Work

Bioremediation of drainwater from soilless cultivation by Tetradesmus obliquus and Raphidonema monicae: growth performance and biochemical composition from lab to industrial scale

Year: 2025

Type: article

Abstract: To meet the demands of the growing population, agricultural practices have been increasing and putting a strain on land and freshwater usage. Soilless agriculture has emerged as a more sustainable practice to mitigate this issue but still generates nutrient-rich drainwater that can harm the environment if not properly managed. In this context, this study explores a circular economy approach to reuse the drainwater of soilless farming as a culture medium for microalgae production. For this, the growth performance of four strains, Chlorella sp., Nannochloropsis limnetica , Raphidonema monicae and Tetradesmus obliquus , was assessed using drainwater under summer and winter conditions at lab-scale. Based on productivity, protein and polyunsaturated fatty acids (PUFA) contents, T. obliquus and R. monicae were selected for comparison in pilot-scale flat-panel photobioreactors (FP-PBR) and raceway ponds (RW). T. obliquus presented significantly higher growth in FP-PBR (0.11 g L −1 d −1 ) compared to RW (0.09 g L −1 d −1 ), with complete nitrate removal in both systems. R. monicae showed similar growth across systems, removing 19 % of nitrate in FP-PBR and 56 % in RW. Principal component analysis indicated species-specific traits drive biochemical profiles, with limited influence from the cultivation system. Both species were cultivated in 19-m 3 tubular photobioreactors, with improved productivities ( T. obliquus with 0.23 g L −1 d −1 and R. monicae with 0.13 g L −1 d −1 ) until stationary phase or legal nitrate limits, yielding about 20 kg of dry weight each. The biomass produced in drainwater was biochemically characterized, showing it was rich in proteins (>30 %), PUFA (>55 %) and phenolics, highlighting their potential application in various sectors, including aquaculture and agriculture. Overall, this study demonstrates the potential of these strains for drainwater treatment, promoting a circular economy by converting waste into valuable biomass.

Source: Algal Research

DOI: 10.1016/j.algal.2025.104468