Study on the Treatment of High Strength Ammonia Wastewater by Using Inner Circulation Impinging Stream Biofilm Reactor

[Objective] The treatment effect of inner circulation impinging stream biofilm reactor(ICISBR) on high strength ammonia wastewater was studied.[Method] By means of ICISBR,high strength ammonia wastewater was treated by using corncob as biological carrier,and the effect of C/N and dissolved oxygen(DO) on the removal effect of chemical oxygen demand(COD) and ammonia nitrogen(NH+4-N) were discussed in our paper.[Result] When NH+4-N and DO in effluent water were 200 and 2 mg/L,respectively,the removal effect of COD was not affected obviously whether C/N was 1.0 or 1.5,reaching above 92%;when C/N was 1.5,the average removal rate of COD and NH+4-N were the highest,namely 92.7% and 41.2%,respectively;when C/N was 2.0,the average removal rate of COD and NH+4-N decreased obviously to 20% and 10%;when C/N and NH+4-N were 1.5 and 200 mg/L,DO had little effects on the removal of COD and great effects on the removal of NH+4-N,namely the removal rate of NH+4-N decreased to 17.1% from 46.4% with the reduction of DO concentration from 4 to 1 mg/L.[Conclusion] Our study could provide theoretical basis for the treatment of high strength ammonia wastewater.

Low-temperature conversion of ammonia to nitrogen in water with ozone over composite metal oxide catalyst

As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people＇s attention. Catalytic ozonation technology, which involves production of ·OH radical with strong oxidation ability, is widely used in the treatment of organic-containing wastewater. In this work, MgO-Co3O4 composite metal oxide catalysts prepared with different fabrication conditions have been systematically evaluated and compared in the catalytic ozonation of ammonia（50 mg/L） in water. In terms of high catalytic activity in ammonia decomposition and high selectivity for gaseous nitrogen, the catalyst with MgO-Co3O4 molar ratio 8：2, calcined at 500°C for 3 hr, was the best one among the catalysts we tested, with an ammonia nitrogen removal rate of 85.2% and gaseous nitrogen selectivity of44.8%. In addition, the reaction mechanism of ozonation oxidative decomposition of ammonia nitrogen in water with the metal oxide catalysts was discussed. Moreover, the effect of coexisting anions on the degradation of ammonia was studied, finding that SO2-4 and HCO-3 could inhibit the catalytic activity while CO2-3 and Br-could promote it. The presence of coexisting cations had very little effect on the catalytic ozonation of ammonia nitrogen. After five successive reuses, the catalyst remained stable in the catalytic ozonation of ammonia.