Deterministic ratchet using sieve structured obstacles for large-scale separation of particle suspensions

J.P. Dijkshoorn*, R.M. Wagterveld, Wetsus, European Centre of Excellence for Sustainable Water Technology; M.A.I. Schutyser, R.M. Boom, Wageningen University, Netherlands

Deterministic ratchets are microfluidic separation devices that employ periodic arrays of obstacles, spaced such that the gaps between obstacles are larger than the largest suspended particle. Separation principle is based on interaction of particles that are larger than the critical diameter with obstacles. This principle lowers the risk of particle accumulation compared to conventional membrane filtration and is one of the reasons why the deterministic ratchet has potential for large-scale separation of particles from suspensions (Kulrattanarak, van der Sman et al. 2008). However, a major hurdle is the translation of the microfluidic device designs into large-scale designs that can handle high capacities.

In our previous work we showed that at increased flow rates (moderate Reynolds numbers) fluid inertia positively influenced particle separation (Lubbersen, Schutyser et al. 2012; Lubbersen, Dijkshoorn et al. 2013). In addition, it was shown that a deterministic ratchet configuration with fewer obstacles could be used to separate particles while reducing the pressure drop(Lubbersen 2015). The latter observation suggested that it could be a feasible strategy to scale deterministic ratchets by employing (micro) sieves in the large-scale design.

Here, we report on this strategy and we show that it is feasible to concentrate particles by using stacked sieves in a deterministic ratchet configuration. Both experiments and numerical simulations were carried out to study the influence of design on particle separation efficiency. With the design of sieves that mimic deterministic ratchet obstacles, it was found that....

Session: L15 - Depth Filtration I
Day: 13 October 2016
Time: 09:00 - 10:15 h

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