Impact of fluidized bed combustion waste on metal content of crops and soil

Abstract

The fluidized bed combustion process for removing SO2 from coal-fired power plant stack gases results in generation of large tonnages of waste requiring environmentally acceptable storage or disposal. A field study was initiated in fall 1985 to determine limits of fluidized bed combustion waste (FBCW) applications to agronomic crops without causing significant yield reduction or accumulation of heavy metals in plants or the soil. Rates of FBW ranging from 22 to 560 t ha−1 were incorporated in soil by plowing down single and split applications. Conventional agricultural lime treatments were included for comparison. Tall fescue (Festuca arundinacea), alfalfa (Medicago sativa L.), corn (Zea mays L.), and soybeans (Glycine max. L.) were grown from 1986–88. Annual applications of 22 t ha−1 did not affect yield or metal uptake of any test crop. A single 112 t ha−1 application had no adverse effect, but repeated applications of that rate lowered corn and soybean yields. The rate of 560 t ha−1 resulted in depressed or eliminated growth of all crops. A high pH and high concentrations of Ca and S were associated with this rate but heavy metals and B concentrations in soil and plant tissue were not significantly affected.