Young Algaeneers Symposium edition:1 location:Wageningen, the Netherlands date:14-16 June 2012
Effluents from secondary wastewater treatment plants often contain high concentrations of nitrogen (N) and phosphorus (P) that lead to nutrient-rich discharges in surface water and, hence, eutrophication. Stimulated growth of algae in these wastewaters can remove these nutrients while producing biomass that can be used for energy, bulk chemicals or animal feed. The molar N:P ratio in effluents of secondary wastewater treatment plants is often well below the average N:P ratio of algal biomass. As a result, algal treatments may not sufficiently remove P. The goal of this project is to optimize algal removal of P from wastewater with low N:P ratios.
More in particular, it will be investigated whether P removal can be optimized by changing the species composition of the algal community or by changing the environmental conditions in the algae wastewater treatment system. In addition, we will also investigate under what conditions either protein or lipid/carbohydrate content can be optimized for valorization of the algal biomass. We will focus on two environmental conditions that can be easily manipulated in algae wastewater treatment systems, i.e. the hydraulic retention time and the light intensity (influenced by water depth). The experiments will be carried out with three model species that are promising for wastewater treatment. These species belong to different phylogenetic groups (Spirulina: cyanobacteria, Chlorella: chlorophytes, Cyclotella: diatoms) and have different valorization potential (Spirulina: protein, Cyclotella: lipids, Chlorella: protein or lipids, depending on growth conditions). Special attention is given to the chemical form of P in the wastewater as low P bioavailability may also limit P removal. Model systems in batch and continuous culture will first be tested and modeled. Subsequently, a range of real wastewaters will be tested for validation of the concepts.