某水厂水源水及不同阶段处理水藻密度的调查

Algae Densities in Source Water and Water at Different Treatment Processes of a Water Plant

[目的]了解海口某水厂水源水及不同处理阶段水的藻密度,及其与水质理化、感官指标的相关性,为集中式供水藻类预防及控制提供依据。[方法]于2013年4—5月,对海口市某水厂水源水藻密度、pH、温度、硝酸盐氮、氨氮、正磷酸盐、浑浊度和色度进行检测,同期检测该厂不同处理阶段(集水槽和滤后)水质藻密度,计算藻类去除率。对上述指标进行Pearson相关分析。[结果]该水厂水源水的藻密度为(5.47±1.69)×106个/L、浑浊度为(7.33±0.23)NTU、色度为(18.24±0.22)度,氨氮为(0.16±0.04)mg/L,硝酸盐氮为(0.46±0.13)mg/L,正磷酸盐为(0.02±0.01)mg/L,pH为7.48,温度为26.8℃。集水槽和滤后水藻类密度分别为(1.15±0.95)×106个/L和(0.81±0.06)×106个/L,出厂水藻密度为1.10×105个/L。水处理过程中去除率分别为:藻密度85.2%、浑浊度83.2%、色度75.4%。源水藻密度与色度、温度成正相关(P<0.05),与正磷酸盐含量呈负相关性(P<0.05)。蓝藻门藻密度与硝酸盐氮含量呈正相关(P<0.05)。[结论]该水厂水源水藻密度较高,并与色度、温度呈正相关,蓝藻密度与硝酸盐氮呈正相关,需关注硝酸盐氮污染对有毒藻的促生长作用。

[ Objective ] To examine algae densities and their associations with selected physiochemical and sensory indicators in source water and water samples at different treatment processes, and to provide basis for control and prevention of algae pollution in centralized water supply. [ Methods ] Algae density, pH, temperature, nitrate nitrogen, ammonia nitrogen, orthophosphate, turbidity, and chromaticity in source water were measured, and the algae densities in water at two treatment processes （water collecting sump and after filtration） were also measured to calculate the removal rates of various pollutants in a water treatment plant from April to May 2013. Pearson correlation analyses were performed. [ Results ] The selected indicators evaluated for the source water were （5.47 ± 1.69） × 106/L for algae density, （7.33 ± 0.23）NTU for turbidity, 18.24 ± 0.22 for chromaticity, （0.16 ± 0.04）mg/L for ammonia nitrogen, （0.46 ± 0.13）mg/L for nitrate nitrogen, （0.02 ± 0.01）mg/L for orthophosphate, 7.48 for pH, and 26.8~C for temperature. The algae density in the water collecting sump, the filtrated water, and the finished water was （1.15 ± 0.95）× 106/L, （0.81 ± 0.06）× 106/L, and 1.10 × 10 5/L, respectively. The removal rates were 85.2% for algae density, 83.2% for turbidity, and 75.4% for chromaticity, respectively. The algae density in source water was positively associated with chromaticity and temperature （P 〈 0.05）, and negatively with orthophosphate （P 〈 0.05）. The density of cyanophyceae and nitrate nitrogen were positively associated （P〈0.05）. [ Conclusion ] The algae density is high in the source water of the selected water plant, and is positively associated with chromaticity and temperature. Moreover, the density of cyanophyceae and nitrate nitrogen is also positively correlated. Effects of nitrate nitrogen pollution on the growth of toxic algae should be a concern.