Effect of phosphogypsum and poultry manure on aggregate-associated alkaline characteristics in bauxite residue. (15th February 2020)

• Record Type: Journal Article
• Authors: Xue, Shengguo; Ke, Wenshun; Zhu, Feng; Ye, Yuzhen; Liu, Zheng; Fan, Jiarong; Hartley, William
• Is Part Of: Journal of environmental management. Volume 256(2020)
• Publication Date: 2020-02-15
• Subjects: Bauxite residue -- Red mud -- Amendments addition -- Aggregate stability -- Aggregate-associated alkaline characteristics -- Soil formation; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2019.109981
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Bauxite residue is a highly alkaline solid waste with poor physical structure which ultimately limits plant growth. Ecological reconstruction is an effective strategy to improve its environmental management, although soil formation process still requires further investigation. Here, an incubation experiment was used to investigate the effects of phosphogypsum and poultry manure, on aggregate size distribution and aggregate-associated exchangeable bases of bauxite residue. Phosphogypsum and poultry manure additions significantly increased the proportion of 2–1 mm residue aggregates and enhanced mean weight diameter (MWD) of residues in the 0–20 cm and 20–40 cm layers, although little effect was evident in the 40–60 cm layer. Phosphogypsum addition reduced pH and EC values to approximately 8.5 and 200 mS/cm in different size aggregates at 0–20 cm. Exchangeable Ca 2+ concentration was improved, especially in 0.25–0.05 mm and <0.05 mm aggregates, following amendment additions. The relative contents of katoite and cancrinite in >0.25 mm aggregate fractions were relatively higher, which was consistent with changes in pH. Phosphogypsum and poultry manure changed the microstructure and surrounding pores of residue aggregates, whilst the concentration of Ca on microaggregate surfaces was higher than that on macroaggregates. These findings reveal that application of phosphogypsum and poultry manure directly alter the distribution of exchangeable bases and alkaline indicators within residue aggregates, resulting in aggregate size distribution and microstructure variations. Highlights: Effect of amendment additions on aggregate-associated alkaline characteristics in bauxite residue were investigated. Amendment additions increased the proportion of 2–1 mm residue aggregates and enhanced aggregate stability. PH, EC, ESP, and exchangeable bases varied significantly within residue aggregates. Amendment additions changed the micro-structure and surface elemental distribution of residue aggregates.