| Author | Batool, Saira |
| Call Number | AIT Thesis no.EV-15-21 |
| Subject(s) | Cassava industry--Waste disposal
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| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-15-21 |
| Abstract | Anaerobic digestion is a competitive source for the production of biogas and as well as efficiency and cost are concerned. Tapioca starch industries produced cassava pulp as solid waste .While; it contains high content of starch on dry weight basis. This cassava pulp has capacity to produce biogas. It is needed to add some co-substrate to enhance the amount of nutrient in cassava pulp to microbial community. Activated sludge used as co-substrate with cassava pulp in this study. Utilization of activated sludge as a co-substrate also positive approach toward the management of solid waste holistically. An anaerobic digestion process of cassava pulp with activated sludge as co-substrate was conducted in semi continues stir tank reactor experiment with different C/N ratio 25 and 35, to investigate the effect of different C/N ratio on various organic loading rate at mesosphilic temperature. To compare which C/N ratio is more suitable for anaerobic co-digestion, in addition methane production effect due to cyanide present in cassava was examined in each the C/N ratio. 15 L CSTR was with C/N ratio 35 was fed with mixed feed of cassava pulp and activated sludge (CP:AS) at ratio 77:25% (w/w) and 10 L reactor with C/N ratio 25 was fed with mixed feed of cassava pulp and activated sludge (CP:AS) at ratio of 54:46% ( w/w). Stability parameters and operational parameters were maintained to evaluate the biogas productivity and methane yield with VS added and VS removed of two C/N 35 and 25 ratio at different OLR (1.0,2.0 and 3.0 kgVS/m³.d for C/N ratio 25 and 1.0,2.0,3.0 and 4.0 kgVS/m³.d of C/N ratio 35). Three phases were investigated in the research. Phase I startup phase was successful in both the 15 L CSTR with C/N ratio 35 and 10 L CSTR with C/N ratio 25, under all the parameters under the recommended range of anaerobic digestion .In the operational phase II, the effect of increasing OLR on biogas production and methane yield was observed in both the C/N ratio 35 and 25.The 15 L reactor with C/N ratio 35 showed gas production rate of 1.2L/L/d, methane production rate of 0.61 L/L/d at and methane yield of 0.23 m³/kgVS at OLR of 3 kgVS/m3 and with the VS removal of 71.57 %, While the 10 L reactor with C/N ratio 25 showed gas production rate, methane production rate and methane yield value 1.13 L/L/d,0.58 L/L/d and 0.19 m3/kgVS respectively at 3 kg VS/m³ OLR, with the VS removal of 78 %. From the result it was concluded that the 15 L with C/N ratio 35 more suitable for the anaerobic as compare to C/N ratio 25. Phase III of the experiment showed that the cyanide level not exceeding the 6 mg/kg, hence cyanide content in both the reactors not caused the inhibition of methane production. As the methane yield is less than the standard value of 0.35 m³/kgVS, hence it is recommended for pretreatment of the activated sludge before operating in anaerobic digestion, in order to enhance the methane yield. |
| Year | 2015 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Annachhatre, Ajit P. |
| Examination Committee(s) | Bohez, Erik L. J.;Thammarat Koottatep |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2015 |