Experimental Study On Pollutants Removal Law Of Media In Constructed Wetlands

Constructed wetland is a low investment, low energy cost and valid wastewater treatment and reuse system that has a obvious removal effect of nitrogen and phosphorus. Media is the medium and carrier of the constructed wetlands. The successful removal of pollutant by media creats a good term for follow-up adsorption by plant and guarantees the quality of effluent.In order to study the media's function of removal pollutant, many tests of pollutant removal are hold including a static test of single media, a dynamic test of single media, a dynamic test of manifold media and a dynamic test of different reaction conditions. A tracer test is carried in the process of the two dynamic tests to study the hydraulic influence.The tests show that:(1) It is found that Freundich adsorption isotherm of every kind of media and the movement law of adsorption capacity influenced by influent concentration and absorbent dosage.(2) Fly ash is valid to removal COD and NH3-N. Hollow brick made of fly ash is also valid to removal P. The COD and NH3-N removal is effective when fly ash and coal cinder are used together. It is also effective when fly ash and hollow brick made of fly ash are used together to removal NH3-N and P. Active carbon is not the kind of media with best removal ability.(3) The longer hydraulic retention time and the less Peclet, the better effect of COD removal. There is no obvious relation between hydraulic retention time and Peclet and the effect of NH3-N.Also is between hydraulic retention time and Peclet and the effect of TP.(4) In the process of COD removal, the influence of hydraulic loading rate is not obvious, the influence of influent concentration is rather obvious, the influence of media is very obvious. In the process of NH3-N removal, the influence of hydraulic loading rate is rather obvious, the influence of influent concentration is not obvious, the influence of media is very obvious. In the process of TP removal, the influence of hydraulic loading rate and influent concentration is very obvious, the influence of media is not obvious.(5) The hydraulic loading rate must be less than 3m3/m2·d.