| The Integrated Vertical Infiltration Treatment System adopted is a new integrated ecological technology.Supported by National Science and Technology Key Program (No.2003BA808A17),it was developed.The experiment within about one year shows that there are some problems on low hydraulic load and not ideal removal effect of nitrogen and phosphorus.Aiming at the problems above,the optimization of Integrated Vertical Treatment System is studied.The optimization is studied from the following aspects,such as substrate gradation, bio-augmentation,Zeolite and Vermiculite-enhancement and so on.Results are as follows:1.The removal rate of CODCrwas increased after increasing the hydraulic load to 0.835m3/m2.d.And there was little change on the removal of NH4+-N,TN and TP,and the system ran well.2.Plants-augmentation by Acrous calamus could increase the removal effect of TP. The average removal rate of TP was 76.98%.The calamus system had higher removal effect for CODCrand TP than the without calamus,however,the removal effect of NH4+-N and TN in the without calamus system was higher than the calamus system.3.Zeolite and Vermiculite could enhance the removal effect of phosphorus and Zeolite can increase removal effect of nitrogen while the nitrogen removal capacity of Vermiculite should be further studied by comparing with the system without Zeolite and Vermiculite.Zeolite system had better removal effect of CODCr,TN,NH4+-N,TP than Vermiculite system under the same condition.And the two systems basically had the same removal rules.4.Adding aeration in effluent flume of Zeolite system and Vermiculite system,the removal rate of CODCr,NH4+-N,TN and TP was improved with different degree,and TP removal rate was improved significantly.The removal effect of Vermiculite system at two DO levels(3.5～4.5mg/L,5.5～6.5mg/L)of aeration indicated that the removal effect of nitrogen and phosphorus was more stable at the high DO aeration. The results of Zeolite system showed that aeration can relieve clogging phenomena. 5.In Zeolite system and Vermiculite system,the relative removal rate of CODCrat the first 20cm was the highest and it accounted for over 30%of the total removal rate. The removal rate of CODCrin the upstream was about 80%of the total removal rate. There was an evident promotion turning point at the 40cm of the removal rate curve Zeolite system and it maybe due to the Zeolite filled in the 20～40cm.The removal rate of TN in the upstream of Zeolite system was over 80%of the total removal rate. The concentration of TN at 40cm of Vermiculite system was accumulated,and there was evident promotion of removal rate at the surface of downstrearn.NH4+-N was accumulated in the first 20cm related with the flow pattern and after that the concentration was gradually reducing along the depth;The change of TP was not evident and the concentration was increasing in whole.6.The urease activities of Zeolite system were bigger than Vermiculite system.In the two systems,urease activities were different at different depth.In the two systems, there was no evident correlation between urease activities and CODCr,NH4+-N removal rate and significant correlation between urease activities and the removal rate of TN.The activities in upstream pool were bigger than in the downstream and it proved that the upstream contributes to TN removal more than the downstream and it was the same with the conclusion of the change along depth.Not ideal removal effect of TN showed that the urease activities were lower and that was weak microbial effect.. |
