小型生活污水受纳水体浮游植物增长的氮、磷限制研究

为研究生活污水处理后其受纳水体中浮游植物增长的氮磷限制,选取某生活污水处理系统的受纳水体为研究对象,依据我国《城镇污水处理厂污染物排放标准》(GB189182002)一级A标准(氨氮5 mg/L和磷0.5 mg/L)进行氮磷营养盐最高浓度和浓度梯度添加微宇宙实验模拟实验。最高浓度添加实验结果显示N、P双添加的实验组中3d后叶绿素a的浓度显著(P0.05)高于单独添加氮和单独添加磷实验组。因此,氮和磷是被研究水体浮游植物生长的共同限制因子。同时结果还暗示受纳水体接纳处理后的生活污水仍可能会造成浮游植物在短期内剧烈增长。浓度梯度添加实验结果显示,将磷控制在0.27 mg/L或者将氮控制在1.0 mg/L以下,可以有效降低被研究水体浮游植物的增长。据此可以进一步严格生活污水处理后的排放标准以降低受纳水体水华的风险。

STUDY OF THE PHYTOPLANKTON GROWTH LIMITED BY N AND P IN A SMALL DOMESTIC SEWAGE-RECEIVING WATER BODY

In order to study the nitrogen and phosphorus limitation of algal blooms caused by domestic sewage treatment in the receiving water body. This study selected a receiving water body of a domestic sewage treatment system and conducted a highest and a gradient nutrient adding experiment. The highest concentrations of nitrogen and phosphorus were based on level A (ammonia nitrogen of 5 mg/L and phosphorus of 0.5 mg/L) in discharge standard of pollutants for municipal wastewater treatment plant in China (GB18918-2002). The highest addition experiment showed that chlorophyll a was significantly (P0.05) higher in the nitrogen and phosphorus addition group (+N, +P) than that in the single nitrogen addition group (+N) and single phosphorus addition group (+P) on the third day. And it indicated that both nitrogen and phosphorus were the limiting factors for algal growth in the studied water. The results also suggested that there was still a risk of algal bloom in the water body receiving treated domestic sewage in the short term. The gradient nutrient addition experiment showed that phosphorus should be below 0.27 mg/L or nitrogen should be below 1.0 mg/L to inhibit the growth of phytoplankton in the studied water. According to this nutrient value, a more strict discharge standard should be demanded to reduce the risk of algal blooms.