Extraction And Advanced Oxidation Of Refractory Nitrogen-Containing Organics In Coal Gasification Wastewater

The coal gasification wastewater is the washing wastewater generated during the process of sewage and gas purification and washing after the crude gas condensate is recycled in the process of coal gasification.In addition to phenolic substances,wastewater contains a large number of nitrogen-containing organic compounds that are difficult to biodegrade.Nitrogen-containing organic compounds have high biotoxicity,difficult biochemical degradation,and many kinds of impurities.They have certain toxic effects on microorganisms in subsequent biochemical treatment,inhibit the growth of microorganisms,and are difficult to be digested and degraded by biochemical treatment.Return water quality.In the study of coal gasification wastewater,the existence of nitrogen-containing organic matter should not be ignored.Therefore,this thesis is aimed at the extraction and advanced oxidative degradation of refractory nitrogen-containing organic compounds.In this paper,a coal-based gas wastewater from Xinjiang and Datang Keqi coal gasification wastewater were used as samples to test and analyze nitrogen-containing organic matter,and combined with literatures,the types and contents of characteristic pollutants in coal gasification wastewater were analyzed to determine the nitrogen-containing organic matter in the gas.The content of the wastewater is 2000-3000 mg/L,and the influent in the phenol ammonia treatment section accounts for 15%-25%of the total organic matter concentration.This paper quantifies the B/C and LD₅₀ values of various nitrogen-containing organic compounds.By preparing nitrogen-containing organic compounds to simulate wastewater,MIBK was used as the extractant,and a three-stage extraction experiment was carried out compared with R=1:4.The content of organic matter in each stage of the aqueous phase was determined.The extraction results showed that the total concentration of simulated wastewater decreased from2190 mg/L to 363 mg/L after secondary extraction.In this paper,the liquid-liquid phase equilibrium experimental data were determined for quinoline and isoquinoline with higher concentration and easier extraction and removal.The NRTL and UNIQUAC models were used to regress the liquid-liquid equilibrium data,and the binary interaction parameters of the model were obtained,which provided basic data for the subsequent simulation and calculation of MIBK extraction of quinoline and isoquinoline.In this paper,Fenton oxidation,ozone oxidation and O₃/H₂O₂ oxidation were used to study the oxidation of model pollutants of nitrogen-containing organic compounds.The influencing factors of three oxidation techniques were analyzed,and the better experiments were selected.The conditions were tested on the model pollutants,and the oxidation removal rate of the model pollutants by three oxidation techniques was determined.For the O₃/H₂O₂oxidation technology,when the ozone concentration is 25 mg/L,the H₂O₂ dosage is 1500mg/L,the initial solution pH is 10,and the reaction time is 50 min,the COD_Cr removal rate of the model pollutants is 71.0%.For the research system of this paper,considering the removal of model pollutants by three oxidation techniques,this paper considers that the removal effect of model pollutants in wastewater by O₃/H₂O₂ method is better than the other two methods.