Introduction: Mini Bio-gas Plant Using Food Waste, Decomposable Organic Material and Kitchen Waste

Picture of Mini Bio-gas Plant Using Food Waste, Decomposable Organic Material and Kitchen Waste

I have been searching for some method of using the food waste, decomposable organic material and kitchen waste efficiently, and came across information on producing bio-gas from organic waste.

The bio-gas produced from food waste, decomposable organic material and kitchen waste, consisting of methane and a little amount of carbon di oxide is an alternative fuel for cooking gas (LPG). Also, the waste materials can be disposed off efficiently without any odor or flies and the digested slurry from the bio-gas unit can be used as an organic manure in the garden.

Components of the Bio-gas Plant

The major components of the bio-gas plant are a digester tank, an inlet for feeding the kitchen waste, gas holder tank, an outlet for the digested slurry and the gas delivery system for taking out and utilizing the produced gas.

This project is also useful for students to have a hands-on learning experience in constructing a Mini Bio-Gas Plant, using locally available material.

Material Required:

1. Empty PVC can 50 ltrs capacity: 1 No. (to be used as Digester Tank)
2. Empty PVC can 40 ltrs capacity: 1 no. (to be used as Gas Holder Tank) (Make sure the smaller can fits inside larger one and moves freely)
3. 64 mm dia pvc pipe: about 40 cm long (to be used for feeding waste material)
4. 32 mm dia pvc pipe: about 50 cm long (fixed inside gas holder tank as a guide pipe)
5. 25 mm dia pvc pipe: about 75 cm long (fixed inside the digester tank as a guide pipe)
6. 32 mm dia pvc pipe: about 25 cm long (fixed on digester tank to act as outlet for digested slurry)
7. M-seal or any water-proof adeshive
8. Gas outlet system: Please see Step 4 below for required materials and construction

Tools required

Do not require many tools here. A hack saw blade for cutting the cans & pipes and a sharp knife for cutting holes on the cans are all the tools we need.

Additional accessories

A single burner bio-gas stove or a Bunsen Burner used in school laboratories

Step 1:

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Bought this 50 ltrs capacity PVC can, which will act as the digester unit and removed the top portion of the can, by cutting it with a hack saw blade:

Step 2:

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The smaller white can, which will act as the gas holder fits inside the red one. Here, again removed the top of the white can, also with the help of a hack saw blade:

Step 3:

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64 mm, 32 mm and 25 mm dia PVC pipes which  will be used for feeding the kitchen waste, guide pipe for the gas holder and guide pipe fixed with the digestion chamber respectively. A small piece of 32 mm dia pipe will be used as outlet for the slurry:

Step 4:

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  1. items required for the gas delivery system: got these items from a hardware store

1. Ball valve : one no ( to adjust the gas flow)
2. 'T' joint : one no ( to connect the gas holder and the ball valve)
3. Cap to block one end of 'T' joint : one no
4. Coupling or Adapter : one no (to connect vertical end of 'T' in to the gas collector)
5. Nipple: one no (added to the coupling in to the gas collector)
6. Gas pipe (flexible) : two meters
7. Barb : one no (fitted with the gas pipe, to join with the Ball valve)
8. Clip : one no (used for crimping the barb with the gas pipe and make it leak-proof)
9. Teflon tape : one roll (used as thread tape in all joints)

Step 5:

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Here I have marked the cuts to be made in the bottom of the gas collection tank. The smaller hole on the left for gas delivery system, center hole for fixing the 32 mm guide pipe and 64 mm hole for fixing the waste feeding pipe on the right side. Made these holes with the help of a sharp knife and hack saw blade.

The next image is Inside of the gas holder showing the 32 mm guide pipe (center) and the 64 mm feeding pipe fixed with M-seal

Step 6:

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Top view of the gas holder showing the feeding pipe, central guide pipe and the gas delivery system: I have closed the feeding pipe withe an old lid  (red one). This will facilitate opening the feed pipe only during feeding the system.

Step 7:

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Digestion tank fitted with the central guide pipe and the outlet pipe for the slurry:

Step 8:

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Completed unit. I have removed the gas pipe, so that the joints will get cured without any stress:

Wait for a day or two before feeding the system, allowing all joints to get cured and become leak-proof.

Initially, cow-dung mixed with water will be fed in to the system, which will start the gas formation process. Subsequently, food waste, decomposable organic material and kitchen waste will be diluted with water and used to feed the system. The gas holder will rise along the guide pipes based on the amount of gas produced. We can add some weight on top of the gas holder to increase the gas pressure. When we feed the system, the excess digested slurry will fall out through the outlet pipe, which can be collected, diluted and used as organic manure.

Initial production of gas will consist of oxygen, methane, carbon di oxide and some other gases and will not burn. These gases can be released to the atmosphere by opening the ball valve at least three / four times.

Subsequent gas will consist of about 70 to 80 percent methane and the rest carbon di oxide, which can be used in a single bio-gas burning stove or a Bunsen burner.

