Solar water evaporation is an efficient and sustainable technology. To reduce energy consumption and improve cost efficiency, the surface modification of wood sponge by polypyrrole-glutathione (PGWS) was achieved using an in-situ synthetic method. The PGWS exhibits excellent adsorption efficiency for Hg(II) ions with adsorption capacity of 330.8 mg g-1 at 25 °C. Following Hg(II) absorption, the PGWS could be upcycled for solar steam generation. A stackable device was constructed by placing two wood sponges under a Hg(II) saturated PGWS [PGWS-Hg(II)], this system exhibited the highest water evaporation rate of 2.14 kg m-2 h-1 under 1 kW m-2 . Moreover, collecting paper was inserted between the stacked PGWS-Hg(II) and wood sponge for the collection of salts. As such salt can be successfully collected from simulated fertilizer plant effluent and then used as a nutrient for growing plants using a hydroponic system. The facile design of stackable evaporation provides an opportunity for wastewater utilization by harvesting solar energy.