Study On The Migration Of NH₃-N During The Industrial Carbocysteine Efluent Treatment By BMED

During the industrial production process of carbocysteine,a large amount of waste mother liquor and washing water is generated.The ammonia nitrogen content in the effluent is as high as ten thousand milligrams per liter,which can lead to the eutrophication.Therefore,it is apparently not allowed to be discharged into the natural water,even not into the municipal drainage system.If the evaporation crystallization adopted,the energy consumption would cost too high,if biochemical process adopted,the high ammonia content would inhibit bacterial growth and propagation.In this paper,the removal of ammonia nitrogen in the industrial carbocysteine effluent was studied by BMED.In the BMED process,the migration of ammonia nitrogen is more complicated,including the counter ions migration,the co-ions leakage,the ammonia diffusion and volatilization,etc.,which effect the removal rate in liquid compartment,the recovery concentration in alkali compartment and the leak concentration in acid compartment.In order to strengthen the understanding of the denitrification process by BMED,the influencing factors,the optimization of operating conditions and the recovery model were studied.It showed that:(1)It is technically feasible to removal the ammonia nitrogen for the industrial carbocysteine effluent by BMED.Four groups of BP-A-C-BP membrane units were used,at the constant current density of 30mA/cm2,the flow rate of 5cm/s,the volume ratio of 1:1,the removal rate of ammonia nitrogen reached 91.48%,the current efficiency 33.36%and the energy consumption 5.25kWh/kg,the recovery rate of ammonia nitrogen reached 66.51%,the current efficiency 33,36%and the energy consumption 5.25kWh/kg.(2)In the initial liquid component,the NH4'concentration,pH and carbocysteine concentration had different effects on the migration of ammonia nitrogen.When NH4+concentration increased,the ammonia recovery and the leakage both increased,when pH reduced,the recovery of ammonia reduced and the leakage increased,when carbocysteine concentration increased,the recovery of ammonia reduced and the leakage increased.(3)The different operating conditions of current density,flow rate and volume ratio have different effects on the migration of ammonia nitrogen.In a certain range,with the increase of current density,the recovery of ammonia increased and the leakage reduced,with the flow rate and volume ratio increased,the recovery and leakage of ammonia nitrogen increased first and then decreased.(4)By designing the current density,flow rate and volume ratio as the variate,the ammonia nitrogen recovery and leakage concentration as the response values in the response surface methodology,the operating conditions of BMED were optimized.The regression equation model showed that the order of the influencing factors is:current density>flow rate>volume ratio,the comprehensive optimal condition with the best effect of ammonia nitrogen recovery and leakage was at the current density 25mA/cm2,flow rate 4cm/s and volume ratio 0.84.(5)In the BMED process,the model of ammonia nitrogen recovery at different current densities was:ct =(m + nj)?t + co or ct=0.06jNSt[(a1+b1j)-(a2+b2j+c2j2)(m+nj)t]+coVoF/FVt...