ZTM-BPD-CIRCOT

Cotton Textile Mills generate about 80,000 to 85,000 tonnes of solid cellulosic wastes popularly known as Willow-dust and cyclone dust. These waste materials are rich in cellulose and hence innately suitable for biogas production. CIRCOT has therefore developed methods for producing biogas using these materials both by a (i) batch fermentation process and a (H) semi continuous fermentation process.

Willow-dust is a voluminous material and hence many a times storing becomes a problem. Further, a lot of heat is generated within the dust making it prone to catching fire.

Willow-dust is rich in cellulose, hemicellulose and lignin. The chemical compostion of willow-dust via -a-vis cattle waste is given in the following Tables.

Experiments under field conditions on cotton crop under irrigations indicated that application of the biomanure prepared from willow-dust at the rate of 5 tonnes per hectare is equivalent to 10 tonnes of FYM or 80:40:40 of N,P and K per hectare.

Proximate Chemical Analysis of Willow-dust and Cattle Waste:

Analysis of Willow-dust and Digested Material for NPK and Na :

  Batch Fermentation Process :

• charging is done every 20th day
• water requirement for the process is very less
• high solid loading
• readily usable bio-manure
• Requirement of a series of digesters

Semi-continuous Process :

• Demands only one digester and a separate gas holder
• Charging has to be done every day
• high water requirement and low solid loading
• slurry handling is difficult

The economics of the process are as follows
(a) Raw material: 100 tonnes/annum
(b) Space : lOOm2
(c) Capital cost: Rs.5-6 lakhs
(d) Total gas generation : loom3 (equivalent to 3 LPG cylinders of 14.5 kg)
(e) Total Income from gas and manure : FRs.2 Iakhs/ annum
(f) Running cost: Rs.40,000 annum
(g) Net income: Rs.1.6 lakhs/annum

A couple of plants have been installed in leading textile mills processing cotton. CIRCOT regularly undertakes consultancy for setting up biogas plants in textile mills.