Enhanced Plant Restoration in Open-Pit Mines Using Maize Straw and Ultrasonically Pre-Treated Coal Fly Ash

Abstract

The rehabilitation of the post-mining landscape is one of the intractable bottlenecks faced by the mining industry. Though plant restoration has been regarded as an efficient way, its application is often restricted by the physicochemical properties of the soil, i.e., macronutrient deficiencies. In this work, a novel plant restoration method was proposed that employs maize straw and ultrasonically pre-treated coal fly ash (UCFA) for soil amelioration. Seed germination experiments were performed to investigate the effect of maize straw leachates (MSLs) on the growth of maize, alfalfa, and soybean. Then, the influence of MSLs and UCFA on the physiological attributes, chlorophyll, and trace element concentrations of maize was studied by plant growth experiments. Our results show that: (i) the MSLs concentration had a significant effect on the plant growth and the optimum concentration was 20%; (ii) considering the physiological attributes of maize plants, MSLs and UCFA benefited its growth in most cases. The UCFA proportion should be less than 20 v.% for optimum performance; (iii) the mixture of MSLs and UCFA could generally increase the chlorophyll and decrease trace element concentrations; and (iv) the optimum proportion was found to be soil:UCFA:MSLs = 70:20:10 and soil:UCFA:MSLs = 60:20:20, which achieved satisfactory performance during engineering applications.

Greening the Brownfields of Thermal Power Plants in Rural Areas, an Example from Romania, Set in the Context of Developments in the Industrialized Country of Germany

“…The fly ash results as a residuum of two thermal power plants placed in rural areas in Romania. Fly ash has also been, however, used for treating soil, as Lu et al [25] and Ou et al [26] show. In addition, the geo-textile employed in these studies is placed directly on the ash, with-out a soil layer, and the layer is created through the decay of the geo-textile.…”