生态滤沟对城市路面径流的净化效果试验及模拟

Pilot scale experiments and simulation of the purification effects of bioswale on urban road runoff

通过试验和模拟,研究生态滤沟对城市路面径流的净化效果及适宜工况。设计了半渗透型和防渗型两套生态滤沟试验系统,每套系统由5种典型填料滤沟组成。不同影响因素的多水平正交试验和单因素试验结果表明:填料组合方式是对整体处理效果影响最重要的因素,且以粉煤灰+沙(FS)为人工填料层的生态滤沟净化效果最好,防渗与半渗透型沟槽综合去除率分别为83.12%和73.18%,最佳淹没区高度为150 mm。建立了污染物(TN、TP)去除率、出水率与各影响因素的多元回归模型,经Nash-Suttcliffe系数和决定系数检验,拟合效果良好。采用Hydrus-1D模型对3种入流浓度下TP在生态滤沟系统中的迁移进行了模拟,TP出水浓度模拟值与实测值平均相对误差分别为14.11%、17.33%和26.57%,模拟结果可靠。

The purification effects and suitable operation conditions of bio-swale on urban road runoff are investigated through experiment and simulation. Two types of bioswale system were designed： one with semi-permeable substrate, and another with impermeable substarte. Each type consists of 5 bioswales with different typical media. The experimen- tal conditions were selected through multi-level orthogonal test with different influence factors and single-factor analy- ses. The results show that media combination is the most important factor affecting the overall treatment effect. The bio- swales achieved the best purification effect with fly ash mixing sand as the media, and the overall removal rates were 83.12% and 73.18% for the impervious and semipermeable types. The optimal submerged zone height was 150 mm. Multiple regression models among the pollutant （TN, TP） removal rate, discharge rate and operation factors were de- rived with high determination coefficient （R2） and Nash-Suttcliffe coefficient. The Hydrus-lD model was then used to simulate the TP vertical migration in the bioswale under three influent concentrations. The mean relative errors of efflu- ent concentration between simulated values and measured data were 14. 11%, 17.33% and 26.57% respectively, in- dicating good modeling results.