城市污水再生处理过程中臭氧氧化脱色及稳定性研究

Decoloration and stability by ozonation for municipal wastewater reclamation

针对城市污水再生处理臭氧氧化脱色效果及稳定性开展了相关研究.结果表明,臭氧氧化处理可以有效降低二级出水的表色与真色.在自然条件模拟过程中,不同臭氧投加量的水样22 d后真色并没有明显变化,表色、叶绿素a和浊度变化呈现出良好的一致性.当臭氧投加量小于6 mg·L-1时,水样表色在12 d内缓慢增加,之后快速上升直至22 d后达到最大.低剂量的臭氧处理(小于6 mg·L-1)反而会促进藻类的繁殖,加剧水体色度的不稳定性.然而,当臭氧投加量大于8 mg·L-1时,可以明显延长水样的复色时间,表色在18 d后才略微上升.水体的色度和浊度变化主要由藻类的生长和繁殖引起的,高的臭氧剂量能够维持水体色度稳定性.因此,推荐城市污水再生处理过程臭氧投加量为8 mg·L-1.

Ozonation decoloration and its stability in municipal wastewater reclamation were investigated in this study. The results indicated that both surface color and true color could be effectively reduced by ozonation treatment. No obvious variation in true color for all samples treated at different ozone dosages was observed under 22-day simulation in natural conditions,while change in surface color,turbidity and concentration of chlorophyll a showed a very similar pattern. When the dosage of ozone was less than 6 mg·L-1,slow increase occurred within 12 days followed by a rapid rise of surface coloruntil22 days. It was noted that decoloration treatment at low ozone dosages( <6 mg·L-1) facilitated growth and reproduction of algae,resulting in deterioration of chroma stability. However,when the dosage of ozone increased to more than 8 mg·L-1,the color reappearance could be significantly extended and only a slight increase of surface color was detected after standing for 18 days. The change in chroma and turbidity was mainly caused by growth and reproduction of algae,and increasing the dose of ozone could improve chroma stability of reclaimed water. Therefore,the ozone dose of 8 mg·L-1was recommended in municipal wastewater reclamation treatment process.