Effectiveness of wind-blown sands on treatment of wastewater from coal-fired power plants

Untreated disposal of wastewater from coal-fired power plants has environmental and public health concerns in the developing Shanbei Energy Base, Northwest China. An in situ experiment was conducted in the easily accessible wind-blown sands to study their efficiency in removal of pollutants. Approximately 245 l of wastewater was used in the test, which lasted 409 min. Sand samples were collected at 5 discrete depths, 0.2, 0.4, 0.6, 1, and 1.5 m from the surface before, at the end of, and 20 days after the infiltration test. Pollutants commonly found in wastewater were analyzed for all the sand samples. 20 days after infiltration, the content of As in the sand samples had a general reduction, decreased from original 0.0109–0.0132 to 0.005 mg/kg. The content of N-NH₄ also decreased from original 1.1–1.5 to 0.8–1.0 mg/kg. But the content of Cd and petroleum was stable and had no decreasing trend. The test indicates the wind-blown sands are more effective for As and N-NH₄, but less effective for petroleum and Cd.