Modelling and optimization of rotating belt filter for wastewater treatment

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Removal of suspended solids from municipal wastewater during primary treatment processes is critical for efficient operation of wastewater plants with minimal environmental impact. By removing the fraction of solids that can be readily settled or removed by physical mechanisms such as filtration, prior to biological treatment, there is a great impact in terms of reduced energy demand in downstream biological processes. Rotating belt filters (RBFs) are an innovative alternative to traditional primary clarifiers, with the following tangible benefits: (i) a significantly smaller physical footprint, (ii) lower capital cost, (iii) easier installation and expansion, (iv) greater opportunities to control the solids removal process. The ability to control the solids separation process in RBFs opens up the opportunity to engineer the sieving process in order to selectively remove particulate fractions corresponding to optimal requirements for operation of downstream unit processes and for energy and nutrient recovery. Trojan Technologies is a manufacturer and worldwide distributer of RBFs under the brand name of Salsnes Filter, and therefore has a strong interest in modelling and predicting performance of RBFs in order to design better products, reduce risk in bidding, and quantify the benefits of RBF systems. Modelling and optimization of RBFs has proven challenging due to the complex interplay between hydraulics and accumulation of solids on the filter, since the mass of solids on the filter directly determines the particle sizes removed as well as the removal efficiency. As a result, Trojan has invested significantly in developing a computational fluid dynamics (CFD) model capable of predicting RBF filtration for current RBF designs and seeks to collaborate with Western University to take this development activity to the level of implementation.