Study On The Hydroponic Plant Purification Bed To Remove Nitrogen And Phosphorus Of Secondary Biochemical Effluent

With the country or area of the sewage treatment effluent water quality requirements enhancing.Beacuse it is difficult to achieve the effluent requirements for nitrogen and phosphorus in many sewage treatment facility,so it is necessary to deeply treat wastewater.This study adopt horizontal hydroponic plant system to treat the secondary biochemical effluent of domestic sewage and to investigate the removal efficiency of TN and TP in wastewater of different seasons.The main results are as follows:In summer and autumn,the hydroponic rice system was suitable for treatment with influent TN concentration between 5mg/L²0mg/L and influent TP concentration between 1.5mg/L²mg/L;the hydroponic mater convolvulus system was suitable for treatment with influent TN concentration between20mg/L²5mg/L and influent TP concentration between 0.4mg/L¹.5mg/L.In autumn and winter,the comparison effects of the hydroponic mater convolvulus system,the hydroponic asparagus lettuce system and the hydroponic celery system,the hydroponic celery system had the best effect on the removal of TN in the inflow,the hydroponic asparagus lettuce system had the best effect on the removal when the influent TP concentration was 0.3mg/L¹mg/L,the hydroponic celery system had the best effect on the removal when the influent TP concentration was 1mg/L¹.9mg/L.In winter,both the hydroponic chlorophytum system and the hydroponic reineckea carnea system of TN and TP have been removed,but the effect is poor in sewage,the daily net removal of TN and TP was lower than the three vegetable systems in autumn and winter.The hydroponic chlorophytum system and the hydroponic reineckea carnea system are not suitable to use hydroponic plants for deep nitrogen and phosphorus removal.In winter,the removal of TN,TP and COD_Crr in wastewater in the four-stage hydroponic celery system was shown:all stages of the system have the effect of removing TN,TP and COD_Cr,adding the stages of hydroponic system can increase the removal efficiency of TN and TP in sewage,the removal rate of the first stage is the same as COD_Crr of the system effluent basically,and it is difficult to increase the removal amount of COD_Crr by increasing the stages.The comparison removal effect of TN and TP in the sewage of three kinds of HRT and two kinds of planting densities were found:the condition of the best removal effect on HRT is 8h and the planting density is all planted on influent TN,TP and COD_Cr.With the increasing of HRT and planting density in three kinds of HRT and two kinds of planting densities,the removal efficiency could improve obviously.The main contribution to the removal of TN and TP in sewage is microorganism and other functions,the absorption of celery itself is the secondary contribution,and the precipitation contribution is the least.Mater convolvulus and rice in summer and autumn,mater convolvulus,asparagus lettuce and celery in autumn and winter all have the ability to remove TN and TP.The effect of hydroponic celery system on TN and TP in sewage is the best in all winter plants.It is suitable to use hydroponic plants for deep nitrogen and phosphorus removal.In winter,Both the chlorophytum and the reineckea carnea can grow normally in the hydroponic environment,although the hydroponic chlorophytum system and hydroponic reineckea carnea system have poor removal ability on TN and TP in sewage,it is suitable to improve landscape of the sewage plant.