Exogenous Electrons Accelerate The Degradation Of P-nitrophenol

Phenolic compounds are difficult to degrade organic substances and are widely found in all walks of life.In particular,with the continuous development of industry,there are more and more phenolicpollutants in water.Among them,p-nitrophenol(PNP)is a kind of phenolic contaminant,which mainly exists in the waste water or waste of dyestuff,medicine,and chemical industry.However,due to its high toxicity and structural stability,it is difficult under natural conditions.Degraded.This study focused on accelerating the degradation rate of p-nitrophenol,and made the following studies:1.Under the condition of acclimation of PNP degradation activated sludge,activated sludge was subjected to a certain pretreatment breakage sludge,and it was explored whether this method could promote the rate of degradation of PNP.In this study,two methods were used to pretreat the sludge — ultrasonic crushing and freeze-thaw crushing.It was found that the two methods are similar to the effect of crushing sludge,and freeze-thaw crushing has the advantages of simple method and large amount of sludge crushing.advantage.Through this study,it was found that the rate of degradation of PNP by broken sludge was faster than that of unruptured sludge,and it was speculated that the reason was that the cell disruption of sludge could release organic substances and other substances,providing electrons for PNP degradation and accelerating the reaction.Meanwhile,PNP degradation of intracellular enzymes and extracellular enzymes participate in the reaction.2.Comparing the rate of degrading PNP in single sludge and mixed sludge,it was found that the rate of degrading PNP in a single sludge was not as fast as that of two sludges,indicating that the broken sludge cells can release certain substances to accelerate the degradation of PNP,and the substance can be degraded by PNP.Use of bacteria.Degradation of PNP by the supernatant further confirmed the conjecture and found that endogenous respiration of sludge cells could promote PNP degradation.3.When investigating the zero-valent iron degradation PNP,it was found that the effect of zero-valent iron alone on the degradation rate of PNP was related to its dosage.The greater the amount of zero-valent iron added,the faster the PNP degradation rate.At the same time,the pH value of the reaction solution also affects the rate of PNP degradation by zero-valent iron.The higher the pH value,the slowerthe degradation rate of PNP.It shows that during the degradation of PNP in zero-valent iron,the acidic solution is more conducive to the degradation of PNP.At the same time,compared with the three groups of methods of degrading PNP alone with hypoxic microorganisms,zero-valent iron alone,and zero-valent iron-coupled hypoxic microorganisms,it was found that the coupling rate of PNP degradation by both methods was faster than that of any two methods alone,indicating that the coupling method can Promotes PNP degradation.4.The dosage of zero-valent iron has an effect on the degradation of PNP by the coupling of zero-valent iron by anoxic microorganisms,and the more the amount of zero-valent iron is added,the faster the coupling method degrades PNP.By analyzing the process of degrading PNP by oxygen-deficient microorganisms coupling zero-valent iron,the reaction is divided into two parts.The first part is anaerobic reaction,that is,the process of converting PNP to p-aminophenol;the second part is aerobic reaction,ie,benzene ring opening.Ring mineralization process.At the same time,the amount of zero-valent iron also has an impact on the coupling of anaerobic microorganisms to degrade PNPs.That is,the greater the amount of zero-valent iron added,the faster the degradation rate of PNP.However,the degradation rate of PNP under anaerobic conditions is limited to the conversion of PNP to p-aminophenol,because the benzene ring cannot be opened and mineralized under anaerobic conditions,resulting in the inability of PNP to completely degrade.5.By controlling the dissolved oxygen at the time of degradation of PNP by the VBBR method,it was found that VBBR degradation of PNP is an aerobic reaction.Based on the degradation of PNP by VBBR method,this group of experiments explored the impact of broken sludge and zero-valent iron on the degradation rate of PNP.Through the addition of broken sludge(Untreated Sludge)and untreated sludge(Sludge)in the reactor,the addition of sludge can effectively promote the rate of degradation of PNP by the VBBR method,and compare the VBBR,VBBR+UT,VBBR+T The degradation rate of PNP can be found that the degradation rate of VBBR+T is the fastest,indicating that the broken sludge contains organic matter that is released by sludge cells and can be used by PNP degrading bacteria,thereby accelerating the degradation rate of PNP.