TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The liquid and solid effluents are derived from nickel production processes. Preferred Process: In the process, before removal of metal from liquid effluent, a liquid effluent equalization step takes place. In the removal of metal from liquid effluent, the precipitation of metals occurs as sulfides, oxidation of metallic sulfides and crystallization as metallic sulfides. The magnesium is precipitated as magnesium hydroxide by means of addition of ammonia in a quantity of 20-150 g/l, in magnesium hydroxide precipitation step. The magnesium hydroxide precipitation presents a pH of 9-11, temperature of 60-100 degrees C, solid content of 1.5-15 wt.%, and residence time of 0.5-2 hours. In the magnesium hydroxide precipitation step, the washing of magnesium hydroxide precipitate takes place, followed by a drying and calcinations resulting in magnesia. The removal of free ammonia takes place in a multistage depletion column, in counter current, with a low pressure air/steam mixture of 2-6 kgf/cm2. At the end of the depletion and removal of free ammonia step, the liquid effluent comprises 90-140 g/l of ammonium sulfate in solution. The liquid effluent is submitted to a clarification for removal of suspended solids, after depletion and removal of free ammonia step. After the clarification, the solution is concentrated through membranes in operation of micro filtering, ultrafiltering, nanofiltering and reverse osmosis resulting in recovered water current and in a saline solution current comprising 200-450 g/l of ammonium sulfate. The ammonium sulfate is submitted to a crystallization through low pressure steam resulting the water removal and ammonium sulfate crystallization. The ammonium sulfate is centrifuged, dried, stored and shipped, after the crystallization. The recovered water of crystallization step is stored with the recovered water of the membrane treatment step to be reused in nickel industrial processing. The process comprises extraction of ammonium sulfate through an addition of quicklime. The ammonium sulfate of the effluent is precipitated through the addition of quicklime generating a suspension of dehydrate calcium sulfate, which is densified in a thickener and pumped to a gypsum storage stack, after extraction of ammonium sulfate step. The thickener supernatant goes to a main tank and to a softening unit with an ionic exchange resins. The recovered water of softening unit is stored with the recovered water of the membrane treatment step to be reused in nickel industrial processing.