Removal of dissolved organic matter in water hyacinth wastewater treatment lagoons /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Secondary treatment of domestic wastewater in water hyacinth lagoons was evaluated under experimental conditions to assess the role of the roots' bacterial biofilm in the removal of dissolved organic matter (DOM). Research was conducted to (1) quantify removal rates by the biofilm as a function of bulk DOM concentration, (2) formulate an analytical model of DOM removal incorporating biofilm activity, and (3) test the model response to variable organic loads in a pilot-scale plant. Removal of DOM by the biofilm was quantified in continuous-flow water hyacinth tanks at ten concentrations ranging from 45 to 330 g COD m^-3. Total DOM removal in the denitrifying, acetate-based experimental system was measured and partitioned into two fractions associated with the activity of biofilm and suspended bacteria. Calculated DOM removal by the biofilm was adjusted for the release of organic compounds by debris decomposition. Values of DOM removal were used to calculate oxygen transfer rates from the water hyacinth roots. Approximately 40% of the DOM removal in the laboratory tests was accounted for by biofilm activity. Removal rates increased with DOM concentration in the bulk solution following a non-linear relation. Uptake per unit mass of biofilm remained nearly constant at about 0.3 g COD g^-1d^-1. Organic flux through the biofilm surface was less than 5% of typical fluxes for trickling filter biofilms. Calculated DOM fluxes indicated that bacterial growth was oxygen-limited. Values of oxygen transfer from the roots to the biofilm were less than 10% of reported oxygen fluxes into biofilms in contact with oxygen-saturated water. A model of DOM removal in water hyacinth lagoons was formulated. The model, composed of four differential equations, was solved at steady-state conditions and the validity of its simulation results was tested in pilot-scale tanks. Hydraulic detection times ranging from 2 to 28 days were evaluated using biofilm density and concentrations of DOM and particulate organics as monitoring parameters of the model response. Simulation results showed uptake by the biofilm as the main DOM removal mechanism in the lagoons, accounting for 60 to 90% of the overall removal... |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Civil Engineering." |
| Physical Description: | x, 133 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |