磷石膏基质改良及生物修复技术探索OA

Taking phosphogypsum from a tailings reservoir in Guizhou as the research object,a comparison with planting soil standards revealed problems such as strong acidity,severe salinization,and poor fertility.Improvement experiments were conducted using quicklime,straw biochar,earthworm manure,and nutrient soil to obtain the optimal improvement scheme.Based on the improved phosphogypsum,studies on phytoremediation and microbial remediation were carried out to screen plants with strong stress resistance and the best fluoride pollution enrichment capacity,as well as to cultivate microorganisms with the best phosphorus pollution fixation and transformation effects.According to the experimental results,plant-microbial combined remediation experiments were conducted to compare the enrichment capacity of plants and microorganisms for pollutants,the adaptability of plant growth capacity,and the improvement effect on the physicochemical properties of phosphogypsum,so as to clarify the synergistic effect between plants and microorganisms.Finally,a plant-microbial combined remediation scheme for in-situ control of phosphogypsum pollution and ecological remediation is proposed.The results showed that when quicklime,straw biochar,vermicompost,and nutrient soil are added at concentrations of 1.0％,1.0％,10.0％,and 10.0％,respectively,the pH of phosphogypsum increases from 2.16 to 4.75,organic matter content increases by 5.3 times,and electrical conductivity decreases to 56.4％.Phytoremediation experimental studies found that ryegrass had the optimal stress resistance and pollutant enrichment effect;microbial remediation experiments revealed that the five strains isolated and screened from phosphogypsum all have the ability to fix and convert phosphorus.After identification,they were identified as the chitinophaga sp.,Pseudomonas sp.,Xanthomonas sp.,Variovorax paradoxus sp.,and Delftia sp..The optimal inoculation amount was 5×107 CFU/300 g,which could reduce the phosphorus concentration of phosphogypsum leachate to 23.3％.Plant-microbial combined remediation experiments found that the addition of microorganisms had a growth-promoting effect on plants.The total phosphorus and maximum fluoride adsorption increased by 39.9％and 78.1％respectively;furthermore,the phosphorus-fixation ability of microorganisms increased by 123.2％.