Study On Ecological Management Of Urban River Eutrophication By Artificial Floating Bed Method

Eutrophication and black smelly water are prevalent problems faced by the urban water environment nowadays.Being an effective,economic and sustainable technology,the floating vegetation has become a focus of research and application in the comprehensive management of urban water environment.In this technology vegetation is the key to the purification of polluted water.The adaptation of the plant to grow in polluted water is a leading factor that influences the purifying effect of the floating vegetation.It is,therefore,very important to choose proper plant species and create suitable growth condition for them so as to improve the restoration of polluted water by means of floating vegetation.This paper takes plants applicable to the floating vegetation as the research object.The static experiment of pot culture was conducted to investigate economic plant appropriate to the floating vegetation in purification sewage.In field tests technical feasibility of the plant floating-bed and removal of pollutants was observed through the net increase accumulation of the plants and accumulation regularity of N and p in different organs.Romaine lettuce and cress was planted both in polluted water and soil,and a comparison was made concerning their yield and quality in the two different patterns of growing with a view of providing an effective guidance for the economic benefit analysis and food safety of the romaine lettuce and cress floating-bed technology.The annual water quality monitoring results indicated that 10 rivers were subjected to different degrees of pollution,the Baodai river and the Hongqi river comprehensive water pollution index was higher.The static pot culture experiment in the laboratory indicated that romaine lettuce and cress could be used for floating vegetation,for the grew well in eutrophic water and remove TN,TP,COD and NH4+-N from water significantly.Other plants grew well in eutrophic water and water purification effect is stable.The floating vegetation outdoor test indicated that romaine lettuce and cress adapted to grow in polluted water and grew well.After 49 days of growth,the dry matter net increase of romaine lettuce and cress were between 91.8-466.7%,and the total absorption of nitrogen and phosphorus accumulation were between 0.2-43.77mg/g.The amount of nitrogen and phosphorus in the ground was higher than that in the underground part,which is beneficial to remove the nitrogen and phosphorus from the plant.Compared with soil cultivation,the yield of romaine lettuce and cress were promoted,and the edible part was excellent in quality,which were coincident with the national sanitation standard.Meanwhile,mature romaine lettuce and cress had a certain effect on the purification of polluted water.