Halimione portulacoides biomass - a sustainable feedstock for bioenergy production from an integrated water-energy-food system

•Simulated aquaculture wastewater was phytoremediated by H. portulacoides (Hp).•Wastewater N-P level did not affect thermal properties of resulting Hp biomasses.•Calorific values of Hp biomasses (16–18 MJ kg−1) and thermal decomposition at 250–650 °C were alike most energy crops.•Hp roots had higher C, H, N and volatiles but lower O and ashes than Hp canes.•Hp biomass has energy potential for a water-energy-food nexus strategy.