Study On Comprehensive Treatment Of The Spent Elecroless Nickel Plating Solution And The High Strength Ammonia Nitrogen Wastewater

This paper researches on comprehensive treatment of the spent electroless Nickel plating solution and the high strength ammonia nitrogen wastewater in order to find suitable methods for reducing environment pollution and ecosystem destruction and recovering nickek phosphorus and ammonia nitrogen resources.First of all, Nickel is removed by chemical precipitation method. The paper found that the factors influencing the residual nickel concentration were pH, temperature and reaction time. When temperature is 90℃, pH at12.5, reaction time is 180min, residual nickel concentration could be reduced to 3.3mg/L.Then, we reclaim nickel from Ni-contained deposit and use it to manufacture Nickel sulfate crystal.Second of all, Using UV-H₂O₂ Advanced Oxidation Processes, the organic acid is decomposed into innoxious small molecule compounds, the phosphite and the hypophosphite are oxidated into the phosphate. When temperature is 70℃, pH at 5.5, reaction time is 180min, The ratio between the actual dosage of H₂O₂ and the theoretic dosage is 1.6, COD is reduced to 472.4ppm, and phosphate concentration could be achieved to 29.13g/L(counted by phosphorus).Third of all, The pretreated spent electroless Nickel plating solution is mixed with the high strength ammonia nitrogen wastewater, then with adding MgCl₂, the phosphate and the ammonia nitrogen can be removed by the struvite precipitate. When pH at 9, reaction time is 120min, [Mg²⁺] : [NH₄⁺] : [PO₄^3-] is 1.4:1:1, residual phosphate concentration could be reduced to 12.28mg/L , and residual ammonia nitrogen concentration could be reduced to 34.07mg/L.The recovered struvite...