Aquatic resources play a key role in supporting and maintaining human activity.  Aquatic systems provide potable water supplies to meet growing drinking and agricultural water requirements, and are used as receiving streams in the disposal of treated wastewater effluent.  Drinking water and wastewater treatment facilities are often located within the same watershed or same river system (i.e., indirect water reuse).  Typically, water taken from the natural environment must undergo some type of treatment before being distributed to the public in order to remove, for example, natural organic material (NOM).  The majority of NOM from aquatic systems is of terrestrial, allochthonous origin.  On the other hand, treated wastewater effluent contains organic material that is derived from microbial sources.  Consequently, organic matter in aquatic systems is changed from terrestrial to microbial origin as water is removed and treated for drinking water, and then returned to the receiving stream as treated wastewater effluent. 

In this seminar, the results of a field study conducted within a well-characterized reservoir system that is heavily supplemented by the Upper Occoquan Sewage Authority (UOSA) advanced wastewater treatment facility are presented.  Samples were collected upstream and downstream of the wastewater discharge point and characterized by fluorescence excitation-emission matrix spectroscopy and gel permeation chromatography.  A tangential-flow filtration system was used to produce a concentrated colloidal phase for fluorescence quenching experiments using perylene as a model polyaromatic hydrocarbon probe.  The purpose of this research was to investigate the impact of treated wastewater effluent on the characteristics and behavior of organic material in a receiving stream. 

Collectively, the results of this study suggest that organic material produced during the activated sludge process (biocolloids) has unique properties (fluorescence, molecular weight distribution, and sorption coefficients) compared to NOM found in the receiving stream.  Consequently, the impact of biocolloids on the water quality of receiving streams needs to be better understood.