N-nitrosodimethylamine and trihalomethane formation and minimisation in Southeast Queensland drinking water

Abstract

This study assesses the prevalence of disinfection by-product (DBP) precursors in some Southeast Queensland drinking water sources by conducting formation potential experiments for the four regulated trihalomethanes (THMs), and the potent carcinogen, N-nitrosodimethylamine (NDMA). NDMA formation potentials were consistently low (<5-21 ng/L), and total THM (tTHM) formation potentials were consistently below the Australian Drinking Water Guideline (250 μg/L). NDMA concentration of finished drinking waters was also monitored and found to be <5 ng/L in all cases. The effect of coagulation and advanced oxidation on the formation of NDMA and THMs is also reported. UV/H(2)O(2) pre-treatment was effective in producing water with very low THMs concentrations, and UV irradiation was an effective method for NDMA degradation. H(2)O(2) was not required for the observed NDMA degradation to occur. Coagulation using alum, ferric chloride or poly(diallyldimethylammonium chloride) (polyDADMAC) was ineffective in removing DBPs precursors from the source water studied, irrespective of the low dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) attained. Rather, coagulation with polyDADMAC caused an increase in NDMA formation potential upon chloramination, and all coagulants led to an increased tTHM formation potential upon chlorination due to the high bromide concentration of the source water studied.

Enhanced coagulation with powdered activated carbon or MIEX® secondary treatment: A comparison of disinfection by-product formation and precursor removal

“…Each formation potential test was extracted in duplicate, and DBP concentrations between duplicates were within 10%. NDMA formation potential tests were as described previously (Knight et al, 2011). In brief, phosphate buffer was added to samples as solid KH 2 PO 4 and Na 2 HPO 4 , to give a final concentration of 10 mM and a pH of 7.…”

“…Nitrosamine analysis was conducted as previously described, and in accordance with USEPA method 521.1 (Knight et al, 2011;Munch and Bassett, 2006). Nitrosamines analysed for were NDMA, NDEA, NMor, NPip, and NDBA.…”

N-nitrosodimethylamine (NDMA) formation potential of amine-based water treatment polymers: Effects of in situ chloramination, breakpoint chlorination, and pre-oxidation

“…Among the potential NDMA precursors, amine-based water treatment polymers that are commonly used as coagulant or flocculant aids have received considerable attention because of their intentional usage in water and wastewater treatment systems. Several coagulant/flocculant polymers have been reported to form NDMA in water that contained free chlorine, chloramines, or ozone [14,15,[21][22][23][24][25][26][27][28]. The dimethylamine (DMA)-based moieties in the water treatment polymers were responsible for their NDMA formation potential (NDMA-FP).…”

MIEX® treatment of an effluent‐impacted stream

“…According to a control experiment conducted in DDI water by up to 20 successive jar tests (i.e., BV = 2,000), minor increases in the NDMAFP (average 5 ng/L) were observed after exposure to the MIEX resin (Gan et al, 2013). An Australian research group has tested NDMAFP under chloramination of raw and MIEXtreated water from the Wanneroo WTP in Perth, Australia, and found that NDMAFP increased from < 5 to 25 ng/L (Knight et al, 2010). Results in upstream surface water were in good agreement with previous findings in other drinking waters that have been tested (Gan et al, 2013).…”