Study On Preparation Of Sludge Activated Carbon And Its Application

Nowadays，the efficiency of wasterwater treatment is continuously improved, and a largenumber of sludges are produced. Without proper treatment and means, it caused lots of wetsludge free to transported out, simple landfill and stacked, producing sludge siege. The sludgetreatment has become a common environmental problems.The municipal sewage sludge, adding peanut hull as recarburizer was used to prepare thesludge-based activated carbon through a chemically activated method. Utilized the orthogonalexperiment to research correlation effect factors of sludge-based activated carbon derivedfrom sludge, which including peanut hull relative to the sludge, activation temperature, theconceration of activation reagent, activation time and the ratio of sludge to activation reagent.Based on the single factor experiment, the best preparation condition was ascertained: peanuthull relative to the sludge20%, activation temperature600℃, the concentration of activationreagent3mol/L, activation time45min and the ratio of sludge to activation reagent1:2.5. Onthe condition, the iodine value of the sludge-based activated carbon is674.3mg/g, the rate ofachievement is47.1%.It was found that activated and pyrolysis make the formation of the pore configuration onthe sludge-based activated carbon surface by elemental analysis, scanning electronmicroscope, specific surface area analysis, X-ray diffraction, Fourier infrared spectroscopicand etc. Different prepraration conditions and activation reagent affect the structure of thesludge-based activated carbon.The speciation analysis of heavy metals had been carried out by BCR extraction methodin sludge-based activated carbon. The acid-soluble and the reduction state of heavy metals inthe sewage sludge could be transformed into the residual states in the sludge-based activatedcarbon after the process of pyrogenation. With the comprehensive studying of various stablestate ratios of heavy metals in the carbons obtained at different conditions, the pyrolysistemperature for the sludge-based activated carbon was obtained at600℃. Moreover, apotential ecological risk assessment on heavy metals in sludge-based activated carbon wasanalysed and it revealed that the lowest risk index product of sludge-based activated carboncould be obtained at the conditions of peanut hull was added bu20%and the activationtemperature was600℃.The sludge-based activated carbon possessed high adsorption capability for MG. At theappropriate dosage, adsorption time and pH, MG simulated wastewater can reach a highremoval rate. Based on research of sludge carbons thermodynamics, it shows that the MG adsorption accords with Langmuir isotherm adsorption, and the adsorption type mainly ismonolayer adsorption. Based on the research of adsorbents dynamics, it shows that theadsorption of MG by sludge-based activated carbon accords with Lagergren dynamicsequation and belongs to the second level dynamics adsorption, and the equilibrium adsorptioncapacity by experiment accords with the second level dynamics equation.