Impact of EfOM in the elimination of PPCPs by UV/chlorine: Radical chemistry and toxicity bioassays

The UV/chlorine process as a potential tertiary municipal wastewater treatment alternative for removing refractory PPCPs has been widely investigated. However, the role of effluent organic matter (EfOM) on radical chemistry and toxicity alteration is unclear. elimination two model PPCPs, primidone (PRM) caffeine (CAF), by co-exposure UV free chlorine was investigated to elucidate impact EfOM. Experimental results indicated that both •OH reactive species (RCS) were importantly involved in decay PRM at acidic condition, while ClO• played dominant alkaline pH. CAF dominated under all conditions. Chlorine dose, initial contaminant concentration, solution pH, water matrix affect efficiency varying degree resulting from their specific effect speciation system. Presence EfOM isolate remarkably inhibited preferentially scavenging RCS particularly ClO•. Good correlations (linear exponential CAF) between absorbance 254 nm observed pseudo first-order rate constants (k'obs) solutions obtained, demonstrating importance aromatic moieties inhibiting degradation targeted contaminants process. Degradation PRM/CAF reconstituted spiked with major constituents (i.e., isolates, Cl-, HCO3-, NO3-) comparable obtained real WWTP fit well correlation k'obs nm, suggesting isolates can be used determine effluent. serves main precursor adsorbable treatment. Bioassays chlorine-containing compounds could induce oxidative stress, mitochondrial dysfunction, increase cell DNA damage. Among evaluated conditions, nature EfOM, hydrophobic versus transphilic fraction, likely predominant factor affecting cytotoxicity. Meanwhile significantly reduce cytotoxicity isolates. adding high level selected (e.g., inhibit this phenomenon due competition radicals.