不同碳源添加量对垂直流人工湿地污水处理效果的影响

以垂直流人工湿地小试系统为研究对象,采用碱处理过的千屈菜(Lythrum salicaria)作为反硝化碳源补充材料,探讨了不同碳源添加量对系统COD及氮、磷去除效果的影响。结果表明,一定剂量经过碱处理的千屈菜材料可以为人工湿地系统脱氮提供反硝化所需要的碳源,而且具有缓效持续释放的特点。添加此碳源材料可明显提高系统的脱氮效率,最高可提升30.85%,但随着C/N比的增加,硝态氮去除率逐渐降低,C/N比为3、5、8时分别为91.20%、87.72%和84.19%。添加碳源量达到C/N比为3时系统能够发生最大程度反硝化,此时不仅人工湿地系统脱氮效果得到提高,同时人工湿地除磷能力也有所增强。碱处理过的千屈菜材料在本系统中的最适宜添加量为5 g,即100 g/m2(C/N=3),远低于在进水中为满足反硝化所需调控的C/N比(5～8),可以节约外加碳源成本。

Impact of solid carbon sources supplement amount on performance of wastewater treatment effect in vertical-flow constructed wetland

Taking alkali-treated Lythrum salicaria as supplementary carbon for denitrification, we studied the effect of different supplementary solid carbon amount on removal efficiency of COD, nitrogen and phosphorus in small-scale vertical flow constructed wetland. The results showed that proper amount of alkali-treated Lythrum salicaria could not only act as suitable carbon sources needed for denitrification, which could obviously improve the removal efficiency of nitrogen in the system, with a maximum removal efficiency of 30.85%, but also had a characteristic of slow and lasting releasing. The removal efficiency of nitrate nitrogen decreased with the improvement of C/N ratio. When C/N ratios were 3, 5 and 8, the removal efficiencies were 91.20%, 87.72% and 84.19%, respectively. With a C/N ratio of 3, the maximum denitrification could be achieved, the removal efficiency of nitrogen could be improved, and the removal efficiency of phosphorus could also be increased. The optimum supplementary amount of alkali-treated Lythrum salicaria was 5 g (C/N=3) in this system, that is 100 g per square meter. This amount is much lower than the amount needed to add to the influent (C/N=5~8). Therefore, alkali-treated Lythrum salicaria could be selected as a kind of economic supplementary carbon source.