Total cost of this proto-type system is about one thousand Indian Rupees (about 20 dollars)

This is a basic prototype of a Bio-gas system using the food waste, decomposable organic material and kitchen waste to produce gas. An one thousand litre capacity Digestion tank will be sufficient for a small household for daily cooking purpose. The bigger commercial models provide a water seal between the digestion tank and gas holder tank.

You can get further information on kitchen waste based mini Bio-gas plant at the following links:

Step 9:

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Charged the digester tank with cow dung diluted with water. Placed the gas holder tank and left it for two three days. The cow dung slurry started the process of gas forming.

Gas formation started and the gas holder tank gets lifted up. I have placed two bricks on top of the gas holder to get more gas pressure.

Step 10:

Note for students who are doing this as their School Project:

1. Take guidance from your teacher while using the gas in a stove or Bunsen burner.
2. Collect surplus food and wastage during lunch, dilute and feed the system.
3. Fruit peels, extracted tea powder, waste milk and milk products  can also be used for feeding the system.
4. DO NOT USE eggshells, Onion peels or left-over bones in this system as they will affect the efficient functioning of the system
5. Plant some seedling
6. while feeding, collect the slurry from the outlet, feed the seedlings and watch them grow


Grade10charity (author)2017-10-21

Sir! I am a student please help ASAP, there was no gas formed, there are no leaks it is completely sealed

antoniraj (author)Grade10charity2017-10-22

Please explain what did you do with photos. Gas will form in a few days time and will not take a month. Immediately when the gas formation started, feeding should be started for getting continuous gas

We let it settle for 1 month already

animal_fk (author)2017-09-14

Dear sir, I have built your plant but have no gas! Does heat or alitude effect the system? thank you

antoniraj (author)animal_fk2017-09-14

Gas formation will start within a week. If your gas holder tank is not raising, then there may a leak. Please check and reseal all joints properly

Abbeybrown01 (author)2017-08-07

Thanks for your previous reply sir, when filling the digester with the diluted cow dung at 1st, will the level be up to the slurry outlet pipe?

antoniraj (author)Abbeybrown012017-08-08

Fill the digester to half of its capacity not up to the slurry outlet level. Once the gas production starts feed regularly. The digester will get filled up automatically.

Abbeybrown01 (author)2017-08-06

Hello sir, when will I open the slurry outlet for it to come out?

antoniraj (author)Abbeybrown012017-08-07

No need to close the slurry outlet. When the digester is filled to top, the excess digested material will automatically drained out through slurry outlet

Abbeybrown01 (author)2017-08-06

Will the slurry pipe be opened since day 1 or when and won't oxygen find its way in the digester?

antoniraj (author)Abbeybrown012017-08-07

Just keep the slurry outlet pipe open from day 1. There is no way oxygen will find its way inside

GovindS32 (author)2017-07-17

hello sir,

is there any way to avoid cow dung completely from biogas plant, my means even for initial feeding also could i use de-oiled cake (made of jatropha )instead of cowdung ?

antoniraj (author)GovindS322017-07-18

You can feed finely chopped or pulverised kitchen waste to half the depth of digester tank and wait. It will take longer, but gas will form. Once gas production starts feed other wastes regularly

AhmedB183 (author)2017-06-08

hello sir, I want to ask you about what is the benefit if I use the solar in bio-gas?

antoniraj (author)AhmedB1832017-06-08

In what way you propose to use solar in Bio-gas?

dillonr_ (author)2017-04-24

Hi there, can you charge the digester tank with food scrap rather than cow dung. Or do you have to use the cow dung first to start the process of gas forming

antoniraj (author)dillonr_2017-06-05

Sorry for my late reply. Initially you need to charge the digester with fresh cow dung for about 1/3 to 1/2 the depth of the digester. Once the gas formation starts, you can feed the tank with food scrap

VidishaP (author)2017-05-01

hello , we live in the US and do not get biogas burners in stores so what can we use instead? is there an alternative for cow dung? does the cow dung have to be fresh ?

antoniraj (author)VidishaP2017-06-05

Just remove the nozzle from the LPG Stove and it should work for Biogas. Fresh cow dung contains useful microorganisms which help in digesting waste and produce gas. Horse dung can also be used instead of cow dung. Waste water treatment people use a starter solution for treating grey water. If you can get some starter solution from them and use it.

