Treatment of wastewater using a pilot-scale membrane-aerated biofilm reactor for the removal of organic matter and total nitrogen | |
| Author | Siriweera, Withanage Buddhima Sharmane |
| Call Number | AIT Thesis no.EV-20-15 |
| Subject(s) | Wastewater--Treatment Membrane reactors Sewage--Purification--Biological treatment |
| 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 | The worldwide issue of eutrophication in water bodies due to nitrogen pollution from wastewater has made it essential to improve nitrogen removal of advanced wastewater treatment methods. Membrane Aerated Biofilm Reactor (MABR) is a recently developed biofilm technology which provide effective simultaneous nitrification and de-nitrification in the same reactor. In this study, a pilot scale MABR modified with PVA gel biocarriers containing denitrifying bacteria was operated with the purpose of enhancing TN removal efficiency from actual low-strength domestic wastewater. Unlike with synthetically prepared wastewater, treating real wastewater is challenging due to variation of COD/N ratios. Two MHF 200 APE membranes were employed in MABR and operated under different HRTs with and without PVA gel biocarriers. Adding the PVA gel biocarriers increased NH4-N and TN removal efficiencies by 11%, 1% and 6% and 18%, 10% and 10% at HRT of 12h, 9h and 6h respectively. Maximum of 88% of nitrification and 79% of TN removal efficiencies were achieved with PVA gel beads at 12h of HRT. At the optimum COD/N conditions around 10, 82% of nitrification and 63% of TN removal efficiencies were reported at 6h of HRT which is a comparatively low HRT value. COD removal performance was mostly maintained above 90% with insignificant improvements from the modification. Cost requirement for pH adjustment in MABR systems was reduced through improved alkalinity production from enhanced denitrification with PVA gel. Sludge yield of PVA gel modified MABR was constantly below 0.2 g TSS/g COD removed, which is significantly lower compared to sludge yield by ASP. Low sludge volume index of 80 mL/g indicated rapid settling characteristics of sludge produced by MABR. Oxygen utilization efficiencies of 78%-92% are in agreement with values reported in previous studies. From the images obtained from the fiber optic camera, satisfactory biofilm formation was observed on the membranes. Additionally, two bench scale MABR systems with straight and spiral membranes of similar surface areas were operated to determine the best configuration for optimum MABR performance. At similar pressures, spiral membrane provided higher oxygen transfer rates and slightly higher NH4-N and TN removal efficiencies compared to straight membrane. |
| Year | 2020 |
| 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, Chettiyappan; |
| Examination Committee(s) | Thammarat Koottatep;Xue, Wenchao; |
| Scholarship Donor(s) | Kurita Water and Environment Foundation, Japan; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2020 |