Study On Relevance Between Surface Properties Of Carbon Fiber And Aerobic Biological Membrane

Now there exist both water shortage and water pollution problems in our country, and the situation of surface water pollution is still serious.It is urgent to protect the water resources, to improve water environment and to improve the efficiency of water treatment. Many municipal water resources are in micro polluted state which can be seen as an oligotrophic environment, leading to the phenomenon that many common used engineering biofilm carrier decrease their water treatment ability occurs.Carbon fiber has properties such as biocompatibility, flexibility, it can be an ideal biofilm carrier material. But the hydrophilicity of CF is bad, and the surface of CF is so smooth that it is difficult to hang biofilms. So it is necessary to modify the surface of CF.This dissertation mainly studied the effect of surface properties of carbon fibers on the aerobic biofilm, and treatment capacity of carbon fiber biofilm carrier in micro polluted water. It is aim to lay the foundation for the modification of carbon fiber biofilm carrier and for the use of carbon fiber as biofilm carrier of municipal polluted water.Carbon fiber has good performance of water treatment when it is used as the biofilm carrier. COD, ammonia nitrogen removal rate can be as high as 97.3%,92%, which were increased by 1.4%,6.6% compared with the polypropylene fiber carrier. Carbon fiber biofilm system has good resistance to low COD loading capacity. In low load conditions, COD and ammonia nitrogen removal rate were increased by 11.9% and 5.6%, respectively, but COD and the removal rate of ammonia nitrogen of polypropylene fiber carrier decreased.When studying the effect of surface nitrogen content on biofilm, the results showed that high surface nitrogen content of carbon fiber biofilm system attained a higher COD and ammonia nitrogen removal rate and a more stable state, especially high surface nitrogen content plays a significant role in promoting the performance of denitrification. Surface nitrogen content of carbon fiber has little effect on phosphorus removal performance of different biofilm system.Surface of carbon fiber were modified by ferrous oxalate and ferric citrate, respectively. The roughness of organic iron modified carbon fiber surface increased greatly. The hydrophilicity and biofilm quantity were also greatly improved, which are 3.3 times,3.2 times that of not modified carbon fiber carrier. The average removal rate of COD, ammonia nitrogen and TP significantly increased, from 94%,93% and 95% to 97%,96% and 97% respectively. Carbon fiber biofilm system still has a good resistance to low COD load impact after being modified by organic iron. The COD value of the effluent is at about 11mg/L or 12mg/L, which is far below the national standard GB 18918-2002 level A emission standard,so they all conform to class I of surface water environment quality standard in GB3838-2002.Ferrous oxalate modified carbon fiber carrier showed excellent performance of denitrification, citric acid iron modified carbon fiber carrier has a good phosphorus removal effect.