Biofilm Attachment And Wastewater Treatment Performance Of Modified Polyurethane Carrier

The only way that common polyurethane(PU) foam plastics carrier fixing microorganism is physical adsorption, resulting in the low growth rate of microorganism and the unstable attachment of biofilm to the carrier. In this article, the PU foam plastics were modified by two different methods. One is chemical oxidation - gelatin protein grafting; the other way is chemical oxidation - surface covering with iron ion. Surface physicochemical properties of the carrier, the speed of biofilm colonization, the quantity of biofilm and wastewater treatment performance are investigated before and after the modification.The results showed that after the modification of chemical oxidation - gelatin protein grafting, the ratio of the hydrophilic C-O bond on surface of the modified carrier increased by 47.86%, and the ratio of the hydrophobic C-C, C-H bond on surface of the modified carrier reduced by 50.66%. The dynamic contact angle of water against the carrier surface was decreased by 17.49°. Hydrophilicity and surface roughness of the carrier increased after the modification. In the experiment of biofilm colonization of different cycle, compared with original carrier, the quantity of biofilm on modified carrier increased by 30% and 60%, and the average growth rate of biofilm increased by 50% and 70%, also the removal efficiency of COD and ammonia was increased significantly. After the biofilm colonization finished, the removal efficiency of ammonia increased by about 15%.After the modification of chemical oxidation - surface covering with iron ion, the surface roughness of the carrier has been increased. The ratio of the hydrophilic C-O bond on surface of the modified carrier has increased by 16.17%, and the ratio of the hydrophobic C-C, C-H bond on surface of the modified carrier was reduced by 15.81%. The dynamic contact angle of water against the carrier surface was decreased by 10.46°. Iron ion was formed as Fe2O3 on the carrier surface, and helped stimulate microorganism growth. In the experiment of biofilm colonization of 12h cycle, the quantity of biofilm on modified carrier increased by 60% and the average growth rate of biofilm increased by 50% compared with original carrier. After the biofilm colonization finished, the removal efficiency of ammonia increased by about 10%. Furthermore, it was found that the biological activity was not increased through the dehydrogenase activity test.