再生水梯级调时絮凝及其参数优化
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摘要
普通的机械搅拌絮凝池各级絮凝时间相同,搅拌强度逐级减弱,称为梯级絮凝。为了探讨各级絮凝时间对絮凝效果的影响,提高絮体的沉降性能,将各级絮凝时间设计为各不相同的形式,并将此种改变絮凝时间的梯级絮凝定义为梯级调时絮凝。基于此絮凝设计思想,以天津市某再生水厂的混凝过程为研究对象,根据絮体分形结构理论对梯级调时絮凝进行了中试研究。结果表明,在速度梯度G逐级减小的常规控制指标基础上,要为各级絮凝阶段配置合理的絮凝时间才能使整个絮凝达到最佳效果。
Cascade flocculation is implemented in ordinary mechanical mixing flocculation tank with constant hydraulic retention time and gradually declined stirring intensity. A cascade time-varying flocculation mechanism was proposed to improve the effectiveness of flocculation,in which the hydraulic retention time was designed to vary among each of the four flocculation tanks. Based on the fractal structure theory of flocs,a pilot-scale study of the cascade time-varying flocculation was carried out at a reclaimed water plant in Tianjin. The results showed that,based on the stepwise decrease of the G value,reasonable allocation of flocculation time at each level was required to achieve the best results for the entire flocculation process.
Cascade flocculation is implemented in ordinary mechanical mixing flocculation tank with constant hydraulic retention time and gradually declined stirring intensity. A cascade time-varying flocculation mechanism was proposed to improve the effectiveness of flocculation,in which the hydraulic retention time was designed to vary among each of the four flocculation tanks. Based on the fractal structure theory of flocs,a pilot-scale study of the cascade time-varying flocculation was carried out at a reclaimed water plant in Tianjin. The results showed that,based on the stepwise decrease of the G value,reasonable allocation of flocculation time at each level was required to achieve the best results for the entire flocculation process.
引文
[1]马媛.再生水混凝机理试验研究[D].天津:天津大学,2013.Ma Yuan.Experimental Research on the Coagulation Mechanism of Reclaimed Water[D].Tianjin:Tianjin University,2013(in Chinese).
[2]Droppo I G,Exall K,Stafford K.Effects of chemical amendments on aquatic floc structure,settling and strength[J].Water Res,2008,42(1/2):169-179.
[3]Bushell G C,Yan Y D,Woodfield D,et al.On techniques for the measurement of the mass fractal dimension of aggregates[J].Advances in Colloid and Interface Science,2002,95(1):1-50.
[4]常颖,张金松,王宝贞,等.基于分形理论的混凝控制研究[J].中国给水排水,2005,21(2):1-5.Chang Ying,Zhang Jinsong,Wang Baozhen,et al.Study on coagulation control based on fractal theory[J].China Water&Wastewater,2005,21(2):1-5(in Chinese).
[2]Droppo I G,Exall K,Stafford K.Effects of chemical amendments on aquatic floc structure,settling and strength[J].Water Res,2008,42(1/2):169-179.
[3]Bushell G C,Yan Y D,Woodfield D,et al.On techniques for the measurement of the mass fractal dimension of aggregates[J].Advances in Colloid and Interface Science,2002,95(1):1-50.
[4]常颖,张金松,王宝贞,等.基于分形理论的混凝控制研究[J].中国给水排水,2005,21(2):1-5.Chang Ying,Zhang Jinsong,Wang Baozhen,et al.Study on coagulation control based on fractal theory[J].China Water&Wastewater,2005,21(2):1-5(in Chinese).