Removal Of Pollutants From Urban Rain Runoff Using Ecotype Water Purifying Box Revetment

.Considering the randomcity and uncertainty of rain runoff combined with the complexity of the surface, carrying out simulation test of ecotype water purifying box revetment dealing with urban rain runoff pollutants. Analyzing the removal effectiveness of COD,NH₃-N,NO₃^--N,P and typical heavy metal pollutions such as Cu and Zn, with the conditions of different influent concentrations,HRTs and hydrophytes growth periods. The results indicate that except the slightly bad removal effect of COD due to TOC release from the palm fiber layer, the other pollutions such as N,P,Cu and Zn all present quite good removal effect under the same performance condition. Meanwhile, contamination removal mechanism has been deeply analyzed.Combined with practical rainfall designed rain water runoff test whose results indicate four layers ecotype water purifying boxes can effectively clean initial stage rain water runoff. The removal ratio of COD,N,P,Cu,Zn,SS and total Escherichia coil are more than 40%. After retention period, the accumulative total removal ratio is over 75%. Ecotype water purifying box revetment system can effectively purify initial rain runoff.Result of absorption and desorption test with ceramsite in ecotype water purifying box show that the absorption capacity of NH₃-N, PO₄^3--P and Cu gradually grow with the increase of substrate liquid concentration, even presents linear correlation. In addition desorption capacity slowly increase with absorption quantity accumulation, it takes 24 hours to reach initial desorption balance condition which show that substrate ceramsite can effectively trap runoff pollutions in short time of water passing period. Substrate ceramsite absorption isotherm analysis result present absorption capacity G can greatly depend on balance concentration C and the plain sequence are Cu> PO₄^3--P >NH₃-N in the condition of 25℃. The most absorption capacity G0 of NH₃-N, PO₄^3--P and Cu are 0.256 mg/g, 0.809 mg and 0.076 mg/g by measurement with Langmuir absorption equation.