Study On The Resin Adsorption Process For The Treatment Of Hydrazine Hydrate Wastewater

The wastewater of hydrazine hydrate production with COD content of 1000-2500 mg/L,ammonia nitrogen content of 300-800 mg/L and sodium chloride content of 15-20%was treated by resin adsorption,membrane separation and oxidation.After treatment,the wastewater COD was less than 40 mg/L and ammonia nitrogen was less than 4 mg/L,which could supply high purity sodium chloride to saturation(360g/L)and supply ion-exchange membrane electrolysis to produce caustic soda,chlorine and hydrogen.Gas and wastewater are treated environmentally and sodium chloride is recovered,which reduces the cost of treatment and produces considerable economic benefits.Static adsorption experiments were conducted to determine the type and amount of resin used.The effects of wastewater pH and temperature on COD removal were investigated.The adsorption isotherm curve was drawn and the kinetic model was determined.The effects of influent velocity and resin column filling height on COD removal were investigated by dynamic adsorption.The effects of desorbent type,dosage,concentration and desorption flow rate on resin regeneration were investigated.The effect of operation time on the temperature of distillation column and the purity of methanol distillate was investigated.The effect of the number of cycles of distillation on methanol re-desorption was explored,and the regeneration ability of resin was evaluated.By means of thermal field scanning electron microscopy(SEM),energy dispersive X-ray spectrometer(EDX)and Fourier transform infrared spectroscopy(FTIR),the surface morphology and element distribution of resin before adsorption,after adsorption saturation and after regeneration were compared,and the rationality of resin regeneration process was determined,and the effect of substances in wastewater on resin structure was determined.The influence of operating pressure,pH value of wastewater,influent flow rate and operating time of nanofiltration membrane on the removal of pollutants was investigated,and the cleaning method of nanofiltration membrane was explored.The effect of hydrogen peroxide solution on COD and ammonia nitrogen removal from wastewater by further oxidation of nanofiltration membrane permeate was investigated.The effects of solution dosage,aeration rate and reaction time on COD and ammonia nitrogen removal rate were investigated.The experimental results show that the adsorption kinetics of COD satisfies the quasi-second-order kinetics(R2=0.99935)and the adsorption isotherm model satisfies the Langmuir model(R2=0.98721)when the dosage of XDA-200G is 50g/L and the temperature and pH of wastewater are not adjusted.The dynamic adsorption velocity of resin is 3 BV/h,the filling height of resin column is 80 cm,the resin penetration time is 6.2 h,and the penetration volume is 18.6 BV.The regeneration efficiency of adsorption saturated resin can reach 98.61%after immersion in methanol with 95%volume fraction of 1BV for 1.5 h and dynamic elution at flow rate of 1BV/h.The distillate was used for 2-11 h in distillation operation,and the methanol concentration was about 96%.DL1812C-34D nanofiltration membrane has the best interception effect with operating pressure of 2.4MPa,influent pH of 7,influent flow of 110L/h and operation cycle of 120 minutes.The nanofiltration membrane was cleaned with NaOH and HCl of 1 mol/L for 30 minutes respectively.The optimum technological conditions are 35 mL/L of hydrogen peroxide solution,0.1 L/min of aeration and 15 min of reaction time.After resin adsorption,nanofiltration membrane separation and hydrogen peroxide oxidation,COD was reduced to 38 mg/L,ammonia nitrogen was 2 mg/L and TOC was 18 mg/L,which met the water quality requirements of ion-exchange membrane electrolysis.Therefore,this process is a new zero-discharge process for hydrazine hydrate wastewater,which takes full account of the recovery of sodium chloride while effectively treating wastewater.It has broad application prospects.