Dear Mr. Rasool,

Please refer to the following basic steps which I previously posted to another question:

1. Cut the plant biomass into small sizes and mix with a certain volume of water to achieve a suitable total solids content (based on desired concentration). You may wish to work at a total solids content of 10%.

2. Adjust the pH of this mixture to approximately 7 using sodium bicarbonate.

3. Mix with a determined amount of inoculum (either digested sludge or cow manure which works well!). Check pH of new mixture and ensure it is within proper range for anaerobic digestion (6.8-7.5).

4. Place inoculum+plant biomass mixture in an air-tight reactor (You may use conical flasks or glass bottles with rubber septum or bigger reactors such as stainless steel digesters or 150-L drums or 1 m3 Intermediate Bulk Containers!).

5. Place reactor in an environment maintained at 35oC (mesophilic) or 60oC (thermophilic). For larger reactor, this might be difficult. As such, you may leave the reactor in ambient conditions but the methane yields will then be much lower!

6. Leave the digestion process and measure biogas volume daily using downward displacement of acidified water.

7. If you want to remove CO2 from the biogas, bubble the gas through an alkaline solution of NaOH or Ca(OH)2. The gas obtained will then be mainly methane gas.

8. If you want to remove H2S from the biogas, bubble through steel wool.

9. You may also check the composition of the biogas using a gas analyser.

Hope these helps...

Kind Regards,

Bundhoo Zumar

Hi Rasool

In our experience, to start anaerobic digestion of agricultural residues, we added some activating microorganism, usually, we use the cattle gut to activate the anaerobic digestion process.

Of course you have to design the digester according to the feed stock.

Regards , 

Dear Kamal,

In order to treat plant or agriculture residue through AD, it needs to apply some pretreatment i.e chemical, biological or mechanical. This makes easy for microbes to digest. And about anaerobic consortia, you can take effluent as seeding material of any biogas plant nearby. Please for more understanding follow link below:

http://tandfonline.com/doi/full/10.1080/15567036.2017.1384866

Best Wishes,

Asim Ali

To start with, first you have to adjust the C:N ratio of your plant biomass. It should be at-least near 30:1. To achieve it you may add cattle dung or urine or urea as per your convenience. It is like composting but in an oxygen-free container/digester. It is a biological process in which naturally occurring anaerobic organisms breakdown plant biomass/ organic wastes and produce gas mostly methane along with some carbon-dioxide. Other end products are bio-gas, which is combusted to generate electricity and heat, or can be processed into renewable natural gas and transportation fuels.

Well, your question seem that simple but its such a complex one when one needs to address it appropriately. anaerobic digestion has several departments and all requires optimization to achieve efficacy. Your reactor design will mainly depend on your feedstock (solid, liquid, semi solid), and this has to be clearly indicated to obtained good and specific answers. some reactors comes with complete stirring technology to enhance microbes and substrate contact whilst others too are operated in either continuous or batch mode. so if your target is aimed at reducing cost, you will need to indicate that. Again, are you targeting at biodegrading and harnessing bioenergy along the lines? you need to indicate this as well. Activated sludge could be obtained from an existing treatment plant regardless of that, it being operated under aerobic condition. this sludge could be cultured under anaerobic condition for your purpose. on the hand you could also culture them from either fresh or dried cow manure. Operational conditions of the anaerobic process such as pH, temperature, organic loading, alkalinity, startup, solids, vss, HRT, SRT, and many others are factors needed to be considered to obtained good results from the anaerobic process.

THANKS TO ALL OF YOU FOR YOUR VALUE ABLE SUGGESTIONS

Supposing you have a simple application, not wish to develop a sophisticated technology, I give you a simple answer: Firstly you must check the C:N ratio that is an essential parameter to know that you have a proper feedstock, capable to be fermented anaerobically. C:N must be in range of 15-30, most plant biomass has this ratio in range of 50-80 so as you must add Nitrogen source that could be pig and chicken dung (this is 13-15 but not add sheep or cows that is 25-29), or even some types of algae that has C:N 10-15. Some plants such as fresh grass, potatoes leaves etc. have C:N 22-30 and they don't need Nitrogen-based co-substrate. So, it depends very much on your feedstock type.

