流速对再生水补水的景观水体藻类水华的影响

Effect of Flow Velocity on Algal Bloom in Landscape Water Replenished with Reclaimed Water

藻类水华一直是制约再生水景观水体利用的瓶颈,改善水动力条件是控制藻类生长的有效方法之一。在识别出典型再生水补水水体优势藻种类别(水华微囊藻、普通小球藻、四尾栅藻)基础上,分析流速(0、0.05、0.1、0.2 m/s)对模拟配水和实际再生水中3种优势藻种生长状况的影响。结果表明,当流速为0~0.05 m/s时,表现为促进藻类生长,优势流速为0.05 m/s;当流速≥0.1 m/s时,表现为抑制藻类生长,3种优势藻种的藻密度在10 d内可下降80%以上,叶绿素a(Chl-a)浓度从180~200 mg/m^(3)左右均降至35 mg/m^(3)以下;当流速增加至0.2 m/s时,水体中的藻密度和Chl-a浓度在第9天便无法检出。所以,水体流速控制在0.1 m/s以上时,可以有效控制以再生水补水的水体中水华的发生。

Algal bloom has always been a bottleneck restricting the application of reclaimed water in landscape water,and improving hydrodynamic conditions is one of the effective methods to control algal growth.Based on the identification of dominant algal species(Microcystis aquatica,Chlorella vulgaris and Tetraodontophora)in a typical water body replenished with reclaimed water,this paper analyzed the effects of flow velocity(0,0.05 m/s,0.1 m/s,0.2 m/s)on the growth of the three dominant algal species in simulated water and actual reclaimed water.When the flow velocity was in the range of 0-0.05 m/s,the algal growth was promoted,and the dominant flow velocity was 0.05 m/s.When the flow velocity was no less than 0.1 m/s,the growth of algae was inhibited,the algal density of the three dominant algal species decreased by more than 80%within 10 days,and the concentrations of chlorophyll a(Chl-a)decreased from approximately 180-200 mg/m^(3)to below 35 mg/m^(3).When the flow velocity was increased to 0.2 m/s,the algal density and Chl-a concentration in the water could not be detected on day 9.Therefore,the occurrence of algal bloom in the water body replenished with reclaimed water could be effectively controlled when the water flow velocity was controlled above 0.1 m/s.