| Pharmaceutical sludge is considered as a major,complex and toxic industrial waste.Due to its high salt content,and containing a variety of pathogenic microorganisms and stubborn antibiotic drug residues,direct landfill or soil application will cause serious environmental problems and harm the health and safety of humans and animals.Therefore,pharmaceutical sludge must be treated effectively to reduce its harm.However,there is a lack of research on the pyrolysis treatment technology of pharmaceutical sludge at home and abroad,and it is urgent to conduct in-depth research on it to solve the harm of pharmaceutical sludge to the environment.Based on this,after analyzing the basic properties of pharmacy sludge pyrolysis was discussed through pyrolysis furnace terminal temperature and residence time on the influence of pharmacy sludge pyrolysis product yield and the change of the biological oil and gas composition,according to the result of the experiment was carried out by engineering amplification experiments,and analyzed the pyrolysis process and stable operation of mass balance,energy balance in the economy.In addition,the application of pharmaceutical sludge-based biochar in promoting sludge pyrolysis and wastewater treatment is also discussed.Firstly,the basic properties of pharmaceutical sludge were analyzed,and the influence of pyrolysis process on the pyrolysis products and yield of pharmaceutical sludge was discussed.The organic components of pharmaceutical sludge are mainly protein,fat and carbohydrate.The thermogravimetric analysis shows that the pyrolysis process can be divided into three stages:dehydration stage,decomposition stage and carbonization stage.The fitting results of two model-free methods showed that the average activation energy of pharmaceutical sludge pyrolysis was 233.11 k J/mol.The analysis of the model function of sludge pyrolysis by the master diagram method shows that the pyrolysis of pharmaceutical sludge conforms to the phase interface reaction at low conversion rate,and conforms to the nucleation growth model at high conversion rate.The effects of pyrolysis conditions on the yield and components of the products were analyzed.The results showed that the yield of biochar decreased with the rise of the final pyrolysis temperature.The yield of biochar increased first and then decreased,while that of biogas maintained an increasing trend.The content of aliphatic hydrocarbons in bio-oil decreases with the increase of the final pyrolysis temperature,which is caused by the cyclization and aromatization of chain aliphatic hydrocarbons at high temperature to form benzene aromatic hydrocarbons.Reasonable increase of pyrolysis temperature can reduce the yield of heterocyclic and oxygen-containing compounds and improve the quality of bio-oil.The content of CO2 in biogas decreases sharply with the rise of final pyrolysis temperature,while the content of H2 and CO increases gradually.Residence time is an important factor affecting the pyrolysis process.The results show that the reaction can reach equilibrium when the residence time is30min.The co-pyrolysis of pharmaceutical sludge and municipal sludge was studied at the final pyrolysis temperature of 600?and residence time of 30min according to different mixing ratios.The synergistic effect was produced during the co-pyrolysis of the two kinds of sludge.This may be due to the different metal oxides contained in the two types of sludge that play a catalytic role.The results of engineering amplification experiment show that the net income of the pyrolysis equipment for treating 1 ton of pharmaceutical sludge with 80%moisture content is 216.33 yuan,indicating that the pyrolysis technology has a very large application prospect for treating pharmaceutical sludge.Secondly,the physicochemical properties of pharmaceutical sludge based biochar were investigated,and it was used as additive in the pyrolysis of pharmaceutical sludge.The results showed that the pharmaceutical sludge based biochar had rich specific surface area,and the scanning electron microscope analysis showed that the surface of biochar was rough and had abundant pore structure.Thermogravimetric analysis and pyrolysis kinetics analysis of the pharmaceutical sludge with the addition of biochar were carried out.The results showed that the solid yield decreased during the pyrolysis process,and the thermal decomposition of organic matter in the sludge was more sufficient.Two model-free kinetic analysis methods showed that the addition of pharmaceutical sludge-based biochar reduced the activation energy of the reaction,which reduced the difficulty of the reaction.The yield analysis of pyrolysis products showed that the addition of biochar reduced the yield of pyrolysis biochar from pharmaceutical sludge,and more biooil was decomposed into biogas.When the final pyrolysis temperature is 600?and the addition of biochar reaches 60%of the sludge feed,the yield of bio-oil is reduced to 25.87%,which is 6.78%less than that without adding biochar.With the increase of temperature and biochar,the yield of biogas increased continuously.When the final pyrolysis temperature was 800?,the yield of biogas reached 31.36%when the biochar added ratio was 60%,which was 10.27%higher than that without adding biochar.The addition of biochar can further reduce the aliphatic hydrocarbon content in bio-oil and generate more aromatic hydrocarbons through cyclization and aromatization reactions.Pharmaceutical sludge based biochar can inhibit the generation of CH4 and CO2,and promote the generation of H2 and CO.Finally,using pharmaceutical sludge as precursor and sodium hydroxide as activator,porous biochar was prepared by impregnation method and dry mixing method for the removal of tetracycline from wastewater.The properties of modified biochar were characterized,and the thermodynamics and kinetics of biochar adsorption on tetracycline were analyzed.The adsorption capacity of biochar for tetracycline was studied.The results showed that Na OH activation could significantly increase the specific surface area of biochar.The biochar prepared by dry mixing method had more mesopores,while the biochar prepared by impregnation method had more micropores.Scanning electron microscopy(SEM)showed that the surface of two kinds of biochar had abundant roughness and irregular cylindrical cracks or holes.The surface of modified biochar has a relatively stable aromatic structure.When biochar adsorbed tetracycline,it had a wide range of adaptability to p H of solution.The ions in the solution will compete with tetracycline,and tetracycline will be strongly shielded at higher ionic strength,resulting in a decrease in adsorption capacity.However,on the whole,the removal effect of the two kinds of biochar on tetracycline is still considerable,indicating that the modified biochar can be applied to the removal of tetracycline in the condition of high salinity.Biochar prepared from pharmaceutical sludge activated by Na OH has good stability and reusability,and has great potential for practical application. |
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