蓝藻泥流变学性质与压滤脱水性能的关系

Relationship between Rheological Properties and Press Filter Dewatering Performance of Cyanobacteria Sludge

蓝藻泥由于富含荚膜多糖类有机质而导致其压滤脱水性能较差且后续处理成本居高不下.采用滤饼比阻(SRF)作为压滤脱水性能的评估指标,分析了不同絮凝剂种类、絮凝剂投加量、温度、pH下蓝藻泥的压滤脱水性能与流变学参数的关系,以期利用流变学性质指导蓝藻泥的压滤脱水过程.结果表明:蓝藻泥温度升至80℃且在不加絮凝剂的情况,可以使蓝藻的压滤脱水性能接近于常温絮凝(藻泥干物质质量分数3%的聚合氯化铝)后的压滤脱水性能.从流变学角度分析,蓝藻泥是一种拟塑性流体,降低含固率、降低pH、升高温度、加入絮凝剂都可以使蓝藻泥的弹性模量和黏性模量降低,从而改善其压滤脱水性能.蓝藻泥的滤饼比阻与其流变学参数〔稠度系数(K)和复数模量(|G^(*)|)〕具有显著线性相关关系,利用方程SRF=9.18×10^(11)×K+6.70×10^(12)和SRF=8.43×10^(10)×(|GG^(*)|)+4.99×10^(12)可描述蓝藻泥流变学性质与压滤脱水性能的关系.研究显示,利用流变学性质与滤饼比阻的关系方程指导实际压滤生产具有可行性,可为利用流变学性质指导实际压滤生产提供依据.

Cyanobacteria sludge has low press filter dewatering performance and high cost of subsequent treatment because it contains high content of organic matter such as capsular polysaccharides.The cake specific resistance was used as the evaluation index of press filter dewatering performance.The relationship between press filter dewatering performance and rheological parameters of Cyanobacteria sludge was investigated by adding flocculant under various conditions,so as to guide the press filter dewatering process of Cyanobacteria sludge by using the rheology analysis method.When the temperature of Cyanobacteria sludge increased to 80℃,the press filter dewatering performance of Cyanobacteria sludge without flocculant was similar to that of room temperature press filter dewatering process containing 3%(w)polyaluminum chloride.From the perspective of the rheology,Cyanobacteria sludge was a pseudoplastic fluid.The elastic modulus and viscous modulus of Cyanobacteria sludge could be reduced by reducing the Cyanobacteria sludge concentration,decreasing pH,increasing temperature and adding flocculant to improve the press filter dewatering performance.The cake specific resistance of Cyanobacteria sludge was significantly linearly correlated with its rheological parameters(consistency index(K)and complex modulus(|G^(*)|)),indicating that the relationship between the rheological properties of Cyanobacteria sludge and the press filter dewatering performance could be described by the equations(SRF=9.18×10^(11)×K+6.70×10^(12) and SRF=8.43×10^(10)×(|G^(*)|)+4.99×10^(12)).The rheological properties of Cyanobacteria sludge could reflect the press filter dewatering performance of Cyanobacteria sludge under certain conditions,and it was feasible to guide the practical press filter dewatering process.