Bioenhanced remediation of dibutyl phthalate contaminated black soil by immobilized biochar microbiota

To address the contamination caused by DBP residues prevalent in black soils, this study developed a multifunctional bioremediation material (BHF@DK-P3) using humic acid and iron-modified corn stover biochar in combination with microbiota. The microbiota contained DBP-degrading bacteria (Enterobacterium sp. DNB-S2), phosphorus-solubilizing bacteria (Enterobacter sp. P1) and potassium-solubilizing bacteria (Paenibacillus sp. KT), and formed a good mutualistic symbiosis. In the biochar microenvironment, the microflora had lower DBP biotoxicity responses and more cell membrane formation. The addition of BHF@DK-P3 brought the structure of the DBP-contaminated black soil closer to the optimal three-phase ratio. The microbiota was able to perform their biological functions stably under both DBP stress and acid-base stress conditions. The stability of soil aggregates and the efficiency of N, P, K nutrients were improved, with available phosphorus increasing by 21.45%, available potassium by 12.54% and alkali-hydrolysable nitrogen by 14.74%. The relative abundance of copiotrophic bacterial taxa in the soil increased and the relative abundance of oligotrophic bacterial taxa decreased, providing a good mechanism for the conversion and utilization of soil nutrients. Biochar and microbiota jointly influenced soil carbon and nitrogen metabolism in response to DBP.