Preparation Of Activated Carbon From Sewage Sludge And Its Application In Sewage Treatment

Sludge treatment and disposal has been solved by sludge pyrolysis technology.However,there are still many problems in the utilization of sludge pyrolysis products.In particular,the sludge pyrolysis solid product is still waste and has not yet been fully utilized.Therefore,in order to solve these problems,the author carried out the experimental research on sludge pyrolysis and prepare activated carbon for adsorption of organics in wastewater.Therefore,in this paper,the dried sludge was used as the raw material for pyrolysis,and Thermogravimetric analyzer（TGA）,pyrolysis-activated reactor and other experimental devices were used to study the pyrolysis characteristics of sludge and the activation characteristics of sludge semi-coke.Then the sludge activated carbon is used for the treatment of organic waste water.Through the above studies,the main conclusions are as follows:（1）The analysis of the basic properties shows that the volatile matter yield in the sludge is greater than 61.20%,but the ash content is also as high as 28.22%.This indicats that the sludge has the characteristics of high volatility and ash,and the pyrolysis technology can be used.The pyrolysis temperature has an important effect on the weight loss rate of sludge pyrolysis.（2）Sludge pyrolysis experiments showed that pyrolysis temperature was 500℃and pyrolysis time was 20 min were the optimum pyrolysis conditions for the sludge.The pyrolysis oil yield was greatest under this experimental condition.Sludge activated charcoal can be prepared from the excess sludge under the experimental conditions.The use of double acid to elute the ash is better than the single acid to elute the ash.（3）The optimal conditions for sludge activated carbon preparation are as follows:ZnCl₂concentration was 8 mol/L,activation temperature was up to 800℃,activation time was 1h.The iodine value and the methylene blue value of activated carbon were highest under this activation condition,which were 816.27 mg/g and 95.25 mg/g,respectively.And the specific surface area was 765.88 m²/g.（4）Sludge activated carbon prepared by using optimum activation conditions was used to treat simulated organic wastewater.It was found that the dosage,the adsorption time and the Simulated wastewater concentration had a great influence on the treatment effect of DMP solution,and the temperature had little effect on the adsorption effect.With the increase of dosage and adsorption time,the removal rate of DMP increased.However,as the DMP concentration increases,the removal rate decreases.At 25℃,DMP was completely removed when the initial concentration of simulated organic wastewater was 30 mg/L,sludge activated carbon was 0.8 g/L,and the adsorption time was 30 min.（5）The effect of activated carbon dosage on the COD removal of actual wastewater was the same as that of simulated wastewater,and the adsorption equilibrium time was shorter than the time required to treat simulated wastewater.With the increase of activated carbon dosage and adsorption time,the removal rate of COD increased.When the activated carbon dosage was 0.6 g/L,the effluent of both activated carbons reaches the standard after adsorption.