Abstract: Objective To clarify the decisive factors affecting the dechlorination performance in the pretreatment system of dialysis water.  Methods Total chlorine concentration, pH and water temperature were monitored in the 5 samples from tap water at input site, resin tank, carbon tank 1, carbon tank 2 and reverse osmotic water in a total of 235 dialysis days from January to September 2020. Pearson correlation analysis was used to investigate the correlation between total chlorine level behind carbon tank 1 and total chlorine, pH and temperature in tap water. Stepwise linear regression (backward) analysis was used to explore the specific correlation.  Results  The total chlorine behind carbon tank 1 was negatively correlated with tap water temperature (r=-0.936, P<0.001), and positively correlated with pH (r=0.360, P<0.001) and total chlorine (r=0.235, P<0.001) in tap water. Stepwise linear regression analysis showed that tap water temperature was negatively correlated with the total chlorine level behind carbon tank 1 (𝛽=-0.936, P<0.001).  Conclusion  Tap water temperature is the decisive factor affecting the dechlorination performance in the pretreatment system of dialysis water. Seasonal low temperature of tap water affected the dechlorination efficiency by the activated carbon tank in the water pretreatment system.

Key words: Activated carbon, Total chlorine, Dechlorination efficiency, Water temperature