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Eutrophication is a globally concerned issue, which brings algal cells and algal organic matter (AOM) into drinking water treatment plants. AOM is an important branch of nitrogenous disinfection byproduct (N-DBP) precursors. The variation of AOM composition in UV-LEDs/chlorine process, and its relationship with N-DBP formation still remain much uncertainty. Herein, we used fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to investigate AOM transformation in UV-LEDs/chlorine process, with UV 285 and UV 365 as light source, and screen for typical precursors of N-DBPs. We found that more nitrogen-containing compounds were generated after UV-LEDs/chlorine process, leading to the larger formation of N-DBPs in postchlorination. Compounds such as lignin, proteins, and amino sugars tends to be oxidized by reactive species in UV-LEDs/chlorine process. Further, compounds with higher O/C and higher weighted average double bond equivalence (DBE w ) are easier to form N-DBPs, including dichloroacetonitrile and trichloronitromethane. Also, influence factors including pH, UV fluence, post-chlorination time and bromide concentration on N-DBP formation were evaluated. The results show that N-DBP formation generally followed the order of UV 285 /chlorine-postchlorination, UV 365 /chlorine-postchlorination, and direct chlorination. Our study provides comprehensive information on N-DBP formation from AOM in UV-LEDs/chlorine-postchlorination from molecular levels., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

2,4-diaminobutyric acid (DAB), a newly identified algal toxins in water, pose a great threat to human health. DAB may react with chlorine or chloramine to produce CX 3 R-type disinfection by-products (DBPs) during water treatment processes. This study mainly investigated the formation and speciation of DBPs from chlor(am)ination of DAB. The results revealed that haloacetic acids (HAAs), trihalomethanes (THMs) and haloacetonitriles (HANs) were the main kinds of CX 3 R-type DBPs generated from DAB during chlor(am)ination, of which dichloroacetic acid yielded the highest. The formation and total toxicity of four CX 3 R-type DBPs from DAB during chloramination was significantly lower than that during chlorination at each Cl 2 :N molar ratio. However, more formation of Br-THMs and I-THMs were observed during chloramination in the presence of Br - /I - . Futhermore, the effects of chlor(am)ine dosage, solution pH, reaction time, and the concentration of Br - and I - on the formation and speciation of CX 3 R-type DBPs were also evaluated during chlor(am)ination. The plausible formation pathways of CX 3 R-type DBPs from DAB were proposed and verified by theoretical calculation. The quantum chemistry calculations indicate that 1N in DAB and 8N in 2,4-diaminochlorobutyric acid (C 4 H 9 O 2 N 2 Cl) were more likely to be attacked by electrophiles, supporting the proposed pathway schemes., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Microcystin-LR (MC-LR) is the most widely distributed and harmful variant toxins released by cyanobacteria, which poses potential threaten to people and aquatic animals when entering natural water. In our research, solar/chlorine process was comprehensively investigated to degrade and detoxify MC-LR. Under the chlorine concentration of 1.0 mg L -1 , MC-LR (1.0 μM) was decreased by 96.7%, 26%, and 9% by solar/chlorine process, chlorination, and solar irradiation respectively. Quenching experiments confirmed that reactive chlorine species (RCS) and hydroxyl radical (HO) were the predominant reactive species in solar/chlorine process at neutral condition, and ozone was generated because of the participation of triplet-state oxygen (O( 3 P)). The respective contributions of each reactive species were calculated with the order as: RCS, HO, ozone, and solar irradiation. The presence of HCO 3 - and natural organic matter in water inhibited the degradation efficiency of MC-LR. Moreover, the transformation products of MC-LR generated during the solar/chlorine process were identified and a possible pathway was proposed. The hepatotoxicity of MC-LR and its transformation products was compared using protein phosphatase 2A. Our experimental results revealed that the concentration and hepatotoxicity of MC-LR both significantly decreased, and most products were not hepatoxic. Overall, the solar/chlorine process is a promising alternative technology to degrade MC-LR during eutrophication., (Copyright © 2019 Elsevier Inc. All rights reserved.)