Biogas generation from cassava pulp : effect of carbon nitrogen ratio by co-substrate utilization | |
| Author | Pornpimol Taengtan |
| Call Number | AIT Thesis no.EV-13-23 |
| Subject(s) | Cassava industry--Environmental aspects Cassava industry--Waste disposal |
| 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-13-23 |
| Abstract | Cassava pulp is a major solid waste from starch industries. Although it has high starch contents, it can be converted to the form of methane giving a value addition. These pulp contains with unsuitable C/N ratio is an important factor for anaerobic digestion. In this research, C/N ratio of cassava pulp was adjusted by addition of co-substrates to improve methane production. In this study, two experimental studies were conducted. First experiment was about BMP assay which used to evaluate methane production potential and optimum co-substrate at suitable C/N ratio. Pig manure and activated sludge were selected as co-substrates and mixed with cassava pulp according to C/N ratio at 15, 25 and 35. The reactors were operated at ambient temperature for 40 days. One-stage semi-continuously fed reactor was employed to develop operational parameters in the second experiment and it was used to evaluate the biogas productivity and VSremoved at various organic loading rates (2.0, 4.0 and 6.0 kg VS/m³·d of OLR). The results of BMP experiment brought out that co-substrates can yield higher methane generation potential of cassava pulp compared to cassava pulp alone. Pig manure was found to be a suitable co-substrate for cassava pulp because of higher methane potential than activated sludge. The best C/N ratio for anaerobic co-digestion of cassava pulp and pig manure was 15 for batch systems. However, the C/N at 35 was selected in AD experiment to avoid ammonia accumulation which usually was a problem for anaerobic digestion at higher OLR. Increasing of organic loading rate affected the reactor’s performance. Biogas production increased while methane yield decreased when comparing to 2.0 kg VS/m³·d of OLR. However, the methane yields at 4.0 and 6.0 kg VS/m³·d of OLR was similar. VSremoved declined as higher OLR. The highest percentage of VSremoved was 79.46% and reported at 2.0 kg VS/m³·d of OLR. When organic loading rate increased, the reactor operation was stable and it showed no inhibition effect from ammonia-nitrogen and VFA due to their concentrations were lowered the inhibition concentration level. |
| Year | 2013 |
| 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) | Anal, Anil Kumar;Thammarat Koottatep |
| Scholarship Donor(s) | Royal Thai Government;Asian Institute of Technology Fellowship |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2013 |