Micro-scale anaerobic digestion of point source components of organic fraction

Micro-scale anaerobic digestion of point source components of organic fraction of municipal solid waste
H.N. Chanakya ^{a ,*}, Isha Sharma ^a, T.V. Ramachandra ^{a , b} ^a Centre for Sustainable Technologies, (formerly ASTRA), Indian Institute of Science, Bangalore 560 012, India ^b Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012, India

Abstract
Introduction
Materials and Methods
Results and Discussion
Conclusion
References

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Waste Management
journal homepage : www.elsevier.com/locate/wasman

* Corresponding author.
Tel. : +91 080 2293 3046/3099; fax : +91 080 23601428.
E-mail addresses : chanakya@astra.iisc.ernet.in, cestvr@ces.iisc.ernet.in

Acknowledgement

We are grateful to the Indian Institute of Science for financial and infrastructure support. We thank Ms. Vinutha Devi for assistance in the analysis of various feedstocks.

Please cite this article in press as : Chanakya, H.N. et al., Micro-scale anaerobic digestion of point source components of organic fraction ..., Waste Management (2008), doi:10.1016/j.wasman.2008.09.014

Abstract

The fermentation characteristics of six specific types of the organic fraction of municipal solid waste (OFMSW) were examined, with an emphasis on properties that are needed when designing plug-flow type anaerobic bioreactors. More specifically, the decomposition patterns of a vegetable (cabbage), fruits (banana and citrus peels), fresh leaf litter of bamboo and teak leaves, and paper (newsprint) waste streams as feedstocks were studied. Individual OFMSW components were placed into nylon mesh bags and subjected to various fermentation periods (solids retention time, SRT) within the inlet of a functioning plug-flow biogas fermentor. These were removed at periodic intervals, and their composition was analyzed to monitor decomposition rates and changes in chemical composition. Components like cabbage waste, banana peels, and orange peels fermented rapidly both in a plug-flow biogas reactor (PFBR) as well as under a biological methane potential (BMP) assay, while other OFMSW components (leaf litter from bamboo and teak leaves and newsprint) fermented slowly with poor process stability and moderate biodegradation. For fruit and vegetable wastes (FVW), a rapid and efficient removal of pectins is the main cause of rapid disintegration of these feedstocks, which left behind very little compost forming residues (2–5%). Teak and bamboo leaves and newsprint decomposed only to 25–50% in 30 d. These results confirm the potential for volatile fatty acids accumulation in a PFBR’s inlet and suggest a modification of the inlet zone or operation of a PFBR with the above feedstocks.