Influence of ultrasound enhancement on chlorine dioxide consumption and disinfection by-products formation for secondary effluents disinfection

Abstract

Chlorine dioxide (ClO2) has been promoted as an alternative disinfectant because of its high disinfection efficiency and less formation of organic disinfection by-products (DBPs). However, particle-associated microorganisms could be protected during the disinfection process, which decreases the disinfection efficiency or increases the required dosage. Besides, the formation of inorganic disinfection by-products is a significant concern in environment health. Ultrasound (US)-combined disinfection methods are becoming increasingly attractive because they are efficient and environmentally friendly. In this study, US was introduced as an enhancement method to identify its influence on ClO2 demand reduction and to minimize the production of potential DBPs for secondary effluents disinfection. Fecal coliform was used as an indicator, and DBPs, including trichloromethane (TCM), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), chlorite (ClO2(-)), and chlorate (ClO3(-)), were analyzed to observe the potential DBPs formation. Results show that US pretreatment could reduce half of ClO2 dosage compared with ClO2 disinfection alone for the same disinfection efficiency, and that an input power density of 2.64 kJ/L pretreatment with the 1.5mg/L ClO2 was enough to meet the discharge requirement in China (i.e., fecal coliform below 1000 CFU/L for Class 1A) for secondary effluent disinfection, and the ClO2(-) concentration in the disinfection effluent was only 1.37 mg/L at the same time. Furthermore, the different effects of US on the two processes (US as pretreatment and simultaneous US/ClO2 disinfection) were also analyzed, including deagglomerating, cell damage, and synergistic disinfection as well as degasing/sonolysis. It was proved that the production of TCM, DCAA, and TCAA was insignificantly influenced with the introduction of US, but US pretreatment did reduce the production of ClO2(-) and ClO3(-) effectually. In general, US pretreatment could be a better option for disinfection enhancement methods combined with ClO2 in terms of both disinfection efficiency and disinfection by-product formation.

Sodium chlorite increases production of reactive oxygen species that impair the antioxidant system and cause morphological changes in human erythrocytes

“…Currently, no technique is available to remove chlorite ion once it has been formed in drinking water. However, recent attempts have been made to detect and decompose the chlorite formed in drinking water by ultrasonic treatment (Zhou et al, ).…”

Sodium chlorate, a major water disinfection byproduct, alters brush border membrane enzymes, carbohydrate metabolism and impairs antioxidant system of Wistar rat intestine

“…Thus necessary steps should be taken to remove and minimize the production of chlorate ion in the water treatment disinfection processes . Recently, attempts have been made by thermal desorption based ionizers, ultraviolet radiation to detect and decompose the chlorate formed in drinking water …”

“…47 Recently, attempts have been made by thermal desorption based ionizers, ultraviolet radiation to detect and decompose the chlorate formed in drinking water. [48][49][50] There are no reports on the effect of NaClO 3 on small intestine. Therefore, in the present work the effect of an acute oral dose of The extent of decline was more in BBMV than in homogenates.…”

Wastewater Chlorination for Reuse, an Alternative for Small Communities

“…Among these by-products, trihalomethanes (THM) and haloacetic acids (HAA) are most notable. Optimizing the chlorine dosage applied on disinfection is a good way to ensure disinfection and reduce the production of by-products (Richardson et al, 2007;Rook, 1973;Zhou et al, 2016) In this context, this study aimed to assess and compare disinfection of wastewater previously treated by a system of constructed wetlands, using calcium hypochlorite and sodium hypochlorite as disinfectant agents, aiming for reuse in agriculture.…”