Comparison of nitrogen removal between conventional membrane bioreactor and attached growth membrane bioreactor | |
| Author | Munasinghe, Pradeep Chaminda |
| Call Number | AIT Thesis no.EV-08-28 |
| Subject(s) | Membrane reactors Bioreactors Sewage--Purification--Nitrogen removal |
| 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 | In this study two MBR systems were experimentally investigated. One was conventional suspended growth MBR with aeration and the other with attached growth MBR with sponge media to compare the nitrogen removal efficiencies and fouling characteristics. There were two types of media; namely cylindrical polypropylene and porous sponge (cubic). After a preliminary study sponge media was selected based on COD and TN removal efficiencies as the attached growth media. In most of the previous literature attached growth MBR used with a moving bed configuration. But in this study a partially fixed bed (media allowed to have a limited movement) was used under low dissolved oxygen (DO) concentration. Experiment was conducted for three different HRT values; namely 10 h, 7 h and 13 h and the organic loading rate (OLR) and nitrogen loading rate (NLR) were kept constants at 2.2 to 2.4 kg COD /m³.d and 0.4 kg N/m³.d respectively. There was no significant difference in COD removal rate was observed during the MBR analysis for both conventional and attached growth (sponge media) MBR systems. Furthermore it was observed a similar COD removal rate for attached growth MBR and conventional MBR. In general the COD removal was not affected by the HRT variation during the study period. It was observed that the biomass assimilation was the major mechanism for total nitrogen (TN) removal in conventional MBR while simultaneous nitrification-denitrification (SND) was the dominating mechanism for sponge media MBR. HRT 10 h was observed to be the most appropriate operational condition to operate the sponge media reactor. It was observed a 98% COD removal rate and 86% TN removal rate during the operation under 10 h HRT. Similarly it was observed a highest SND rate (around 70%) under 10 h HRT and SND rates for HRT 7 h and 13 h were observed as 20% and 42% respectively in the sponge reactor. Both the systems were operated more than 70 days during the 10 h HRT, without membrane fouling. Attached growth system showed 1.5 times greater fouling propensity than the conventional reactor under the operation of 7 h HRT. Fouling rates for attached growth and conventional reactors were found to be 0.058 and 0.056 kPa/d respectively for 13 h HRT. The study further revealed that there was no significant relationship between EPS and membrane fouling for all HRT values. |
| 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 and Management (EV) |
| Chairperson(s) | Visvanathan, C. |
| Examination Committee(s) | Chongrak Polprasert;Annachhatre, Ajit P. |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2008 |