Study On Treatment Of Municipal Wastewater By Strengthen Primary Treatment-Partial Nitrification/Anaerobic Ammonium Oxidation Process

At present,the domestic sewage treatment is still using the degradation of pollutants as the core,a large number of delayed aeration treatment method has been used,consuming a lot of energy,is not match with energy saving and emission reduction of international water treatment trend.This study selects enhanced primary treatment and PN/ANAMMOX process to realize the city sewage in carbon,nitrogen and phosphorus removal.The effects of different aeration methods and dissolved oxygen on the start-up of PN/ANAMMOX process and different forms of iron influence on ANAMMOX process are investigated by laboratory experiments.The technological parameters of rapid start-up of PN/ANAMMOX reactor are obtained.Subsequently,through a set of 20m3/d scale pilot plant,the effect of the process in the treatment of actual municipal wastewater is investigated,which is expected to provide a reference value for the new low consumption and high efficiency sewage treatment.The main conclusions obtained in this paper are as follows:?1?In the primary treatment of bioaugmentation,the removal rate of COD is between 40%⁶0%,the average removal rate is about 45%,the average removal rate of ammonia nitrogen is about 20%,and the average removal rate of total phosphorus is around 50%.?2?In the process of chemical biological strengthening primary treatment.In the domestication process,the removal rate of COD is between 40%⁶0%,and the removal rate of COD in the stable phase is between 50%⁷0%,the overall average removal rate is about 53%,which is about 10%higher than that of the biological enhanced primary treatment.After stabilization,the average removal rate of ammonia nitrogen is about 40%,which is about 20%higher than that of biological enhanced primary treatment.The removal efficiency of total phosphorus is divided into two sections,the commissioning stage is between 60%⁸0%,and the stability is about 85%,which is about 30%higher than that of biological enhanced primary treatment,and the effluent of TP met the level A standard basically.Therefore,adding chemical agents has the good effect on strengthening nitrogen and phosphorus removalling,and in the subsequent process,to increase the ability of the first part,it is necessary to increase the dosage of chemicals.Taking into account of the on-site pilot plant,influent water quality is complex and fluctuating,the process can still better remove COD and nitrogen and phosphorus removal effect,therefore,the chemical biological strengthening primary treatment is basically successful.?3?It is found that intermittent aeration is more favorable to start the reactor than continuous aeration and intermittent aeration when the start-up process of PN/ANAMMOX process is influenced by different dissolved oxygen and aeration operation mode.In the continuous aeration operation,when the dissolved oxygen is0.2mg/L and below,the operation state of the reactor is better.At this time,the removal rate of ammonia nitrogen is 30%,and the total nitrogen removal rate is about 20%.In intermittent aeration,the removal rate of ammonia nitrogen is 64%,the average removal rate of total nitrogen is about 54%,and the maximum removal rate of ammonia is 44%,and the reactor is basically started when the DO is controlled at 0.7mg/L,20/15min,and the hydraulic retention time is 12h.?4?The effect of different forms of iron on the ANAMMOX reactor is tested in a small test.It is find that FeSO₄ has the highest enhancement effect on ammonia nitrogen,nitrite nitrogen removalling and nitrogen generation rating,The effect of ferric oxide?HFO?on ammonia nitrogen and nitrite nitrogen removalling is basically the same as that of blank,so,there is no strengthen action,but it has a slight promoting effect on the formation rate of nitrogen,NZVI has a bad effect on ammonia nitrogen,nitrite nitrogen removaling and nitrogen production rating,but the final inhibition is not obvious.At the same time,compared to blank group,Fe²⁺of bacterial extracellular polymer?EPS?strengthening role is the strongest secretion and enzyme activity of ANAMMOX.The effect of HFO on bacterial extracellular polymeric substances?EPS?and ANAMMOX enzyme activities is basically the same as that of blanks.NZVI of bacterial extracellular polymers?EPS?and ANAMMOX activity in promoting effect is weaker than the blank.?5?During the operation of the PN/ANAMMOX pilot plant.The removal rate of COD in the early stage of the process is nearly 60%⁸0%and stable in80%.Because of the PN/ANAMMOX process,the removal rate of COD decreased in the late part of the process.The ammonia nitrogen removal process,in the stable stage,the ammonia nitrogen removal rate maintained at about 90%.Removaling rate of TP,maintained at about 70%when the first part of dosing phase,no drug is maintained at about 60%.The whole PN/ANAMMOX pilot plant,when the main parameter control in:Intermittent aeration,oxygen dissolved oxygen controlling does not exceed 0.8mg/L,aeration than in the operation mode of 7/4min.The basic process of partial nitrification has occurred,anaerobic ammonium oxidation showed relatively weak processes,considering that the start-up cycle of anammox process is long,the running time of the pilot plant is shorter,and the influent of the pilot plant is complex,big fluctuation,difficult to control and so on,and the PN/ANAMMOX pilot plant is in a good condition at present.The follow-up process needs to keep the normal operation of the pilot plant,adjust the optimized operation parameters,or change the operation mode,let anaerobic ammonia oxidation start...