Study On Advanced Treatment Of Swine Wastewater By New Mg-Ti Combined Electrolysis Reactor

In order to solve the problems of pH regulation in sacrificial magnesium anode electrolysis and ammonia nitrogen can not be completely removed from the wastewater,a combined method of sacrificial magnesium anode electrolysis and titanium anode electrolysis was proposed.Based on the two aspects of removing nitrogen and phosphorus in magnesium anode electrolysis and removing ammonia nitrogen in titanium anode and reducing pH,the change rule of pH,ammonia nitrogen removal rule and removal path of titanium anode in the electrolysis process were discussed,and the key parameters of removing nitrogen-containing wastewater in titanium anode were optimized.The effect of electrolytic combination of sacrificial magnesium anode and titanium anode on nitrogen and phosphorus removal from wastewater was discussed,and the related parameters were optimized.The thesis mainly obtains the following conclusions:(1)In the titanium anode electrolysis experiment,the optimal current density and Cl~-concentration were 21.8 m A/cm~2 and 1200 mg/L,respectively.Under the optimal conditions,the removal rate of ammonia nitrogen,COD removal rate and current efficiency of simulated wastewater were above 98%,60%and 55%,respectively.The pH of wastewater in titanium anode electrolytic can be decreased rapidly(the rate of decline is 1.86/h),which provides experimental basis for the combined electrolytic process of sacrificial magnesium anode and titanium anode.In the process of electrolysis,the variation of ammonia nitrogen concentration,residual chlorine concentration and pH in wastewater is closely related.The depletion of ammonia nitrogen is concided to the pH knee point and residual chlorine concentration.During the electrochemical oxidation of ammonia nitrogen,by-products such as chloramine,dichloramine,trichloramine,nitrite nitrogen and nitrate nitrogen are also produced.According to the change of the concentration of by-products and the change of the proportion of all nitrogen compounds in the wastewater,it can be deduced that the ammonia nitrogen in the wastewater is mainly removed in the form of nitrogen.(2)In the electrolytic combination test of sacrificial magnesium anode and titanium anode,the optimal nitrogen-phosphorus ratio of wastewater is determined as 4:1.Under optimal conditions,the final removal rate of ammonia nitrogen in simulated wastewater was over 98%,and the final effluent concentration of phosphorus was less than 7mg/L.Sacrificial magnesium anode combined with titanium anode electrolysis experiments,COD removal rate is greater than in magnesium anode in the titanium anode electrolytic removal rate,which can be resulted from that the humic acid combined with magnesium ions is easy to form a complex,and the adsorption and crystal surface,or humic acid adsorption in the form of monomer on the precipitation in the reaction process of crystal,the humic acid concentration decreased.The presence of humic acid can also change the shape of the crystalline precipitate of magnesium ammonium phosphate.(3)In the pilot experiment of electrolysis combined sacrificial magnesium anode unit and titanium anode unit,PAC flocculant did harm to the removal of ammonia nitrogen.During the electrolysis of effluent from the A/O biological treatment facility,it was found that the removal rate of ammonia nitrogen and phosphorus in the wastewater was the fastest in the electrolytic part of the first cycle magnesium anode.After four cycles of electrolysis,the final effluent phosphorus concentration was lower than 20mg/L,the removal rate was up to 90%,and the final ammonia nitrogen removal rate was up to 50.4%.The cost analysis of the pilot plant was carried out.Considering the power consumption,magnesium consumption and reagent consumption,the running cost of the novel pilot-scale set-up was 9.79 yuan per ton.