By Brad Buecker, process specialist, Kiewit Power Engineers
Multiple methods of dealing with waste stream discharges are examined in light of the recent clampdown on industrial processes.
I began my career in the power industry in 1981 at a coal-fired plant in the Midwest. At that time, U.S. EPA National Pollutant Discharge Elimination System (NPDES) guidelines focused upon a small core of primary impurities in wastewater discharge streams. These included total suspended solids (TSS), oil and grease (O&G), pH, and free chlorine (or other oxidizing biocide). A common guideline is shown below in abbreviated form.
My former plant, like many other plants then, utilized once-through cooling, so these limits were often easy to achieve. The majority of problems arose at coal-fired power plants from the discharge of coal-pile runoff ponds and wet-ash disposal ponds. The constituents in these streams that required the most oversight tended to be TSS and pH, but straightforward methods were available to control this chemistry.
Image credit: "Coal-Fired Power Plant at Sunset, Turceni," © 2012 Emilian Robert Vicol, used under an Attribution-ShareAlike 2.0 Generic license: http://creativecommons.org/licenses/by-sa/2.0/deed.en