Treatment of domestic wastewater using electroconductive moving-bed membrane bioreactor | |
| Author | Wanalee Sutthiwanit |
| Call Number | AIT Thesis no.EV-21-25 |
| Subject(s) | Wastewater--Treatment Membrane reactors Bioreactors |
| 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 electroconductive moving bed membrane bioreactor (EcMB-MBR) was developed from introducing conductive media into electrically assisted membrane bioreactor (EMBR). EMBR allows wastewater to be simultaneously treated through 3 processes: biological, filtration, and electrochemical processes. The electrode materials were combination of iron and graphite as anode and stainless steel as cathode. The effects of introduction of graphite felt as conductive media in EcMB-MBR on energy saving and treatment efficiency improvement were explored in this study. The experiment was carried out with synthetic domestic wastewater injected with 8 pharmaceutical and personal care products (PPCPs) to represent the contaminants of emerging concerns in domestic wastewater. The reactor had been operated at 3 different media packing densities under the same current density of 6.67 A/m2 and intermittent current exposure with on/off ratio of 5 mins/5 mins. The experiment started by operating as EMBR (0% media packing density), then density was increased to 10%, and finally to 20%. Energy consumptions for direct current supply per unit effluent volume were 0.510 kWh/m3 , 0.495 kWh/m3 , 0.486 kWh/m3 from the media packing densities of 0%, 10%, and 20% respectively. The energy reductions in EcMB-MBR by conductive media were 3.05% and 4.68% at 10% and 20% media packing densities compared to EMBR. Results showed that the addition of conductive media affected the pH and oxidation reduction potential (ORP) in the mixed liquor when the current was applied. The averages of pH and ORP were 8.34±0.93 and -103±27 mV, 9.37±0.26 and -128 ±14 mV, and 3.46±0.29 and 206±18 mV at 0%, 10% and 20% media packing densities, respectively. At 0% and 10% media packing densities, current induced reductive environment in the reactor, but it did oxidative environment at 20%. Increase in media packing density improved COD removal. Average COD removal efficiencies at different media packing densities were 91.16±3.84%, 93.76±1.63%, and 98.46±1.30% at 0%, 10% and 20% respectively. Total phosphorus removals were not significantly different as the same current was applied. The percentage of TP removal efficiencies were 98.53±1.04%, 98.85%±0.74% and 96.77%±1.32% at packing density 0%, 10% and 20% respectively. As a result of ORP change, denitrification was demoted at 20% packing density. Ranging from the highest to the lowest, the average TN removal efficiency were 48.45±14.87%, 38.29±7.29% mg/L, and 25.57±9.42 mg/L at 20%, 10%, and 0% media packing densities, respectively. The CECs in influent and effluent were quantified to study the removal efficiency by EcMB-MBR. Regarding membrane fouling, development of transmembrane pressure was slower at 20% packing density resulting in longer usage period increasing from 9 days in EMBR to 14 days. Compared to EMBR, the overall treatment efficiencies were improved, and DC energy input was reduced slightly by the conductive media addition in EcMB-MBR. Conductive media provided the sites for attached microbial growth enhancing biological treatment as well as electrochemical treatment through several reactions and mechanisms. |
| Year | 2021 |
| 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) | Xue, Wenchao |
| Examination Committee(s) | Visvanathan, Chettiyappan;Anal, Anil Kumar |
| Scholarship Donor(s) | Her Majesty the Queen’s Scholarships (Thailand) |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2021 |