| Coal chemical wastewater contains high concentrations of oil,phenol,ammonia nitrogen,etc.,the composition is complex and changeable,the toxicity is large,is a typical refractory industrial wastewater,effective pretreatment technology has a vital impact on the stable operation of subsequent biochemical treatment processes.For the separation of oil and phenols in the wastewater,most of the current processes used are "air flotation skimming oil + solvent extraction",the process separation efficiency is low and the energy consumption is high,the added demulsifier not only increases the cost of treatment,and the addition of the agent will produce secondary pollution,which seriously affects the resource and harmless treatment of coal chemical wastewater.Based on this,this study uses macroporous resin to adsorb and separate the oil and phenolic substances in the coal chemical wastewater,constructs the "adsorptionregeneration-recovery" process method of the oil and phenol substances in the coal chemical wastewater,and conducts field tests,hoping to find an efficient,stable,simple operation,low investment and operation cost of the pretreatment process of coal chemical wastewater oil and phenol substances,which provides a reference for the recovery and harmless treatment of resource substances in coal chemical water.The main findings are as follows:(1)The characteristics of raw water quality are analyzed,and the oil content in raw water is 1600～2000 mg/L,of which emulsified oil accounts for more than 85%,which is the key to the removal of oil substances.Other types of pollutants are also in a high concentration state,including phenol content of 5000～7500 mg/L,ammonia nitrogen content of 5000～6000 mg/L,COD content of 30000～45000 mg/L.(2)The high concentration of oil and phenol in coal chemical wastewater was adsorbed with macroporous resin,and it was found that under the operating conditions of room temperature,p H value of raw water(p H =9),volume ratio of resin and sewage,and stirring and adsorption time of 0.5 h,the concentrations of oil,phenol and COD could be reduced from 1600.0 mg/L,6560.3 mg/L,40230.7 mg/L to 792.3 mg/L,4581.1 mg/L,24420.0 mg/L,respectively.The removal rates were 50.44%,30.17%,and 39.30%,respectively.Under the investigation of orthogonal experiments,it was found that the influence of various factors on the adsorption performance of the resin was as follows: resin dosage> resin adsorption time> initial concentration > raw water p H value,and the adjustment of the system p H value did not have a significant impact on the removal rate of wastewater oil,phenol and COD.The results show that the resin has good adsorption performance on oils and phenols,and has a good adsorption and separation effect on polycyclic aromatic hydrocarbons,benzene and heterocyclic compounds.Adsorption kinetics and adsorption thermodynamic studies have shown that the adsorption of resins is more in line with Lagergren’s quasi-first-order kinetic equation,which is an exothermic process based on physical adsorption,and the rate control step is the diffusion process.Analysis of the Langmuir and Freundlich isothermal equations shows that the adsorption of the resin is more in line with the Freundlich isothermal adsorption model,which is a singlemolecular layer adsorption.The combination of resin and adsorbent molecules is the result of a combination of van der Waals force,hydrogen bonding,and π-π.(3)The regeneration study of the macroporous resin after adsorption saturation was carried out,and it was found that the amount of methanol at room temperature,speed 150 r/min,regeneration time of 30 min,and 2.5 times the resin volume was added,combined with the clean water cleaning scheme of 3 times the resin volume,the resin regeneration performance was guaranteed to be good,and the influence order of each factor on the resin regeneration performance was found under orthogonal experiments:regeneration time> temperature> the amount of regeneration liquid > The volume of clean water flushing,the adjustment of the water flushing scheme has no significant effect on the desorption efficiency,and can be used as an additional scheme for deep regeneration.The resin maintains a stable adsorption efficiency of 90.00% after 10 cycles of "adsorption-regeneration".SEM was used to analyze the microstructure of the resin before and after the regeneration,and it was found that the resin surface would accumulate a small amount of amorphous sediment with the adsorption,and after 10 cycles of resin adsorption-regeneration,the resin was deeply regenerated in combination with the Na OH solution,and the adsorption performance of the resin was restored to nearly 100.00% after the comprehensive cleaning device.The saturated resin desorption solution is distilled and regenerated,and the reuse rate of methanol is about94.40%.(4)The large pore resin adsorption method was used to conduct field tests on the removal effect of oil and phenol in coal chemical wastewater.The concentrations of oil and phenol in the raw wastewater after being filtered by grease trap were 1850.0 mg/L and 7400.0 mg/L,respectively.After the resin adsorption treatment,its content was reduced by 48.53% and 25%,respectively,and the regeneration performance was relatively stable,which can be applied to the production of emulsified oil and phenol adsorption and separation in coal chemical wastewater.However,due to the high temperature of raw water at the site,the fluctuation of water quality is large,and the overall adsorption efficiency is low,there is still room for further improvement. |
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