Search

2-Methylisoborneol (MIB) and geosmin (GSM) are taste and odor compounds produced by cyanobacteria in surface waters. While the strong odors and musty flavors of MIB and GSM are generally associated with poor water quality, the removal of these semi-volatile compounds presents a significant challenge to drinking water providers. Likewise in aquaculture, accumulation of these compounds in fish meat leads to quality problems and reduces marketability. Conventional water treatments are ineffective at removing low concentration of odor compounds. We report herein ultrasonic irradiation at 640kHz leads to rapid degradation of MIB and GSM. While radical processes generally dominate during ultrasonic-induced degradation, pyrolysis appears to be responsible for a significant fraction of the observed degradation. Several pyrolytic products from MIB and GSM have been identified and degradation pathways are elucidated. The degradation of MIB and GSM follows the first-order kinetics and the rate constants are 0.07 and 0.12min−1, respectively. These results suggest ultrasonic irradiation maybe applicable as an effective method for removal of taint compounds from potable water supplies and fish farms. [Copyright &y& Elsevier]

The ozonation of 2-methylisoborneol (MIB) and geosmin was investigated in both pure and raw water. In a semi-batch reactor, a series of experiments was performed to determine the effect of pH on the ozonation of MIB and geosmin. The results show that pH has a significant effect on the ozonation of both compounds, which supports the theory that OH radical plays an important role on the destruction of MIB and geosmin. Compared with MIB, geosmin is more readily destroyed by ozonation. The ozonation kinetics follow approximately a first-order equation with respect to MIB and geosmin at the pH of 5, 7 and 9, and their rate orders of CO3 at pH 7 are 0.44 and 0.61, respectively. Ozonation of organic matters in the water decreases the ozone concentration leading to a lower removal of MIB and geosmin; at the same time, the formation of OH radical initiated by the organic matters accelerates the ozonation of MIB and geosmin. The ozonation of MIB and geosmin spiked in raw water, settled water and pure water shows that background organics have no significant effect on the removal of MIB and geosmin; hence, the simplified rate equations acquired in pure water may have potential application in real water. [ABSTRACT FROM AUTHOR]

The main, relevant, solved problems associated with taste and odour incidents in Barcelona's drinking water area in the last 14 years are reviewed. Events produced by creosote, dioxanes and dioxolanes, dicylopentadiene, and diacetyl, among the anthropogenic compounds; geosmin, MIB and iodinated trihalomethanes and chlorobromoanisoles as examples of compounds of natural origin are exemplified. The determination of the odour threshold concentrations of selected odorous compounds is also shown as a tool to gain a better knowledge of future taste and odour events. [ABSTRACT FROM AUTHOR]

Taste and odour problems of tap water in Seoul are attributed to 2-methylisoborneol (2-MIB) and trans-1, 10-dimethyl-trans-9 decalol (geosmin), which are the result of metabolism of algae and chlorine for disinfection. This study was carried out to measure 2-MIB and geosmin in the raw water from the Han River, to investigate removal efficiency of GAC and BAG integrated with post-ozonation, and to minimise and quantify the required chlorine concentration as a final disinfectant through the candidate process. [ABSTRACT FROM AUTHOR]

The presence of unpleasant taste and odour in drinking water is an ongoing aesthetic concern for water providers worldwide. The need for a sensitive and robust method capable of analysis in both natural and treated waters is essential for early detection of taste and odour events. The purpose of this study was to develop and optimise a fast stir bar sorptive extraction (SBSE) method for the analysis of geosmin and 2-methylisobomeol (MIB) in both natural water and drinking water. Limits of detection with the optimised fast method (45 min extraction time at 60°C using 24 µL stir bars) were 1.1 ng/L for geosmin and 4.2 ng/L for 1 MIB. Relative standard deviations at the detection limits were under 17% for both compounds. Use of multiple stir bars can be used to decrease the detection limits further. The use of 25% NaCI and 5% methanol sample modifiers decreased the experimental recoveries, Likewise, addition of 1 mg/L and 1.5 mg/L NaOCI decreased the recoveries and this effect was not reversed by addition of 10% thiosulphate, The optimised method was used to measure geosmin concentrations in treated and untreated drinking water. MIB concentrations were below the detection limits in these waters. [ABSTRACT FROM AUTHOR]