All environmental improvements come at a cost. The question that’s not always answered and sometimes not even asked is: At what cost exactly and to what benefit? And after that: Does the benefit justify the cost?
The cost versus benefit question comes up at various times in wastewater treatment, perhaps most often as it relates to nutrient removal. Phosphorus discharges into streams and lakes can seriously degrade water quality, feeding excessive growth of weeds and algae. In marine waters, nitrogen loadings have been responsible low-oxygen dead zones in Chesapeake Bay and the Gulf of Mexico, and elsewhere.
The nutrients come from various
