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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 12, No. 9, 2015, pp. 3029-3038
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Bioline Code: st15285
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 12, No. 9, 2015, pp. 3029-3038
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Kinetic studies on anaerobic co-digestion of ultrasonic disintegrated feed and biomass and its effect substantiated by microcalorimetry
Priyadarshini, R.; Vaishnavi, L.; Murugan, D.; Sivarajan, M.; Sivasamy, A.; Saravanan, P.; Balasubramanian, N. & Lajapathi Rai, C.
Abstract
Studies were carried out on anaerobic codigestion
of primary and secondary excess sludge obtained
from tannery effluent treatment plant. Anaerobic biomass
collected from a treatment plant was used as the source of
micro-organisms. The optimum feed to micro-organism
ratio was evaluated as 0.7 on the basis of volatile solids
reduction cum gas production. Both feed and anaerobic
biomass were subjected to ultrasonic pre-treatment in order
to enhance the digestion process. Experiments carried out
on batch mode showed significant increase in the gas
production for pre-treated feed and biomass. Optimum pretreatment
durations were evaluated as 5 min for feed and
3 min for anaerobic biomass. Heat flow analyses of the
anaerobic biomass using isothermal microcalorimetry
throw light on different stages of digestion process. The
effect of ultrasonic pre-treatment on anaerobic biomass
was also substantiated using this technique. The heat
energy released by pre-treated and untreated anaerobic
biomass was evaluated as 16.3 and 7.6 kJ/kg, respectively.
Kinetic analysis revealed that the overall rate constant of
digestion process increased by 1.5 times due to pre-treatment.
However, the initial lag time increased by about
20 % for the optimally pre-treated sample compared to
untreated sample. Modified Gompertz equation was used to
model, and the parameters were evaluated. The significance
of this work lies on energy production (bio gas) and
at the same time increasing the maintenance metabolism
rate thereby minimizing excess sludge biomass generation.
Keywords
Activated sludge; Anaerobic digestion; Isothermal microcalorimetry; Ultrasonic pre-treatment
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