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This report has been prepared with the idea of briefly summarizing the most important principles underlying the coagulations/flocculation process as it applies to water and wastewater treatment. The production of potable water from a supply which has been contaminated by naturally-occurring or man-made pollutants has been an object of concern throughout history. Several broad aspects have been considered in the report, such as the history, the nature and physical chemistry of colloidal particles, the theories of and the factors affecting coagulation/flocculation, and control of the coagulation/flocculation process. It is advisable for those persons engaged in the dynamic environmental sciences to occasionally review the basic principles having to do with the processes being employed. In this light, this report provides a cursory review of pertinent literature with regard to the history, the stoichiomentry and physical mechanisms involved, the techniques of process control and an assessment of the state-of-the-art of the coagulation/flocculation process. Of course, this discussion could have been written more extensive detail, but the volume of such an enterprise would be excessive. For those desiring further information, and extensive bibliography of references has been appended.

The presence of hydrogen sulfide in a ground water source is noted by its rather obnoxious odor, similar to a "rotten egg". Concentrations as low as 0.05 ppm are noticeable, therefore, almost its entire removal is demanded prior to potable consumption. Hydrogen sulfide is formed primarily by the decomposition of organic matter in anaerobic conditions. Removal of this gas has been accomplished by means of aeration, detention, and chlorination over the years. The mechanisms behind each of these processes are complex and discussed in this paper. During the course of this investigation, a literature survey concerning the mature and sources of hydrogen sulfide, its removal by aeration and detention, and the experimental methodology has been conducted. Samples were collected from two ground water locations in Central Florida, namely City of Apopka Terrace Plant, and the City of Maitland Thistle Plant. These samples were taken before and after aeration and detained in containers similar to the storage tank dimensions. These samples were tested for Hydrogen Sulfide and pH with respect to time. The aerators were determined to remove 13 to 15 percent H2S, respectively. The pH values ranged between 7 - 8 prior to detention and rose slowly during H2S ionization to 8-8.6. Both locations were evaluated to determine the most economic operating conditions. Ideally, Apopka should be removing between 30 - 40 percent by means of aeration, and Maitland, between 40 - 50 percent. Chlorination will remove the remaining H2S. Although the existing aerators were operating less than their optimum removal range, they should remain in service. This is based on deducting the aerator "sunk costs" from the economic evaluation. Efforts should be encouraged to improve aerator efficiencies by increased agitation, contact time, and weir overflow rates in the aerator trays. These measures should increase the H2S reaction rate and improve its removal. Detention only removes the odor problem, but the chlorine demand still remains, as exerted by the forms HS- and S=.

Lake Eola, in downtown Orlando, was the subject of extensive research to determine the impact of stormwater runoff to the lake and possible management alternatives. The focus of this research was stormwater treatment by chemical coagulation followed by detention. Phosphorus was the main parameter targeted for removal. Various chemical parameters were also evaluated included: TSS, VSS, NVSS, COD, TKN, NH3, TOC, TP, Ca, As, Cd, Cu, Cr, Ni, Mg, Zn, Fe, and Pb. The chemical coagulants used for this research included: alum, ferric chloride, and lime. The study involved settling column tests for the various treatment methods to determine stormwater settling characteristics and pollutant removal rates by depth and time. Detention of the runoff in the column for 120 minutes resulted in average removal rates of 55% for TSS and 30% for TP. Both alum and ferric chloride coagulation followed by 60 minutes of settling resulted in average removal rates of over 90% for both TSS and TP. Lime coagulation followed by 60 minutes of settling resulted in over 50% removal for both TSS and TP. Regression analysis was used to develop equation relating pollutant removal with time and settling velocity. Isoconcentration lines were also developed to predict pollutant removal rates for specific parameters.

Nitrogen is an essential nutrient for plant and animal life; however, its presence in concentrations exceeding assimilative capacities of receiving water bodies is undesirable. Therefore, the form and concentration of total nitrogen released in wastewater effluents is of great concern. During the course of this study, the nitrogen analysis was performed on the various unit processes of the Florida Technological University wastewater treatment plant. The average percent removal of nitrogen between plant influent and clarifier effluent was 30.5% during the month of August 1975. It is believed that the nitrogen removal is attributed to luxury uptake by the biomass through the plant. The clarifier effluent was highly nitrified containing an average ammonia nitrogen concentration of 0.76 milligrams per liter and a nitrate nitrogen concentration of 16.47 milligrams per liter. The extent to which nitrification took place was 93 - 98% with an average of 96.5% for the month of August.

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Ph. D.

This study analyzed data that had been previously collected by the Occoquan Watershed Monitoring Laboratory under the National Urban Runoff Program, to obtain an understanding of the degree of treatment of stormwater runoff obtainable in retention (maintains a water pool) and detention (drains completely) basins. Three basins were studied, two retention and one detention, and a total of 191 storm events were monitored using automatic sampling equipment. The samples were analyzed by the laboratory for COD, all nitrogen forms, all phosphorus forms, total suspended solids, and heavy metals (iron, manganese, etc.). It was concluded that detention and retention ponds achieve substantial reduction in the pollutant loads carried by stormwater runoff from residential areas. Non-soluble settleable materials were removed to a comparable degree by both basin types. However, the pool of water characteristic of a retention basin offered a superior environment for the removal of soluble pollutant forms, particularly nitrogen and phosphorus. The treatment obtainable in detention and retention basins make them effective devices for the abatement of urban runoff pollution. Through the mechanisms of solids settling and microbial degradation, a basin can treat polluted runoff to a considerable extent and reduce damage to receiving bodies of water. / M.S.

Master of Science