Abstract
Endogenous pollution from sediments is gradually becoming a critical pollution source of the drinking water reservoir. Odorants can be released from sediments into the overlying water which further deteriorate the water quality of the drinking water reservoir. In this work, we set the sediment-overlying water systems under various water pH (6.5, 8 and 9), temperature (4, 20 and 30 °C) during 30 days and intermittent or continuous hydraulic disturbances (at 100 r/min or 200 r/min) in 5 days, and investigated the dynamic release of odorants from the drinking water reservoir sediments via using headspace solid-phase microextraction (HSPME) and gas chromatography-mass spectrometry (GC-MS). The result shows that weakly alkaline environment slightly but not significantly increased the concentration of dimethyl disulfide (DMDS) in the overlying water. Furthermore, low temperature promoted the release of bis(2-chloroisopropyl) ether (BCIE) and geosmin to 108.36 and 18.98 ng/L, respectively, while high temperature facilitated the DMDS release to 20.33 ng/L. Notably, hydraulic disturbances drastically elevated the level of seven odorants released from the sediments. Specially, benzaldehyde exhibited highest concentration at 260.50 ng/L. The continuous disturbance greatly enhanced the release of benzaldehyde, DMDS, dimethyl trisulfide (DMTS), BCIE and 1,4-dichloro-benzene (1,4-DCB) from sediments with a positive disturbance speed-dependence. However, the intermittent disturbance promoted higher level of geosmin in the overlying water compared to the continuous disturbance. Only continuous hydraulic disturbance at high speed could lead to the release of ethylbenzene from sediments, which was up to 4.89 ng/L in 12 h.
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•High temperature enhanced the level of DMDS in the overlying water.•Low temperature facilitated the release of BCIE and geosmin from sediments.•Released odorants were mainly determined by disturbance intensity and duration.•Only high-speed continuous hydraulic disturbance induced release of ethylbenzene.