Phosphorus Uptake by Fixed Biological Slimes

There has been a growing concern in the past few years concerning the eutrophication of our lakes and streams. Eutrophication is the aging of these waters through rich organic production, such as algal blooms, caused by a large supply of plant nutrients. Nitrogen and phosphorus are the two most important nutrients related to the eutrophication problem. By limiting one of these nutrients autrophic [sic] metabolism of algae in lakes and streams will slow down and the rate of aging of these water bodies will decrease. Nitrogen can be added to the water by the natural microbial process of nitrogen fixation so phosphorus is considered by most authorities to be the nutrient to limit. The Lake Michigan Enforcement Conference, sponsored by The Federal Water Pollution Control Administration, and held in Chicago during 1968, recommended that all cities in the Lake Michigan basin must provide at least 80% removal of phosphorus from their raw sewage by the end of 1972. The trickling filter, a biological sewage treatment process, accomplishes a maximum of about 20% phosphorus removal based on limited data which is available. Communities with trickling filter units are usually small with very limited budgets. They cannot afford the high cost of chemical treatment of sewage for phosphorus removal so any increase in the biological uptake of phosphorus will help reduce the cost of removal at these plants. This research study is designed to determine whether a thinner biological slime will store more phosphorus per unit weight of cell mass than a thicker slime. By increasing the rate of flow over the cell mass, scour will reduce the slime thickness and the thinner slime would most likely remain in an aerobic condition throughout its entire depth. This study will attempt to determine whether luxury uptake of phosphorus is possible for a trickling filter during these completely aerobic conditions. Luxury uptake of phosphorus is the storage of phosphorus in excess of that which is normally required by the cell for metabolism