A new class of treatment processes called advanced reduction processes (ARPs) is proposed. ARPs combine activation methods and reducing agents to form highly reactive reducing radicals that degrade oxidized contaminants. Batch screening experiments were conducted to identify effective ARPs by applying several combinations of activation methods (ultraviolet light, ultrasound, electron beam, and microwaves) and reducing agents (dithionite, sulfite, ferrous iron, and sulfide) to degradation of four target contaminants (perchlorate, nitrate, perfluorooctanoic acid, and 2,4 dichlorophenol) at three pH-levels (2.4, 7.0, and 11.2). These experiments identified the combination of sulfite activated by ultraviolet light produced by a low-pressure mercury vapor lamp (UV-L) as an effective ARP. More detailed kinetic experiments were conducted with nitrate and perchlorate as target compounds, and nitrate was found to degrade more rapidly than perchlorate. Effectiveness of the UV-L/sulfite treatment process improved with increasing pH for both perchlorate and nitrate. We present the theory behind ARPs, identify potential ARPs, demonstrate their effectiveness against a wide range of contaminants, and provide basic experimental evidence in support of the fundamental hypothesis for ARP, namely, that activation methods can be applied to reductants to form reducing radicals that degrade oxidized contaminants. This article provides an introduction to ARPs along with sufficient data to identify potentially effective ARPs and the target compounds these ARPs will be most effective in destroying. Further research will provide a detailed analysis of degradation kinetics and the mechanisms of contaminant destruction in an ARP.

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Natural organic matter (NOM) is ubiquitous in the aquatic environment and if present can cause varied drinking water quality issues, the major one being disinfection byproduct (DBP) formation. Trihalomethanes (THMs) are major classes of DBP that are formed during chlorination of NOM. The best way to remove DBPs is to target the precursors (NOM) directly. The main aim of this review is to study conventional as well as advanced ways of treating NOM, with a broad focus on NOM removal using advanced oxidation processes (AOPs) and biofiltration. The first part of the paper focuses on THM formation and removal using conventional processes and the second part focuses on the studies carried out during the years 2000–2018, specifically on NOM removal using AOPs and AOP-biofiltration. Considering the proven carcinogenic nature of THMs and their diverse health effects, it becomes important for any drinking water treatment industry to ameliorate the current water treatment practices and focus on techniques like AOP or synergy of AOP-biofiltration which showed up to 50–60% NOM reduction. The use of AOP alone provides a cost barrier which can be compensated by the use of biofiltration along with AOP with low energy inputs, making it a techno-economically feasible option for NOM removal.