Dynamic model validation and advanced polymer control for rotating belt filtration as primary treatment of domestic wastewaters

Rotating belt filters are a primary treatment technology currently used in municipal wastewater treatment plants as a high-rate alternative to primary clarifiers. Such systems are reported to efficiently remove particulates in the form of total suspended solids, achieving the highest removal efficiencies (>60%) when polymer is added as pre-treatment step. In this paper, a new dynamic model describing the RBF performance is presented. The model includes the dynamic effects of influent flow rate and TSS concentration and can also describe the effects of polymer dosing on RBF performance. The validated model was used to perform a plant-wide impact assessment using the Benchmark Simulation Model n.2. For a TSS removal efficiency that is identical to primary clarifiers (50%), rotating belt filters were found to only slightly decrease the aeration energy demand in the activated sludge unit (−0.5%), while increasing methane production and slightly increasing effluent TN concentrations (+1.5% and +1.9%, respectively). Furthermore, considerable savings in polymer costs could be attained using an advanced control strategy for polymer dosing, successfully tested in this work.