Secondly you need some inoculum. Inoculum can be anaerobically fermented sludge or cow dung (in this case you add it as inoculum, not to adjust C:N), in fact any dung from herbivore animals contains anaerobic microrganisms able to start the process. If add 10% v/v inoculum in plant grass (only for start) the mix is adequate to sustain a basic, simple, natural anaerobic process. After that plant biomass can be added alone (if C:N is optimal).

Dear Mr Rasool, Suggestions by previous answers are excellent. Particularly Mr Philip explains exactly what is needed. In addition, most important aspect is the pre-treatment of your substrates. you have not specifically mentioned type of your plant biomass whether leaves, or residues etc. Particle size matters a lot for biological processes, thus try to use disintegration techniques such as crushing to reduce particle size. If you have different substrates such as food waste, you can introduce anaerobic co-digestion by mixing with plant biomass. This has to be done by carefully by manipulating parameters as C:N ratio of the mixed feed.

Dear Mr. Rasool,

Please refer to the following basic steps which I previously posted to another question:

1. Cut the plant biomass into small sizes and mix with a certain volume of water to achieve a suitable total solids content (based on desired concentration). You may wish to work at a total solids content of 10%.

2. Adjust the pH of this mixture to approximately 7 using sodium bicarbonate.

3. Mix with a determined amount of inoculum (either digested sludge or cow manure which works well!). Check pH of new mixture and ensure it is within proper range for anaerobic digestion (6.8-7.5).

4. Place inoculum+plant biomass mixture in an air-tight reactor (You may use conical flasks or glass bottles with rubber septum or bigger reactors such as stainless steel digesters or 150-L drums or 1 m3 Intermediate Bulk Containers!).

5. Place reactor in an environment maintained at 35oC (mesophilic) or 60oC (thermophilic). For larger reactor, this might be difficult. As such, you may leave the reactor in ambient conditions but the methane yields will then be much lower!

6. Leave the digestion process and measure biogas volume daily using downward displacement of acidified water.

7. If you want to remove CO2 from the biogas, bubble the gas through an alkaline solution of NaOH or Ca(OH)2. The gas obtained will then be mainly methane gas.

8. If you want to remove H2S from the biogas, bubble through steel wool.

9. You may also check the composition of the biogas using a gas analyser.

Hope these helps...

Kind Regards,

Bundhoo Zumar

i have the same question for my project

Dear Marr Iya, Please follow the answers and especially for starting the process foloow the steps exlpained by Zumar Muhammad Ali,

Please refer to the following basic steps which I previously posted to another question:

1. Cut the plant biomass into small sizes and mix with a certain volume of water to achieve a suitable total solids content (based on desired concentration). You may wish to work at a total solids content of 10%.

2. Adjust the pH of this mixture to approximately 7 using sodium bicarbonate.

3. Mix with a determined amount of inoculum (either digested sludge or cow manure which works well!). Check pH of new mixture and ensure it is within proper range for anaerobic digestion (6.8-7.5).

4. Place inoculum+plant biomass mixture in an air-tight reactor (You may use conical flasks or glass bottles with rubber septum or bigger reactors such as stainless steel digesters or 150-L drums or 1 m3 Intermediate Bulk Containers!).

5. Place reactor in an environment maintained at 35oC (mesophilic) or 60oC (thermophilic). For larger reactor, this might be difficult. As such, you may leave the reactor in ambient conditions but the methane yields will then be much lower!

6. Leave the digestion process and measure biogas volume daily using downward displacement of acidified water.

7. If you want to remove CO2 from the biogas, bubble the gas through an alkaline solution of NaOH or Ca(OH)2. The gas obtained will then be mainly methane gas.

8. If you want to remove H2S from the biogas, bubble through steel wool.

9. You may also check the composition of the biogas using a gas analyser.

Hope these helps...

Kind Regards,

Bundhoo Zumar

thanks :)