Application of forward osmosis on dewatering of high nutrient sludge

► High nutrient sludge dewatering by forward osmosis was systematically investigated. ► Higher biomass loading achieved higher nutrient removal but more flux water decline. ► Membrane pore radius and sludge barrier layer played main role to remove nutrient. ► Membrane fouling was subject to cake formation and concentration polarization. ► Two FO stages are designed to incorporate with conventional biological treatment.