Inactivation of Tubifex (Monopylephorus limosus) in Water by Six Common Disinfectants

Six common disinfectants were studied for their effects in water on Tubifex species, Monopylephorus limosus, frequently found in tap water in many places of China recently. These disinfectants include sodium hypochlorite, liquid chlorine, chloramines, chlorine dioxide, hydrogen peroxide, and potassium permanganate composite. It was found that 100% mortality rate could be achieved within two hours at the concentration of 50 mg/L for hydrogen peroxide and below 10 mg/L for all the other disinfectants. Although this rate could be reached within a shorter time (30 min) and at a lower concentration (2 to 3 mg/L) for sodium hypochlorite and liquid chlorine than for chlorine dioxide (7 mg/L for 60 min or 5 mg/L for 120 min), the latter would be recommended due to its advantage without formation of toxic chlorine-organic disinfection by-products.