Simulation of Biodegradation in Infiltration Seepage-- Model Development and Hydrodynamic Calibration

• Published in: Water, air, and soil pollution air, and soil pollution, 2006-11, Vol.177 (1-4), p.19-43
• Main Authors: Wanko, A, Mose, R, Carrayrou, J, Sadowski, A.G
• Format: Article
• Language: English
• Subjects: air flow; Applied sciences; Bacteria; Biodegradation; biofilm; Biological and medical sciences; Biological treatment of waters; biomass; Biotechnology; Calibration; Computational fluid dynamics; Computer simulation; Convection; Dispersions; Environment and pollution; Environmental monitoring; equations; Exact sciences and technology; Fluid flow; Fundamental and applied biological sciences. Psychology; General purification processes; human population; Hydrodynamics; hydrologic models; Industrial applications and implications. Economical aspects; Infiltration; infiltration (hydrology); kinetics; Mathematical models; Oxygen consumption; oxygen requirement; Oxygen transfer; Oxygenation; Pollution; Pollution control; Pollution load; population size; Porous media; Sanitation; Seepage; Simulation; simulation models; Studies; unsaturated conditions; wastewater treatment; Wastewaters; water flow; Water treatment and pollution
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-005-9046-1

Wastewater sanitation using infiltration seepage belongs to the attached growth treatment line for pollutant waste. In a specific geographical context, and for a population of approximately 500 to 1000 population equivalent, it seems to be a good choice. Despite its rustic reputation, it is a considerably complex treatment line. The aim of this study is to contribute--using numerical simulation--to the understanding of the physical and biochemical phenomena which develop inside an infiltration seepage bed. The aspects which are essential to bacterial activity--the hydrodynamics of the porous medium, the development of the active biomass, transport of substrate, oxygen transfer and consumption--are dealt with. The splitting operator technique is used; its advantage is the separate solution of the convection, dispersion and kinetics equations; each with appropriate numerical techniques. By testing a methodical verification of the model, based on the analytical solutions, we learn that the hydrodynamic dispersion and the rate of degradation have opposite effects on the efficiency in decreasing the pollution loads. Moreover, a significant result which is obtained is the evaluation of the oxygenation capacities in relation to some of the treatment line's key parameters. Finally, we carried out by experiments a successful calibration of the flow model.