Dilution rates of cattle slurry affect ammonia uptake and protein production of duckweed grown in recirculating systems

Duckweed is a potential collector of nitrogen from animal liquid manure and source protein suitable as feed for livestock fish. Therefore, it provides opportunities circular economy systems. Two duckweed species, Spirodela polyrhiza Landoltia punctata , were grown in five recirculating systems each connected to reservoir tank filled with water graded organic cattle slurry concentrations. Fresh dry biomass, production amino acid profiles among the removal evaluated. showed significantly higher fresh biomass but L. matter content was generally resulting similar both species This study shows clearly that crude content, ranging between 29.3 37.9% matter, positively correlated total ammonia (TAN) concentration substrate, independent species. Total yield range 1.37–1.95 g m −2 d −1 following quadratic function regarding TAN concentrations, marginal differences Biomass yields optimal at 19 mg l which corresponded dilution 1:8. The results this provide important information operation on operators should aim keep concentrations optimization conjunction removal. • differed produced amounts. S. FM DM content. Crude concentration. reached almost 38%. Optimum