Study On Enriching Nitrifying Bacteria In Advance To Strengthen Ultrafiltration To Meet The Emergency Of Seasonal Ammonia

In recent years, the frequency of source water contamination by the sudden increasing ammonia is higher and higher. The Pollution often happens in special season, which traditional chlorination and biological methods can not effectively deal with. Membrane technology is considered to be the21st century’s water treatment technology,which has been used to the water treatment plant more and more. Therefore, this paper present a new emergency process for UF,which is adding highly active nitrifying bacteria to reactor to deal with sudden ammonia contamination.This paper explores How to enrich nitrifying bacteria fast, compares the advantages and disadvantages of two methods to maintain the activity of nitrying bacteria,compares the effictiveness of different conditions of this emergency ProcessFirstly, the abilitys of UF and MBR to deal with sudden ammonia contamination were studed. Ultrafiltration process can not effectively deal with sudden ammonia pollution, even adding powdered activated carbon to membrane reactor,but adding powdered activated carbon can increase soluble organic matter’s removal; MBR has a good resistance to ammonia load shock. Ammonia of MBR decline to0.4mg/L in one hour after ammonia burst to8.5mg/L.Secondly, the effects of different conditions on enriching nitrifying bacteria rapidly are studyed. For the concentration of powdered activated carbon in membrane tank,20g/L and60g/L were compared.when When it is24±1℃the maturation time of nitrate bacteria and nitrite bacteria is17d and25d respectively. When the temperature drops to16±1℃, the concentration of effluent ammonia and nitrite change slightly when the concentraton of powdered activated carbon is60g/L. and AUR of nitrifying bacteria is higher, therefore, higher concentration of powdered activated carbon in MBR may be favorable to enrich nitrifying bacteria at lower temperature. Different source water is studied, the Songhua River water and laboratory water are compared.The results show that the maturation period of nitrite bacteria and nitrate bacteria is24d and34d respectively, Which is9d later and7d later than laboratory water.Intermittent enrichment of nitrifying bacteria was studyed, the results show that the maturation period of nitrite bacteria and nitrate bacteria is18d and22d, which is Id later and3d earlier than continuous enrichment.Again, how to maintain nitrifying bacteria’s activity was studied. When MBR runs normally and adds ammonia periodicly to maintain the activity of nitrifying bacteria, intermittent aeration is better than continuous aeration. When MBR runs normally and no aeration to maintain the activity of nitrifying bacteria, the nitrification activity retention rate was92%,69%and40%when it is at6d,12d and18d. The cycle of adding ammonia has an impact on the activity of nitrifying bacteria recovery, The results show that the activity can recovery in3hours when adding ammonia at the12th day. For preserving nitrifying bacteria staticlly, the nitrification activity retention rate drops to16%at the20th day when continuous aeration; The nitrification activity retention rate drops to45%at the26th day when no aeration. The nitrification activity retention rate drops to45%and53%respectively the tempetature is lab temperature and4℃. The nitrification activity retention rate was64%and45%at the26th day respectively when matrix includes ammonia and has no ammonia.Finally, the abilitys of different conditions on the new emergency process for UF are studyed. The results showed that the more dosage of nitrifying bacteria, the stronger buffer capacity this process has. The dosage can be calculated based on ammonia load. when the dosage is half the theoretical value, water quality can meet the standerd in2hours. It can not strengthen the ability of decling ammonia when adding powdered activated into membrane tank, but can improve the removal rate of dissolved organic matter. Aeration can affect the performance of the emergency treatment process, continuous aeration treatment works better than a longer interval aeration, considerating economic factor and treatment effect, aeration lmin/stop4min is more appropriate. In addition, the effects of different conditions on membrane fouling is studyed, adding powdered activated carbon into membrane tank can delay irreversible pollution; continuous aeration and aeration lmin/stop4min have no significant difference on membrane fouling; membrane flux has a significant impact on membrane fouling rate, TMP grow slowly when flux is10L/(m2·h).10L/(m2·h) may be the critical flux.