Factors Influencing Luxury Uptake of Phosphorus by Microalgae in Waste Stabilization Ponds

Abstract

Phosphorus removal in waste stabilization ponds (WSP) is highly variable, but the reasons for this are not well understood. Luxury uptake of phosphorus by microalgae has been studied in natural systems such as lakes but not under the conditions found in WSP. This work reports on the effects of phosphate concentration, light intensity, and temperature on luxury uptake of phosphorus by WSP microalgae in continuous culture bioreactors. Increasing temperature had a statistically significant "positive effect" on intracellular acid-insoluble polyphosphate concentration. It is likely that elevated temperature increased the rate of polyphosphate accumulation, but because the biomass was not starved of phosphate, the stored acid-insoluble polyphosphate was not utilized. Increasing light intensity had no effect on acid-insoluble polyphosphate but had a "negative effect" on the acid-soluble polyphosphate. A possible explanation for this is that the faster growth rate at high light intensity results in this form of polyphosphate being utilized by the cells for synthesis of cellular constituents at a rate that exceeds replenishment. The variability in the phosphorus content of the microalgal biomass shows that with this new understanding ofthe luxury uptake mechanism there is the potential to optimize WSP for biological phosphorus removal.

Nutrient availability limits biological production in Arctic sea ice melt ponds

“…twice as high as estimated from the Redfield ratio in Table 1. Similarly, a luxury uptake of PO 4 3− of up to 4 times the growth requirement has been observed in microalgae (Powell et al 2011). Such an uptake could explain the missing PO 4 3− in the enclosure with the dual nutrient addition, but not in the enclosure with the single addition of PO 4 3− (Table 1).…”

Algae for Africa: Microalgae as a source of food, feed and fuel in Kenya

“…This simple idea is used in small communities globally to treat local wastewater systems (Powell and Shilton, 2008), however, this can then be taken a step further by employing this microalgae as a biofertiliser.…”

Influence of sunlight on the proliferation of cyanobacterial blooms and its potential applications in Lake Taihu, China

“…However, nutrients were found to be significantly correlated with phytoplankton biomass in those groups treated with high shading ratios (EG3 and EG4). This phenomenon might be caused by light limitations (Nalewajko et al, 1981;Havens et al, 2001;Powell et al, 2008;Duhamel et al, 2012), which was consist with the results by Sterner et al (1997). In this study, phosphorus was considered to be enhanced if the light was reduced (Sterner et al, 1997).…”