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| 008 | 020719s2002 th uzm rtt 00| a1eng d | ||
| 035 | _a.b11861691 | ||
| 099 | 9 | _aAIT Diss. no. EV-02-01 | |
| 100 | 0 | _aNguyen Phuoc Dan | |
| 245 | 1 | 0 | _aBiological treatment of high salinity wastewater using yeast and bacterial systems |
| 260 |
_aBangkok : _bAsian Institute of Technology, _c2002 |
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| 300 | _a109, [24] p. | ||
| 490 | 1 |
_aDissertation ; _vno. EV-02-1 |
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| 500 | _aA dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Environment, Resources and Development | ||
| 502 | _aThesis (Ph.D.) - Asian Institute of Technology | ||
| 520 | _aThis study aimed to compare the performance of aerobic treatment using wild mixed yeast and bacterial culture for high salinity wastewater. The operating conditions of yeast treatment under high salinity such as pH, sludge retention time (SRT) and dissolved oxygen (DO) were examined. The comparative evaluation is based on determination of biokinetic coefficients using the respirometric method and treatment efficiency of longterm operation of two laboratory-scale membrane bioreactor systems. The biokinetic experiments reveal that yeast culture has a lower observed maximum specific grow rate (oobs) at low salt content (20g/L) than that of bacteria. But oobs of yeasts at higher salt contents (above 30 g/L) did not decline dramatically and had higher value than that of bacteria. The osmotolerant yeast mixture was able to tolerate a wider pH range than bacterial culture. The chemical oxygen demand (COD) removal rate of the yeast mixture was highest at pH values 5.0-5.5. Two laboratory-scale membrane bioreactor systems were investigated to treat high salinity wastewater containing high organic (5,000 mg/L COD) and salt content (32 g/L NaCl), namely: the Yeast Membrane Bioreactor (YMBR), and Yeast pretreatment followed by Bacterial Membrane Bioreactor (BMBR). In the YMBR system, experimental runs were conducted with a mean biomass concentration of 12 g MLSS/L. Here, the maximum COD removal rate of 0.93 g COD/g MLSS.day was obtained at F/M of 1.5 g COD lg MLSS.d, whereas the BMBR system was operated with a biomass concentration of up to 25 g MLSS/L, resulting in maximum COD removal rate of 0.32 kg COD /kg MLSS.day at F/M ratio of 0.4. In comparison the BMBR, the YMBR could obtain higher COD removal rate at higher organic loading, indicating the potential of the yeast reactor system to treat high salinity wastewater containing high organic concentration. Transmembrane pressure in the BMBR was progressively increased from 2 to 60 kPa after 12d, 6 d and 2 d at hydraulic retention time (HRT) of 14h, 9 hand 4h, with average biomass concentration of 6.1, 15 and 20 g MLSS/L respectively. By contrast, the transmembrane pressure in YMBR was only increased from 2 to 60 kPa only after 76 days of operation, with an average biomass concentration of 12 MLSS/L and an operating HRT range of 5 - 32 h. The comparative evaluation of treatment performance of both YMBR and BMBR with the low organic-feed wastewater (1,000 mg/L COD and 32 g/L NaCl) was examined. COD removal of both processes were above 90% at HRT of 5 h. Under the same operating conditions, the YMBR could run under transmembrane pressure 10 times lower than the BMBR with a significantly reduced membrane fouling rate. This may be due to low production of adhesive extracellular polymers (ECP) and the secondary filtration layer formed from large free yeast cells. ECP production of bacterial sludge was increased considerably at high salt contents and high sludge retention time (SRT). For the bacterial sludge, the increase salinity led to increase in ECP value, whereas the ECP content of the yeast sludge was relatively very small. | ||
| 650 | 1 | 0 |
_aSewage _xPurification _xBiological treatment |
| 700 | 1 |
_aVisvanathan, C., _eChairperson |
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| 700 | 0 |
_aChongrak Polprasert, _eExamination Committee |
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| 700 | 1 |
_aNguyen, Cong Thanh, _eExamination Committee |
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| 700 | 1 |
_aTrankler, Josef, _eExamination Committee |
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| 700 | 1 |
_aRakshit, Sudip Kumar, _eExamination Committee |
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| 700 | 1 |
_aSimard, Ronald E., _eExamination committee |
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| 710 | 2 |
_aSwiss Development Cooperation (SDC), _eScholarship donor |
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| 810 | 2 |
_aAsian Institute of Technology. _tDissertation ; _vno. EV-02-1 |
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| 856 |
_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B07215 |
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