Toxicity of chlorinated algal-impacted waters: Formation of disinfection byproducts vs. reduction of cyanotoxins

Disinfection Byproduct Recovery during Extraction and Concentration in Preparation for Chemical Analyses or Toxicity Assays

“…While THMs and HAAs have been used to measure DBP exposure for epidemiology studies, there is growing interest in measuring unregulated (semi-)­volatile classes (e.g., haloacetonitriles) based on studies indicating that they could contribute more to the cytotoxicity of disinfected waters and that their concentrations do not correlate with THM concentrations . Recoveries of unregulated, (semi-)­volatile DBPs were lowest for XAD resin extraction (<30%), one of the most frequently employed techniques, ,− , including the U.S. EPA studies. , While recoveries were generally higher with SPE and LLE, they were below 70% for most of the (semi-)­volatile DBPs examined. Even these mediocre recoveries required solvent exchange, risking the potential for toxicity associated with incomplete removal of MtBE or EtOAc from the DMSO during N 2 blowdown.…”

“…Even these mediocre recoveries required solvent exchange, risking the potential for toxicity associated with incomplete removal of MtBE or EtOAc from the DMSO during N 2 blowdown. Recoveries of most unregulated, (semi-)­volatile DBP classes would be negligible for XAD resin extraction coupled with EtOAc elution when the EtOAc is evaporated nearly to complete dryness before resuspension in DMSO. ,− , …”

“…As most DBPs occur at relatively low concentrations (ng/L to μg/L levels) in disinfected water, extraction and concentration are needed to identify novel DBPs and facilitate the detection of biological effects in toxicity assays. Solid-phase extraction (SPE) using XAD resins has been used extensively to extract and concentrate DBPs in disinfected waters for bioassays, ,− including a standard operating procedure for studies by the U.S. EPA . XAD resin extraction typically involves passing ≥10 L of disinfected water through a mix of XAD-2 and XAD-8 resins, eluting the sorbed compounds with ethyl acetate, and concentrating the extract to ≤1 mL using rotoevaporation and nitrogen (N 2 ) blowdown .…”

The Impact of Extreme Weather Events on Bacterial Communities and Opportunistic Pathogens in a Drinking Water Treatment Plant

“…Cyanobacteria are known to impact water quality through the release of cyanotoxins and it has been proven that they might be present in treated drinking water supplies when cyanobacterial blooms occur in source waters [57]. Furthermore, the formation of toxic halogenated byproducts (DBPs) during chlorination in the presence of cyanobacteria represents an increased health risk in drinking water [58]. However, the relative abundance of Cyanobacteria in finished water samples did not increase after the first rainfall event (Figure S2b).…”

Effects of harmful algal blooms on regulated disinfection byproducts: Findings from five utility case studies

“…The importance of precursor removal is quantified by the total organic carbon (TOC) removal requirements included for enhanced coagulation in the Stage 1 and 2 DBPRs (USEPA, 2006). While chlorination of AOM (including cyanobacteria and others) typically yields lower TTHM and HAA5 concentrations than chlorination of other organic material per unit of carbon (Goslan et al, 2017; Li et al, 2012; Liu et al, 2020), the hydrophilic nature of AOM makes it a difficult precursor to remove and more likely to be available to react with subsequently applied disinfectant to form other types of DBPs (Park et al, 2019; Tomlinson et al, 2016). For example, chlorination of AOM, particularly nitrogen fixing cyanobacteria, can be associated with the formation of unregulated nitrogenous DBPs (N‐DBPs) (Chu et al, 2012; Fang et al, 2010; Fang et al, 2010; Gonsior et al, 2019; Zhao et al, 2018), which have generally been found to be more toxic than carbonaceous DBPs (Plewa et al, 2004, 2008).…”