Thermophilic-aerobic treatment of high strength wastewater in sequencing batch reactor and membrane bioreactor | |
| Author | Halgahawaththa, H. R. L. W. |
| Call Number | AIT Thesis no.EV-06-45 |
| Subject(s) | Sewage--Purification--Sequencing batch reactor process Membrane reactors |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in · Environmental Engineering and Management, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-06-45 |
| Abstract | Thenmophilic-aerobic wastewater treatment was studied in laboratory scale sequencing batch reactor (SBR) and sidestream air-lift membrane bioreactor (MBR) using diluted cane molasses distillery wastewater. The reactors were operated separately at 55°C, 40°C and 27°C to compare the performances. Both types of reactors were loaded with 9.69 kg of COD!m3.d at each temperature. The filtered COD, BOD and TKN were analyzed for effluents from sequencing batch reactors. Similarly, effluent for 0.1m pore size ceramic membrane was analyzed in terms of COD, BOD and TKN. Sequencing batch reactors were operated at two different stages of feed conditions. Feed in stage 1 had BOD: N: P as 100: 6.7: 0.29 (phosphorus deficient feed conditions) and BOD: COD as 0.33. In stage 2, phosphorus level and readily biodegradable fraction of feed were increased to BOD: N: P as 100: 5.4: 1 and BOD: COD as 0.41 (phosphorus sufficient feed conditions). MBRs were only operated at stage 2. SBR and MBR at 55°C showed less biodegradability compared to 40°C and 27°C temperatures. COD removal from SBRs at 27°C, 40°C and 55°C were 51.7%, 44.9% and 25.0% respectively in stage 1. COD removal of SBR at 55°C was increased up to 31.1% while other two reactors did not show a significant difference in stage 2. COD removal efficiencies of MBRs were, 71.7%, 62.2% and 43.0% at 27°C, 40°C and 55°C correspondingly. SBR and MBR at 40°C and 27°C had BOD removal higher than 94.0% irrespective of the feed change. BOD removal of SBR at 55°C was increased from 63.2% to 77.7% from stage 1 to stage 2; showing aerobic-thermophilic systems are suitable for readily biodegradable wastewaters and need high nutrient requirement. BOD removal from MBR at 55°C was 78.9%. Nitrogen removal was less than 55% in all the reactors in terms of TKN. Thermophilic SBR and MBR had the lowest removal of TKN indicating inability of thermophilic microorganisms to accomplish organic nitrogen removal. Sludge retention time was found to be in similar range (8-10 days) at 27°C and 40°C in sequencing batch reactors and membrane bioreactors. At 55°C in SBR operation, most of the biomass was washed-off, and sludge production was low, making it difficult to estimate solid retention time. Increase sludge production due to no biomass wash-out in MBR 55 gave SRT to be 16 days. SVI was experienced to be an inappropriate parameter to predict the sludge settleability in aerobic-thenmophilic as well as mesophilic high strength wastewater systems due to high fraction of unsettleable solids. |
| Year | 2006 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. EV-06-45 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Visvanathan, Chettiyappan |
| Examination Committee(s) | Annachhatre, Ajit P.; Shipin, Oleg |
| Scholarship Donor(s) | France;AIT fellowship |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2006 |