Sehbajpur farmer says NO to stubble burning; uses paddy straw for biogas

Ajmer Singh, afarmer of Sehbajpur villagein Raikot block of Ludhiana district in Punjab has successfully installed a biogas plant which utilizes crop residue and cow dung as feed to generate biogas, within his household premises. The family of 3 now avails of 3-4 cum per day of clean cooking fuel and organic compost for their fields, free of cost.

The initiative of utilizing agricultural and animal waste such as paddy straw and cattle dung to produce biogas is timely and urgently needed given that the northern region of India and Punjab in particular, find itself in the midst of a paradoxical situation.  Production of rice and wheat to meet the country’s food requirement co-exists with the growing problem of stubble burning and straw disposal.  

That the practice of burning paddy and wheat straw in the fields during the rabi harvesting season affects the environment is common knowledge, as reported time and again.

About the initiative:  A farmer by profession and a resident of village Sehbajpur, Sh. Ajmer Singh has been proactively working towards the promotion of organic farming.  Having pledged to protect the environment in the best way he can, he has refrained from burning stubble for the last 4 years and has not used chemicals or pesticides to meet the nutrient demands of the crops.  Rather, he has saved stocks of paddy straw, keeping it aside. Observing his sincerity towards an eco-friendly lifestyle, an NGO named Gadri Baba Dulla Singh Giani Nihal Singh Foundation (GBDSGNS) of which the farmer is an active member decided to step in support his endeavours.

With a view to promoting sustainable agricultural practices and mitigating the effects of stubble burning, Gadri Baba Dulla Singh Giani Nihal Singh (GBDSGNS) Foundation, Confederation of Indian Industry (CII) has initiated some work in partnership with Royal Enfield in 10 villages of Raikot block in Ludhiana District. The progressive farmers in these villages with the CSR support of organizations have made efforts to turn useful resources such as agricultural and animal waste into energy.    The project was technically supported by the Punjab Agricultural University (PAU) and Agriculture Department, Ludhiana and the district administration.

Objectives of GBDSGNS: GBDSGNS aims to promote sustainable agricultural practices and mitigate the issue of crop residue burning that would lead to a safer environment.  The Foundation which has a huge volunteer support is headed by Dr Harminder Singh Sidhu (President).  Among its objectives are to spread awareness and provide farmers with technical assistance, to enable them to stop the practice of stubble burning.  Dr. Sindu encouraged farmer Singh to set up a biogas plant at his household and use his stock of paddy straw to convert into biogas.  The initiative has resulted in monetary savings and optimum utilization of crop residue.  

Installation of plant:  The biogas plant was installed as a pilot project in March 2020, prior to the COVID-19 lockdown.  With the support of 8-10 labourers, the plant funded by the CSR unit of Hindustan Petroleum and CII-New Delhi, and costing Rs. 2.5 lakh was installed in 3 days with zero investment from the farmer. 

Technical details of plant:

Volume of Digester20 Cum
Diameter of Digester3.00 m (10 feet)
Height of Digester3.00 m (10 feet)
Capacity of Floating Drum Gas holder2 Cum
Diameter of Floating Drum Gas holder1.50 m (5 feet)
Height of Floating Drum Gas holder1.20 m (4 feet)
Diameter of Well1.80 m (6 feet)
Depth of Well1.50 m (5 feet)
Paddy straw required per batch16 quintal (1.6 MT)
Cattle dung required per batch4 quintal (0.40 MT)
Paddy straw utilization per year64 quintal (6.4 MT)
Paddy straw collection area2.5 acre/1.0 hectare
Bio gas generation3-4 Cum/day (Equivalent to 2.5-3 cylinders of LPG per 3 months

Dry Fermentation Biogas Plant for Anaerobic digestion of paddy straw:  Having commenced functioning in September 2021, the initial feed used was paddy straw, cattle dung and water. Layer by layer with the help of ladder it was poured inside the bio digester. Paddy straw was cut into small fractions so that it can be digested well. Approximately 16 quintals of paddy straw, 4 quintals of cow dung and 18000 litres of water was used in the process.

Paddy straw is digested by anaerobic means which produces biogas as a fuel for kitchen and can also be used for lighting.  This method of anaerobic digestion or dry fermentation of organic waste requires very little labour but produces large amounts of biogas, over a three-month period when straw or stubble is available.  The digested material so produced from anaerobic digestion is good quality manure, ready for use in the fields. The disposal of the digested material is not difficult as it can be lifted from the plant with the help of a semi-automatic system.

Punjab Agriculture University, Ludhiana has designed and manufactured the M.S. based structure as a digester to generate biogas from paddy straw above the ground, the life of the structure being about 15 years. Given that the structure is above the ground, it can be easily moved.  The process of dry fermentation is a batch process, and once the digester is loaded and activated, it would produce sufficient gas for a period of 3 months.

The digester is made completely air tight unlike conventional biogas plant digester in which only the gas holder is air tight. In the conventional biogas plants, digestion takes place in the presence of a large amount of water and the gas bubbles are free to move in a vertical upward direction only.  However, in this case, the quantity of water is low, thus the gas bubbles are free to move in all directions. If the digester is not air tight, storage of gas will not be possible.

Process for operating the plant:  Feeding of paddy straw is done in layers and on top of each layer, a small quantity of cattle dung is added till it is filled to the top.   Openings of the digester are closed and made air tight.  Water is added into the digestor with the help of a pipe connected at the bottom of the digestor till the water starts flowing through the gas outlet pipe fitted on the top of the digester.  The objective of adding water is to make the paddy straw wet after which anaerobic digestion commences in the digestor.  Production of biogas starts after about 7-10 days.  It is then stored with the help of a MS gas holder connected to the digestor through a HDPE pipe near the gas outlet pipe.

Operation and Maintenance:  Once in 6 months, the batch of paddy straw with cattle dung mixed has to be removed and further shredded and utilized in agricultural fields.  Emptying of the plant is quite simple and no additional cost has to be incurred for emptying the plant.  Skilled labour is not required for construction of the plant. 

Since the plant began in September 2021, requirement for operation and maintenance has been nil. The biogas plant has been working perfectly and the household is able to avail of the gas without a problem. Although it was advised that every 6 months, the first batch of bio-waste inside the plant has to be replaced with new material, so far it has not been necessary. In September, the manure generated will be taken out and used in the fields.

The farmer and his wife are delighted that their straw is being used without harming the environment while providing biogas and manure at their door.  They plan to use the compost generated for agriculture.  Best of all, it saves money.   The Sarpanch – Sh. Darshan Singh Mann hopes that the system can be replicated in other households or at community level.

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