Preliminary study of coal fly ash (FA) phytoremediation by selected cereal crops

This study focuses on the environmentally friendly utilization of coal combustion residue, fly ash (FA) containing significant amounts of heavy metals. Knowledge about the potential use of FA as a component of growth media for plants is fragmentary. Preliminary experiments tested the possibility to grow cereal crops on media composed exclusively of FA. The analysis of seven different FA from lignite and semi-bituminous coal from North Dakota and Montana sources using inductively coupled plasma emission spectrophotometry showed high concentrations of heavy metals in coal (up to, in mg/kg): As:65, Cd:3.9, Co:38, Cr:77, Li:109, Mn:1547, Pb:106, Ni:41, V:306. Seedlings of rye, wheat, oats, barley, triticale, and regreen (hybrid between wheat and ryegrass) were planted in Petri dishes (10 cm in diameter) in growth media containing FA from lignite coal, FA from semi-bituminous coal, bottom ash, and Fargo clay soil as the control. Each treatment was performed in 3 replications, and each experiment was repeated 3 times. Germination rates, plant growth analysis, and dry matter yield were determined 2-3 weeks after planting. Germination rates and dry matter yield of oats, winterwheat and regreen were greater (10-20% above controls) in media composed of coal ash, but rye, barley, and wheat seedlings were affected by FA in media. These results show the potential for the utilization of FA as a growth media for cereal crops. Therefore, these plants might be used as green cover preventing wind erosion over the coal ash piles. However, this issue requires additional in depth investigation, including a thorough chemical analysis of plant material.