Study On Water Purifying Technology Combined With Plants And Porous Medium In Liaohe Estuary Reed Field

There are plentiful wetland resources in Liaohe estuary area which is one of important wetland in china. For achieving the multilevel use of reed filed wetland, aquaculture industry has developed rapidly. Some field engineering constructions were built, which provided favorable conditions to develop ecological aquaculture economy in the reed filed wetland However, the content of ammonia nitrogen and CODCr in the water have arrived to high levels because of perennial overstocking. The contaminant accumulating in the reed filed wetland brings certain influence to the ecological system of wetland and coastal environment. There are some individual characters with the aquaculture in the reed filed wetland, which is different from the traditional breeding method. The aquaculture developed according to the mode of high yields of reed, and water requirement is large. But the demand for water varies with the seasons, and drain off water with a long interval. In addition, there is no water in the reed filed wetland after fishing and reed harvest So the traditional water treatment technology is not applicable to the aquaculture water in estuary reed field wetland.According to the pollution characteristics of reed field wetland aquaculture, a coal cinder-zeolite honeycombed sorbent was developed. And the adsorption performance of the new sorbent, its thermal regeneration and the biological attachment condition were carried in the laboratory. Then, constructed purification system combined with simulate reed wetland. The purification effect of slightly polluted water was researched using ammonia nitrogen, CODCr and TP as evaluation index, which provide some technical parameters for the application The results showed that:(1)Synthesis method of the coal cinder-zeolite honeycombed sorbent was determined. The better ratio of cinder and zeolite in the honeycombed sorbent was 2:1,which combined effectively the advantages of cinder and zeolite. The maximum removal percentages were 57.2% and 512% for ammonia nitrogen and CODCr, respectively. Scanning electron micrographs clearly showed a large number of pore structure in the material surface, which provide more active sites.(2) Fitting with experimental data using kinetic model and intral-particle diffusion equation, the results showed that the adsorption process of the sorbent could be expressed with pseudo-second-order kinetic model. This adsorption process was chemical adsorption, which was relatively complex and influenced by the intral-particle diffusion and boundary diffusion Studies on isothermal adsorption process by using Freundlich equation and Langmuir equation showed that this process obeyed Langmuir equation, and the adsorption of ammonia nitrogen and CODCr on the surface of the material was mainly monolayer adsorption The adsorption capacities of ammonia nitrogen and CODCr calculated from Langmuir equation were 0.1798mg/g。 0.9804mg/g. Then the regeneration performance of coal cinder-zeolite honeycombed sorbent evaluated by readsorption experiment. The results showed that the optimal conditions for regeneration was 170℃,4h, and the regeneration efficiency were 50.42% and 73.55% for ammonia nitrogen and CODCr, respectively. Besides, the coal cinder-zeolite honeycombed sorbent still had certain adsorption capacity in case of low concentrations of pollutants.(3)Biofilm cultivation was carried out under natural conditions using campus landscape river water, which provided rich microbial flora as the source of microbes. The biofilm culturing time need 30 days and the biofilm was relatively thin, because of the low concentration of substrate in river. Scanning electron microscopy observation showed that the main biological membrane in biofilm was rotifers, vorticella, sarcodina and dero digitata, etc.(4) The purification system was constructed combined with the sorbent and simulate reed wetland. The removal efficiency on ammonia nitrogen,CODCrand TP arrived to 50.4%、44.3%、 31.9%,respectively, which was the highest purification efficiency in the experiment under the water inflow with 1 OL/h. The removal efficiency of purification system on ammonia nitrogen, CODCr and TP became higher along with the increased concentration of inflow water. The concentration of pollutants in the effluent changed significantly as the fluctuation influent concentration Both of the sorbent and reed field wetland could remove certain pollutants under the inflow condition of 10、 20、40、80L/h. While the average removal efficiency decreased with the increased inflow water. According to the experiments on August and September, the purification system showed a good stability with the removal of ammonia nitrogen, CODCr and TP. However the removal efficiency on organics was not high, as the concentration of organics in slightly polluted water was low and the biofilm on the sorbent was relatively thin.