Experimental study on sewage treatment with ecological pond for northern railway stations and depots in winter

Ecological pond test system composed of the soil layer, insulation layer, influent layer, water distribution layer, multivariate catalytic filler layer, water catchment layer, grille well, submersible sewage pump, sewage pretreatment devices, etc. was developed to remove the sewage of northern railway stations and depots with low temperature in winter. In November to next April of each year, the sewage treatment mechanism and pollutant removal effect about the ecological pond in winter was studied by the sewage into the ecological pond from water distribution pipes under soil layer, covering about 300 mm thick withered reeds on the surface of the ecological pond etc., creating the intermittent aeration in the middle sampling mouth of the multivariate catalytic filler layer, and the optimal hydraulic loading of 0.2, 0.4 and 0.5 m³·(m²·d)^-1. The results showed that the sewage was effectively removed by the coupling between the microbial metabolism, and absorption, chemical reactions and primary cell reactions of the multivariate catalytic filler in the ecological pond. The removal rates of organics, ammonia, total nitrogen and total phosphorus by the ecological pond test system were respectively 80%, 85%, 80% and 98% under the best hydraulic loading of 0.4 m³·(m²·d)^-1 in winter. The ecological pond test system in winter had the same treatment effect as that in spring and summer, and has stronger adaptability to seasonal changes comparing with the common used ecological pond.