水生植物类型及生物量对污水处理厂尾水净化效果的影响

Influence of aquatic plant types and biomasses on purification effects of tail water of wastewater treatment plant

为阐明水生植物类型和生物量对污水处理厂尾水净化效果的影响,选取空心菜(Ipomoea aquatica Forsk)、苦草(Vallisneria natans L.)、粉绿狐尾藻(Myriophyllum aquaticum)3种水生植物对宜兴市周铁镇污水处理厂尾水进行净化。实验对不同植物分别设置4个生物量梯度以及无植物的对照组,考察不同植物和生物量对尾水净化效果的影响。结果表明:不同植物对污水处理厂尾水净化效果存在差异,总氮净化效果(30 d)受植物类型影响显著(P<0.05)。粉绿狐尾藻对总氮和硝氮净化效果(30 d)最好,分别为95.28%和98.50%;苦草对氨氮和总磷净化效果(30 d)最好,分别为95.30%和95.80%,且苦草生长有利于降低亚硝氮的产生量。不同生物量对尾水净化效果影响较小,空心菜、苦草和粉绿狐尾藻去除总氮的最佳生物量分别为157.50、460.80和1 120.00 g,去除总磷的最佳生物量分别为157.50,609.40和590.00 g。不同生物量对空心菜生长存在影响,高空心菜生物量到后期会衰败,而低生物量处理组在实验周期内持续生长,造成高生物量净化效果低于低生物量,建议使用空心菜净化污水时,使用低生物量处理,且在其达到最大生物量(610.00~880.00 g)之前进行收割。

In order to elucidate the influence of aquatic plant types and biomasses on purification effects of tail water of wastewater treatment plant, three species of aquatic plants, including Ipomoea aquatica Forsk, Vallisneria natans L. and Myriophyllum aquaticum were selected to purify the tail water of wastewater treatment plant in Zhoutie town,Yixing city, China. A total of 4 biomass gradients and a control without plants for each aquatic plant were set up to study the influence of different aquatic plants and biomasses on the tail water purification. The results showed that the purification effects were different among the aquatic plants, and the removal rate of TN（30 d） was significantly affected by the type of aquatic plants（P〈0.05）. The removal effect of TN and NO_3^--N by Myriophyllum aquaticum（30 d） was the highest, which were 95.28% and 98.50%, respectively, while the removal effect of TP and NH_4^＋-N by Vallisneria natans L.（30 d） was the highest, which were 95.30% and 95.80%, respectively. The growth of Vallisneria natans L. was benefit for reducing the production of NO_2^--N. The removal rate was slightly influenced by the biomass of aquatic plants. The most appropriate biomasses of Ipomoea aquatica Forsk, Vallisneria natans L. and Myriophyllum aquaticum to remove TN were 157.50, 460.80 and 1 120.00 g, respectively, and to remove TP were 157.50, 609.40 and 590.00 g, respectively. The biomass influenced the growth of Ipomoea aquatica Forsk.The high biomass resulted in the decline and death of plants in the later phase of experiments, while the plants with relatively low biomass maintained a better growth state. As a result, the purification effect of high biomass was better than the low biomass. It is suggested that the low biomass of Ipomoea aquatica Forsk should be used, and it is also necessary to harvest before they grow up to the highest biomass（610.00 to 880.00 g）.