| Author | Juanga, J eanger P. |
| Call Number | AIT Thesis no.EV-05-11 |
| Note | A thesis submitted in partial fulfillment of the requirements for the
degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | The triggering potential environmental problems linked to municipal solid waste landfills and its disposal, diminishing land resources and depletion of fossil fuels have fostered the need of biological treatment of solid waste, the anaerobic digestion. This process is considered as innovative and attractive technology for waste stabilization with significant mass and volume reduction with the generation of valuable by products such as biogas and fertilizer. This research work focused on the optimization of both pre-stage and methane phase in order to enhance the overall digestion process. The anaerobic digestion technology under
combined process and sequential staging concept were both conducted. The former
includes enhanced pre-stage operation that includes flushing and microaeration, starting up methane phase by pH adjustment and inoculum addition. While the latter employs the old bioreactor coupled with newly loaded reactor with the use of mature leachate for crossrecirculation as start-up strategy and direct recirculation was conducted after the new reactor was fully shifted to active bioreactor. Moreover, this study presents several runs of experiment and analysis with the aim of
shortening the duration of overall stage of digestion process while optimizing the biogas generation with higher methane content. In this view, a combined process under mesophilic and thermophilic reaction temperature were examined; a reduced substrate particle size as well as a reduced pre-stage condition with lesser volume of flushing water was further investigated to verify its effectiveness; importantly, a sequential staging concept was demonstrated to develop the process performance. Moreover, process
efficiency evaluation based on biochemical methane potential test and energy balance was conducted. The study was conducted in solid state batch system in pilot scale bioreactors. Market waste and organic fraction of municipal solid waste were used as feedstock in this research. It was found out that thermophilic condition performed well over mesophilic condition. The former showed higher rate of waste conversion process. Reduced substrate particle
size of 30 mm offer degradation benefits over 60 mm. Furthermore, a reduced pre-stage operation with reduced volume of flushing water (3 days, 360 L) was able to generate equal load of pollutants with 5 days of flushing (600 L) with higher biogas production. A successful attempt on sequential staging was able to display much improved performance as an answer to the objective of this study. According to the energy balance study, thermophilic systems generates higher energy yield over mesophilic condition. After several runs for optimization process, significant volume and mass reduction of 80% and 86% was achieved respectively. Importantly, almost 86% of volatile solids reduction with equivalent methane yield of 334 L CH4/kg VS was obtained. An overall assessment of
84% process efficiency was gained.
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| Year | 2005 |
| 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 and Management (EV) |
| Chairperson(s) | Visvanathan, C.; |
| Examination Committee(s) | Annachhatre, Ajit P.;Aramaki, Toshiya |
| Scholarship Donor(s) | Government of France ; |
| Degree | Thesis (M.Eng.) -- Asian Institute of Technology, 2005 |