kitchen waste to energy 0.5 Ton capacity plant

Introduction: kitchen waste to energy
Add kitchen bio degradable Solid waste to a 5 HP mixer to process the waste before putting it into predigestor tank. The waste is converted in slurry by mixing with water (1:1) in this mixture.
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 tank where it undergoes mainly anaerobic degra-dation by a consortium of archae-bacteria belonging to Methanococcus group. These bacteria are naturally present in the alimentary canal of ruminant animals (cattle). 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. 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.
As the gas is generated in the main tank, the dome is slowly lifted up. It reaches a maximum height of 8 feet . 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 lamp posts. 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 manure generated is high quality and can be used in fields.
Success of this biogas plant depends a great deal on proper segregation of the kitchen waste. The materials that can pose problems to the efficient running of plant are coconut shells and coir, egg shells, onion peels, bones and plastic pieces. Steel utensils like dishes, spoons etc. are likely to appear in the waste bags from canteens. While bones, shells and utensils can spoil the mixer physically, onion peels, coir and plastic can have detrimental effects on microbial consortium in the predigester and main digestion tanks which could be disastrous for the plant.

THE PROPOSAL:


Breakup of the 0.5 T Biogas Project Cost

Civil Construction of Biogas Plant

1. Mixer with stirrer to mix hot water (1:1) to form a slurry,
2. Aerobic Digester,
3. Anaerobic digeter

Mechanical Items :
Gas Holding MS Steel Dome
Steel Fabricated Covers on Manure Pits,
Mixer Stirrer ,3 HP, 1 no
Air Compressor
Solar Water Heater
Water Pump and Slurry Pump
Water and Gas Pipelines on Plant area
Electric Fittings & Miscellaneous

---

Total Project cost Rs.5,50,000/-
Technology and Consultancy Rs. 1,00,000/-

---

Grand Total Cost of Project Rs.6,50,000/-


POWER GENERATION: Bio Gas production = 100 cu mtr /day for 0.5 ton of waste
Methane content (65.75%) = 65.75 cu mtr
Calorific value =28.9 MJ/N.cu mtr
Energy content 65.75x28.9x273/(273+30)=1712 MJ/Day
Generator efficiency--- 30%
Electricity generated =0.3x1712x1000000/3600x1000
= 142.66
Electric power generated = 142.66x0.04167=5.944 kw say 6 kw
= 1.25x 6= 7.5 kva.
We can go for a gas engine of capacity 5 KW . If any gas is left , it will be flared or supplied to staff quarters

Bio Gas from Kitchen Waste

THE PROPOSAL:

Breakup of the 0.5 T Biogas Project Cost

Civil Construction of Biogas Plant

Gas Holding MS Steel Dome

Steel Fabricated Covers on Manure Pits,

Mixer

Tank

Air Compressor

Solar Water Heater

Water Pump and Slurry Pump

Water and Gas Pipelines on Plant area

Electric Fittings & Miscellaneous

Stirrer for mixer

---

Total Project cost Rs.5,50,000/-

Technology and Consultancy Rs. 1,00,000/-

---

Grand Total Cost of Project Rs.6,50,000/-

Bio Gas from Kitchen waste

Literature Study : Bio Gas from Kitchen waste
The Principle: Biomass in any form is ideal for the Biomethanation concept, which is the central idea of the Biogas plants. Based on thermophilic microorganisms and microbial processes develop the design of the biogas plant. The plant is completely gravity based.
Brief process description: The segregated wet garbage (food waste) is brought to the plant site in bins and containers. It is loaded on a sorting platform and residual plastic, metal; glass and other non-biodegradable items are further segregated. The waste is loaded into a Waste Crusher along with water, which is mounted on the platform. The food waste slurry mixed with hot water is directly charged into the Primary digester.
This digester serves mainly as hydrolysis cum acidification tank for the treatment of suspended solids. For breaking slag compressed air is used for agitation of slurry. Compressed air will also help in increasing aeration since bacteria involved in this tank are aerobic in nature. The tank is designed in such a way that after the system reaches equilibrium in initial 4-5 days, the fresh slurry entering the tank will displace equal amount of digested matter from top into the main digester tank.
Main digester tank serves as a methane fermentation tank and BOD reduction takes place here. The treated overflow from this digester is connected to the manure pits. 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.
The biogas is collected in a dome (Gas holder) is a drum like structure, fabricated either of mild steel sheets or fibreglass reinforced plastic (FRP). It fits like a cap on the mouth of digester where it is submerged in the water and rests in the ledge, constructed inside the digester for this purpose. The drum collects gas, which is produced from the slurry inside the digester as it gets decomposed and rises upward, being lighter than air. 1" GI piping will be provided up to a distance of 50 m from the Biogas plant. Biogas burners will be provided. The biogas can be used for cooking, heating and power generation purpose.
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


8-10


8,000/-


100-120


0.1


300


5hp(2hr)


2


2


200


2-3


2


10-12


12,000/-


200-240


0.2


500


5hp(3hr)


3


3


400


4-5


4


20-22


22,000/-


400-480


0.3


700


5hp(3hr)


4


5


400


8-10


5


28-30


30,000/-


500-600


0.5


800


10hp (4hr)


5


7


600


12-14 (25Kw)


10


65-70


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 – cylinder
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.



