| In this thesis, the removal of pollutants in rainwater runoff by land treatment system and wetland ecological system was compared. On basis of the experiment, a design concept of an ecological system which can be applied for collection, treatment and utilization of rainwater runoff was presented.Sampling and measurement of rainwater runoff in Xili, Shenzhen leads to a conclusion that pollutants mainly come from first flush of road runoff. Pollutants such as COD and SS may reach 1g/L and 0.8g/L respectively in the period of first flush and they account for 80% of the total contamination quantity. Analysis and calculation of one rain case show the area of Xili Bei Road can wash 160.9kg SS and 182.1kg COD to natural watershed.Road solid particles were collected at the sampling spot. Experiment of solid-particle solution shows after adding road particles into water, the quantity of pollutants released by particles has a good positive relationship with the quantity of solid particles, which means the accumulation of road solid particles can degrade water quality of runoff and is one source of pollutants in rainwater runoff. The degradation of aesthetic parameters of natural watershed is the main negative effect of road solid particles.The runoff treatment experimental instrument is comprised by two parallel systems: one is land treatment system whose pollutant removal function is realized by substrates; another is wetland ecological system, which has substrates, plants and non-woven as functional factors. The instrument was fed by simulated rainwater runoff. The results demonstrate that land system can perform good treatment effects in the first 2~3d, To turbidity and SS the removal ratios are between 70% and 80%, and to COD, TN, TP the removal ratios are 92.1%, 3.2%, 46.0% respectively; while the combined functions of plant roots oxygen transportation, adsorption of substrates and water transportation of non-woven in wetland system maintain good treatment quality in a longer period (4~6d). It can reach removal ratios of more than 80% for turbidity and SS, and 89.8% for COD. Besides, wetland system has better removal ratios for N and P than land system. The results of TN and TP show wetland system's removal ratios are 3 and 1.3 times of land system respectively. Latter experiment shows land treatment has a bigger porosity which is 1.75 times of wetland system for better adjustment of water quantity.Flowerpot experiment illustrates: calamus shows 4~8 times of better performance than reed; limestone has better removal ratios when used separately from anthracite, and it is the main factor for TP removal. Compared with anthracite's inefficiency of TP treatment, limestone can remove 36.5% of TP; non-woven gets optimized treatment effect when it is set vertically to the flow, which has 2~12 times of better removal ratios than parallel-to-the-flow setting. Moreover, the combination of vertical and parallel setting has better pollutant removal effects.The results of comprehensive research can reach a conclusion that land system is suitable for retaining and pre-treating runoff; wetland system should be constructed after land system to perform its removal effect under longer HRT. The engineering design set land system and wetland system in series to reach optimized treatment effects.
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