Spatiotemporal effects on oxygen level in waste stabilization pond at high altitude

Abstract:

Dissolved oxygen is an essential controlling factor in the operation of facultative and maturation ponds since their purification processes take many advantages from algal photosynthetic oxygenation. The rate of this photosynthesis strongly depends on the location within a pond and climatic conditions which can be extreme at high altitude, such as strong solar radiation, low mean temperature and its intensive daily fluctuations. To investigate these influences, a linear mixed effect model was built on the data collected from three meticulous sampling campaigns in a waste stabilization pond (WSP) in Cuenca, Ecuador. In general, the high altitude entailed both benefits and disadvantages to these treatment ponds. Large diurnal variations of temperature (7-20 oC) enhanced mixing and reduced short-circuits at top layers. High solar radiations, above 1400 Wm-2, also boosted the oxygen level up to 20 mg. L-1 during the highest light-intensity period. This first application of mixed model on WSPs proved its pbkp_redictive performance and applicability. By adding spatiotemporal effects as random factors in the model, the goodness-of-fit of the model increased from 0.64 to 0.79. These findings indicate that spatiotemporal characteristics need to be accounted for in the design and operation of pond systems, especially at high altitude.

Año de publicación:

2017

Keywords:

Fuente:

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