To ensure the water quality in long distance pipeline transportation

the influence of dissolved oxygen (DO) on water quality and recovery process after aeration oxygenation were studied in a pipeline reactor that could simulate this long distance pipeline transportation. The results showed that the decrease of DO could reduce the removal of ammonia nitrogen (NH4+-N)

and the lower DO concentration was the more unfavorable removal of NH4+-N

the slower recovery after aeration oxygenation was. The removal rate of NH4+-N declined from 90% to 21% and 85% after reactor run 95 h at DO=0.5 mg·L-1 and 1.5 mg·L-1

and the recovery after aeration oxygenation took 54 h and 3 h respectively. The accumulation of nitrite nitrogen (NO2--N) increased significantly as DO reduced

and the lower DO concentration was the more favorable accumulation of NO2--N

the slower recovery after aeration oxygenation was. At DO=0.5 mg·L-1 nitrite nitrogen increased from 0.02 mg·L-1 to 0.354 mg·L-1 after reactor run 95 h

and the recovery after aeration oxygenation took 54 h. While the maximum value of nitrite nitrogen was 0.112 mg·L-1 after reactor run 32 h at DO=1.5 mg·L-1

and the recovery after aeration oxygenation took only 4 h. The decrease of DO concentration could lead to rise of UV254. UV254 increased by 70.8% and 20.8% after reactor run 2 h at DO=0.5 mg·L-1 and 1.5 mg·L-1

respectively

and both recovery took 32 h

and then it was relatively stable after aeration oxygenation. Therefore

DO is of important impact on water quality in long distance pipeline transportation

and could used for the regulation of water quality.