Effect Of Low Frequency Ultrasound Radiation On Harmful Gases Control And Biofilm Structure In Sewer

Hydrogen sulfide（H₂S）will seriously corrode sewer and cause pipeline leakage,which has a serious impact on the normal operation of sewage pipelines.The research group recently proposed a sewage pipeline system based on Low Frequency Ultrasound Radiation,which destroys the biofilm in the pipeline and chemically oxidizes the sulfide in the water phase of the sewage pipeline through Low Frequency Ultrasound Radiation,thereby realizing a new control strategy for harmful gas control.In this research,a mixed reactor system built in the laboratory to simulate actual sewage pipelines and batch continuous intermittent tests have proven the optimal conditions for Low Frequency Ultrasound Radiation,and explored the control of low-frequency ultrasound radiation on harmful gases in sewage pipelines.Effect:Through the microscope and flow cytometer analysis system,the physical structure characteristics,community activity,adhesion changes and control mechanisms of biofilms under Low Frequency Ultrasound Radiation conditions are explained.The results are as follows:（1）Considering the influence factors of treatment efficiency and economy,the optimal operation parameters of low frequency ultrasound radiation treatment are 0.9W/m L and 20 min based on response surface methodology.（2）Low Frequency Ultrasound Radiation can effectively control the generation of H₂S in the gas space of sewage pipeline.Compared with the traditional anaerobic pipeline,under the condition of low frequency ultrasound radiation,the concentration of dissolved sulfide,H₂S_（g）and sulfate conversion rate in the sewage pipeline are reduced.CO concentration decreased significantly after treatment.The effect of Low Frequency Ultrasound Radiation on the control of harmful gas in sewage pipeline is remarkable.（3）The Low Frequency Ultrasound Radiation affects the sewage quality in the sewage pipe to a certain extent.After Low Frequency Ultrasound Radiation treatment,the ORP level of sewage pipe sewage increased significantly,and the ORP value in sewage increased from-274.6 m V to 51.3 m V in 1～9 h,which changed the water quality characteristics of sewage and tended to be oxidizing.After 20 min of Low Frequency Ultrasound Radiation treatment,a large amount of·OH was produced in the wastewater,and the concentration reached 384.9±22.1μmol/L.This shows that Low Frequency Ultrasound Radiation can improve the anaerobic environment of sewage in sewage pipe,and increase the chemical oxidation of sulfide.（4）Low frequency ultrasound radiation has adverse effects on the structure of the biofilm of sewer pipe,and change the activity of bacteria and the abundance of anaerobic microorganisms in the biofilm of sewer wall.Low frequency ultrasound radiation makes the biofilm in the inner wall of sewer pipe from dark black to light brown and loose,and only the skeleton structure of biofilm is left after LFUR.The physiological structure of anaerobic microorganisms in the biofilm was seriously damaged,and the EPS in the biofilm was destroyed,resulting in the adhesion from-16.37±41 n N to-1.36±0.44 n N.These results indicate that low frequency ultrasound radiation can effectively produce biofilm on the wall of sewer pipe,which has rapid and strong damage effect.It can be used as an environment-friendly intermittent control strategy for harmful gas in sewer pipe.