Study On The Preparation, Modification And Application Of Activated Carbon From Sludge

With the improvement of sewage collection and treatment rate,the yield of sludge was also showing an increasing trend,the production of a great amount of sludge not only caused sewage treatment enterprises to face huge sludge disposal costs,but also brought serious environmental pollution problems.At present,the traditional sludge disposal method cannot meet the increasingly high environmental protection requirements,and the resource utilization of sludge will be the only way to solve this problem.Titanium white waste acid caused widespread concern in the community due to its high outputs and environmental hazards,but titanium white waste acid contained about 20%of waste sulfuric acid and a small amount of metal ions,it can be used as an activator for the preparation of sludge activated carbon,thereby realizing turning waste into treasure.Excess sludge from an urban sewage treatment plant was invoked as raw materials and titanium white waste acid as an activator to prepare sludge activated carbon(SAC)by chemical activation method.The process parameters for the preparation of SAC with titanium white waste acid activation by single factor experiment were as follows:solid-liquid ratio 1:3,carbonization time 75 min,carbonization temperature 350?,the SAC iodine adsorption value prepared under this process condition was 406.40 mg/g,the oxygen-containing functional group was 1.6530 mmol/g,the specific surface area was 753.76 m2/g,and the pore volume was 0.4757 cm3/g.The primary and secondary order of influence on the adsorption performance of SAC prepared by orthogonal experiment was as follows:carbonization temperature>carbonization time>solid-liquid ratio.Specific surface area and pore volume test,element analysis,pH analysis,scanning electron microscopy(SEM)analysis,infrared spectroscopy(FTIR)analysis,heavy metal leaching concentration analysis and so on were adopted,it was concluded that the surface appearance of SAC prepared by activation of titanium white waste acid present a large number of uneven and irregular pore structures,after activation and carbonization,the main elements combine to form the surface functional group of sludge activated carbon,the pH value of SAC met the requirements of "Activated Carbon for Wood Water Purification"(GB/T 13803.2-1999)for the use of pH value,and the content of heavy metals in the leaching solution was much lower than the concentration limit of harmful components in the leaching solution by the "Dangerous Waste Identification Standards Identification of Leaching Toxicity"(GB5085.3-2007),etc relevant standards.In order to further improve the adsorption performance of SAC on the adsorbate,prepared SAC was Oxidative modification with H2O2 as a modifier.Through single factor experiment,the optimum modification concentration of H2O2 was 10%,and optimum modification time was 60 min.The modified sludge activated carbon(MSAC)iodine adsorption value was 493.40 mg/g,the oxygen-containing functional group was 1.7925 mmol/g,the specific surface area was1021.45 m2/g,and the pore volume was 0.6228 cm3/g,increased by 21.4%,8.44%,35.5%,30.9%than before modification,respectively.Finally,the sludge activated carbon before and after modification were used for the adsorption comparison research of slaughterhouse wastewater.the effects of dosage,shaking adsorption time and pH value on adsorption performance were compared.The results showed that compared with the unmodified,the modified sludge activated carbon was more conducive to the adsorption of slaughterhouse wastewater,the adsorption of slaughterhouse wastewater by MSAC was more suitable for describing by the Freundlich model,and it is endothermic and favorable adsorption.The adsorption of slaughterhouse wastewater by MSAC accorded with the quasi-secondary kinetic model,and the equilibrium adsorption amount calculated by the model was more closed to the experimental determination value.