Method for recycling ammonia from low-concentration ammonium chloride wastewater

A method for comprehensively treating low-concentration ammonia-nitrogen wastewater by completely recycling, wherein the method comprises steps of:

• (1) mixing-reacting which comprises uniformly mixing the low-concentration ammonium chloride wastewater and carbide slag by stirring, reacting with each other sufficiently, and obtaining a mixed solution containing ammonia water and ammonium chloride;
• (2) ammonia separating-absorbing which comprises transferring the mixed solution obtained from the step (1) through a material pump into an ammonia-water evaporative concentration tower, separating the ammonia water, and obtaining an ammonia vapor and a calcium chloride waste solution;
• (3) cooling-recycling which comprises transferring the ammonia vapor obtained from the step (2) into an ammonia-water cooler, cooling, absorbing, and after the cooling treatment, storing the obtained ammonia water in an ammonia-water storage tank for standby;
• (4) calcium-chloride purifying which comprises introducing the calcium chloride waste solution obtained from the step (2) into an aging pool, aging, filtering and obtaining a purified calcium chloride solution;
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• (5) calcium-chloride recycling which comprises introducing the purified calcium chloride solution obtained from the step (4) into an MVR triple-effect evaporator, evaporating, obtaining distilled water and a concentrated calcium chloride solution with a concentration by weight of 35%-40%, then introducing the concentrated calcium chloride solution into a fluidized bed spray granulator, and obtaining an anhydrous calcium chloride product.