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Haloacetamides (HAMs) are a class of newly identified nitrogenous disinfection byproducts (N-DBPs) whose occurrence in drinking waters has recently been reported in several DBP surveys. As the most prominent HAM species, it is commonly acknowledged that 2,2-dichloroacetamide (DCAM) is mainly generated from dichloroacetonitrile (DCAN) hydrolysis because the concentrations of these two compounds are often well correlated. Instead of DCAM, a previously unreported N-DBP, N-chloro-2,2-dichloroacetamide (N-Cl-DCAM), was confirmed in this study as the actual DCAN degradation product in chlorinated drinking waters. It is suspected that N-Cl-DCAM has been erroneously identified as DCAM, because its nitrogen-bound chlorine is readily reduced by most commonly used quenching agents. This hypothesis is supported by kinetic studies that indicate almost instantaneous N-chlorination of DCAM even at low chlorine residuals. Therefore, it is unlikely that DCAM can persist as a long-lived DCAN decomposition product in systems using free chlorine as a residual disinfectant. Instead, chlorination of DCAM will lead to the formation of an equal amount of N-Cl-DCAM by forming a hydrogen bond between hypochlorite oxygen and amino hydrogen. Alternatively, N-Cl-DCAM can be produced directly from DCAN chlorination via nucleophilic addition of hypochlorite on the nitrile carbon. Due to its relatively low pK value, N-Cl-DCAM tends to deprotonate under typical drinking water pH conditions, and the anionic form of N-Cl-DCAM was found to be very stable in the absence of chlorine. N-Cl-DCAM can, however, undergo acid-catalyzed decomposition to form the corresponding dichloroacetic acid (DCAA) when chlorine is present, although those acidic conditions that favor N-Cl-DCAM degradation are generally atypical for finished drinking waters. For these reasons, N-Cl-DCAM is predicted to have very long half-lives in most distribution systems that use free chlorine. Furthermore, an analytical method using ultra performance liquid chromatography (UPLC)/negative electrospray ionization (ESI)/quadrupole time-of-flight mass spectrometry (qTOF) was developed for the detection of a family of seven N-chloro-haloacetamides (N-Cl-HAMs). Combined with solid phase extraction (SPE), the occurrence of N-Cl-DCAM and its two brominated analogues (i.e., N-chloro-2,2-bromochloroacetamide and N-chloro-2,2-dibromoacetamide) was quantitatively determined for the first time in 11 real tap water samples. The discovery of N-Cl-DCAM or, more broadly speaking, N-Cl-HAMs in chlorinated drinking waters is of significance because they are organic chloramines, a family of compounds that is perceived to be more toxicologically potent than halonitriles (e.g., DCAN) and haloamides (e.g., DCAM), and therefore they may pose greater risks to drinking water consumers given their widespread occurrence and high stability.

Increasing economy and population result in the rapid growth of solid waste in China, with more than 70% being carbonaceous components. The generated carbon-bearing solid waste is called as organic solid waste (OSW). In this Review, OSWs from both municipal and industrial sources are discussed and divided into municipal solid waste (MSW), organic sludge, polymer solid waste, and biomass-like solid waste, according to their variations in origins and characteristics in China. Agricultural waste (i.e., biomass) and large-scale industrial solid waste (e.g., coal waste) are not considered, because of their well-established fundamentals. Incineration is becoming the most common method of energy recovery for OSW in China, while it has to face the problems of relatively low thermal efficiency, high air pollutant emission, and the high risk of fly ash products. Compared with MSW incinerators, coal-fired power plants own efficient power generation systems and centralized air pollution control devices (APCDs). With the fact that mixed coals are widely used in existing power plants, it is of great significance to study and discuss the current status of cocombustion of OSW and coal in China. In this work, the physicochemical properties of OSW were first introduced, with a subsequent detailed summary on their co-combustion fundamentals, such as devolatilization, ignition, char reactivity, and combustion efficiency, and ash-related issues, including fouling/slagging, high-temperature corrosion, and leaching behavior of ash residue. Furthermore, pollutants emissions regarding conventional pollutant [CO, SO 2 , NO x , HCl, particulate matters (PM)], heavy metals, and hazardous organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed. Some pretreatment methods to reduce the risk of co-combustion were also discussed, including pelletization, drying, torrefaction, hydrothermal carbonization, and low-temperature pyrolysis. Lastly, discussions and perspectives on the future co-combustion technology of OSW with coal were presented. This work aimed to gain systematic knowledge on the co-combustion technology of OSW and coal, providing guidelines for further applications of OSW in power plants in China, as well as other countries in the world.

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