Exploring advanced phycoremediation strategies for resource recovery from secondary wastewater using a large scale photobioreactor.

Aim of the study was to use a microalgae-based membrane photobioreactor system (1000L) in a greenhouse for continuously treating a secondary wastewater using green microalgae Desmodesmus sp. isolated from a sewage plant in Germany, during summer and winter to get a comprehensive understanding of the underlying tendencies and optimisations necessary for unhindered yearlong operations. Maintaining the photobioreactors at lower cell concentrations during times of light inhibition seem to benefit the nutrient uptake rates. Cell mass recycling has been shown to be an effective strategy in enhancing algae-based wastewater treatment; especially during strong light availability. Compared to regular continuous cultivation operations, using cell recycling and higher dilution rates during light availability and using lower cell concentrations and dilution rates during light inhibition, the overall biomass productivity was boosted by 80% and 10 % during summer and winter respectively, while N/P removal rates were improved by 23% in winter and remained unchanged in summer.