长沙市洋湖人工湿地冬季去污效果与植物效应

The decontamination effect and plant effect of Yanghu constructed wetland in Changsha city in winter

【目的】为了更好地研究人工湿地,进一步了解人工湿地的冬季去污效果,更科学的开展污水处理厂尾水的净化工作。【方法】对洋湖人工湿地2019年12月的水质和植物进行采样分析。【结果】1)洋湖人工湿地系统中植物生物量变化为一级人工湿地>二级人工湿地>三级人工湿地;人工湿地中植物茎叶和根部分的氮的比值均大于1,说明植物吸收的氮能较多的向茎叶部分迁移,有利于植物吸附这部分氮。人工湿地中植物茎叶和根部分的磷的比值均小于1,说明植物吸收的磷较多的停留在根部,没有向茎叶转移;2)植物污染物去除量与人工湿地污染物去除量有正相关关系,且一级人工湿地冬季对氮磷去除率最高,随后递减;3)洋湖人工湿地系统对污水处理厂尾水的净化效果很好,总氮、总磷、COD、硝态氮均呈现下降趋势。溶解氧和pH值达到《地表水环境质量标准》(GB3838—2002)Ⅰ类水的标准。总磷、总氮、氨氮和COD达到《城镇污水处理厂污染物排放标准》(GB18918—2002)一级A。亚硝酸盐氮达到《渔业水质标准》(GB11607—89)。硝酸盐氮达到《生活饮用水卫生标准检验方法》(GB/T 5750—2006)。电导率达到《生活饮用水卫生标准》(GB5749—2006)。【结论】1)从植物氮磷积累量来看,可以通过收割人工湿地中植物的茎叶来达到去除氮磷的目的,植物茎叶部氮磷含量越高越有利于通过收割植物去除氮磷,定期收割植物可以部分提高水质净化效果;2)污水处理厂尾水经过洋湖人工湿地后,水质逐渐提升。

【Objective】This work was designed to comprehensively study the constructed wetland and discover its decontamination effect in winter,to carry out the purification of the sewage tailwater of the treatment plant more scientifically.【Method】In this study,the water and plants from Yanghu constructed wetland were collected in December 2019 as the experimental materials,which were then analyzed in the lab with physical and chemical indicators.【Result】1)The variation of plant biomass in the three-level constructed wetland(CW1,CW2 and CW3)system was CW1>CW2>CW3;the ratios of nitrogen in the stems,leaves and roots of plants were all greater than 1,indicating that the nitrogen absorbed by plants migrated more to the stem and leaf parts,which was conducive to the absorption of nitrogen by plants.The ratios of phosphorus in the stem,leaf and root parts of plants were all less than 1,which indicated that the phosphorus absorbed by plants stayed in roots rather than transferring to stems and leaves.2)There was a positive correlation between the removal amount of plant pollutants and the removal amount of constructed wetland pollutants,and the removal rate of nitrogen and phosphorus in CW1 was the highest in winter,and then decreased.3)This system had a good purification effect on the tailwater of the sewage treatment plant,and the total nitrogen,total phosphorus,COD and nitrate nitrogen all showed a downward trend.The dissolved oxygen and pH met the standards of class I water in“the surface water environment quality standard”(GB3838—2002).The total phosphorus,total nitrogen,ammonia nitrogen and COD have reached grade A of“pollutant discharge standard for urban wastewater treatment plant”(GB18918—2002).The nitrite nitrogen content met the“fisheries water quality standard”(GB11607—89).The nitrate nitrogen content met the“Hygienic standard test method for drinking water”(GB/T 5750—2006).The conductivity reached the“drinking water sanitation standards”(GB5749-2006).【Conclusion】1)From the perspective of plant nitrogen and phosphorus accumulation,harvesting the stems and leaves of plants in constructed wetlands can achieve the purpose of removing nitrogen and phosphorus.The higher the nitrogen and phosphorus content in the stems and leaves of plants,the more beneficial it is to remove nitrogen and phosphorus by harvesting plants.Regular harvesting of plants can partially improve the water purification effect.2)The water quality is gradually improved after the tailwater of the sewage treatment plant passes through the Yanghu constructed wetland.