Optimized Degradation Of Total Petroleum Hydrocarbons C₁₀-C₄₀ By Immobilization Of Phanerochaete Chrysosporium,Achromobacter And Their Mixed Bacteria

Total petroleum hydrocarbons（TPHs）are hydrocarbon compounds in petroleum.Human activities such as oil extraction and processing,waste incineration,transportation and so on lead to the entry of total petroleum hydrocarbons into the environment,resulting in a decline in the quality of the atmospheric environment,malformation and death of aquatic organisms,and induction of human multiple organ diseases and other hazards,seriously endangering human health and ecological safety.At present,the remediation of total petroleum hydrocarbons pollution mainly uses microbial bacteria to degrade it,but there are still some problems.The main reason is that microbial bacteria have poor resistance to environmental toxicity,resulting in low effective concentration,which not only has poor degradation efficiency of total petroleum hydrocarbons,but also is difficult to degrade continuously.In this study,based on the components of fungal and bacterial culture medium,two kinds of mixed culture medium of fungi and bacteria were optimized by orthogonal design method and single variable method.The degradation of TPHs(C₁₀-C₄₀)by two kinds of single bacteria of Phanerochaete chrysosporium and Achromobacter and their mixed bacteria were studied.In order to improve the degradation rate,Cu Cl₂,soil amendment and Tween-80 were added to optimize the medium composition.The degradation time of TPHs(C₁₀-C₄₀)by immobilized mixed bacteria balls with ionic liquid regenerated cellulose as carrier was carried out by cross-linking fixation method,which improved the continuous degradation time of immobilized bacteria balls.The degradation rate of TPHs(C₁₀-C₄₀)by immobilized bacteria balls could be significantly improved by adding appropriate concentration of H₂O₂ and guaiacol and optimizing the composition of immobilized mixed bacteria balls.The main results of this paper are as follows:（1）When Cu Cl₂ was 0.002g/L,soil amendment was 0.2g/L and Tween-80 was 2g/L,the mixture of the three substances had the best effect on the growth of Phanerochaete chrysosporium.When Cu Cl₂ was 0.02g/L,soil amendment was 0.02g/L,Tween-80 was 20g/L,the mixture of the three substances had the best effect on the growth of Achromobacter.When Cu Cl₂ was 0.002g/L,soil amendment was 0.0002g/L,and Tween-80 was 0.002g/L,the mixture of the three substances had the best growth effect on the mixed bacteria of the two bacteria.（2）TPHs(C₁₀-C₄₀)（0.22mg/L）were degraded by two kinds of single bacteria and mixed bacteria under the optimal concentration ratio of three substances at 30°C and 150r/min for 19days.The degradation rate of Phanerochaete chrysosporium was 65.26%.The p H of the medium decreased from 4.8 to 4.5,and the degradation environment was weakly acidic.The degradation rate of Achromobacter was 65.54%,the p H of the medium increased from 7.2 to9.0,the degradation environment was weakly alkaline.The degradation rate of the mixed bacteria was 72.98%.The p H of the medium increased from 5.5 to 8.3,and the degradation environment changed from weak acid to weak alkaline.TPHs(C₁₀-C₄₀)（2.10mg/L）were degraded for 19 days,the degradation rate of Phanerochaete chrysosporium was 79.95%,the p H of the medium decreased from 4.7 to 4.6,and the degradation environment was weakly acidic.The degradation rate of Achromobacter was 76.71%,and the p H of the medium increased from 7.2 to 9.0,and the degradation environment was weakly alkaline.The degradation rate of the mixed bacteria was 83.42%.The p H of the medium increased from 5.4to 8.3,and the degradation environment changed from weak acid to weak alkaline.The enzyme secreted by both single bacteria and mixed bacteria during the degradation process has a small change in activity,is at a high level of activity and is stable,which is conducive to the degradation of TPHs.（3）When Cu Cl₂ is 0.002g/L,soil conditioner is 0.0002g/L,and Tween-80 is 0.002g/L,the degradation rate of TPHs(C₁₀-C₄₀)（0.22mg/L）was 83.41%after 19 days under the condition of 30°C,150r/min,and the p H of medium increased from 8.0 to 8.2.The degradation rate of TPHs(C₁₀-C₄₀)（2.10mg/L）was 96.89%,and the p H of medium increased from 8.0 to 8.3.In the optimized mixed bacteria agent,0.1g/L H₂O₂ and 0.2 g/L guaiacol were added to immobilize the immobilized mixed bacteria.The degradation rate of TPHs(C₁₀-C₄₀)contaminated soil for30 days reached 65.40%,which was 23.56%higher than that of TPHs(C₁₀-C₄₀)in soil without these two substances.In conclusion,this study shows that the appropriate concentration of Cu Cl₂,soil modification and Tween-80 are conducive to the degradation of TPHs(C₁₀-C₄₀)by Phanerochaete chrysosporium and Achromobacter and their mixed bacteria.The mixed bacteria produce synergistic degradation and improve the degradation rate,and the degradation rate of TPHs(C₁₀-C₄₀)at higher concentrations is greater.At different degradation stages,the enzymes secreted by the bacteria to play the main degradation role are different.Using ionic liquid regenerated cellulose as carrier,the degradation rate of immobilized mixed pellets obtained by cross-linking fixation method was higher than that of free bacteria.The appropriate concentration of H₂O₂ and guaiacol significantly improved the degradation rate of immobilized pellets.The optimized immobilized mixed bacteria balls of Phanerochaete chrysosporium and Achromobacter prepared in this study have a high degradation rate of TPHs(C₁₀-C₄₀)and a good application in contaminated soil.It provides a reference scheme and technical support for the future research on the remediation of medium and long chain TPHs pollution,and has a good application prospect in the remediation of TPHs pollutants.It has important application value and practical significance for maintaining human and ecological security.