营养物质和藻类在再生水制取及景观水体补给中的变化

Changes of nutrient and algae in the production of reclaimed water and the supply of landscape water

通过实际监测了再生水处理单元中营养物质及藻生物量的沿程变化,探讨了其相关性,并以满足景观水体水质要求的再生水进行了静态模拟试验研究,分析了氮、磷在水华形成过程中的演变规律.结果表明,再生水制取过程中,絮凝-沉淀对进水中的无机氮磷、藻密度和叶绿素a的去除发挥着主要作用,其中对进水中藻密度和叶绿素a的去除率分别为72.29%和77.68%,出水中二者均值分别为4.44×10~3 cells/mL和5.97μg/L;沿程的藻密度和叶绿素a与NH_4^+-N、PO_4^(3-)-P和TP呈显著正相关(相关系数r>0.80).模拟试验证明,在炎热的夏季,再生水静置4d时,藻华爆发,优势藻主要为小球藻,藻密度和叶绿素a浓度分别可达8.08×10~5 cells/mL和81.73μg/L,为原水的27.76倍和5.10倍,因此,为有效降低景观水体藻类暴发增长的风险,景观回用的再生水静止停留时间不宜超过3d.所得结论对城镇污水厂再生水回用景观水体水质目标控制具有实用价值.

The changes of nutrients and algae concentration in the process of traditional reclamation treatment were monitored firstly and the correlation between them was discussed in this paper.Then,a static simulation test was conducted to reveal the evolution of nitrogen,phosphorus and algae with reclaimed water meeting the water quality standard for landscape reuse.The results showed that flocculation-precipitation played a major role in the removal of inorganic nitrogen and phosphorus,algal density and chlorophyll a during the process of reclaimed water preparation,which the removal rates of algae density and chlorophyll a were 72.29%and 77.68%respectively,and the average values of both them in the effluent were 4.44×10 3 cells/mL and 5.97μg/L,respectively.Meanwhile the algal density and chlorophyll were positively correlated with NH+4-N,PO 3-4-P and TP r>0.80.The simulating test showed that the algae density dominated by Chlorella vulgaris and chlorophyll a were up to 8.08×10 5 cells/mL and 81.73μg/L,which were 27.76 and 5.10 times of those in raw water,when the residence time of reclaimed water was 4 days in summer.Hence,in order to reduce the risk of algal outbreaks effectively,the residence time of reclaimed water for landscape reuse should not exceed 3 days.This conclusion is of important application value for controlling the reclaimed water quality of landscape reuse in the company dealing with wastewater treatment and reuse.