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 implementation 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, maintaining 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.