Design And Operation Of Anaerobic Ammonium Oxidation Reactor And Electric Field Enhanced Treatment Of Low Ammonia Nitrogen Wastewater

Anaerobic ammonia oxidation as a new way of microbial transformation of nitrogen,has been highly recognized by many domestic and foreign experts as a new type of sustainable energy-saving,pollution-free biological treatment technology.At medium temperature,activated sludge was taken from a stable anaerobic ammonia oxidation reactor as inoculation sludge,and the anaerobic ammonia oxidation reaction was started in a conventional UASB reactor and operated stably for 46 days.In culture,the activity of anammox oxidizing bacteria was restored,and the reactor achieved a removal effect of more than 82%.The load was increased by 60 and 90 mg/L,and the total running time was 50 days,and the removal rate could reach 95% or more.When the load was increased to 120 mg/L,the effluent basically met the degradation of ammonia nitrogen: nitrite nitrogen: nitrate nitrogen = 1:1.32:0.26.Through the control of dissolved oxygen,the anaerobic ammonium oxidizing bacteria influent nitrogen purge time is reduced by half,the processing capacity is reduced by 13%,and still reaches over 80%.The sludge changed from light red floc to deep red granules.The anaerobic ammonia oxidation reaction produced a certain degree of alkalinity,and the pH of the effluent increased from 7.3 to 7.8,which is still a suitable pH condition for anammox bacteria.The sludge in reactor R1 was inoculated into an electric field enhanced anaerobic ammonia oxidation UASB reactor(reported as R2).The voltage was controlled from 0 to 2V to investigate the activity of anammox bacteria.When reactor R2 is at a voltage of 0.6~0.8V,the activity of anammox bacteria is the strongest,and the removal rate of total nitrogen reaches more than 95% at 0.6V.When the voltage is higher than 1.8V,the removal rate is less than 20%.Anammox bacteria basically lose their activity.Subsequently,the voltage was restored to 0.6 V,and the anammox bacteria recovered their activity,indicating that the suppression of anammox bacteria by high voltage is reversible.When no voltage is applied,the zero-valent iron in the UASB reactor with electric field enhancement releases some ferrous ions,the ferrous ion concentration is about 2.3 mg/L,and the concentration of ferrous ions increases to about 4.5 mg/L when 0.6 V is applied.The reactor's processing capacity increased by 22.3%.The study showed that the UASB reactor was successfully inoculated with anaerobic activated sludge 46 d activated by anammox.Through 122 d culture,the anaerobic ammonia oxidizing bacteria had strong denitrification ability and gradually granulation.The voltage and ferrous ions in the electric field promoted the proliferation of anammox by the electric field and the coupling effect of ferrous ions.It can promote the cultivation of anaerobic ammonia oxidizing bacteria.