VinayK145 (author)2017-05-04

Dear Sir,

If i want to install presure checking watch. Then which type of pressure checking watch/meter will be use LPG Or nitrogen gas meter.

antoniraj (author)VinayK1452017-06-05

You can use any kind of pressure checking meter, but the pressure produced by the floating type Biogas plants are very less unless you add enough weight on top of the gas holder

Wastenvironmentw (author)2017-04-28

Interesting tutorial. I was able to make it after a lot of attempts.

mdyes (author)2017-03-31

Good day sir can you please assist me with this PDF document my email is

antoniraj (author)mdyes2017-04-04

you can download it from this Dropbox link

Mini Biogas Plant

rrjally99 (author)antoniraj2017-04-12

Thnx bro

GovindS32 (author)2017-03-03

sir is there any way to measure the efficiency of biogas plant ? how can we know the efficiency of biogas plant ?

antoniraj (author)GovindS322017-03-04

Please see Step 6 of my other instructable where I did some rough calculations comparing with LPG consumption. But it is very rough estimation only and not accurate

RajarajanD (author)2017-03-02

Hello Sir,

Please send this PDF to

Please send me your contact details. We wish to see the medium sized biogas plant directly. We will come to your place with your appointment. Thanks.

antoniraj (author)RajarajanD2017-03-04

Where are you from ? Please give your location and I will guide you with routes and contact information

Tomas Meyer (author)2017-03-01

I also trying to make a small black colour plastic hut around the digester so that it can trap the sun heat and makes the digester around hotter. HERE is very good guide for everyone who needs energy for home devices. Thank you antoniraj!

GovindS32 (author)Tomas Meyer2017-03-03

so does that black hut works fine for your plant ? have you able to increase the formation rate of biogas ?

Valery Ndayishimiye (author)2017-02-05

Hello sir, thanks for this tutorial it is really interesting ! Do we necessary have to wait for the initial gas to be produced before we start feeding with kitchen waste ? Again does the biogas digester have to be completely full of the mexiture ?

Initial gas will be produced within 3 to 4 days of feeding with cow dung. It is better to wait for few days before feeding kitchen waste as the microorganisms in the cow dung will multiply and become active.

Initially, fill the digester to about 1/3 to 1/2 of its capacity. Once the gas production starts you can feed the tank with kitchen waste. There will not be any output slurry till the digester gets filled. Once it is full the digester slurry will be drained out whenever you feed the tank

Thank you very much. I appreciate your quick support.

saravanans44 (author)2017-01-24

hi like to this for as a small scale industries can you help me to guide sir

antoniraj (author)saravanans442017-01-25

Please go through my other instructable on how to construct a medium sized Biogas Plant at this link. You can make one as per your requirement

ebinpayikad (author)2017-01-12

I'm a building contractor I'm planning to construct a biogas plant for my labours. They are nearly 15 members.

antoniraj (author)ebinpayikad2017-01-12

you need to build a large scale system to serve 15 members. Please go through my other instructable on how to construct a medium sized Biogas plant at the following link. This provides 50 % gas requirement for a family of 5 persons

ebinpayikad (author)2017-01-12

Could i get ur contact number sir

ebinpayikad (author)2017-01-12

Is this the same method tat i want to use sir

ebinpayikad (author)2017-01-12

Hi sir

lyninsairam (author)2017-01-05

Hello sir,this is sai. I make a biodigester 20 days back in my home with 220ltrs drum. Now its produce the gas. but its not flameble(ignite). Plz help me mail id:

antoniraj (author)lyninsairam2017-01-05

The gas produced initially will not burn properly as it contains less methane and other impurities. Release the gas few times from the gas holder till you get burnable gas. Start feeding the plant regularly with kitchen waste or other organic material.

Please go through my other instructables on Biogas for more information at the following links


MatijaB7 (author)2017-01-04

Looking at step 7 I see you had used the M-seal to hold the guide pipe 25mm dia pvc pipe. However my question is, how would the other gas that are not methane go up to that pipe if its fully sealed? Did you made a small hole at the bottom or am I wrong?

antoniraj (author)MatijaB72017-01-04

The guide pipe should be completely sealed and should not allow any gas to pass through even if there are other gasses. There should not be any hole at the bottom also. The purpose of the guide pipe is to keep the gas holder in vertical position. Without the guide pipe, the gas holder tank will tilt to one side.

GovindS32 (author)2016-12-13

sir, kitchen waste or food waste having the C:N , 15:1 but the ideal C:N ratio for bio-gas production should be 25:1 so my question is will it effect bio-gas production upto any extent and if yes so what we need to do to solve it ?

antoniraj (author)GovindS322016-12-13

I am having a medium sized Biogas plant producing regular gas for more than two years. we feed all kitchen / food and garden waste regularly and the gas production never seems to be affected by the kind of material we feed. Anyhow, how do you find out the C:N ratio of your feed material without proper equipment ?

GovindS32 (author)antoniraj2016-12-22

this food ratio was i found in some books as a stander for kitchen waste that's why i asked you sir,

antoniraj (author)GovindS322016-12-23

you can go through these books to see any mention of how they can determine the C:N ratio of food waste

GovindS32 (author)antoniraj2016-12-28

No sir the there is no any article which shows how to find or determine the C:N ratio of organic matters, if i get i will share with you sir

About This Instructable




Bio: I like to make things more simple with easily available resources. My favorite quote: A human being should be able to change a diaper, plan ... More »
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