雨水是城市水资源的重要组成之一，然而随着我国城镇化进程加快，区域不透水面增加、雨水下渗量减少，径流量增大，其所携带的大量污染物已经成为城市水环境污染的主因。研究城市降雨径流污染控制，对解决城市水环境问题意义重大。生态滤沟作为典型的低影响开发(LID)技术之一，可将径流调节与污染控制相结合，对缺水干旱地区雨水资源化利用具有重要的现实意义。 本文首先通过静态吸附试验及朗格缪尔式吸附等温线拟合研究了生态滤沟特殊填料的吸附性能，为生态滤沟模拟装置填料的选配提供了依据。随后设计了6组30支生态滤柱小试装置及6座生态滤沟中试试验装置，通过小试及中试试验、数理统计和数学模拟，全面研究了填料类型及组合方式、填料厚度、植被条件、淹没区的深度与碳源投加量等内部因素及模拟径流水力负荷、污染负荷、模拟降雨间隔时间等外部因素对生态滤沟径流综合调控效果的影响。最后，基于水量平衡法提出了一套生态滤沟设计方法，并按此方法设计建造了一座现场试验装置，并对其调控径流及其污染的效果做了研究。 通过以上研究所获得的主要结如下： (1)在特殊填料选择方面，沸石及活性炭对氨氮、总氮、总磷吸附容量较高，活性炭及粉煤灰对COD的吸附容量较好；粉煤灰在总磷吸附方面略优于活性炭，在COD吸附方面略优于沸石；炉渣在氨氮、总磷吸附方面与活性炭及粉煤灰相差不大；从经济及环保角度而言，粉煤灰及炉渣可选优先作为生态滤沟系统的特殊填料。 (2)在径流水量削减方面，种植土层因渗透系数小，土层厚度成为制约生态滤沟的水量削减的关键因素；沙子、炉渣等填料因空隙率大对水量调控效果明显；粉煤灰填料对水量调控效果较差；植被根系可使土层相对蓬松，对水量削减具有促进作用；设置内部淹没区对水量削减率有一定的抑制作用，需结合水质净化综合考虑。试验条件下生态滤沟对径流迟滞时间可达15-25mim对径流总量削减率最高可达约为84%-91%，对径流洪峰削减率最好可达85%-93%。 (3)在污染物净化效果方面，随径流污染负荷增加，生态滤沟净化效果逐渐降低；总体上，特殊填料的引入对污染物净化效果有明显的提升作用，填料厚度增加，水质净化效果有所提高，粉煤灰对COD、TP净化效果明显；在降雨时段所处的短时间内，植被的净化效果表现不明显；外加碳源及设置内部淹没区对径流废水TN的净化有较好提升作用，但外加碳源对COD净化有不利之处。生态滤沟装置对径流中TN净化率可达10%-40%，对TP净化率可达40%-80%，对氨氮净化率可达30%-90%。 (4)多元回归分析结果显示，填料种类、填料厚度与TN去除率呈线性正相关关系，、进水流量、进水污染程度与TN去除率呈线性负相关关系；填料种类、填料厚度与TP去除率呈线性正相关关系，进水流量、进水污染程度与TP去除率呈线性负相关关系；经过逐步回归模拟得到的TN、TP去除率与各影响因素之间的标准化回归方程模拟值与实测结果较为接近，残差均较小，说明模拟值具有较高的可信度，在进行试验设计时具有一定的指导意义。 (5)运用Hydrus-1D软件模拟径流污染净化效果时，生态滤沟出流污染物中TP浓度模拟值与实测值较为接近；中高负荷时TN出流浓度模拟值与实测值较为接近，在低负荷时，整体上模拟值略低于实测值。 (6)基于水量平衡原理，提出了生态滤沟汇流比速算法，该方法考虑因素较多，涵盖80种典型工况，方法简单，便于工程技术人员掌握运用；依据此方法设计的生态滤沟于2015.05-2016.06共有效监测降雨7场次，降雨量介于2.5㎜～30.4㎜之间，仅有3场次降雨有出流现象；对于接近3a重现期的短时较强降雨，降雨径流量削减率可达83%，主要污染物负荷削减率均达80%以上，该装置对降雨径流量削减及主要污染物负荷削减效果均较为显著，对中小降雨径流控制效果较好，充分体现出低影响技术对道路径流综合调控效果。此外，研究结果还表明以生物滞留(生态滤沟)为主的绿色雨水基础设施建设，对西咸新区海绵城市试点区域热岛效应缓解也起到了促进作用。 关键词：低影响开发；生态滤沟；道路径流；污染；调控 基金项目：国家自然科学基金-低影响开发(LID)生态滤沟技术对旱区城市路面径流净化机理研究(51279158)

 Rainwater is one of the important components of urban water resources. However, with the acceleration of China's urbanization process, the impervious surface increases, the rainfall infiltration decreases, and the runoff increases. A large number of pollutants carried by rainwater have become the main cause of urban water pollution. It has great significance to study the control of urban rainfall runoff pollution to solve the problem of urban water environment. As one of the typical low impact development (LID) technologies, bioswale can combine runoff regulation with pollution control, which has important practical significance for rainwater resource utilization in arid and water-deficient areas. Firstly, through static adsorption test and Langmuir adsorption isotherm curve fitting, the adsorption performance of special filler in bioswale was studied, which provided a basis for the selection of bioswale fillers. Subsequently, six types of 30 bench-scale columns and six pilot-scale grooves were designed. Through bench-scale and pilot-scale tests, and through mathematical statistics and mathematical simulation, the internal factors such as the type and combination of fillers, the thickness of fillers, vegetation conditions, the depth of submerged area and the amount of carbon source added, and the external factors such as hydraulic load, pollution load and simulated rainfall interval were comprehensively studied. Finally, a set of ecological filter ditch design method was proposed based on water balance, and a field test device was designed and constructed according to this method, and the effect of runoff regulation and pollution control was studied. The main research conclusions are obtained as follows: (1)The adsorption capacity of zeolite and activated carbon on ammonia nitrogen, total nitrogen and total phosphorus was higher, and the adsorption capacity of activated carbon and fly ash on COD was better. In terms of total phosphorus adsorption, fly ash is slightly better than activated carbon and COD is slightly better than zeolite. The adsorption of slag in ammonia nitrogen and total phosphorus is not different from activated carbon and fly ash. From the economic and environmental point of view, fly ash and slag can be