Continuous Organic Characterization for Biological and Membrane Filter Performance Monitoring

Organic matter present in natural water sources is a concern in drinking water treatment because of its role in reacting to form disinfection by-products, contributing to membrane filtration fouling, and binding and transporting contaminants (Leenheer & Croué 2003). When the effects of organic matter on treatment processes are considered, a major source of uncertainty is the variable composition of natural organic matter (NOM), which includes humic and fulvic substances, carbohydrates, proteins, and other organic compounds (Her et al. 2003). Furthermore, NOM composition can vary temporally as well as spatially within and between water bodies (Matilainen et al. 2010). Organic concentrations are commonly measured through broad measures such as dissolved organic carbon (DOC) and ultraviolet absorbance (UVA) at 254 nm (UV254) that estimate concentrations but do not provide information regarding the makeup and diversity of organic compounds. Several characterization approaches (including resin fractionation and size exclusion chromatography) have been used to better define NOM on the basis of such properties as hydrophobicity and molecular weight. However, these techniques have limited use for routine control of water treatment systems because of their complexity and sample pretreatment requirements (Her et al. 2003). Since the properties of NOM are strongly associated with its treatability, analytical methods that allow for the characterization of subfractions of NOM are therefore essential to understanding compositional complexity and are expected to improve optimization and control of drinking water treatment systems.