浓缩湖泊蓝藻液的加压混凝沉淀处理

Treatment of coagulation and sedimentation about concentrating Lake's cyanobacteria after being pressured

为了提高蓝藻液浓缩效率,降低能耗,采用外加压力压破蓝藻气囊,使蓝藻失去气囊浮力易于混凝沉淀分离。采用中试实验研究了加压混凝浓缩蓝藻液的技术方法,优化了工艺参数,并进行了经济分析。结果表明,在原藻液含水率99.4%~99%时,最佳的混凝剂(PAC)投加量与干藻质量比为1/20,最佳的助凝剂(PAM)投加量与干藻质量比为1/1 500。浓缩后出水浊度在1~5 NTU之间,出水叶绿素a在10 mg·m^(-3)以内,浓缩藻泥含水率都小于97%,原藻液浓缩了3.52~5.51倍。加压破蓝藻气囊能耗0.008 k W·h·m^(-3),比现有高速旋转法破蓝藻气囊工艺节省能耗0.6 k W·h·m^(-3)。

To improve the efficiency of producing concentrated cyanobacteria and reduce energy consumption,applied pressure can be used to crush cyanobacteria balloons,and the cyanobacteria will lose buoyancy to enable isolation,coagulation,and sedimentation. A pilot experiment was conducted to study the technique and methods,and to optimize the process＇ parameters and analyze its economic cost. The results show that,when the moisture content in the original algae is 99. 4% to 99. 0%,the optimum dosage of coagulant（ PAC） on dry algae is 1/20,and the optimum dosage of flocculant（ PAM） on dry algae is 1/1 500. At this dosage,water turbidity is 1—5 NTU,chlorophyll-a in the water is less than 10 mg·m^-3,cyanobacteria mud moisture content is less than 97%,and the original algae-water is concentrated 3. 52 to 5. 51 times. Energy consumption of the process is 0. 008 k W·h·m^-3,which is far less than the energy consumption of the existing high-speed rotation process of 0. 6 k W·h·m^-3.