Effects of organic nitrogen and carbon supplementation on biomethanation of rice bran

What is it about?

The effects of organic nitrogen, sucrose and starch on the bio-methanation of rice bran were investigated using digesters of 1-litre capacity operated at ambient temperature (30oC – 32oC) and pH of 7 for 20 days. Rice bran and organic nitrogen supplement were varied at ratios 2:1, 3:1, 4:1 and 5:1, while 20g of sucrose and 20 g of starch were added to rice bran as supplements. Fresh strained cow rumen liquor was used as inoculum. There was no significant difference (P<0.05) between non-supplemented and sucrose-supplemented feedstock. Starch-supplemented feedstock produced more biogas than the sucrose supplemented and the non-supplemented feedstock (P>0.05). Varying the organic nitrogen had no significant effect on the biogas yield (P<0.05).

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Why is it important?

The results show that though nitrogen is needed by Methanogens, its ratio should be minimal and monitored in order to avoid the toxicity of the biodigester which may lead to a stoppage of digestion and reduction in biogas yield. Starchy feedstocks are better used for biogas generation than cellulose, lignocellulose and sucrose feedstock because they will enhance the generation of gas almost immediately and the production of more biogas over a long period of time. It is recommended that rice bran to organic nitrogen ratio of 2:1 be used for charging biogas plants when rice bran is to be used as feedstock material. Biogas is produced as a result of the metabolic activities of Microorganisms, regular biogas production could be mastered when the living conditions, operational parameters and mechanisms of metabolism of the fermenting Microorganisms are recognized