Gas Engineering Texas A&M Unwersitg-Kingsville Kingsville, ?x 78363The standard solvent casting method for preparing particle/polymer composites is reviewed. Unless extraordinary conditions are used, the standard process is restricted to thin films because of difficulties (blistering) that occur during the solvent removal. These thin films have better dispersion and less clustering of the metal particle loading than if comparable materials were made by adding metal powder into a polymer melt. However, the best dispersion is obtained in a new process where thin films in the standard process go through a redissolving step (or steps) described herein. Characterization by the large particle end of the particle size distribution confirms the reduced clustering tendency of particles in the new process.

This study focused on evaluating different support media for COD and nitrogen compound removal from an Upflow Anaerobic Sludge Blanket (UASB) reactor fed with swine wastewater. Maximum specific nitrification (MSNA) and denitrification (MSDA) activity tests were performed in two fixed-film systems with (1) polyurethane foam (R1) and (2) polyethylene rings (R2). The results showed that the R2 system performed more efficiently than R1, reaching organic matter removal of 77 ± 8% and nitrogen of 98 ± 4%, attributed to higher specific denitrifying activity recorded (5.3 ± 0.34 g NO3--N/g VTS ∙h). In this sense, MSDA tests indicated that the suspended biomass was responsible for at least 70% of nitrogen removal in the form of ammonium compared with 20% attributed to biomass in the form of biofilm. On the other hand, 40 ± 5% of initial nitrogen could not be quantified in the system effluents, but 10 ± 1% was attributed to loss by volatilization. According to the analyses, the previous information infers the development of simultaneous nitrification-denitrification (SND) routes. Respect to the analyses of microbial diversity and abundance in the biofilm of R2 rings, the presence of the genus Pseudomonas dominated the prokaryotic community of the system in 54.4%.