Research On Pretreatment Process And Storage Safety Of Liquid Hazardous Waste Based On SCWO System

Liquid hazardous waste poses a great threat to the ecological environment and human survival and health due to its flammable,explosive,corrosive,poisonous and susceptible infections.With the rapid development of China’s industry,the problem of excessive production of liquid hazardous waste and low disposal capacity of hazardous wastes has gradually emerged.Traditional landfill and incineration technologies have poor applicability to liquid hazardous waste and have certain defects.Supercritical water oxidation(SCWO)technology has become a hot spot for liquid hazardous waste disposal at home and abroad due to its high efficiency and applicability.However,the SCWO system has strict limits on the salinity,calorific value,chlorine,phosphorus and nitrogen of liquid materials due to its equipment.Therefore,in this paper,the feedstock index proposed by the SCWO system introduced in a hazardous waste disposal demonstration plant in Tianjin is studied with the hazardous waste liquid of the cooperative enterprise.The liquid waste pretreatment feeding process based on SCWO system is designed.And conduct basic research on the safety of liquid hazardous waste storage to ensure the stable operation of the disposal process.This paper first proposes a general procedure for the detection and analysis of physical and chemical properties of liquid hazardous waste(including nitrogen,phosphorus,chlorine,sulfur,organic components,salinity,calorific value,particle size,etc.)and a series of optimized reference methods.Through the analysis of the physical and chemical properties of 15 different types of liquid hazardous wastes in 11 companies received in this study.Then,according to the hazardous waste classification principle proposed in this paper,the classification of the primary storage tank is determined by the compatibility experiment.Then based on the material in the first-class storage tank,according to the material compatibility principle and the mixed experimental phenomenon,the matching feeding route between the first-class storage tanks is finally determined,and the material compatibility optimization calculation model is established based on the linear programming algorithm using Matlab software,to maximize the benefits of disposal.Finally,the parameters such as flash point,freezing point,ignition point,corrosiveness and toxic gas composition of the material are determined by simulation experiments to provide guidance parameters for the safe design of the actual liquid hazardous waste storage.Studies have shown that the physical and chemical properties of different types of liquid hazardous waste vary widely.Statistical and experimental analysis The liquid hazardous waste in Tianjin is still dominated by waste acid and alkali with low calorific value and high salinity,followed by high calorific value and low salinity organic liquid,with a ratio of about 6:1.In some materials,the content of phosphorus and chlorinehave exceeded the standard seriously.After the experimental determination,it is proposed that the benzene residue in the food factory is difficult to be used as the material of the SCWO system,and other materials can be adjusted through the subsequent process;According to the theoretical basis and experimental verification,five types of primary storage tanks,acid,alkali,amphiphilic reaction,organic and organic perchloride,are determined.The classification of storage tanks is also of great generality to the material liquids not included in the experiment.According to the compatibility principle and mixing experiment,three compatible feeding routes were determined: acid,organic and organic high chlorine were the first route,alkali,organic and organic high chlorine were the second route,and the double reaction classes and organic classes are the third route.Based on the current received materials,the simulation calculation shows that when the first route compatibility ratio is 13.13:1.87:1,the second route compatibility ratio is 17.6:1.5:1,and the third route compatibility ratio is 73.07:1,the maximum consumption can be achieved.At the same time,hazardous waste does not need to rely on exogenous combustion improver to maximize benefits.The storage safety research shows that the organic storage tank area is a Class A fire hazard,the alkali and the amphoteric reaction type storage tank area are Class B fire hazard,the acid storage tank area is a Class E fire hazard,and the organic high chlorine storage tank area is a Class C fire hazard;For storage tanks and pipeline corrosion,if for economic reasons,bisphenol A materials may be considered for acid materials,carbon steel materials for alkali materials,stainless steel materials for organic materials and amphoteric reaction materials,while high quality phenolic epoxy ethyl dilute ester material is the only choice for organic perchloride material.There are about 15 kinds of volatile organic gases in the material,including isopropanol,tetrahydrofuran,methyl isobutyl ketone,toluene and 2-chlorotoluene.