JEE Main · 2023 · 10 Apr 2023 · Shift 1 · Environmental Chemistry

Each industry is identified by the characteristic solid waste it discharges. A steel plant separates the molten gangue from the ore in its blast furnace as slag, so steel plants go with slag. A thermal power plant burns pulverised coal and the fine non-combustible residue carried off with the flue gases is fly ash, so thermal power plants go with fly ash. A fertilizer unit that makes phosphatic fertilizers from rock phosphate rejects large amounts of gypsum (phosphogypsum), so fertilizer industries go with gypsum. A paper mill works up wood pulp and cellulose, and its effluent is rich in organic matter that rots away, so paper mills go with bio-degradable wastes. Thus steel plants give slag, thermal power plants give fly ash, fertilizer industries give gypsum and paper mills give bio-degradable wastes.