[Digestion] [Stoves] Karve connecting Biochar and Biogas

[Hoysall Chanakya]

Adding to Duncans Assessment,
My experience suggests that in suspended growth dependent anaerobic
digesters and for inoculum derived from cattledung the system tolearates a
daily turnover of 2-3g VFA equivalent daily depending upon temperature. 
Food waste, that is amenable to rapid VFA generation, would be bound by
this seemingly important limit.  I agree with duncan the very same reasons
that adding biochar is unlikely to provide long term solutions - biofilms,
if any would soon be saturated.

About banana peels - this reference might help somewhat in understanding
the problem.  The skin largely cemented by water soluble pectin degrades
very rapidly to leave little solid matter but a lot of VFA.  When you
build a digester for it this would be the limiting issue.  BMP is quite
high.  VFA accumulation and build up in some zone of the digester could be
overcome by simply recycling 10% of the digester liquid from the outlet. 
This helped a great deal and could avoid neutralization and lime addition
in coffee wastewater plants which is also a large pectin load.

Chanakya, HN, Isha Sharma, T. V Ramachandra.. Microscale anaerobic
digestion of point source components of organic fraction of muncipal solid
waste* (2009) Waste Management 29 (2009) 1306–1312.




-- 
Dr. Hoysall Chanakya
Centre for Sustainable Technologies
(Assoc. Faculty at Centre for Infrastructure, Sustainable Transport and
Urban Planning (CiSTUP) and Centre for Contemporary Studies)
Indian Institute of Science, Bangalore 560 012
ph 91-80-2293 3046; fax-91 80 2360 0683


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