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Upgrading existing activated sludge with fine pore aeration systems
M.K.Stenstrom,Joon-Hyun Kim 江原大學校 附設 環境硏究所 1992 環境硏究 Vol.9 No.-
Over the past ten years aeration systems development in the United States has centered around fine pore diffuser upgrades to existing activated sludge plants. A variety of older aeration systems have been replaced with new diffuser systems which include full floor coverage systems, composed of ceramic or plastic discs, ceramic and plastic tubes, and membrane tubes or discs. This manuscript reports on aeration system upgrades at six different full scale treatment plants. Seven different devices were evaluated using the off-gas analysis technique. Diffuser cleaning methods were also evaluated. Results are presented which show the economic incentives for upgrading and the increased plant capacity which resulted from increased aeration efficiency. It was found that the effects of process operation, such as step feed, F/M. MLSS concentration, mean cell retention time and air flux had a major impact on transfer efficiency. The effects of diffuser fouling and cleaning methods are presented.
An integrated study on management techniques for surface and subsurface water resources and quality
Joon-Hyun Kim,M.K. Stenstrom 江原大學校 附設 環境硏究所 1992 環境硏究 Vol.9 No.-
A general comprehensive theory has been studied to describe surface and underground fluid flow and mass transport. Using multispecies multiphase approach, an integrated mathematical model is developed. The comprehensive governing and constitutive equations have been derived considering mass and force balances of chemical species over four phases (water, oil, air, soil phase) in schematic elementary volume. Traditional governing equations for surface and groundwater flows and pollutant migrations are derived and compared. Provisions have been made for the inclusion of physical, chemical and biological processes which complicate the analysis of multispecies multiphase fluid flow and pollutant transport. To make the analysis possible, continuity of each phase and equilibrium among phases are assumed. The developed model is constructed using nonlinear governing and constitutive equations. To study the applycability of the developed integrated mathematical model, numerical models were developed or simulations were performed using traditional computer models such as WQRRS, QUAL2E and WASP4. As the developed numerical model. there are TIDE model for the two dimensional tidal flow and multidimensional CMGM model for underground fluid flow and mass transport. TIDE model was applied for Saemangum Area in which embankment project is now going on. Verifications of TIDE were performed by the comparison with the analytical solution and with the results of physical hydraulic experiments. To demonstrate the CMGM's versatility. several hypothetical problems were simulated: unsaturated flow through an embankment: one-, two-, three-dimensional multiphase flow and composite multiphase contaminant migration. Three dimensional water quality prediction was performed on Lake Chungcho using WASP4. The hydraulic computations required for water quality prediction were done by TIDE. The possibility of computer model using integrated theory on surface water was studied by applying WQRRS on Lake Soyang, Chungjoo and the vicinity of Namyih Island, and QUAL2E on Stream Bokha, Chungmi, and Shin. Computer model was developed using advanced numerical analysis techiques such as multidimensional upstream weighted finite element method and harmonic finite element method. To handle the difficult problems such as irregular geometry. complex boundary conditions and various governing equations with simple modifications, upstream weighted finite element method has been adopted. By using the dynamic allocation of arrays in coding, the code is flexible to work on an IBM 3090 VF, workstations such as IBM-RT, SUN4, Mips, and PC's for one-, two- and three-dimensional problems. To reduce the computation time and storage requirements, decoupling of the system equations, banded global matrix and vector and parallel processing were used. The program was highly structured for the simple inclusion of future development of the constitutive equations. The instability and convergence criteria of the nonlinear problems were studied. Parameter dependency of the model was also studied. Tide model can analyze the elevation and velocity of tidal flow on complicated coastal region like Korea, and also applicable to land water such as reservoir and stream. CMGM model can simulate the transport and transformation of a complex mixture of groundwater contaminants (e.g. a mixture of light and heavy hydrocarbons, water-born contaminants and volatile contaminants). Also, movement of soil species such as land subsidence can be simulated using this model. Therefore, these developed or traditional models can provide the practical informations of fluid flow and pollutant migration and transformation, impact to ground to policy makers, which will allow them to predict future developments of projects and to manage practical contamination problems and remedial plans. Therefore, developed models are important tools for the feasibility study or the decision of direction of project. For the field development of surface and groundwater resources and quality management, we need systematic aknowledgement of hydraulic, hydrology, environments, geology and waste load parameter, Using computerized GIS (geographical information system), collection and analysis of great amount of data can easily is done, present condition and approximate prediction of future change is possible. And by combining the simulation package with GIS, best information management system can be constructed. Using GIS, computerization of data management on map, cad input and output can be accomplished. So, the spreading effects on natural desaster and several projects can be enhanced by operation of general system of informations on enviromental and water resources projects.