Research On The Recovery Of Copper Ammonia From Printed Circuit Treatment Wastewater By The Combined Process Of MAP Method And Breakpoint Chlorination Method

In this paper,the copper ammonia wastewater produced by the printed circuit board is treated as the research object.The ammonia nitrogen and copper are treated and recovered by the MAP method and the sodium hypochlorite oxidation method.The MAP method first removes and recovers part of the ammonia nitrogen to reduce the subsequent sodium hypochlorite oxidation method.Consumption,in the destruction of copper ammonia complex by sodium hypochlorite oxidation,while precipitating copper,to achieve ammonia nitrogen and copper recovery.Firstly,the influencing factors of MAP method were tested.The results showed that the removal rate of ammonia nitrogen was greatly affected by the pH value and the dosage of precipitant.Considering the influence of copper removal rate,phosphate,magnesium salt and water were added.The amount of ammonia nitrogen has a certain relationship.When the molar ratio of nitrogen,phosphorus and magnesium is 3:1:1,the removal rate of ammonia nitrogen is close to the theoretical value;when the molar ratio of nitrogen,phosphorus and magnesium is 4:1:1,At pH 9-10,ammonia nitrogen has a good removal effect.At this time,the copper ion removal rate is about 1%;at pH 9.5,the maximum removal rate of ammonia nitrogen is 24.67%.At this time,the content of ammonia magnesium phosphate reaches 96.8%..When an excessive amount of magnesium salt is added,the removal rate of ammonia nitrogen is increased,and the formation of magnesium phosphate can be promoted,and the shortage of magnesium salt causes a large residual amount of phosphate in the solution to form a side reaction of copper phosphate.Examination of the dosing method showed that the simultaneous treatment of each agent in solution form had the best effect,followed by the addition of magnesium salt followed by the addition of phosphorus salt;when added in solid form,other side reactions were caused by mass transfer effect;When a phosphorus salt is first added,a copper phosphate precipitate is formed,which is disadvantageous to the reaction of magnesium phosphate.Secondly,the sodium hypochlorite oxidation process was studied.When the N/Cl molar ratio was 1:1.6,the ammonia nitrogen removal rate was 99.11%,the dosage continued to increase,and the removal rate was close to saturation.At pH 7 or so,the ammonia nitrogen removal effect was the best.However,considering the simultaneous recovery of ammonia nitrogen and copper,the pH should not be too low,and the optimum is about 9.5.Third,the comprehensive research results of actual wastewater treatment.The conditions of the MAP method were determined to be pH 9.5,the molar ratio of nitrogen,phosphorus and magnesium was 4:1:1.1;the initial pH of the sodium hypochlorite oxidation method was 9.5,and the molar ratio of N/Cl was 1:1.6,and the removal rate of ammonia nitrogen by the MAP method was obtained.The copper removal rate was 2.27%,the sodium removal rate was 98.8%,the copper removal rate was 99.8%,the ammonium phosphate magnesium was 95.43%,and the copper hydroxide was 99.57%.The benefit estimate shows that the cost of treating waste water with sodium hypochlorite alone is about 39 yuan/ton,and the cost of the combined process of MAP and sodium hypochlorite oxidation is about 17 yuan/ton,and the cost is saved by nearly 50%.