selected as special filler of ecological groove system. (2)In the aspect of runoff water reduction, soil layer is the key factor that restricts the water reduction of bioswale due to its low permeability coefficient. Sand and slag have obvious effects on water control due to large void fraction. The effect of fly ash filler on water control is poor. The root system of vegetation can make the soil layer relatively fluffy and can promote water reduction. It is necessary to consider the water purification comprehensively to set the flood area to restrain the rate of water reduction. Under the experimental conditions, the delay time of bioswale to runoff could be up to 15-25min,the total reduction rate of runoff could be up to about 84-91%, and the flood peak reduction rate could be up to 85-93%. (3)In terms of the purification effect of pollutants, with the increase of runoff pollution load, the purification effect of ecological filter trench decreased gradually. Overall, the introduction of special fillers can significantly improve the purification effect of pollutants, the thickness of fillers increases, the water quality is improved, and the effect of fly ash on the purification of COD and TP is obvious. In the short time of rainfall, the effect of vegetation purification is not obvious. The addition of carbon source and the area with internal flood can improve the purification of TN in runoff wastewater, but the addition of carbon source has disadvantages for COD purification. The bioswale can achieve 10%-40% of TN, 40%-80% of TP and 30%-90% of ammonia nitrogen. (4)The results of multiple regression analysis showed that there is a linear positive correlation between filler type and filler thickness with TN removal rate, and a linear negative correlation between the water inflow quantity and the pollution degree of runoff with the removal rate of TN. It also showed that there is a linear positive correlation between filler type and filler thickness with TP removal rate, and a linear negative correlation between the water inflow quantity and the pollution degree of runoff with the removal rate of TP. The simulated values of the standardized regression equation between TN and TP removal rates with the influencing factors obtained by stepwise regression are close to the measured results, and the deviation is small, which indicates that the simulation value has high credibility and has guiding significance for the test design. (5)When using hydrus-1 d software to simulate the purification effect of runoff pollution, the simulation value of TP concentration of pollutants in the outflow from the ecological channel is close to the measured value. At medium and high load, the simulated value of TN outflow concentration is close to the measured value,while at low load, the simulated value is slightly lower than the measured value. (6)Based on the principle of water balance, a quick calculation method of the confluence ratio of the bioswale is proposed. This method takes many factors into account and covers 80 typical working conditions. A bioswale designed according to this method and effectively monitored 7 times rainfall from May, 2015 to June, 2016. The rainfall was between 2.5 mm and 30.4 mm. For a return period nearly three years and short-time strong rainfall, the runoff reduction rate can reach 83%, main pollutants load reduction rate is above 80%, and the device for rainfall runoff reduction and main pollutant load reduction effect is more significant, for small and medium-sized rainfall runoff control effect is better, which fully reflects the good effect of impact development technology on urban road runoff and pollution control. From the perspective of the mitigation of heat island effect in the sponge city pilot area of XiXian New Area, it can also prove that the green rainwater infrastructure which is mainly based on bioswale has ecological value. Keywords: Low impact development; Bioswale; Road runoff; Pollution; Control