ENVO BIO GAS PLANT

POST NUMBER :08   Date : 02/05/2004
BIO GAS PLANT PROCESS DESCRIPTION:

FLOW CHART: CRUSHER(less than 7mm particle size)----thermophilic Aerobic digester(Temp 55 degree C  )---Mesophilic Anaerobic Digester(37 Degree C )---Manure Pit

Biotechnology process

stage one : hydrolysis by hydrolytic bactaria, conversion of extracellular molecules

stage two : thermophilic fermentation based on carbohydrates

stage three : synthesis of volatile fatty acids by acetogenic bacteria

stage four : synthesis of methane by methanogenic organisms

The Principle:

Add bio degradable Solid waste  into predigestor tank. 

Use of thermophilic microbes for faster degradation of the waste. The growth of thermophiles in the predigestor tank is assured by mixing the waste with hot water and maintaining the temperature in the range of 55-60oC. The hot water supply is from a solar heater. Even one-hour sunlight is sufficient per day to meet the needs of hot water.

After the predigestor tank the slurry enters the main anaerobic tank where it undergoes mainly anaerobic degra-dation by a consortium of archae-bacteria belonging to Methanococcus group.  They produce mainly methane from the cellulosic materials in the slurry.

The undigested lignocellulosic and hemicellulosic materials then are passed on in the settling tank. After about a month high quality manure can be dug out from the settling tanks. Earth worm can be introduced to settling tank to speedup the process.There is no odour to the manure at all. The organic contents are high and this can improve the quality of humus in soil, which in turn is responsible for the fertility.The manure generated is high quality and can be used in fields.This manure can be supplied to farmers at the rate of 4-5 Rs. per Kg. Alternatively municipal gardens and local gardens can be assured of regular manure from this biogas plant.

As the gas is generated in the main tank, the dome is slowly lifted up. This gas is a mixture of methane (70-75%), carbondioxide (10-15%) and water vapours (5-10%). It is taken through GI pipeline to the gas purification unit. Drains for condensed water vapour are provided on line. This gas burns with a blue flame and can be used for cooking as well.

The gas generated in this plant is used for gas lights fitted around the plant. The potential use of this gas would be for a canteen. The purified gas can be fed to bio fuel electric generator to produce electricity. Gas can be bottled and used to run vehicles.

Tanks of Biogas Plant

1.     Mixer with stirrer to mix hot water (1:2) to form a slurry,

2.     Aerobic Digester,

3.     Anaerobic digeter

Mechanical Items :

1.Gas Holding MS Steel Dome

2.Steel Fabricated Covers on Manure Pits,

3.Mixer Stirrer ,

4.Air Compressor

5.Gas Holder and gas purification system

6.Water Pump and Slurry Pump

7.Water and Gas Pipelines on Plant area

8. Electric Fittings & Miscellaneous

Cost details, saving and payback period from a biogas plant:

The cost details and the savings envisaged from the plant are given in the following table. The life of the plant could be 20-30 years and payback period is 4-5 years.

Capacity (Tons / Day)	Installation Cost (Rs In Lacks)	Monthly Operation and Maintenance Charges (Rs)	Methane Generation M3	Manure production (tons /day)	Area Required M2	Power	Manpower	Fresh Water (KL /day)	Hot water (Ltr / day of 50-60 C0)	Cooking Fuel (Equivalent to LPG Cyl / day)
1	30-35	8,000/-	100-120	0.1	300	5hp(2hr)	2	2	200	2-3
2	36-39	12,000/-	200-240	0.2	500	5hp(3hr)	3	3	400	4-5
4	60-65	22,000/-	400-480	0.3	700	5hp(3hr)	4	5	400	8-10
5	85-87	30,000/-	500-600	0.5	800	10hp (4hr)	5	7	600	12-14 (25Kw)
10	1 cr -1.2 cr	50,000/-	1000-1200	2.5	1200	15hp (4hr)	10	15	1000	22-25 (50Kw)

* This is an approximate cost for biogas generation plant and may increase by 10%–20%, depending on location, site-specific parameters, cost of materials, labour cost, etc., in different states/cities. Cost of additional infrastructure like office space, toilets, security, Godown, Shades and power generation will be extra, if required.

Rs – rupees; m3 – cubic meters; m2 – square meters; h – hour; kL – kilolitre; LPG – liquefied petroleum gas; kW – kilowatt; cyl –

Decentralised treatment options introduced in new rules.

The earlier rules relied on costly centralised facilities for treating and disposing municipal wastes while approximately 50 per cent of it can be easily turned into compost at the local level. Thus, the draft rules have made the much-needed provision for providing incentives to decentralised waste treatment facilities. 

http://www.downtoearth.org.in/blog/a-clean-country-in-the-offing-with-new-solid-waste-rules-49484

Considering an average garbage generation per capita per day as 0.450 Kg, we can assume a total garbage generation for a population of 100,000 as 45,000 Kg per day

Proven on wide range of wastes and feedstocks including

• Livestock and agricultural wastes
• Biomass
• Sewage and industrial sludges
• MSW and catering wastes
• Food industry wastes
• Vegetable market waste
• Restaurant Waste
• Farm House/Cattle manure waste
• Slaughter House/Tannery waste
• Presumed waste

Suitable locations for installation of plant

Hotel premises, army/big establishment canteens (private/ government), residential schools/colleges, housing colonies, religious places / temple trusts, hospitals, hotels, sewage treatment plants, villages, etc.