芦苇不同部位作为碳源对人工湿地脱氮除磷效果的影响

Effect of Adding Different Parts of Reed as Plant Carbon Source on Nitrogen and Phosphorous Removal in Constructed Wetland

针对人工湿地中有机碳源不足造成脱氮效率较差的问题,寻找更高效的植物碳源以改善人工湿地内部碳氮比低的状况。通过试验比较芦苇穗(芦穗)、芦苇茎(芦茎)和芦苇根(芦根)3个部位在不同预处理方式下的静态释放规律,筛选出最佳的植物碳源,并通过小试人工湿地试验分析其作为植物碳源对脱氮效果的影响。分析结果表明:碱热处理能够提高COD释放量,相较其它预处理方式,其最大COD释放浓度提高10%,并提前释放一部分氮类化合物和含磷化合物;芦穗碱热处理初期COD释放量达到各部位中的最高值182.00 mg/L;从144 h内的平均TN释放量来看,芦穗碱热处理(6.16 mg/L)>芦根碱热处理(4.21 mg/L)>芦茎碱热处理(2.99 mg/L),芦茎释放量最少,比芦穗少一半以上;经过碱泡、碱热处理后,TN、TP、NH^(+)_(4)-N、NO^(-)_(3)-N和NO^(-)_(2)-N释放量均小于简单处理。碱热处理后的芦苇茎是最佳植物碳源,具有较强的持续释碳能力,并且对氮、磷积累的影响最小;在小试人工湿地系统中添加碱热处理后的芦茎在不显著提高系统出水COD前提下,显著提高了TN和TP的去除率,相对对照组分别提高了61.14%和32.53%,达到同步强化脱氮除磷的效果。

The lack of organic carbon in constructed wetlands leads to low efficiency of nitrogen removal.The aim of this research is to find a more efficient plant carbon source to improve the C/N ratio in constructed wetland.The optimum plant carbon source was selected according to the static carbon release of the fringe of reed,stem of reed and root of reed subject to different pretreatments,and the effect of plant carbon source on nitrogen removal was analysed by bench-scale constructed wetland experiment.Compared with other pretreatment methods,alkali-heat treatment(AHT)could boost Chemical Oxygen demand(COD)release by 10%,and release some nitrogen and phosphorus compounds ahead of time;the highest COD release of fringe of reed reached 182.00 mg/L in the early stage of AHT.Moreover,the average TN release in 144 hours of fringe of reed after AHT(6.16 mg/L)was larger than those of root of reed after AHT(4.21 mg/L)and stem of reed after AHT(2.99 mg/L)in sequence.The TN release of stem of reed was the smallest,more than half smaller than that of fringe.The releases of TN,TP,NH^(+)_(4)-N,NO^(-)_(3)-N and NO^(-)_(2)-N of reed treated by alkali soaking and AHT were all smaller than those by simple treatment.Alkali-heat treated stem of reed has strong persistent carbon releasing capability and minimal impact on nitrogen and phosphorus accumulation,hence was chosen as the optimum plant carbon source.By adding alkali-heat treated stem of reed,the denitrification and dephosphorization capabilities of constructed wetland both enhanced markedly in the meantime of increasing inconspicuously the COD in system effluent.The average removing rates of TN and TP augmented by 61.14%and 32.53%,respectively,compared with those of control group.