Adaptation of water treatment processes for controlling disinfection byproducts in supply waters to compensate the effects of climate change

The water treatment processes (WTPs) need adaptation to climate change. Safe water supply is being challenged by the deteriorating trend of water quality, which can increase disinfection byproducts and impose cancer/non-cancer risks to humans. In this study, implications of climate change and water quality deterioration on the formation of trihalomethanes' (THMs), and risks from 2020 to 2050 were predicted. In 2020, averages of temperature, dissolved organic carbon (DOC) and pH in source waters from Newfoundland (Canada) were 7.92 °C, 6.40 mg/L and 6.53 respectively, which were predicted to be 9.95 °C, 8.56 mg/L and 7.65, respectively in 2050. Three scenarios of free chlorine and bromide ions [(2.0 mg/L, 10 μg/L), (3.5 mg/L, 25 μg/L) and (5.0 mg/L, 50 μg/L)] were simulated. Two models (Model-1 and Model-2) were applied for predicting THMs, risks and allowable DOC for target risks. For Model-1, DOC in 2030, 2040 and 2050 were predicted to be in the ranges of 4.53–4.92, 3.32–3.84 and 2.49–3.06 mg/L respectively to impose similar risks as of 2020. For Model-2, DOC ranges were 5.02–5.95, 3.92–4.99 and 3.60–4.80 mg/L respectively. The lower ranges of DOC in future years were due to increased effects of pH and temperature. To maintain the risks of 2050 to the levels of 2020, WTPs need to reduce DOC by 64.3–70.9 % (Model-1) and 43.8–57.9 % (Model-2). The granular activated carbon filtration is widely used for reducing DOC, which can be further assessed for extensive applications in the WTPs.