure to sun and rain.
The object of the present invention is to provide a process which will overcome the problems faced in the existing process and to provide a rich compost, and biogas minimising the composting time, the land/space requirement.

The process is based on anaerobic digestion and also generates biogas for capital use in the process and for generation of electricity.
Accordingly the present invention provides jan anaerobic process for producing organic manure and/or biogas from substances such as pressmud from sugar mills, agricultural and/or industrial wastes, said process comprising preparing a slurry with water and/or treated spent wash effluent from the plant, adjusting the pH of the slurry between 6 to 8 using standard chemical additives biologically braking the partidle size to desired level by adding a nitrogen or phosphate base|d nutrient, pumping the slurry into bio-reactors and adding an anaerobic innoculum, retaining the slurry in said bio-reactors for 2 to 7 days for digesting to obtain required carbon to nitrogen ratio, centrifuging the slurry after recovering the bio-gas generated during digestion, discharging the wet cake from the bio-reactor by decanting, dewatering, drying and pelletising to obtain pellitised organic manure.
Accompanying drawing shows a flow chart of the process according to the invention.
The pressmud and/or agricultural waste is mixed with water and/or effluent such as spent wash in a mixer tank fitted with agitators. The solid to liquid ratio may be 1:1 to 1:3. The pH of the slurry was ad.iusted between 6 and 8 by the addition of

standard chemical additives. If the slurry is acidic additives
such as caustic lye, soda ash, potassium hydroxide are added for
adjusting pH. If the slurry is basic the pH is adjusted by
adding HCl. After nixing, a nitrogen or phosphate based nutrient
for niorobes is added to the slurry for biologically braking
the particle size. Typical exanples of nutrients are urea,
miiBonijajfr- 8ulphate-r aamoniuii phds and phosphoric acid. The
•lurry is then pumped into the bio-reactors. An anaerobic
innoculam derived from one or more sources such as oowdung,
press-nud or sewage is added to the slurry in the bio-reactors
for digestion. Bio~gas generation will be triggered innediately.
Past of the bio-gas used for drying and the
remaining may be passed to flare. The particle size of the solid
in the slurry gets reduced by biological braking. The slurry
may be kept for 2 to 7 days in the bio-reactor for digestion.
The carbon to nitrogen ratio (C:N) is checked and when the
desired level of carbon to nitrogen ratio for using asan organic
manure is reached, the slurry from the bio-reactors are
transfered to a decanter for seperating the solid portion. The
wet cake is dried to obtain free flowing solid manure with less
than 35X moisture. The solid manure is pellatised »»"'* '■-"

EXAMPLE :
8 Tonnes of presBOud were enptied, into a nixer tank and frosh spent wash was punped into the nixer tank in the ratio 1:2.5. Agitators were run for half an hour to obtain an uniform oonsistenoy of the slurry. At this stage, caustic lye through seai-autonatio dosing systen was gradually dosed to adciust the pH range of the slurry to 7.1. Sinultaneously the nutrients for Bioro organisms were manually added into slurry and agitators were run for next 10 minutes.
The slurry was then pumped into the bio-reactor, pumping time took around 45 minutes. After the charge; anaerobic innooulum previously prepared in the Seed reactor was pumped into the bio-reaotor. There was immediate jump in the bio-gas generation and this was monitored regularly by a flow meter by frequent pH adjustments. On the 4th day of the digestion, sample was drawn and analysed for the oarbon/nitrogen ratio and it was found to be around 18:1.
Thereafter, the digested slurry was emptied directly into the decanter where the liquid portion was separated and the wet oake fed into the dryer to reduce moisture level. From there, dry products were passed through a pelletiser and the pellets packed in 25 kg HOPE bags.

The Bio gas gonerated during the period of operation waa between 12 to 6n3 per hour. The product produced analysis is as below:
Nitrogen 1.8
Phosphorous pentoxide : 1.5
Potassiua (K) 0.6
Carbon (C) 32
Moisture 25X
Pellets 6mm size
The total quantity of organic manure produced is 1.6 tonnes. The product appearance, colour and odour were excellent.

WE CLAIM:
1 An anaerobic process for producing organic manure and/or biogas from substances such as pressmud from sugar mills, agricultural and/or industrial wastes, said process comprising preparing a slurry with water and/or treated spent wash effluent from the plant, adjusting the pH of the slurry between 8 to 8 using standard chemical additives biologically braking the particle size to desired level by adding a nitrogen or phosphate based nutrient, pumping the slurry into bio-reactors and adding an anaerobic innoculum, retaining the slurry in said bio-reactors for 2 to 7 days for digesting to obtain required carbon to nitrogen ratio, centrifuging the slurry after recovering the bio¬gas generated during digestion, discharging the wet cake from the bio-reactor by decanting, dewatering, drying and pelletising to obtain pellitised organic manure.
2. A process as claimed in claim 1. wherein the chemical additives for adousting pH is selected from caustic lyre, soda ash and potassium hydroxide, when the slurry is acidic.
3. A process as claimed in claim 1. wherein the chemical additive for adjusting pH is HCl when the slurry is basic.

4 A process as claimed in claim 1. wherein the nutrient is selected from urea, ammonium sulphate, ammonium phosphate and phosphoric acid .
b. A process as claimed in claim 1. wherein the anaerobic
innocuium is derived from one or more sources selected from cowdung, press-mud and sewage.
6. An anaerobic process for producing organic manure and/or biogas from substances such as pressmud from sugar mills, agricultural and/or industrial wastes, substantially as hereinabove described and illustrated with reference to the accompanying drawings.