Fractionation of UV and VUV pretreated natural organic matter from drinking water.

Recent studies have examined the potential of ultraviolet (UV, 254 nm) and vacuum ultraviolet (VUV, 185 nm + 254 nm) irradiation as either a pretreatment for a biological process or as a sole treatment for the removal of natural organic matter as dissolved organic carbon from drinking water. To understand the potential of UV and VUV irradiation followed by subsequent biological treatment, treated water was fractionated into four components: very hydrophobic acid (VHA), slightly hydrophobic acid (SHA), hydrophilic charged (CHA), and hydrophilic neutral (NEU). The VHA fraction was found to be very susceptible to both UV and VUV irradiation, and the fragmentation products of the high molecular weight VHA and SHA molecules contributed to the CHA and NEU fractions to form a pool of biodegradable, non-UV-absorbing, low molecular weight moieties. The NEU fraction was the most difficult to remove, as most of the components in this fraction were refractory to both the biological and photo-oxidative processes. Therefore, enhanced removal of the NEU fraction is required to increase the effectiveness and potential of the treatment process.