Deep Denitrification Of Landfill Leachate By SBR And SBBR

With the continuous increase of urban population and the improvement of people's living standards,the output of urban garbage is increasing.Because of the complex composition of toxic substances,high ammonia nitrogen,high COD and large fluctuation of water quality,the landfill leachate has always been the difficulty in wastewater treatment in China.In this experiment,the landfill leachate with ammonia nitrogen of 1200 mg / L and CODcr of 6500 mg / l was used as the research object.SBR(sequencing batch activated sludge process)and SBBR(sequencing batch biofilm process)with two different fillers(sponge and fiber fillers)were used to study the deep denitrification of landfill leachate,and the start-up,domestication and stable operation of the three systems were carried out Record and experiment to study the effect of deep denitrification on landfill leachate.In this experiment,three systems record pH,DO and ORP in real time,and observe the two characteristics of nitrate knee and ammonia Valley to control the process of nitrification and denitrification.·The experiment is divided into three stages: acclimation stage,short nitrification stage and full load operation stage.The total experimental days are 119 days.The first 1-45 days are acclimation stage.The ratio of carbon to nitrogen in acclimation stage is 2:1.In acclimation stage,the total nitrogen removal rate of SBR is 20%-30%,COD removal rate is 70%-80%,nitrification time is about 4.8h,sludge concentration is 5250 mg / L,SVI is 99.In acclimation stage,the total nitrogen removal rate of SBBR is 20%-30% The removal rate of COD is between 20% and 30%,the removal rate of COD is between 75% and 85%,the nitrification time is about 6.6h,the sludge concentration is 5241 mg / L,and the SVI is 101;the removal rate of total nitrogen is between 20% and 30%,the removal rate of COD is between 75% and 85%,the nitrification time is about 6.3h,the sludge concentration is 5012 mg / L,and the SVI is 69.From the 46 th day to the 85 th day,there was a short nitrification period.During the short nitrification period,the ratio of carbon to nitrogen increased from 2:1 in the domestication period to 4.9:1,so the total nitrogen removal rate of SBR increased to 93%,the COD removal rate was85%-89%,the nitrification time was about 4.2h,the sludge concentration was 12411 mg / L,the SVI was 78;the total nitrogen removal rate of SBBR with sponge packing was 93%,the COD removal rate was 85%-89%,and the nitrification time was 4.8h Right,the sludge concentration is 11777 mg / L,SVI is 88;the total nitrogen removal rate of SBBR is about 99%,COD removal rate is about 92%,nitrification time is about 5.7h,sludge concentration is 10200 mg / L,SVI is62.From the 86 th day to the 119 th day,it is the full load operation period,in which the influent is the real landfill leachate with the carbon nitrogen ratio of 5:1,The total nitrogen removal rate of SBR is more than 94%,COD removal rate is between 90%,nitrification time is about 4h,sludge concentration is 14358 mg / L,SVI is 66;the total nitrogen removal rate of sponge packing SBBR is about 99%,COD removal rate is about 90%,nitrification time is about 4.4h,sludge concentration is 13971 mg / L,SVI is 71;the total nitrogen removal rate of fiber packing SBBR is about 99.9%,COD removal rate is about 92%,nitrification time is about 90% The sludge concentration was 12457 mg / L and SVI was 51.After stable operation,the three systems were compared with different parameters,including short cut nitrification rate,time of a typical cycle,aeration time and the amount of nitrogen treated by simultaneous nitrification and denitrification and internal denitrification.On the 51 st day,the short-range rate of SBBR was more than 50%,which was 14 days earlier and 19 days earlier than that of SBBR(66 days)and SBR(70 days).The nitrification time of the three systems was stable at about 5 hours.The total reaction period of SBBR with fiber filler is 14 h,that of SBBR with sponge filler is 19 h,and that of SBR is more than 24 h.The simultaneous nitrification and denitrification rate and internal denitrification rate of two SBBR were higher than those of SBR.The experiment compares the treatment effect of Landfill Leachate under different conditions,including the effect of temperature,dissolved oxygen and carbon nitrogen ratio on denitrification efficiency.In the aeration stage,the reaction period of dissolved oxygen controlledat 2mg / l-3mg / L is 14 h,that under low dissolved oxygen is 16 h,and that under over aeration is20h;lower temperature will affect the denitrification efficiency of the system,especially in the denitrification stage,the nitrification time under high temperature(30 ?)and normal temperature(25 ?)is about 5h,which is less than that under low temperature(20 ?)for 6h.The denitrification efficiency and nitrification time at high temperature and normal temperature are almost the same,so as long as the temperature is controlled above 25 ?,higher denitrification efficiency can be achieved.Considering economic considerations,there is no need to increase the operating temperature of the system;when the carbon nitrogen ratio is about 5.5:1,the total nitrogen removal rate is about 99%,which can achieve stable deep denitrification.When the carbon nitrogen ratio is 4:1,the total nitrogen removal rate is reduced As low as 92%,the denitrification efficiency of the system is seriously affected.The carbon nitrogen ratio is not as good as the more.Too much carbon source will increase the operating cost of the system and reduce the effluent quality of the system.