USING CONSTRUCTED WETLANDS TO IMPROVE WATER QUALITY AND REDUCE NONPOINT POLLUTANT LOADINGS INTO THE TRUCKEE RIVER

摘要

A small-scale wetland system was constructed along Steamboat Creek, the majorrnnonpoint source of total nitrogen for the Truckee River. The wetland system consisted ofrnthree parallel trains. Two trains functioned as vegetated free surface wetlands and onerntrain functioned as an unvegetated attached growth media bed. Each train was operated atrna relatively high hydraulic loading rate (13.3 cm/d) and had a relatively short hydraulicrnresidence time (12 hours).rnThe ability of the wetland system to reduce total nitrogen in Steamboat Creek wasrnroutinely monitored. Over the period of one year, total nitrogen was reduced by anrnaverage of 42 percent or 0.44 mg/L in the two vegetated trains and an average of 21rnpercent or 0.27 mg/L in the unvegetated train. The speciation of nitrogen was anrnimportant factor influencing the effectiveness of nitrogen removal within the wetlandrnsystem. Ammonia, nitrate, and nitrite were more effectively removed than organicrnnitrogen.rnBased on the results obtained for the small-scale wetland system, vegetated surface flowrnconstructed wetlands along Steamboat Creek have the potential to reduce the loading ofrntotal nitrogen into the Truckee River by an average of 47 kg/d on an annual basis, whichrnrepresents an overall reduction of 30 percent.