In pursuance of SDG Goal 7: Ensure access to affordable, reliable, sustainable and modern energy, Anaerobic digestion is one of the viable technologies that can contribute immensely to the actualisation of this goal in developing countries.
Anearobic digestion is the sequence of steps in which microorganisms breakdown insoluble biodegradable materials in an oxygen free environment. It has four main stages namely: Hydrolysis,Acidogenesis, Acetogenesis and Methanogesis.
The process starts with bacterial hydrolysis of the feed materials mainly organic polymers like carbohydrates and proteins and breaks it down into monosacharides and amino acid.
The second stage is Acidogenesis, in this stage, acidogenic bacteria convert the sugars and amino acids formed in the first stage into carbon dioxide, , ammonia, hydrogen and organic acids.
Subsequently , Acetogenesis commences, in this stage, acetogenic bacteria convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide.
And finally, methanogenic bacteria which convert these products to methane and carbon dioxide.
ANEAROBIC DIGESTER TECHNOLOGIES
Different anaerobic digester systems are available commercially, However the picture above is an experimental DIY mini continuous stir tank reactor(CSTR) made with recycled plastic water bottle and plastic bucket for the digester tank and the gas holder respectively, a scrubbing unit made with water filter for the removal of carbon dioxide from the biogas, 1 inch Polyvinyl Chloride pipe (PVC ) for conveying biogas from the digester tank to the scrubbing unit, 8mm flexible hose for transporting the scrubbed gas from the scrubbing unit to the gas holder and metal support frame.
The setup has a total volume of 98 litres digester tank , daily feed rate of 2 kg of cow dung, water and food in the ratio of 1:1:2, and daily output of 17.6 litres of biomethane.
It is was a challenging and exciting project. You can Do It Yourself.
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From @gowealth