Optical Brighteners (OBAs)
Optical Brighteners (OBAs) or Fluorescent Whitening Agents (FWAs) are added to products, such as laundry soaps, detergents, or cleaning agents. They adsorb to fabrics or materials during the washing or cleaning process. When illuminated by ultraviolet light they fluoresce and make products and fabrics appear brighter.
Laundry wastewater is the largest contributor of brighteners to wastewater systems. FWA or OBA contributions to the total volume of most laundry detergents is less than 0.5%, however a large portion (5-80%) can remain in discharged wastewater as dissolved compounds (molecular). The presence of brighteners in water systems to which wastewater is being discharged could mean failing septic systems, sewage leaks, or complete lack of water treatment. Therefore, detection of optical brighteners in aquatic systems can help water municipalities or researchers correct system failures and avoid increased anthropogenic input that may greatly impact ecosystems.
Studies have shown a correlation between fluorescence of brighteners and fecal coliform levels in aquatic environments. Water quality is currently being assessed by fecal coliform standards through federal, state, and municipal agencies. Public access to water bodies such as lakes, rivers, or beaches that do not meet these standards can be restricted thereby impacting tourism and ultimately the local economy. The main problem in prevention of increased fecal coliform levels is the inability to determine the source of the contamination (human/non-human). Laundry wastewater is typically discharged through the household sewer or septic systems thus brighteners are a component of sewage wastewater. Brightener correlation to fecal coliform levels can provide valuable information to help researchers determine if contamination sources are attributed to human waste.
Brighteners are highly susceptible to adsorption. They are removed from surface and ground water by adsorption onto soil and organic material. This allows researchers to also assess the effectiveness of natural cleansing of wastewater by determining brightener concentrations in ground or surface waters