Soilization utilization of solid waste: Ecological regulation of phosphorus tailings-based soil with physicochemical improvement and Bacillus_cereus-addition.

Extraction and utilization of effective phosphorus from solid waste have been an important approach for alleviating phosphorus resource shortage. The extraction of available phosphorus by microbial method with low cost, mild conditions and simple process has been drawing attention from the majority of research scholars. However, relevant studies on special microbial communities for effective phosphorus extraction from solid waste are less. In this work，a functional Bacillus_cereus strain screened from phosphate tailings, phosphate ore and forest rhizosphere soil was inoculated into phosphate tailings (PT), modified phosphate tailings (IS) and highland red soil (SS). Compared with SS, the water-holding properties, fertility, leaching toxicity and microbial community diversity of PT and IS with and without bacteria were analyzed. PT+, SS+ and IS+ (after adding bacteria to PT, SS and IS) showed moderately alkaline pH, and the available phosphorus content enhanced by 31.73%, 20.05% and 39.41% respectively. The leaching toxicity phosphate of PT+ and IS + decreased by 4.89 mg/kg and 2.61 mg/kg respectively, while that of SS + increased by 5.45 mg/kg, indicating differences in the phosphorus solubilization mechanism of Bacillus_cereus for different soils. Furthermore, the modification and bacteria treatment improved the relative abundance of Pedobacter, Alcaligenaceae and Pseudomonas, thus enhancing the phosphorus solubility of the PT bacterial community. This work may achieve efficient utilization and ecological restoration of phosphorus tailings-based soil and contribute to long-term sustainable agricultural development.

Aluminium sulfate synergistic electrokinetic separation of soluble components from phosphorus slag and simultaneous stabilization of fluoride.

In this study, fluoride (F) was stabilized and soluble components, namely phosphate (P), K, Ca, Cr, Mn, and Pb, were extracted from phosphorus slag (PS) by using aluminum sulfate (AS) synergistic electrokinetic. PHREEQC simulation was used to determine the occurrence form of each ion in the PS. The mechanisms by which various electrokinetic treatment methods affected conductivity and pH distribution were carefully investigated. Electrokinetic treatment increased P concentration of the anode chamber from 22.7 mg/L to 63.39 mg/L, whereas K concentration increased from 15.26 mg/L to 93.44 mg/L. After AS-enhanced electrokinetic treatments, the concentrations of the different components were as follows: P, 131.66 mg/L; K, 198.2 mg/L; and Ca, 331.3 mg/L. The removal rate of soluble P in PS slices increased to 80.88% by 1.5 V/cm of treatment, and it increased to 94.04% after AS enhancement treatment. For water-soluble F, the removal rate from the PS slices in the anode region was 86.03%, decreasing F concentration in the electrode chamber to 9.57 × 10-3 mg/L. Different extraction efficiencies and stability levels of each component in the PS were regulated at various electrode regions by using different processes such as electromigration, electro-osmotic flow, flocculation, and precipitation. Good results can be obtained if fluoride is solidified concurrently with the removal or recovery of P, K, Ca, and other elements using 2%-4% AS enhanced electrokinetic treatment. Furthermore, CaSO4·2H2O whiskers were produced in the electrode regions when AS content was 6%. The findings of this study indicated that the AS synergistic electrokinetic method is suitable for stabilizing F and removing heavy metals from PS, thus providing a promising technology for recycling valuable components such as P, K, Ca, and Sr and for the simultaneous production of CaSO4·2H2O whiskers. This study provides insights for developing novel technologies for the clean treatment and high-value utilization of PS.