Chemical effects on UV irradiation absorption of fouled quartz sleeves in ultraviolet disinfection

Abstract

The effects of foulant chemical composition on ultraviolet (UV) absorbance of fouled quartz sleeves in UV disinfection systems were studied. Statistical analysis was conducted to examine the effects of nine fouling chemicals on the UV transmittance changes of fouled quartz lamp sleeves. The results demonstrated that the main effects were attributable to surface concentrations of iron and manganese. The surface concentrations of calcium and copper had no significant effects on the UV absorbance of fouled sleeves. The interaction effects of copper with iron and magnesium with manganese were also revealed from the statistical analysis. The model is able to give reasonable predictions of the UV absorbance characteristics of foulants from other UV systems. However, several limitations of this model were identified. First, the model does not accurately predict the absorbance at relatively high chemical surface concentrations. Second, the model does not account for the possible effects of anions and organics on UV absorption of fouled quartz sleeves.

Model of Radiation Transmittance by Inorganic Fouling on UV Reactor Lamp Sleeves

“…A variety of experiments have been conducted to help identify the conditions that increase the probability of sleeve fouling, and determine the rates of fouling reactions when they do occur. In these, iron has been identified as a significant overall constituent of foulants that can form on lamp sleeves (Sun et al, 2008), including those that are not subject to regular physical and chemical cleaning measures (Peng et al, 2005). Iron also has been identified as the foulant present on lamp sleeves in the greatest quantities when ferric chloride (FeCl 3 ) is added at a wastewater treatment plant using UV disinfection (Sehnaoui and Gehr, 2001).…”