MBR Process For Treatment Of Rare Earth High-salt And Am Monia-nitrogen Wastewater

Ganzhou is the main producing area of rare earth production in China.During the extraction and separation process of rare earth,a large amount of rare earth high salt containing ammonia nitrogen wastewater has been produced.In order to provide a good and stable biological treatment scheme for this kind of wastewater,this paper taking the treatment of wastewater from the total polluted water discharging port of a rare earth mine industrial park in Ganzhou as the processing object that A-O-MBR technology was applied to gradient salt-tolerant acclimation culture of activated sludge and examine the performance of activated sludge and its effect on the removal of pollutants with salinity.Then the optimal value of DO,HRT,MLSS and mixture reflux ratio are Determined through the single factor experiment.Finally,the wastewater treatment effect of the system was studied under the optimal conditions and the dynamic model of COD and NH₄⁺-N removal was discussed.The study obtained the following conclusions:?1?During the 66 days of salt tolerance acclimation,keep the influent NH4⁺-N concentration at 50-55 mg/L,COD concentration at 160-200 mg/L,and then increased the system salinity to 0.5 g/L NaCl to 16.5 g/L,the results of sludge flocculation particle tended to be tiny and compact,SV%of sludge and SVI from the initial fluctuations of 45%and108.1mL/g dropped to 27.7%and 64.9m L/g;COD removal by the system was above 85.6%,the average removal efficiencies of COD comed up to 91.0%.However,the effect of NH₄⁺-N removal by the system has experienced a fluctuation process that decreased firstly and then increased.Finally,the average removal rate of NH₄⁺-N reached 84.2%,and the average effluent's concentration was 8.4 mg/L.?2?Study the removal rule of COD and NH₄⁺-N under the operating conditions of different DO,HRT,MLSS and R.The results show that appropriately extended the HRT and increased DO and MLSS,the removal of COD and NH₄⁺-N by the system could be improved.When HRT=24h,R=300%,DO and MLSS was 3.0⁴.0 mg/L and 3000³500 mg/L respectively,the system achieved the best treatment effect,the average removal rate of COD and NH₄⁺-N was 95.49%and 88.31%,the average effluent's concentration dropped to 8.64mg/L and 6.21 mg/L,respectively.?3?Under the optimal conditions,the removal efficiency of COD and NH₄⁺-N in the actual wastewater was investigated.Experiments show that both the removal efficiency of COD and NH₄⁺-N were good after 3 to 5 days of adaptation of the system.The average removal rate reached 91.80%and 81.35%,and the average effluent's concentration was 15.1mg/L and 9.83 mg/L.?4?Through reasonable assumptions and analysis of operational data,the dynamic model of COD removal was obtained as ???,the dynamic model of NH4⁺-N removal was obtained as ???.