Investigation on simultaneous nitrification/denitrification and fouling of an aerobic granular membrane airlift bioreactor | |
| Author | Vijayalayan, Prashanthini |
| Call Number | AIT Thesis no.EV-08-29 |
| Subject(s) | Bioreactors Nitrification Denitrification |
| Note | A thesis submitted in partial fulfillment of the requirements for the Degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Aerobic granulation is a novel biological process developed to treat the high strength organic wastewater. It could be coupled with membrane airlift bioreactor (MABR) which would create an attractive alternative treatment technology in the near future. The objective of this study is to investigate the performance of the aerobic granular membrane airlift bioreactor based on organic and nitrogen removal efficiencies and membrane fouling behavior. Further, the stability of granular sludge with long sludge retention time and simultaneous nitrification and denitrification (SND) in the MABR were also evaluated. For this study, the organic and nitrogen loading of sequencing batch airlift reactor (SBAR) were maintained at 4 kg COD/m³ .d and 0.4 kg N/m³ .d respectively. Subsequently, the supernatant from the batch granulation reactor was discharged into the MABR to treat further where both aerobic and anoxic zones were existing. Due to the long sludge retention time (SRT) of the granular sludge and sudden changes in OLR, the granules commenced to disintegrate after 300 days of operation. As a result of this, the performance of SBAR and MABR based on removal efficiencies were unable to evaluate and the nitrogen loading was reduced to 0.4 from 0.6 kgN/m³ .d. However, it was identified that the SVI of MABR was 2.5 fold higher than that of granular sludge. Later, the SBAR and MABR were separated to evaluate the performance of MABR alone. Eventually, it was found that the MABR could achieve maximum of 70% of nitrogen removal including 50% of denitrification and 80% organic removal with external carbon source addition. The organic and nitrogen removal in AGMABR were 99% and 61% including 35% of denitrification respectively after combining SBAR and MABR. On the other hand in conventional MBR the organic and nitrogen removal achieved were 98% and 27% respectively. Hence, the AGMABR system could remove both organic and nitrogen more when compared to the conventional MBR. During this research the granule size was 1.7±0.1 mm and flocs were seen in the SBAR. Flocs had low settling ability and they were washed out to MABR during each cycle of operation. The EPS of flocs was 19.1 mgEPS/mgVSS which lead to rapid fouling in MABR. Once, the granules become matured and bigger, the flocs would be less and the nitrogen removal through denitrification would be more in the system. As a result the fouling in MABR would also be reduced. The production of soluble EPS in conventional MBR was 2 fold higher than that of MABR which shows that the fouling due to soluble EPS is less in MABR. Hence, the AGMABR system would be an attractive alternative option for water reuse and recycling in near future. |
| Year | 2008 |
| 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) | Visvanathan, C.; |
| Examination Committee(s) | Shipin, Oleg V.;Preeda Pakpian; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2008 |