The objective of this project is to improve the process by which fixed film, biofilm reactors are designed for treatment of wastewaters. The investigator plans to characterize the size distribution and biodegradability of organic matter in complex wastewaters as a step toward more efficient design of processes that utilize biologically active films. Initial efforts will be concentrated on the dextrans as model carbohydrates and albumins as model proteins. Following development of analytical techniques in the laboratory utilizing these readily characterized organic compounds, macromolecule consumption and production will be studied in complex wastewaters obtained from operational wastewater treatment systems that use a biofilm reactor process. Fixed-film, bioreactors are potentially capable of being more extensively used in place of or complementary to suspended-growth bioprocess systems. This research offers the potential of making it possible to design fixed-film systems without going through a pilot-plant stage for adapting design criteria to a specific wastewater's characteristics.