| The use of coal-based columnar biological activated carbon in water treatment combines the adsorption properties of activated carbon and the degradation function of surface microorganisms,which can purify micro-polluted water sources in a more long-term and efficient manner.However,the long-term use of activated carbon due to the adsorption of a large number of pollutants,the surface biofilm thickness increases,beyond a certain value will lead to the disappearance of biological activity and failure,forming a saturated biological activated carbon that can not continue to use.There are many ways to achieve activated carbon regeneration and achieve good results,but there are few methods for regenerating saturated biological activated carbon.This paper combines the thermal-electricity regeneration method,and improve the original equipment,design a new low voltage pilot arc regenerative furnace,analyze the failure of coal-based columnar biological activated carbon regeneration,and measure the iodine and methylene blue values after regeneration.The recovery rate of adsorption capacity is over 90%,and study on the mechanism in the regeneration process,the following aspect work is carried out:(1)Firstly,biological activated carbon background and the advantages and disadvantages of activated carbon regeneration method commonly used in water treatment are reviewed,and a new technology of low voltage pilot arc regeneration is introduced.In the small pilot arc regeneration test furnace,the influence of the conductivity characteristics of saturated biological activated carbon on low voltage pilot arc regeneration were investigated.The single-particle resistance was measured to analyze the material resistivity.The pilot arc phenomenon during the regeneration process was verified by the arc-inducing furnace to study the regeneration process.Factors such as carbon particle group state,pretreatment method,structural parameters(flow rate,electrode plate spacing)and other factors affect the conductivity characteristics.It is found that the particle group resistance is much larger than the single grain resistance.The particle group resistance is lower than the static state in the flowing state.The water volatilization and temperature increase in 200? can reduce the carbon particle group resistance,but the carbon particle group resistance after dynamic drying treatment the rate of decline is more significant.After 300? dynamic drying,the effect of low voltage pilot arc was optimal,and the recovery rates of iodine and methylene blue reached 91.3%and 93.3%.(2)Saturated biological activated carbon will desorb a large amount of organic matter during the process of low voltage pilot arc regeneration.In order to further study the regeneration mechanism,the adsorption mechanism of the activated carbon is first explored.The typical contaminated phenol in water pollution was selected as the adsorbate,and the adsorption performance of phenol was tested with new activated carbon.The removal rate of phenol by new activated carbon can reach 96.67%.The data of isothermal adsorption are calculated by Langmuir and Freundlich models.The correlation coefficient after fitting is 0.96 or more.It is suitable for two models.It is concluded that adsorption of phenol is an exothermic process with both physical and physical properties.Adsorption also has chemisorption,which has good adsorption to phenol.The adsorption conforms to the pseudo second-order kinetic model,and then the sample is analyzed for particle size,surface morphology and surface elements.(3)Analyze the mechanism of low voltage pilot arc regeneration of saturated biological activated carbon,and explore the mechanism of pyrolysis desorption regeneration and plasma degradation.TG-FTIR was used to investigate the change of gas phase product of saturated biological activated carbon with temperature.It was found that the decarburization temperature reached 885? and the basic desorption and decomposition of organic matter was complete.The optimal regeneration temperature was determined at 850?,and the regeneration was optimized with low voltage pilot arc regeneration.The temperature matches.There is a biofilm on the surface of the spent coal-based bio-activated carbon.During the pyrolysis process,a small amount of biofilm pyrolysis products NH3 and HCN can be detected.The pyrolysis is mainly H2O.CO2 and CO,and the yield is up to 810? at the peak of DTG.(4)According to the temperature segment divided by thermogravimetric analysis,the thermodynamic method was used to investigate the mechanism function of saturated biological activated carbon and phenol-loaded activated carbon in each temperature range.Two samples were calculated by Kissinger method and Flynm-Wall-Ozawa method.The activation energy at the peak of weight loss is the reference value,and Coats-Redfern is used to solve the activation energy and the most probable mechanism function of saturated bio-activated carbon and phenol-loaded activated carbon in various temperature ranges at different heating rates.When the saturated biological activated carbon is pyrolyzed,the heating rate has no effect on the selection of the most probable mechanism function.The thermal desorption behavior of different adsorbed materials in the same temperature range is different. |
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