A simple technique for water disinfection with hydrodynamic cavitation: Effect on survival of Escherichia coli

Effect of hydrodynamic cavitation on disinfection of Escherichia coli was investigated in laboratory scale device. The cavitation was generated using a rotor, driven by a simple milling cutter, in the thin layer of water which was circulated from and to a reservoir. Disinfection efficacy was analyzed by measuring respiratory activity using 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) method and the ability to multiply with direct viable count (DVC) method. Experiments showed that hydrodynamic cavitation was very effective in reducing bacterial ability to divide. Exposure of 3 min using energy input of 490 W/L stopped the division of 75%of E. coli cells. However, analyses with CTC showed that most of the cells sustained respiratory ability, indicating that bacteria enter active but not culturable (ABNC) state. Thus, the potential of bacteria to resuscitate from ABNC state should be further investigated. The study showed that hydrodynamic cavitation is a simple technique and could potentially be used for drinking water disinfection in rural communities.