不同级配基质方式下垂直流人工湿地净化效果及渗透性能研究

本研究设置了基质正、反级配垂直流人工湿地,通过测定系统对CODCr、TN、TP、NH4＋-N等指标的去除效率、有效孔隙率和渗透系数的变化来比较两种级配方式下垂直流人工湿地净化效果和系统渗透性能。结果表明,两种级配方式下,垂直流湿地系统对污染物去除的综合效果优于单一粒径的无烟煤湿地系统;反级配系统在除磷方面存在优势,正级配系统在CODCr去除方面显著强于反级配系统,在脱氮方面两者不存在显著性差异;反级配系统的有效孔隙率在各层的降幅变化不大,而正级配系统表层及上层有效孔隙率的降幅显著大于中层和底层;正级配系统渗透系数的变化显著高于反级配系统,且出现了持续性表面滞水现象。以上结果均表明,反级配垂直流湿地系统可以在保证净化效率的同时,缓解湿地基质堵塞,有效延长基质的使用寿命。

Treatment Efficiency and Permeability of Vertical Flow Constructed Wetland in Different Gradation Substrates

When constructed wetlands（CWs）were applied in the sewage treatment,the clogging of the substrates appeared to be the crucial limited factor.Therefore,anti-graded system was proposed.This paper presented a comparative study on the treatment efficiency of some main pollutants including CODCr,TN,TP,NH4＋-N and the permeability between progressively-graded and anti-graded vertical flow constructed wetland system.The results showed that in the two gradations,the comprehensive effects to main pollutants were significantly higher than that of the system which was filled with single size anthracite.The progressively-graded system showed better performance in the removal of CODCr,while anti-graded system in the removal of TP.As for the removal of N,there was no significant difference between the two systems.The depressed extents of available porosity rate in different layers of the anti-graded system were similar.While in the progressively-graded system,the depressed extents of available porosity rates in surface and upper layers were significant higher than those in middle and bottom layers.Variation of penetration coefficient in the progressively-graded system which appeared the upper backwater for a long time was obviously greater than that in the anti-graded system.These results indicated that the anti-graded system had advantages to slow down the clogging,prolong the longevity of the substrates in CWs,as well as maintaining higher removal efficiency.