Some influences of sediments in aerated lagoons and waste stabilization ponds

Respirometric tests have been undertaken on sediments in aerated lagoons an d waste stabilization ponds to quantify their oxygen demand and to determin e the main factors governing the process. Factors such as seasonal variatio ns, temperature, substrate, sediment layer thickness. density of macroinver tebrates and suspended sediments were investigated. The results showed that temperature and substrate concentration are the main factors that influenc e sediment oxygen demand; followed by spatial heterogeneity and resuspensio n of sediments, whereas the density of macro-invertebrates could have an ef fect in summer (hot season). Sediment layer thickness had no effect. A mode l of sediment oxygen demand is developed for the two main factors (temperat ure and substrate) with an r(2) of 0.98.