Study On The Denitrification And Dephosphorization In The Treatment Of Salinity Municipal Domestic Wastewater

The shortage of freshwater resource has been a worldwide problem. Seawater utilization such as seawater desalination, direct seawater utilization and so on, is one of the important routes to solve the shortage of freshwater resource of. coastal areas. Therefore, studying on the denitrification and dephosphorization for the salinity wastewater caused by direct seawater utilization is important.The SBR process is used to treat the salinity domestic wastewater, and its operating way is improved according to the operation conditions for denitrogenation and dephosphorization.According to the study on the test of the denitrification and dephosphorization for the salinity wastewater, the conclusions are summarized as follows:1. When the salinity is 3500mg/L, the effects of salinity on the nitrogen and phosphorus removal are neligile. The results of activated sludge acclimatization indicate: the microorganisms of the reactor observed by microscope are similar with which in the saltless environment, and just the zoogloea became to be closely; after acclimatization, the sedimentation of activated sludge is well, the activated sludge bulking is impossible; the removal rates of COD, NH₄⁺-N and PO₄^3- are over 90%, and the effluent quality has been up to the first class A criteria specified in GB 18918-2002.2. Under the stable operation, when the salinity is 3500mg/L, the sludge loading among 0.11-0.17kgCOD/(kgMLSS·d), the effect of SBR process is well. When the influent COD_cr content is among 300⁴00mg/L, the effluent COD content is less than 50mg/L, and the removal rate is more than 90%; when the influent NH₄⁺-N content is among 21-36mg/L, the effluent NH₄⁺-N content is less than 0.5mg/L, the effluent NO₃^--N content is among 2.5-8mg/L, the effluent NO₂^--N content is below 0.05mg/L, and the removal rate of NH₄⁺-N is over 98%; with the increasing of the phosphorus anaerobic release, the aerobic phosphorus uptake increases, therefore, when the influent PO₄^3- content is 5-11mg/L, the effluent PO₄^3- content is less than 0.1mg/L, and the removal rate of PO₄^3- is over 98%. The effluent COD,NH₄⁺-N,PO₄^3- have been up to the first class A criteria specified in GB 18918-2002.3. The dynamic model of the substrate degradation process is:...