| Existing urban industrial areas have a large number of industrial buildings.The water quality of runoff from industrial buildings is closely related to production activities,surrounding environment and other factors.Industrial areas generally have the characteristics of large building area,and some factories have heavy metal or petroleum pollution.As a rainwater management measure,the rainwater garden can control rainwater runoff.In the case of insufficient space and industrial pollution,it needs to be improved to improve its function to cope with the actual situation of the industrial zone.By summarizing the design method of the rainwater garden and querying the relevant design manuals,taking the existing urban industrial zone D as an example,a front pond rainwater garden system is proposed to design and assemble the experimental device,aiming at the characteristics of the industrial zone.The runoff water volume control test was carried out under the conditions of rainfall recurrence period of 0.5a,1a,2a,and duration of 30 min,60min,120 min.And through the experiment of water distribution,the effect of the system on the reduction of COD,TN,TP,Pb,Zn,Cu,Cd,SS and petroleum was explored.Finally,through the establishment of the SWMM model,a runoff simulation study was carried out.The results show that under the experimental conditions,the total runoff reduction rate of the front pond rainwater garden system ranges from 51.71% to 100%,in the front pond rainwater garden system,the inflow time of the rainwater garden was delayed by 34 minutes compared to the rainwater garden system,the total runoff reduction rate was increased by 43.7%,and the overflow time was delayed by about 40 minutes,which greatly reduced the overflow flow.The reduction of COD,total nitrogen,and total phosphorus in the Front pond Rainwater Garden System is relatively stable,and the reduction rates range from 53.08% to 71.57%,35.24% to 75.85%,and 58.04% to 90.01%.The reduction effects of COD,total nitrogen,and total phosphorus indicators were increased by 4.17% to 27.24%,8.54% to 24.15%,and 12.24% to 28.32%,respectively.The removal rates of heavy metals Pb,Zn,Cu,and Cd in the whole system were 98.03%,92.83%,86.05%,and 82.50%,respectively.The removal rate of Pb and Zn in the whole system is high and stable.Compared with ordinary rainwater gardens,the removal rates of Pb,Zn,Cu,and Cd were increased by 15.34%,8.65%,22.45%,and 5.66%,respectively.The reduction range of SS reduction rate of the whole system is 87.8% ～ 96.34%.Compared with ordinary rainwater gardens,the reduction rate of SS indicators has increased by 40.24%-85.37%.The reduction rate of petroleum effluent of the entire system ranges from 77.73% to 89.33%.Front pond contributes a lot to the reduction of oil,with an average value of 50.39%.The SWMM simulation results show that under different rainfall conditions,the total outflow of the front pond rain garden system is less than that of the non-facility system,and it is also smaller than that of the conventional rain garden system.Compared with the conventional rain garden system,the Front pond rain garden system The reduction rate of the total outflow has been increased by 32.52% to 78.90%,and the reduction rate of flood peak flow can be increased by up to about 98.59%.In addition,the conventional rain garden system basically has no obvious delay to the peak present time,while the Front pond rain garden system delays the flood peak in the range of 0 ～ 29 min,which shows that the simulation and test results have similar conclusions.Whether it is from experimental data or SWMM simulation,compared with the conventional rainwater garden system,the Front pond rainwater garden system can improve the stagnant storage performance of roof rainwater and effectively improve low-impact development in large roof buildings,such as large industrial plants effect. |
PDF Full Text Request