The overall objective of this study, conducted by the University of Pittsburgh and Carnegie Mellon University, is to assess the potential of three types of impaired waters for cooling water makeup in coal-based thermoelectric plants.  The impaired water studies include: secondary treated municipal wastewater; passively treated coal mine drainage; and ash pond effluent (see Figure 1).  Researchers are using a combination of pilot and laboratory scale studies, engineering and regulatory assessments, and mathematical modeling efforts.

To determine the feasibility of impaired water use, a variety of activities are conducted, including: assessment of the availability and proximity of impaired waters at twelve power plant locations spanning the major geographic regions of the continental 48 states; assessment of regulations and permitting issues relevant to use of impaired waters for cooling operations; determination of general water quality for each of the three types of impaired waters being studied and specific water quality of impaired waters at the selected sites; construction and testing of model cooling towers; field testing of key operational parameters for the cooling system operated with the three different impaired waters; development of a mathematical model for water quality characteristics in cooling systems operated with different impaired waters; and assessment of the treatment needs for the cooling tower discharge streams.

This technology development encourages the use of impaired waters by coal-fired power plants by providing necessary information on geographic proximity, pretreatment requirements, available quantities, and regulatory and permitting issues that are relevant for application of these impaired waters.  Additionally, understanding the key design and operating parameters aids in successful use of impaired waters without detrimental impact on cooling system performance.