Municipal Sludge Supercritical Water Gasification And Phosphorus Resources Recycling Experimental Research

The output of municipal sludge in China is increasing with the accelera tion of urbanization,sludge volume in 2020 is expected to exceed 60 millio n tonnes.If the sludge is not treated in time,it will pose a great threat to the social environment.At present,the main methods of sludge treatment an d disposal are landfill,compost,combustion,etc.,but the treatment effect is not good,and the treatment efficiency is very low.At present,phosphorus resources are in short supply,which will be exhausted if human beings cont inue to unrestrained exploitation or use.Municipal sludge is complex and ri ch in phosphorus.Just think whether the phosphorus in sludge can be recycl ed.The application of supercritical water gasification(SCWG)technology to the treatment of coal,waste water and other biomass has achieved certain results,which has attracted the attention of many scholars due to its efficien t and rapid reaction and the ability to obtain clean energy hydrogen.Howev er,there are few experimental studies on hydrogen production and phosphor us recovery by supercritical water gasification technology.In this paper,hydr ogen production from municipal sludge by supercritical water gasification is studied and discussed.In this experiment,the factors affecting hydrogen pro duction from supercritical water gasification sludge were carried out in seque nce: temperature,residence time,single factor experiment of oxidant peroxid e ratio,orthogonal experiment,hydrogen production mechanism study of sup ercritical water gasification,and related experiments of phosphorus recovery.(1)as the temperature increases,the effect of hydrogen production beco mes better and better,indicating that the process of hydrogen production is endothermic;With the extension of residence time,the hydrogen production first increases and then decreases,and the maximum amount of hydrogen ca n be reached at 6min.The effect of hydrogen peroxide in the oxidant is du e to potassium permanganate.The experimental results show that the hydrog en generated when the hydrogen peroxide ratio is 1/0.5 is the same as the hydrogen generated when the hydrogen peroxide ratio of potassium permanganate is 1/2.(2)the range analysis of the orthogonal experiment results shows that t he influencing factors are in the following order: for hydrogen production,t he order of influencing factors is in the following order: oxidant peroxide ra tio > temperature > residence time;The order of influencing factors of orga nic matter removal rate is: temperature > residence time > oxidant peroxide ratio.(3)based on the GC-MS analysis results,the reaction mechanism of thi s experiment was preliminarily discussed.Under the condition of supercritica l condition,the macromolecular organic matter in the sludge was cracked an d dehydrogenated,which may generate hydrogen or reintegrate with other un saturated substances to generate other organic matters.In addition,the proce ss of supercritical reaction includes not only the pyrolysis but also the refor ming process.The reformed macromolecular organics may be repyrolyzed int o small molecule organics with the extension of residence time or the additi on of oxidant.(4)the experiment of phosphorus recovery of SCWG solid product by adsorption and analytical attachment was carried out.It was found that the s trong acid solution could dissolve and release more than 90% of inorganic p hosphorus(IP)in the residue,which laid a foundation for subsequent adsorp tion experiments.Main factors affecting adsorption: initial concentration of s olution,adsorption time and adsorbent dosage.Lengthening the adsorption ti me can increase the adsorption capacity but reduce the adsorption efficiency,indicating that the adsorption capacity of the adsorbent is limited.In consid eration of economic benefits and resource conservation,the larger the adsorb ent dosage,the better.