Biofuels production 189
Remedy a) Temperature may be raised by, e.g., solar heating, heating with biogas, and composting around the digester wall. b) Remove the scum layer by agitating the drum daily and seeing to it that no straw or grass, etc. get into the plant. c) Correct amount of slurry should be added daily. d) Slurry mixture should not be altered too much at a time. e) Daily feed with dung and water only, to be continued.f) Leak should be located and repaired. g) Slurry to be made of the right consistency. Gas jet to be cleaned with split bamboo or needle.Cause a) Temperature too low. b) Thick scum on top of slurry. c) Too much slurry put in daily. d) Slurry mixture suddenly changed a lot. e) Chemicals, oil, soap or detergent put into slurry. f) Gas leak. g) Slurry mixture too thick or too thin. Gas jet is blocked.Table 4.19 Problems with the operation of the biogas plant (adapted from Tata Energy Research Institute 1982) (continued) Problem 3. Gas holder or bag or pressure (in fixed dome digester) rises very slowly. 4. Too little gas although pressure is correct.