Research On Hydrogen Sulfide Removal And Generation Suppression In Wastewater Pipeline Based On Enhanced Oxidation Of Iron-based Substances

Hydrogen sulfide produced by sewage pipelines is the main cause of pipeline corrosion and odor release,and its control technology has gradually attracted people’s attention.This paper proposes a technology system based on the enhanced oxidation of iron-based substances to remove hydrogen sulfide from sewage pipes and inhibit the production of hydrogen sulfide.The main body of the system is divided into two stages.The first stage is mainly aimed at the relatively low amount of biofilm in sewage pipes and the production of hydrogen sulfide.When it is relatively small,it is used to remove the hydrogen sulfide that has been generated in sewage,specifically using cheap iron scraps to enhance oxygen oxidation to remove sulfide in the water phase;the second stage is mainly for the high amount of biofilm in sewage pipelines,and the amount of hydrogen sulfide produced When it is difficult to solve the problem of liquid-gas interface dissipation by simply oxidizing to remove sulfide in water,from the perspective of inactivating sewage pipeline biofilm to inhibit hydrogen sulfide production,it is proposed to use Fe²⁺activated persulfate(Fe²⁺/PDS)to enhance oxidation and rapid elimination.The biofilm in the living sewage pipeline can completely suppress the production of sulfide.This paper carries out experimental research around the above two technical systems,and its main conclusions are as follows:（1）The experimental results show that compared with the result of aeration alone,the iron-oxygen system constructed by scrap iron filings can effectively enhance the removal of sulfide in water.When the aeration water ratio is 2,the iron filings dosing volume ratio is 1.25%,The removal rate of sulfide in water can reach 79.3%,and the concentration of H2S in the gas phase is reduced by 89.5%.In the 30d long-term test cycle,the ferrite system can completely remove the sulfide,and the concentration of the escaped hydrogen sulfide is reduced by 81.3%compared with the single aeration,and the control efficiency is stable.Under the action of the ferrite system,the p H of the sewage during operation was increased to 7.9,the COD of the sewage was reduced by an average of 32.5%,TP was reduced by an average of 23.6%,and TN had no significant impact.Mechanism studies have shown that the main removal path of sulfide in the ferrite system is:the iron ions(Fe²⁺,Fe³⁺)produced by the internal electrolysis of scrap iron scraps by oxygen can be directly precipitated to remove sulfide,and the produced iron ions can catalyze the oxidation of sulfide by oxygen.The low p H environment is more conducive to the production of iron ions,and the high p H is more conducive to the catalytic oxidation of sulfides.The main products of sulfides are Fe S,S0,and S2O3^2-.（2）The Fe²⁺/PDS system can effectively inactivate biofilms in sewage and control the production of sulfides.The research results show that the amount of Fe²⁺/PDS added to the reactor at a time is 1.5 mmol,the molar ratio is 1,and the reaction time is 20 minutes,the concentration of sulfide effluent from the reactor can be reduced from about 8mg/L to close to 0mg/L,and then the sulfide level will slowly recover,and it will take about 9days for the sulfide generation to recover to 50%concentration,and it will be completely restored to the dosage.The previous level takes about 13 days.The sulfide concentration in the reactor is restored to about 50%for half-process control,a total of four times,during which the required days for the sulfide concentration to return to 50%are 8,11,12,and15 days respectively,indicating that Fe²⁺/PDS has been added multiple times can effectively improve the recovery period of sulfides.（3）Through optical microscope,electron microscope（SEM）,three-dimensional fluorescence spectroscopy,Fourier infrared spectroscopy（FTIR）,the biofilm morphology,extracellular polymer（EPS）and functional groups after the action of Fe²⁺/PDS system were analyzed,and the results showed that Fe²⁺/PDS destroyed the structure of the biofilm and reduced the EPS content,and the functional groups of the biofilm changed significantly;the microbial community analysis showed that the abundance of SRB after treatment was reduced from 4.1%to 0.99%;further analysis by electronic paramagnetic spectroscopy（EPR）The free radicals produced in the Fe²⁺/PDS system are mainly sulfate radicals（SO4·-）and hydroxyl radicals（·OH）.The above results indicate that the Fe²⁺/PDS system produces strong oxidizing sulfate radicals（SO4·-）and hydroxyl radicals（·OH）to destroy the biofilm structure and inactivate the SRB in it,thereby achieving the inhibition of sulfide formation.effect.