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Aluminum Sludge thickening: Novel helical pipes for aggregation by dual flocculation and thickening by filtration applied to water treatment plants
Separation and Purification Technology ( IF 8.1 ) Pub Date : 2020-01-14 , DOI: 10.1016/j.seppur.2020.116560
Manoel Maraschin , Keila Fernanda Soares Hedlund Ferrari , Andressa Paolla Hubner da Silva , Elvis Carissimi

There are significant challenges associated with sludge treatment in water treatment plants (WTP). Treatment aims to remove water that makes up the sludge, and consists of three consecutive steps: suspension flocculation, thickening and drying. In this study, the flocculation of the sludge was the main objective, and it was evaluated through a novel Helical Tubular Flocculator (HTF) followed by a static thickener. The study explored the mechanisms involved with the flocculation process, by tracing the sludge characteristics, from the study of hydraulic and hydrodynamic parameters performed in HTF units. The sludge used in this study was sampled in settling basins of a conventional WTP with a total solid concentration (TS) of 5 g.L-1, due to the dilution with tap water. Regarding the conditioning with flocculant polymers, two mechanisms were evaluated. First, cationic polymer conditioning in a dosage of 15 mg in (gTS) -1. Second, dual flocculation, with the implementatin of cationic and anionic polymers at a dosage of 4 mg in (gTS) -1 each one. The studies involving dimensional parameters of the tested HTFs demonstrated that the best configuration of the unit presented 12 m of flexible tubing with an inner diameter of 1.25 cm wrapped in a 10 cm PVC pipe, operating at a flow rate of 3 L.min-1. Under these optimal conditions, the dual flocculation mechanism had advantages over single polymer flocculation. As a result, it was possible to reduce, approximately, 50% of the total volume of polymers prepared from the same concentration, maintaing the flocs formation. The application of polymers and the use of this helical hydraulic mixing enabled a compact thickening unit that has had great potential for industrial application. Results showed that the helical flocculator presented residual turbidity in the clarified water, after sedimentation, up to ten times lower (8.5 UNT) than that registered by the mechanical mixing, maintaining similar hydraulic and hydrodynamic patterns. The sludge thickening was evaluated by filtration, after flocculation, through a static thickener constructed. Results showed a high concentration of solids, and it was possible to record concentrations higher than 18%, from the sludge at the initial concentration of 0.5%. The data showed the high performance of the helical flocculator in the treatment of WTP wastes by aggregation with high solids content, as well as the thickening by filtration in the static thickener, and it validated a compact treatment process applicable to sludge.



中文翻译:

铝污泥增稠:适用于水处理厂的新型螺旋管,通过双重絮凝进行聚集,并通过过滤增稠

在水处理厂(WTP)中,污泥处理面临着巨大的挑战。处理的目的是除去构成污泥的水,该过程包括三个连续步骤:悬浮液絮凝,浓缩和干燥。在这项研究中,污泥的絮凝是主要目标,并通过新型螺旋管式絮凝器(HTF)和静态增稠剂对其进行了评估。该研究通过追踪HTF装置中的水力和水动力参数,通过追踪污泥特性,探索了与絮凝过程有关的机制。本研究中使用的污泥在常规WTP的沉降池中取样,总固体浓度(TS)为5 gL -1,由于用自来水稀释。关于用絮凝剂聚合物进行的调理,评估了两种机理。首先,在(gTS)-1中以15 mg的剂量调节阳离子聚合物。第二,双重絮凝,阳离子和阴离子聚合物的实现素的剂量分别为(gTS)-1中的4 mg 。涉及测试的HTF尺寸参数的研究表明,该装置的最佳配置是将12 m挠性管包裹在10 cm PVC管中,内径为1.25 cm,流速为3 L.min -1。在这些最佳条件下,双重絮凝机理优于单一聚合物絮凝。结果,可以减少由相同浓度制备的聚合物的总体积的约50%,以维持絮凝物的形成。聚合物的应用和这种螺旋液压混合的使用使得紧凑的增稠装置具有了工业应用的巨大潜力。结果表明,螺旋絮凝器在沉淀后的澄清水中残留的浊度比机械搅拌所记录的低(8.5 UNT)十倍,保持了相似的水力和水动力模式。絮凝后,通过构造的静态增稠器过滤,评估污泥的增稠。结果显示出高浓度的固体,在初始浓度为0.5%时,可以从污泥中记录高于18%的浓度。数据表明,螺旋絮凝器在高固体含量的聚集作用下处理WTP废物的性能很高,并且在静态增稠剂中通过过滤增稠,证明了紧凑的处理工艺适用于污泥。

更新日期:2020-01-15
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