Production of a novel slow-release coal fly ash microbial fertilizer for restoration of mine vegetation.

Driven by a need for economic development, a large number of mines have been exploited, resulting in the destruction of large areas of vegetation and a significant deterioration in local ecological environment. In order to restore vegetation of mines in a timely manner, a new type of organic fertilizer needs to be developed. However, until now, there has been a lack of organic fertilizer with slow-release suitable for mine virescence. As the largest amount of solid waste in coal-fired power plants, coal fly ash presents a promising basis as a bioresource for developing this type of organic fertilizer. In our study, for the first time, fly ash was demonstrated to be an effective carrier matrix via hydrothermal-alkali treatment sintering process for solving the problem of low efficiency of fly ash adsorption for microorganisms via sintering process. Then, a novel slow-release microbial fertilizer which can adsorb a variety of microorganisms was produced using ethyl cellulose as a solvent adhesive. Finally, the pot experiment showed that the soil fertility of abandoned mines can be improved after applying the fly ash microbial fertilizer, and demonstrated the regreening effects with Pseudodrynaria coronans and Buxus microphylla. Our study provides a green engineering approach to recycle fly ash for regreening mines, as well as a new development direction for high-value green recyclable pathway of fly ash.