The formations of THMs, HAAs, and HNMs from chlorination and chloramination of water from Jinlan Reservoir were investigated in this study. Results showed that monochloramine rather than chlorine ...generally resulted in lower concentration of DBPs, and the DBPs formation varied greatly as the treatment conditions changed. Specifically, the yields of THMs, HAAs and HNMs all increased with the high bromide level and high disinfectant dose both during chlorination and chloramination. The longer reaction time had a positive effect on the formation of THMs, HAAs and HNMs during chlorination and HNMs during chloramination. However, no time effect was observed on the formation of THMs and HAAs during chloramination. An increase in pH enhanced the levels of THMs and HNMs upon chlorination but reduced levels of HNMs upon chloramination. As for the THMs in chloramination and HAAs in chlorination and chloramination, no obvious pH effect was observed. The elevated temperature significantly increased the yields of THMs during chlorination and HNMs during chloramination, but has no effect on THMs and HAAs yields during chloramination. In the same temperature range, the formation of HAAs and HNMs in chlorination showed a first increasing and then a decreasing trend. In chloramination study, addition of nitrite markedly increased the formation of HNMs but had little impact on the formation of THMs and HAAs. While in chlorination study, the presence of high nitrite levels significantly reduced the yields of THMs, HAAs and HNMs. Range analysis revealed that the bromide and disinfectant levels were the major factors affecting THMs, HAAs and HNMs formation, in both chlorination and chloramination. Finally, comparisons of the speciation of mono-halogenated, di-halogenated, tri-halogenated HAAs and HNMs between chlorination and monochloramination were also conducted, and factors influencing the speciation pattern were identified.
► NH2Cl generally produced lower THMs, HAAs and HNMs yields than Cl2. ► Bromide level and disinfectant dose are two most important factors affecting THMs, HAAs and HNMs formation. ► Addition of nitrite significantly increased HNMs formation during chloramination, but was not necessary in the chlorination. ► The factors affect the speciation of mono-halogenated, dihalogenated, and trihalogenated HAAs and HNMs were assessed.
This study investigated the effects of preozonation on disinfection by-products (DBPs) formation during chlorination and chloramination of the water collected from Tai Lake. Results showed that the ...high ozone dose (0.6–1.0mg O3/mg DOC) pretreatment reduced the yields of trihaloacetic acids (reduced 62–63% in chlorination), dihaloacetonitriles (reduced 53–55% and 14–26% in chlorination and chloramination, respectively) and trihaomethanes (reduced 19% in chloramination), but markedly increased the formation of halonitromethanes (increased 4.7–5.6 times in chlorination and 2.1–2.7 times in chloramination), haloketones (increased 4.8–7.1 times in chlorination and 2.5–2.9 times in chloramination) and dihaloacetic acids (increased 1.5–2.4 times in chlorination and 0.3–0.6 times in chloramination). Thus the high ozone dose pretreatment should be avoided during chlorination/chloramination of Tai Lake water. Also, chloramination (with and without preozonation) produced much lower DBPs yields as compared with chlorination (with and without preozonation), indicating that chloramine was a better choice to control the DBPs yields. Further analysis also revealed that the bromine substitution factors (BSFs) of DBPs varied with disinfection mode. In chlorinamination, the BSFs generally showed a decrease trend with the ozone dose, yet in chlorination, the BSFs mostly exhibited first an increase and then a decrease trend. Moreover, the BSFs of DBPs in chloramination (with or without preozonation) were dominantly lower than those in chlorination (with or without preozonation).
•Preozonation markedly increased some DBPs in chlorination/chloramination.•Chloramine was a good choice for reducing the bromo- and total DBPs yields.•The BSFs of DBPs changed with disinfection modes.
Diffuse alveolar epithelial cell (AEC) death occurs extensively during acute lung injury (ALI). Due to the limited proliferative capacity of alveolar type 1 epithelial (AT1) cells, the ...differentiation and regenerative capacity of alveolar type 2 epithelial (AT2) cells are required to restore the barrier function of AECs. However, during lung injury, AT1 cells are particularly susceptible to injury, and ATII cells die in the presence of severe or certain types of injury. This disruption ultimately results in a hindrance to the ability of AT2 cells to proliferate and differentiate into AT1 cells in time to repair the extensively damaged AECs. Therefore, understanding the mechanism of injury death of AT2 cells may be beneficial to reverse the above situation. This article reviews the main death modes of AT2 cells, including apoptosis, necrosis, necroptosis, pyroptosis, autophagic cell death, and ferroptosis. It compares the various forms of death, showing that various cell injury death modes have unique action mechanisms and partially overlapping pathways. Studying the mechanism of AT2 cell death is helpful in screening and analyzing the target pathway of AEC barrier function recovery. It opens up new ideas and strategies for preventing and treating ALI.
