Hydroxyl radical (•OH)-based decontamination approach is considered an efficient and eco-friendly technology, which can be a competitive solution to odor pollution. Geosmin (GSM) is an odor metabolite produced by the cyanobacterium Anabaena sp., which can seriously compromise the drinking water source quality. The independently developed •OH equipment based on strong ionization discharge produced •OH solution with high concentration, which was identified using electron spin resonance spectroscopy. Complete inactivation on Anabaena sp. and efficient degradation on GSM (to 4.26 ng/L, which is below the odor threshold of 10 ng/L) by •OH occurred concurrently within 12 s at a total reactive oxidant (TRO) concentration of 1.1 mg/L. The scanning electron microscopy results revealed that Anabaena sp. cells kept their physical integrity during •OH inactivation. The intracellular GSM barely released from the cells. The results of gas chromatograph/mass spectrometer analyses showed that the chromatogram converged to the baseline with a TRO concentration of 3 mg/L in 12 s, demonstrating that GSM was mineralized. •OH can open the ring structures to finally form CO2, H2O, and inorganic ions. While O3 and ClO2 failed to mineralize GSM when the reaction times are 10 and 60 min. Hence, •OH can inactivate Anabaena sp. without cell integrity loss and mineralize GSM simultaneously, the results of which support that the •OH technology may serve as the next-generation drinking water treatment to control algal odor problems.
Zhang et al. (Thu,) studied this question.