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008			050927s2005 th uu|m rtt 0| a1eng d
035			_a.b11971551
099		9	_aAIT Thesis no.EV-05-12
100	0		_aJenyuk Lohwacharin
245	1	0	_aBiological sulphide oxidation in an airlift bioreactor
260			_aPathum Thani, Thailand : _bAsian Institute of Technology, _c2005
300			_a79 leaves
490	1		_aThesis ; _vno. EV-05-12
500			_aA thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering
502			_aThesis (M.Eng.) - Asian Institute of Technology, 2005
520			_a Performance of an airlift reactor for biological sulphide removal process employing obligate chemolithotrophs was investigated for 155 days under ambient temperature. The experimental setup was consisted of feed tank, 5-1 airlift reactor, and settling tank for removal of biologically-produced sulphur. The airlift reactor was equipped with a draft tube through which air was sparged continuously for maintaining DO level in the range 0.2-1.0 mg/l as well as to generate airlift condition in the reactor. The reactor was also equipped with pH controller to maintain pH in the range 7.8-8.0. Effluent recirculation was employed whenever necessary in order to maintain oxygen-limited condition in the reactor. Deoxygenating with N2 gas was conducted to obtain low dissolved oxygen in the feed and nutrient tanks. At volumetric sulphide loading rate lower than 2.18 kgS/m3 -day, maintaining oxygenlimited condition was critical in optimizing elemental sulphur production. This was achieved by partial recirculation of the effluent to maintain dissolved oxygen below 0.2 mg/l. 50% of influent sulphide was converted to elemental sulphur. Beyond the loading rate of 2.18 kgS/m3 -day and DO concentration below 1.0 mg/l, elemental sulphur production gradually increased. The result implies that volumetric sulphide loading rate is the significant operational parameter under high influent-sulphide concentration. The airlift bioreactor was operated at the maximum volumetric sulphide loading rate of 4.0 kgS/m3 -day yielding the maximum sulphide consumption rate of 4.3 kgS/kgVSS-day and over 93 %-sulphide removal. 90% of sulphide removed was converted into elemental sulphur which was separated in settling tank as sulphur sludge with 40 percent sulphur content by weight. Addition of the selected coagulant, Polyaluminium chloride, was found to be effective for sulphur-particle aggregation. Optimal coagulant dose was found to be 0.71 g/l at pH 7.5 and a temperature of 30°C. Morphological examination of biomass suspension in the reactor by Scanning Electron Microscopy (SEM) showed that elemental sulphur was excreted on the bacterial surface and deposited extracellularly.
650		0	_aSulphides _xOxidation
650		0	_aBioreactors
700	1		_aAnnachhatre, Ajit P., _eChairperson
700	1		_aVisavanathan, C., _eExamination committee
700	0		_aPreeda Pakpian, _eExamination Committee
710	2		_aRoyal Thai Government Fellowships, _eSchorlarchip donor
810	2		_aAsian Institute of Technology. _tThesis ; _vno. EV-05-12
856			_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B09364
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