Cultivation in Wastewater Increases Growth and Nitrogen Content of Seaweeds: A Meta-Analysis

The growing world population demands sustainably produced proteins and cultivation of seaweeds may become an important solution for this so-called protein-shift. To increase the biomass yield and protein content of seaweeds, nutrient-rich wastewaters originating from different processes and activities such as aquaculture, industrial food processing, and municipal wastewater management could be used. Our aim was to synthesize previous literature to assess the impact that different wastewaters have on seaweed growth and protein content, and to identify research gaps. We show, by using standardized and quantitative methods, that cultivation in wastewaters increases both growth and nitrogen content (often used as an approximation for protein) of seaweeds. We further show that all groups of seaweeds (green, brown, and red) benefit from cultivation in wastewater, that the effect is similar between ocean- and land-based seaweed cultivations, and that seaweed cultivation with wastewater is not limited to only fish aquaculture wastewaters. Our results clearly demonstrate that seaweeds can be cultivated in a wide range of wastewaters to generate protein-rich biomass with increased growth and biomass yields. These results can be valuable when searching for sustainably produced proteins for the growing human population.