Fouling behavior and nitrogen removal in the aerobic granulation membrane bioreactor | |
| Author | Bui Xuan Thanh |
| Call Number | AIT Diss. no.EV-09-02 |
| Subject(s) | Sewage--Purification--Biological treatment Sewage--Purification--Nitrogen removal |
| Note | A dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. EV-09-02 |
| Abstract | This study investigated the fouling behavior and nitrogen removal of two operational modes of granulation MBR, namely Batch Granulation MBR (BG-MBR) and Continuous Granulation MBR (CG-MBR). Additionally, the characteristics of sludge and supernatant were examined during the experimental course. Coupling of Sequencing Batch Airlift Reactor (SBAR) with MBR in a batch operation (i. e., BG-MBR) showed better performance than the CG-MBR based on granule stability, simultaneous nitrification denitrification and fouling control. On the other hand, due to granule breakage after two weeks of operation, the CG-MBR system functioned similar to conventional MBR. At the OLR of 2 kgCOD/m³.d, granular sludge in the BG-MBR was maintained up to 18 gVSS/L while sludge flocs in CG-MBR was only up to 5 gVSS/L. Aerobic granules in the BO-MBR system were unstable under anaerobic conditions and with long retention of granules. By contrast, the anoxic/aerobic conditions in the reactor enhanced the retention, settling ability, denitrification and filterability of flocculent sludge. The simultaneous nitrification denitrification was achieved in the BG-MBR system due to the spherical structure of the granule where aerobic and anoxic conditions exist in the surface and the core of the granule respectively. It was observed that the TN removal rate was 47% or 22 mgTN/L.h (1.76 mgTN/gVSS.h) at OLR of 2 kgCOD/m³.d. The fouling rate of the BG-MBR system was much lower than the CG-MBR or conventional MBR. Soluble microbial products were found to be the main cause for fouling where soluble polysaccharides and protein were deposited on membrane. More to the point it was noted that the polysaccharides were the dominant deposited substances. The specific deposition loading on membrane during membrane filtration was 11 mg/L.m² and 8 mg/L.m² for soluble polysaccharides and soluble protein respectively. High aeration rate and anoxic phase in the granulation reactor released different types of soluble microbial products which had influenced the filtration behavior of the system. The release of soluble microbial products in the BG-MBR system depends on the HRT maintained in the MBR. Besides, the HRT of 2-5 h was found to be the suitable range for operating the MBR which can reduce the fouling, increase the supernatant quality and reduce the energy consumption. However, the granule breakage in the BG-MBR increased the fouling propensity due to release of soluble microbial products. It was found that the filtration resistance of the SBAR effluent was higher when compared with the mixed liquor in anoxic/aerobic operational conditions. Furthermore, the resistance and irreversible resistance rates of SBAR effluent were increased at aeration rate of granulation process as high as 2.2 cm/s due to release of macromolecules (30-50 kDa) and small particles while the soluble microbial products were only released at lower aeration rate. Around 60% of the hydrophobic fraction was found at high aeration rate (2.2 crn/s) in the soluble fraction of SBAR effluent with low hydrophobic intensity. On the other hand, at the low aeration rate (0.6 crn/s) with anoxic growth, 20% of the hydrophobic fraction was noticed with high hydrophobic intensity |
| Year | 2009 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. EV-09-02 |
| Type | Dissertation |
| 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) | Shipin, Oleg V. ;Viljakainen, Esa ;Sperandio, Mathieu |
| Scholarship Donor(s) | French Government |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2009 |