OUR RECENT PROJECT ON BIO GAS GENERATION AND UTILIZATION:
BHOLABA DAIRY LIMITED. ALIGARH, U.P.
Bio Gas Generation from Dairy waste :
Ms Bhole Baba Milk food Industries Ltd. is coming up with a new plant at khair road, Aligarh
The Dairy will handle about 10-lac litre of milk every day. Depending on the season, major differences occur in the quantities of milk received from cooperative milk federation and in the use of butter, butter oil and milk powder. The value added products manufactured will be Casein,Milk Protien Concentrate,Lactose-Both Food &Pherma,Demineralised Whey Protien,Whole Milk Powder,Skimmed Milk Powder, & White Butter In Bricks Form, with future planning to produce processed Cheese/Mozerella.

CHARACTERISTICS OF GENERATING EFFLUENT WATER:

The values of incoming wastewater at ETP is as under:

S.No.

Parameter


Unit


Value



pH



6.0 – 10.5



Total Suspended Solids


Mg/l


1500.0 – 2000.0



B.O.D.


Mg/l


1500.0 – 1800.0



C.O.D.


Mg/l


2500.0 – 3500.0



Oil & Grease


Mg/l


150.0 – 250.0



Rated capacity of ETP


KL/Day


1,000.0

Feeding of Effluent to USAB Reactor: Anaerobic digestion takes place here. Methane gas is generated because of anaerobic degradation. The top supernatant from the USAB reactor flows by gravity to the aeration tanks inlet. Three reactors are planned. When one reactor is out of operation, calamity flow is the designed flow. One distribution box will distribute the flow into the three reactors.

1. Bio-gas collection & utilization or Flaring: The gas produced in the UASB reactors is led to the gas holder through a moisture trap and gas flow meter.The outlet of the gas holder is to be branched off in two directions, one going to the generator room for supply to the engines and the other to the gas flaring equipments. The primary purpose of a gas holder is to adjust the difference in the rate of gas production and consumption.The gas engines demand a constant supply of bio gas at a constant pressure. The bio gas holder is designed for a storage of 4 hours of bio gas production normally at a pressure of 40m bar. As bio gas enters or leaves, the holder rises or falls with the help of guide rails. Valves in the gas lines will be operated manually to maintain the gas dome at 90%(Gas flaring level), 80%(Engine level) and 20% (Low levels, where engine as well as flaring will be stopped and the dome will be allowed to rise.).

GAS PRODUCTION & POWER GENERATION:
The gas flowing upward with the liquid will be prevented from escaping with the treated flow by GLSS and beam deflector, which will divert it to the gas collector domes. The gas produced shall be passed through 100 mm dia FRP pipe for individual domes and collected at a common point for each reactor by a common header of 200 mm dia pipe from where it will conveyed to the gas holder for constant flow to the gasomete generator or flaring in open atmosphere at about 6 meter above ground level.

Quantity of Gas Production:

PARAMETER

INLET OF UASB


OUTLET OF UASB


REMOVAL IN UASB


BOD


1700 ppm


340 ppm


80%


COD


3300 ppm


1320 ppm


60%


TSS


1800 ppm


450 ppm


75%


FLOW IN UASB = 1500 KLD (Taking full future capacity into account) Influent COD@ 3300 ppm = 4950 Kg
Effluent COD = 1980 Kg
COD removed in a day = 2970 kg
Bio gas produced @ 0.1 cu mtr per kg of COD removed = 297 cu mtr per day.
Capacity of gas holder: The primary purpose of a gas holder is to adjust the difference in the rate of gas production and consumption. As bio gas enters or leaves, the holder rises or falls by guide rails.
Provide a gas holder of 300 cu mtr capacity.
POWER GENERATION:
The bio gas produced in UASB process should be utilized for production of electric power. The amount of electric power generated shall be as under:
Bio Gas production = 297 cu mtr /day
Methane content (65.75%) = 195.28 cu mtr
Calorific value =28.9 MJ/N.cu mtr
Energy content 195.28x28.9x273/(273+30)=5048 MJ/Day
Generator efficiency--- 30%
Electricity generated =0.3x5048x1000000/3600x1000
= 420.66
Electric power generated = 420.66x0.04167=17.5289 kw say17 kw
= 1.25x 17= 21.25 kva.
We can go for a gas engine of capacity 10 KW . If any gas is left , it will be flared or supplied to staff quarters.


NOTE FOR COMPARISION : A 56 mld UASB plant having Inlet COD =400 ppm can safely run a 45 KW gas engine.