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Design considerations and operating procedures were investigated for nitrogen removal in an extended aeration-denitrification facility. Both past and present removal efficiencies were evaluated for the facility, along with capital and operating cost data. The findings of this research indicate that at very long detention times, significant nitrification and denitrification occurred in the plant without the use of chemicals. Overall nitrogen, BOD5, and suspended solids removals were extremely high. The significance of this research is that future plants may achieve high rates of nitrogen removal through innovative design and operating procedures without the use of costly chemicals. However, capital costs needed to achieve longer detention items will have to be evaluated for the individual plant.

Periphytic algae biomass, periphyton taxonomic composition and water quality were monitored from October, 1978 through October, 1979 in three experimental ponds on the University of Central Florida campus, Orlando, Florida. Differences in the abundance and seasonal periodicity of phytoplankton in the ponds presumably arose from intrinsic differences in the nature of the pond sediments. Ceramic tile and pressboard wood artificial substrates were sampled at two-month intervals to provide estimates of periphyton biomass and productivity; there was no significant difference in algal biomass on wood and tile substrates. Algal productivity on continuous-immersion (cumulative) substrates which supported a large accumulation of periphyton was substantially lower than productivity on uncolonized substrates immersed during the same period. thus indicated the existence of a carrying capacity for the periphyton community. Turbidity, which was largely determined by phytoplankton abundance, was significantly higher in Pond 2 (7.50 FTU) than in Ponds 1 and 3 (2.60 and 2.53 FTU, respectively) and resulted in reduced light penetration and development of a heterotrophic periphyton community in Pond 2. The algal flora of Pond 2 was dominated by small conditions, whereas Ponds 1 and 3 possessed periphyton communities dominated by large, filamentous green algae indicative of "clean" water.

Benthic macroinvertebrates and physicochemical parameters were sampled monthly in Spring Lake, Florida from July, 1978, to June, 1979. Spring Lake is a slightly acidic, sand bottom lake located in the sandhill region of the Central Highlands. While submersed vegetation is not dense, the lake does contain an abundance of the endemic submersed plant Mayaca aubletii. The littoral zone is dominated by plants belonging to the genera Panicum, Nuphar, Hydrocotyle, Nymphaea, Satittaria, and Typha. The benthic macroinvertebrates collected consisted of 51 species; approximately 50 percent were in the family Chironomidae. The annual mean number of individuals was 947/m2. The mayfly Hexagenia munda Orlando was the most numerous species (18.4 percent of the annual mean); the Chironomidae was the most numerous family (31.6 percent of the annual mean). The annual mean value for the Simpson's Index was 0.25 while the annual mean value for the Shannon Index was 2.60.

The settling characteristics of urban stormwater runoff emanating from the Lake Eola Watershed (Orlando, Florida) were evaluated through a series of 7 column studies. The percentage removal that occurred due to sedimentation was observed for various stormwater pollutants and constituents. These included the General Water Quality Parameters: Total Suspended Solids, Non-volatile Suspended Solids, Volatile Suspended Solids, Chemical Oxygen Demand, Total Kjeldahl Nitrogen, Ammonia Nitrogen, Total Organic Carbon, and Total Phosphorus. The metals parameters: Zinc, Cadmium, Arsenic, Nickel, Copper, Magnesium, Iron, Lead, Chromium and Calcium were also considered. The results of the settling analysis indicates that the quality of Lake Eola stormater can be improved by plain sedimentation of detention as convincing removals were displayed by the solid parameters displayed trends of weak removal. Regression equations were developed that describe percent removal as a linear and logarithmic function of time and settling velocity. Isoconcentration lines were also developed for total suspended solids and total phosphorus removals. In addition, the effect of this treatment on the productivity of Lake Eola was assessed in terms of existing trophic state models.

Stormwater detention systems as they are frequently designed do not provide good water quality control of stormwater runoff. A filtration media to be used in conjunction with detention ponds to improve their pollutant removal efficiencies was tested at the University of Central Florida and found to be effective. The filtration media, which consisted of a mixture of sand and alum sludge, substantially improved effluent water quality. Average reductions of over 80 % were observed in concentrations of dissolved orthophosphorus, total orthophosphorus and total phosphorus. Reductions were also experienced in iron, aluminum, copper and zinc concentrations. A prototype filtration model is presently being tested on the Lake Eola watershed in Orlando, Florida. A stormwater management and design aid computer program originally written by Tim Curran (Curran 1980) to calculate stormwater hydrographs and retention volumes, and updated by the author to also calculate detention volumes will incorporate results from the prototype study.