Dry anaerobic digestion of municipal solid waste as pre-treatment prior to landfill | |
| Author | Nguyen Pham Hong Lien |
| Call Number | AIT Thesis no.EV-04-14 |
| Subject(s) | Salvage (waste, etc.) Sanitary landfills--Leaching Sewage sludge digestion |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-04-14 |
| Abstract | The major environmental problem associated with landfilling of municipal solid waste is related to the long-term discharge of the leachate to environment as well as greenhouse gases emissions into atmosphere. Biological pretreatment prior to landfill could be an new and attractive alternative to reduce the environmental impact of this problem. Pre-treatment through anaerobic digestion could help ensure that the residue to landfill is stabilized while producing profitable energy. The objective of the study was to develop and optimize a combined process with anaerobic dry anaerobic digestion as a basic unit to pre-treat organic fraction of municipal solid waste. The process was carried out in three stages. First stage was flushing and acidification. Second stage was methanization where biogas was produced intensively. Finally, air flushing was practiced to flush out the remaining biogas inside the waste prior to landfills. Batch study was conducted on pilot scale digesters using vegetable waste as feedstock. Optimization of the first two stages was focused. It was found that flushing fresh waste with additional water (3L/kg waste) for short duration of 5 days was able to wash as much as 30% of volatile solid into leachate, out of which more than half was VF A. Hydrolysis yield was approximately 130 kgDOC/kgTS and acidification yield was about 180 g VFA/kg TS. The removal of VFA prevented their accumulation in the waste bed accompanied by low pH, which is known as inhibitors for biogas production. Application of micro-aeration showed the equivocal result in terms of enhancing hydrolysis and acidification. In the performance of methanization, biogas production could not be successfully started up without initial pH adjustment accompanied with addition of inoculums. Importantly, the study highlighted the importance of leachate percolation in the enhancement of biogas production shortening the retention time of the process. Micro-aeration during pre-stage appeared to give benefit in biogas production during methanization. After 60 days, 260 L CHJkg flushed VS was obtained. Since the methane potential of the waste was 300 L/kg VS, it was implied that 75 % biogas conversion could be achieved in real system. Overall results showed 61 % volatile solid destruction. This reduction was contributed by (1) flushing into leachate (30%C of fresh waste) and (2) stabilization through biogas production (25%C of fresh waste). |
| Year | 2004 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. EV-04-14 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Visvanathan, Chettiyappan |
| Examination Committee(s) | Annachhatre, Ajit P.; Shipin, Oleg V. |
| Scholarship Donor(s) | The Royal Netherlands Government |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2004 |