Analysis of Odorous Compounds in Drinking Water

• Main Authors: Kao, Sheau-Ping, 高小萍
• Other Authors: Lin Tsair-Fuh
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/21538492737484402098

碩士 === 國立成功大學 === 環境工程學系 === 86 === Analysis of odorous compounds in the drinking water in southern Taiwanwas investigated. Two approaches, including flavor profile analysis (FPA) forodor group and intensity analysis, and closed loop stripping analysis (CLSA)followed by gas chromatograph/mass spectrometry detector (GC/MSD) for odorantspecies and concentration identification, were employed to qualitatively andquantitatively determine the common odors observed in the drinking water. FPAwas selected to replace the traditionally used threshold odor number (TON) me-thod, as it can describe odor intensity andodor group more precisely. An odoridentification kit developed by University of Pennsylvania was first used toscreen the qualified panelists. Eleven classes were then conducted to trainthe qualified panelists. After two-stage training courses, higher precisionwas found for each panelist. Laboratory experiments indicated that FPA odorintensity is proportional to the logarithmic concentration of an odorant,2-MIB. In the CLSA-GC/MSD analysis, two commonly observed earthy odorcompounds, Geosmin and 2-MIB, were selected as representative odorants. Afterprocessing in the CLSA system, a 40,000 times of concentration of bothcompounds were found to be linear between 30 and 500 ng/L, and the detectionlimit of 2-MIB was 12.3 ng/ L, were below its odor threshold (29 ng/L).　To test the two approaches, water samples from Cheng-Chin Lake WaterTreatment Plant (CCLWTP) in Kaohsiung and Kong-Si Water Treatment Plant(KSWTP) in Ping-Tung were collected and analyzed. The panel was able toconduct FPA for all the water samples collected. The odor groups observed bythe panelmainly include earthy, fishy, grassy, and chlorine. Based on theexperiment results of CLSA-GC/MSD, 2-MIB was observed in CCLWTP for one time,and was observed in KSWTP for almost all the samples. The concentrations of 2-MIB found were between 46 and 403 ng/L. In addition, samples collected in thetransfer line and consumers'' houses were also observed to have 2-MIB.　The relation among FPA odor intensity, residual chlorine concen-trations, and 2-MIB concentrations were also investigated. The FPA intensityof chlorine odor was found to correlate with residual chlorine concentration.Although the earthy odor in water samples can be easily detected by the FPApanel at the sampling points before chlorine addition, unlike the laboratorysamples, no strong correlation can be observed between 2-MIB concentration andassociatd FPA odor intensity. In addition, no earthy odor was found withchlorine residual in the samples, as the odor was masked by the residualchlorine.